Delay through GPS antenna splitter/amplifier -- an answer, and a question
I had a chance recently to look at the performance of the two-port and
eight-port HP GPS antenna splitters on a super-duper network analyzer.
Screenshots of the results are at
http://www.febo.com/time-freq/pages/gps-splitter.
In short, the minimum delay (at the center of the passband) from antenna
port to output port is around 15 nanoseconds for the eight way unit, and
about 22 nanoseconds for the two way one. The delay seems consistent on
all the ports, with less than 1 nanosecond variation.
However, there is also a hump in the delay near the edges of the
passband, about 12 MHz above and below the center. The delay at the
edges increases by perhaps 5 nanoseconds, though depending on the port,
it's not always symmetrical.
So, an interesting question for any of you real GPS experts is what
effect a variation in group delay of the RF input has on the timing
solution? Is the true "length" of the amp/splitter some average of the
delay across the passband, or, given the spread spectrum nature of the
signal, does it not really matter? In fact, is the "length" of the
splitter even related to the measured group delay?
This also raises the issue that any GPS antenna that has RF filtering is
likely to have similar delays; I've never seen that sort of data published.
John
From my experience, your position and hence derived time is based on the
antenna centre. Cable, splitter, connector, and antenna filter delays all
need to be taken into account when looking at very accurate "nanosecond"
timing applications.
For most applications in the microsecond or tens of microsecond region it
isn't worth worrying about.
Rob K
----- Original Message -----
From: "John Ackermann N8UR" jra@febo.com
To: "Discussion of precise time and frequency measurement"
time-nuts@febo.com
Sent: Monday, March 12, 2007 3:03 PM
Subject: [time-nuts] Delay through GPS antenna splitter/amplifier -- an
answer, and a question
I had a chance recently to look at the performance of the two-port and
eight-port HP GPS antenna splitters on a super-duper network analyzer.
Screenshots of the results are at
http://www.febo.com/time-freq/pages/gps-splitter.
In short, the minimum delay (at the center of the passband) from antenna
port to output port is around 15 nanoseconds for the eight way unit, and
about 22 nanoseconds for the two way one. The delay seems consistent on
all the ports, with less than 1 nanosecond variation.
However, there is also a hump in the delay near the edges of the
passband, about 12 MHz above and below the center. The delay at the
edges increases by perhaps 5 nanoseconds, though depending on the port,
it's not always symmetrical.
So, an interesting question for any of you real GPS experts is what
effect a variation in group delay of the RF input has on the timing
solution? Is the true "length" of the amp/splitter some average of the
delay across the passband, or, given the spread spectrum nature of the
signal, does it not really matter? In fact, is the "length" of the
splitter even related to the measured group delay?
This also raises the issue that any GPS antenna that has RF filtering is
likely to have similar delays; I've never seen that sort of data
published.
John
time-nuts mailing list
time-nuts@febo.com
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
In message: 001501c764bd$eb38e740$0202a8c0@quaddra
"Rob Kimberley" rk@timing-consultants.com writes:
: >From my experience, your position and hence derived time is based on the
: antenna centre. Cable, splitter, connector, and antenna filter delays all
: need to be taken into account when looking at very accurate "nanosecond"
: timing applications.
Getting cable delay wrong isn't the end of the world. However, rather
than seeing a few ns of variance in pps data, you'll see something
more in the tens of ns variance. The absolute offset isn't always a
good indication if you have the cable delay right. The variance in
your data tends to be a better indication, at least for the systems
that I've worked on.
Of course, if you have an "on-time" pps to test against, things are a
lot easier than if you just have a stable PPS to test against.
: For most applications in the microsecond or tens of microsecond region it
: isn't worth worrying about.
60m of cables + splitters, etc is only going to add 180-200ns to the
propigation time. That's well below 1us or 10us :-).
Warner
But we're time-nuts... we DO worry about those things. :-)
While we were at it with the network analyzer, we did FDR (frequency
domain reflectometry) to measure the cable delay to the antenna, and I
spent yesterday making up six matched cables to go from the splitter to
the receivers -- they all test within about 1 nanosecond of each other.
Obsessive compulsive? Me?
John
Rob Kimberley wrote:
From my experience, your position and hence derived time is based on the
antenna centre. Cable, splitter, connector, and antenna filter delays all
need to be taken into account when looking at very accurate "nanosecond"
timing applications.
For most applications in the microsecond or tens of microsecond region it
isn't worth worrying about.
Rob K
----- Original Message -----
From: "John Ackermann N8UR" jra@febo.com
To: "Discussion of precise time and frequency measurement"
time-nuts@febo.com
Sent: Monday, March 12, 2007 3:03 PM
Subject: [time-nuts] Delay through GPS antenna splitter/amplifier -- an
answer, and a question
I had a chance recently to look at the performance of the two-port and
eight-port HP GPS antenna splitters on a super-duper network analyzer.
Screenshots of the results are at
http://www.febo.com/time-freq/pages/gps-splitter.
In short, the minimum delay (at the center of the passband) from antenna
port to output port is around 15 nanoseconds for the eight way unit, and
about 22 nanoseconds for the two way one. The delay seems consistent on
all the ports, with less than 1 nanosecond variation.
However, there is also a hump in the delay near the edges of the
passband, about 12 MHz above and below the center. The delay at the
edges increases by perhaps 5 nanoseconds, though depending on the port,
it's not always symmetrical.
So, an interesting question for any of you real GPS experts is what
effect a variation in group delay of the RF input has on the timing
solution? Is the true "length" of the amp/splitter some average of the
delay across the passband, or, given the spread spectrum nature of the
signal, does it not really matter? In fact, is the "length" of the
splitter even related to the measured group delay?
This also raises the issue that any GPS antenna that has RF filtering is
likely to have similar delays; I've never seen that sort of data
published.
John
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Since we are on the subject... I came across this page the other day and am
curious about what other's thoughts are about it.
http://tf.nist.gov/service/gpstrace.htm
If I understand correctly looking at the graphs, they are saying the time
from GPS is currently off about 24-30ns from the NIST frequency standard. So
does that mean that a person wanting every last ns should adjust their delay
according to the data on that page (and of course things like cable delay
and other circuitry)?
Jason
But we're time-nuts... we DO worry about those things. :-)
While we were at it with the network analyzer, we did FDR (frequency
domain reflectometry) to measure the cable delay to the antenna, and I
spent yesterday making up six matched cables to go from the splitter to
the receivers -- they all test within about 1 nanosecond of each other.
Obsessive compulsive? Me?
John
In short, yes. If you want true traceability to NIST, you need to take
into account UTC(GPS) versus UTC(NIST).
I don't think you would do this by adjusting the cable delay, because
that offset will change over time. Instead, you post-process by getting
the offset for the time during which you made the measurement, and
adding it to your solution.
John
Jason Rabel wrote:
Since we are on the subject... I came across this page the other day and am
curious about what other's thoughts are about it.
http://tf.nist.gov/service/gpstrace.htm
If I understand correctly looking at the graphs, they are saying the time
from GPS is currently off about 24-30ns from the NIST frequency standard. So
does that mean that a person wanting every last ns should adjust their delay
according to the data on that page (and of course things like cable delay
and other circuitry)?
Jason
But we're time-nuts... we DO worry about those things. :-)
While we were at it with the network analyzer, we did FDR (frequency
domain reflectometry) to measure the cable delay to the antenna, and I
spent yesterday making up six matched cables to go from the splitter to
the receivers -- they all test within about 1 nanosecond of each other.
Obsessive compulsive? Me?
John
time-nuts mailing list
time-nuts@febo.com
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
If I understand correctly looking at the graphs, they are saying the time
from GPS is currently off about 24-30ns from the NIST frequency standard. So
does that mean that a person wanting every last ns should adjust their delay
according to the data on that page (and of course things like cable delay
and other circuitry)?
Jason
It means a person wanting every last ns should adjust their
expectations. There's no point in measuring your cable
delays to the foot when there may be tens of ns of delay in
the antenna, the survey, the cable, the splitter, the receiver,
etc. Not to mention multipath, antenna/cable tempco...
When you get to the sub-100 ns level UTC is not GPS. And
UTC(NIST) isn't UTC(USNO). Even the national labs don't
agree down to the last ns.
/tvb
From: John Ackermann N8UR jra@febo.com
Subject: [time-nuts] Delay through GPS antenna splitter/amplifier -- an answer, and a question
Date: Mon, 12 Mar 2007 11:03:12 -0400
Message-ID: 45F56BB0.90009@febo.com
John,
I had a chance recently to look at the performance of the two-port and
eight-port HP GPS antenna splitters on a super-duper network analyzer.
Screenshots of the results are at
http://www.febo.com/time-freq/pages/gps-splitter.
Hmm... I would have zoomed in closer to only have a +/- 20 MHz span or so.
I have an E5071A at work.
In short, the minimum delay (at the center of the passband) from antenna
port to output port is around 15 nanoseconds for the eight way unit, and
about 22 nanoseconds for the two way one. The delay seems consistent on
all the ports, with less than 1 nanosecond variation.
However, there is also a hump in the delay near the edges of the
passband, about 12 MHz above and below the center. The delay at the
edges increases by perhaps 5 nanoseconds, though depending on the port,
it's not always symmetrical.
As expected.
So, an interesting question for any of you real GPS experts is what
effect a variation in group delay of the RF input has on the timing
solution? Is the true "length" of the amp/splitter some average of the
delay across the passband, or, given the spread spectrum nature of the
signal, does it not really matter? In fact, is the "length" of the
splitter even related to the measured group delay?
The electrical length of the splitter needs to go into the cable delay
compensation.
The C/A signal has it's main peak at 1,57542 GHz (with doppler +/- 6 kHz) and
the first nulls is at +/- 1,023 MHz of that peak. The secondary peaks is at
+/- 2.046 MHz but much reduced in amplitude and additional peaks roll of fairly
quickly. There are some fancy plots showing this in the literature, I don't
have the numbers from the top of my head.
Most commercial receivers have a +/- 1,023 MHz window so the delay differances
outside of that is not really relevant. The flatness of their groupdelay within
that window is however an issue.
I'd expect the effect to be somewhat similar to multipath-effects.
This also raises the issue that any GPS antenna that has RF filtering is
likely to have similar delays; I've never seen that sort of data published.
Indeed. You should also ask yourself this question about the input filter and
MF1, MF2 and maybe even MF3 filters of the GPS receiver. What is the net
effect of these skews?
Cheers,
Magnus
I had a chance recently to look at the performance of the two-port and
eight-port HP GPS antenna splitters on a super-duper network analyzer.
Screenshots of the results are at
http://www.febo.com/time-freq/pages/gps-splitter.
Super nice plots, John.
Tom Clark, do you have comments?
John, next time you can borrow that instrument blow
some hot/cool air on the antenna and see what changes
and by how much.
I've heard that the older GPS antennas, the ones with zero
or less RF filtering, were much better for timing applications
but have never seen data to prove it.
For example, do you have one of the old Motorola hockey
puck ones you could test? If not, I can send you a bunch
of different GPS antenna to try.
/tvb
From: John Ackermann N8UR jra@febo.com
Subject: Re: [time-nuts] Delay through GPS antenna splitter/amplifier -- an answer, and a question
Date: Mon, 12 Mar 2007 12:04:06 -0400
Message-ID: 45F579F6.2070501@febo.com
But we're time-nuts... we DO worry about those things. :-)
Indeed!
Oh my goodness, the PPS is 10 ps late due to unmatched cable-lag! What should I
dooooo? (For the egg-clock in the kitchen)
While we were at it with the network analyzer, we did FDR (frequency
domain reflectometry) to measure the cable delay to the antenna, and I
spent yesterday making up six matched cables to go from the splitter to
the receivers -- they all test within about 1 nanosecond of each other.
I would use TDR/TDT for that. :)
Obsessive compulsive? Me?
Naaa....
Cheers,
Magnus
Tom Van Baak wrote:
John, next time you can borrow that instrument blow
some hot/cool air on the antenna and see what changes
and by how much.
I've heard that the older GPS antennas, the ones with zero
or less RF filtering, were much better for timing applications
but have never seen data to prove it.
That would make sense. The HP splitter has a single filter of some sort
(probably SAW) on each output port. It is probably very similar to the
filters used in current antennas.
Just a swag, it's probably reasonable to assume that each stage of
filtering adds about 10ns of delay.
The tempco of the antenna amplifier/filter is certainly another factor
to consider. If I can get hold of the analyzer again, we can do a hair
dryer test on the splitter to see how it's affected. My mantra has
become "every resonator is a thermometer".
For example, do you have one of the old Motorola hockey
puck ones you could test? If not, I can send you a bunch
of different GPS antenna to try.
My hockey puck died and has been replaced by a Timing 2000 antenna. I
do have a couple of others sitting on the shelf that I could test.
But, I'm not sure how to non-destructively test an antenna, as the
measurements we did require two-port analysis. I'm not sure if we could
radiate enough signal into the antenna to get a usable output.
By the way -- for anyone who's considering similar tests of amplified
GPS antennas or splitters, note that common network analyzer output
levels will drive the amplifier into compression and cause messed up
readings. You need to shove as small a signal as possible into the
device; 0dBm will definitely hose the readings (though it probably won't
damage anything). I think we found that -30dBm was about the maximum we
could use without seeing gain compression.
John
Magnus Danielson wrote:
I would use TDR/TDT for that. :)
My buddy the expert tells me that using frequency sweep rather than
pulse techniques is preferred these days. With multi-GHz sweeps, you
can get better resolution, and you also minimize the problems that
strong external signals can cause when you're measuring a feedline with
an antenna at the end.
But that's just what I'm told...
John
From: John Ackermann N8UR jra@febo.com
Subject: Re: [time-nuts] Delay through GPS antenna splitter/amplifier -- an answer, and a question
Date: Mon, 12 Mar 2007 13:17:50 -0400
Message-ID: 45F58B3E.5000103@febo.com
Magnus Danielson wrote:
I would use TDR/TDT for that. :)
My buddy the expert tells me that using frequency sweep rather than
pulse techniques is preferred these days. With multi-GHz sweeps, you
can get better resolution, and you also minimize the problems that
strong external signals can cause when you're measuring a feedline with
an antenna at the end.
The TDR I have access to is far supperiour to the FDR in the E5071A. The main
reason is that the bandwidth of the E5071A is limited (8.5 GHz).
Network analysers have a far supperiour dynamics, but timing precission miss
out a little. Measuring the group delay would however be a much better solution
if possible (i.e. access to both sides and with suitable connectors).
Cheers,
Magnus
I used to be bothered when I was working on this stuff full time, especially
when we were testing equipment in labs for customers on a "mission". Now, as
long as all my clocks are on the same second.....
:-)
Funny story however.. Was at NPL on Thursday for our bi-annual Time &
Frequency Club meeting. There was a small exhibition running and one of the
companies - Time & Frequency Solutions had a natty new T&F analyser - nice
box - touch screen etc. The sales guy wanted to demo it and show me how it
checked the delay on a sample piece of cable (with BNCs and a BNC T on the
end). He asked me to guess the delay. I looked at it, did a mental
calculation based on the assumed length and the connectors and told him 6nS.
He put it on the machine, and guess what....6nS. He said I'd been watching
and knew the result! Had to explain that I'd been around the T&F "block" a
few times and that sometimes experience (and an inspired guess!) count more
than hardware!!
Cheers
Rob
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of John Ackermann N8UR
Sent: 12 March 2007 16:04
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Delay through GPS antenna splitter/amplifier -- an
answer, and a question
But we're time-nuts... we DO worry about those things. :-)
While we were at it with the network analyzer, we did FDR (frequency domain
reflectometry) to measure the cable delay to the antenna, and I spent
yesterday making up six matched cables to go from the splitter to the
receivers -- they all test within about 1 nanosecond of each other.
Obsessive compulsive? Me?
John
Rob Kimberley wrote:
From my experience, your position and hence derived time is based on
the antenna centre. Cable, splitter, connector, and antenna filter
delays all need to be taken into account when looking at very accurate
"nanosecond"
timing applications.
For most applications in the microsecond or tens of microsecond region
it isn't worth worrying about.
Rob K
----- Original Message -----
From: "John Ackermann N8UR" jra@febo.com
To: "Discussion of precise time and frequency measurement"
time-nuts@febo.com
Sent: Monday, March 12, 2007 3:03 PM
Subject: [time-nuts] Delay through GPS antenna splitter/amplifier --
an answer, and a question
I had a chance recently to look at the performance of the two-port
and eight-port HP GPS antenna splitters on a super-duper network
analyzer.
Screenshots of the results are at
http://www.febo.com/time-freq/pages/gps-splitter.
In short, the minimum delay (at the center of the passband) from
antenna port to output port is around 15 nanoseconds for the eight
way unit, and about 22 nanoseconds for the two way one. The delay
seems consistent on all the ports, with less than 1 nanosecond variation.
However, there is also a hump in the delay near the edges of the
passband, about 12 MHz above and below the center. The delay at the
edges increases by perhaps 5 nanoseconds, though depending on the
port, it's not always symmetrical.
So, an interesting question for any of you real GPS experts is what
effect a variation in group delay of the RF input has on the timing
solution? Is the true "length" of the amp/splitter some average of
the delay across the passband, or, given the spread spectrum nature
of the signal, does it not really matter? In fact, is the "length"
of the splitter even related to the measured group delay?
This also raises the issue that any GPS antenna that has RF filtering
is likely to have similar delays; I've never seen that sort of data
published.
John
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In short, yes. If you want true traceability to NIST, you need to take
into account UTC(GPS) versus UTC(NIST).
And it gets uglier yet. If you want UTC you have to take
into account the UTC - UTC(NIST) delta, which was about
16 ns in January. See the full 2006 record:
http://tf.nist.gov/timefreq/pubs/bulletin/nistutc2006.htm
The point is GPS, NIST, USNO often vary up to tens of
ns over the span of days and months. It highlights the
problem of knowing what the "true time" is.
Also note that, strictly speaking, there is no such thing
as "UTC(GPS)" and BIPM frowns on the phrase UTC(k)
where k isn't one of the national time labs (e.g., NIST,
USNO, NPL, PTB).
What we call "GPS time" is in fact a good approximation
to UTC(USNO) but since the official UTC(USNO) clock
goes through so many levels of distribution, Kalman filters,
uplinks, downlinks, 24+ individual SV clocks, and PLL'd
disciplined oscillators before it reaches your 1 PPS BNC
output, it is no longer "UTC(USNO)".
For ns-level work the key is post-processing, where many
of the systematic and variable offsets can be estimated
days or months later and mathematically backed out from
your archived physical time interval measurements.
/tvb
UTC-GPS is based on UTC-USNO, and therefore there will be a small offset
between other establishments like NIST, NPL who contribute to the UTC.
As you say, the offset will vary with time, so post-processing is the answer
in critical applications (which is the way UTC is determined anyway).
Rob K
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of John Ackermann N8UR
Sent: 12 March 2007 16:51
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Delay through GPS antenna splitter/amplifier -- an
answer, and a question
In short, yes. If you want true traceability to NIST, you need to take into
account UTC(GPS) versus UTC(NIST).
I don't think you would do this by adjusting the cable delay, because that
offset will change over time. Instead, you post-process by getting the
offset for the time during which you made the measurement, and adding it to
your solution.
John
Jason Rabel wrote:
Since we are on the subject... I came across this page the other day
and am curious about what other's thoughts are about it.
http://tf.nist.gov/service/gpstrace.htm
If I understand correctly looking at the graphs, they are saying the
time from GPS is currently off about 24-30ns from the NIST frequency
standard. So does that mean that a person wanting every last ns should
adjust their delay according to the data on that page (and of course
things like cable delay and other circuitry)?
Jason
But we're time-nuts... we DO worry about those things. :-)
While we were at it with the network analyzer, we did FDR (frequency
domain reflectometry) to measure the cable delay to the antenna, and
I spent yesterday making up six matched cables to go from the
splitter to the receivers -- they all test within about 1 nanosecond of
each other.
Obsessive compulsive? Me?
John
time-nuts mailing list
time-nuts@febo.com
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
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Funny story however.. Was at NPL on Thursday for our bi-annual Time &
Frequency Club meeting. There was a small exhibition running and one of the
...
Rob,
That's a great story. And then this is how I was humbled...
I've had a few people over to my time lab and most are really
impressed. But I was showing an expert mechanical engineer
friend that one could actually calculate the length of a cable
using nano- and picosecond time interval measurements
(drum roll...). So it came to 10 feet and he simply said, holding
the cable up in the air, "well that seems about right", but was
not the least bit impressed that I took two minutes and used
thousands of dollars of weird blinking timing gear to measure
something his experienced eye saw immediately or that a $1
measuring tape could have confirmed...
From: "Tom Van Baak" tvb@LeapSecond.com
Subject: Re: [time-nuts] Delay through GPS antenna splitter/amplifier -- ananswer, and a question
Date: Mon, 12 Mar 2007 10:46:40 -0700
Message-ID: 002b01c764ce$64606cf0$0300a8c0@pc52
Tom and Rob,
I often estimate time/distance relationships using simple rule-of-thumb
calculations, and I often find that it is more than sufficient from getting the
basic hang of things.
But both your stories indicate that you should never select a problem to demo
which has an obvious, simple and low-tech solution to it when you want to demo
your high-tech toys^H^Hols. It needs to be utterly important, hard to measure
except with your toys^H^Hols. :)
Cheers,
Magnus
In message: 20070312.180426.-1621061084.cfmd@bredband.net
Magnus Danielson cfmd@bredband.net writes:
: Oh my goodness, the PPS is 10 ps late due to unmatched cable-lag! What should I
: dooooo? (For the egg-clock in the kitchen)
Put a tiny kink in the cable. That should be good for an offset of
that magnitude.
:-)
Warner
Magnus Danielson wrote:
From: "Tom Van Baak" tvb@LeapSecond.com
Subject: Re: [time-nuts] Delay through GPS antenna splitter/amplifier -- ananswer, and a question
Date: Mon, 12 Mar 2007 10:46:40 -0700
Message-ID: 002b01c764ce$64606cf0$0300a8c0@pc52
Tom and Rob,
I often estimate time/distance relationships using simple rule-of-thumb
calculations, and I often find that it is more than sufficient from getting the
basic hang of things.
But both your stories indicate that you should never select a problem to demo
which has an obvious, simple and low-tech solution to it when you want to demo
your high-tech toys^H^Hols. It needs to be utterly important, hard to measure
except with your toys^H^Hols. :)
This is the basic problem with our hobby... I proudly tell people that I
can measure time to trillionths of a second, but am hard pressed for a
good answer when they ask "why do you need to?"
is that a really tiny or maybe a medium tiny or are we talking a pico kink
(which is also smaller than a nano kink)???
i needed a smile for today as my time is up.....
tom w0kgw@citlink.net
When you get to the sub-100 ns level UTC is not GPS. And
UTC(NIST) isn't UTC(USNO). Even the national labs don't
agree down to the last ns.
/tvb
Remember that no one lab has the true UTC clock. UTC is an offset to Atomic
Time (TAI), and TAI is the weighted average of hundreds of clocks in dozens
of National Labs all over the world. The Bureau International des Poids et
Mesures (BIPM formerly BIH) collects data and publishes TAI, the
International Earth Rotation Service (IERS), determine when Leap Seconds
increment/decrement the offset based on variations of the earths rotational
period.
See: http://www.bipm.fr/en/scientific/tai/tai.html for details!
-Mike-
This is the basic problem with our hobby... I proudly tell people that I
can measure time to trillionths of a second, but am hard pressed for a
good answer when they ask "why do you need to?"
I find myself giving the deer-staring-into-headlights look when people ask
me that same question!
In message: 000701c764d6$cfdc51d0$0a00a8c0@Inspiron
"Jason Rabel" jason@extremeoverclocking.com writes:
: >This is the basic problem with our hobby... I proudly tell people that I
: >can measure time to trillionths of a second, but am hard pressed for a
: >good answer when they ask "why do you need to?"
:
: I find myself giving the deer-staring-into-headlights look when people ask
: me that same question!
I usually give the Sir Edmund Hillary answer: because it is there.
Warner
M. Warner Losh said the following on 03/12/2007 02:52 PM:
In message: 000701c764d6$cfdc51d0$0a00a8c0@Inspiron
"Jason Rabel" jason@extremeoverclocking.com writes:
: >This is the basic problem with our hobby... I proudly tell people that I
: >can measure time to trillionths of a second, but am hard pressed for a
: >good answer when they ask "why do you need to?"
:
: I find myself giving the deer-staring-into-headlights look when people ask
: me that same question!
I usually give the Sir Edmund Hillary answer: because it is there.
There it is. Wait, it just was there. Oh, there it is. Darn it,
missed again.
Sounds like Heisenberg :). -
Mike B. Feher, N4FS
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of John Ackermann N8UR
Sent: Monday, March 12, 2007 3:06 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Delay through GPS antenna splitter/amplifier --
ananswer, and a question
M. Warner Losh said the following on 03/12/2007 02:52 PM:
In message: 000701c764d6$cfdc51d0$0a00a8c0@Inspiron
"Jason Rabel" jason@extremeoverclocking.com writes:
: >This is the basic problem with our hobby... I proudly tell people that
I
: >can measure time to trillionths of a second, but am hard pressed for a
: >good answer when they ask "why do you need to?"
:
: I find myself giving the deer-staring-into-headlights look when people
ask
: me that same question!
I usually give the Sir Edmund Hillary answer: because it is there.
There it is. Wait, it just was there. Oh, there it is. Darn it,
missed again.
time-nuts mailing list
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John Ackermann N8UR jra@febo.com wrote:
But we're time-nuts... we DO worry about those things. :-)
While we were at it with the network analyzer, we did FDR (frequency
domain reflectometry) to measure the cable delay to the antenna, and I
spent yesterday making up six matched cables to go from the splitter to
the receivers -- they all test within about 1 nanosecond of each other.
Obsessive compulsive? Me?
At the lab I worked at in the 80's, all the cables hanging on
the wall-racks were calibrated and labeled in nanoseconds.
But... after the ECL signals got turned into TTL, we just didn't
care anymore :-).
Tim.
Tim Shoppa wrote:
John Ackermann N8UR jra@febo.com wrote:
But we're time-nuts... we DO worry about those things. :-)
While we were at it with the network analyzer, we did FDR (frequency
domain reflectometry) to measure the cable delay to the antenna, and I
spent yesterday making up six matched cables to go from the splitter to
the receivers -- they all test within about 1 nanosecond of each other.
Obsessive compulsive? Me?
At the lab I worked at in the 80's, all the cables hanging on
the wall-racks were calibrated and labeled in nanoseconds.
But... after the ECL signals got turned into TTL, we just didn't
care anymore :-).
Tim.
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John
Your not quite obsessive enough.
The cable delays (including the antenna to splitter cable) should also
be a multiple of half the signal period to minimise the effects of
residual mismatches at either end of the cable.
Bruce
This is, incidentally, why isolators should be used on these runs.
This does create a problem with LNAs that are DC powered via coax, however
the reality is that many antennas and receivers do not have that great a
match to the coax impedance and could benefit from the clean up of an
isolator. (however as magnetic devices, I wonder about the delay stability
of isolators as a function of temperature)
And while on the obsessive kick, if using splitters, unused ports must be
terminated.
Group delay measurements of an RF transmission system can reveal a lot of
problems that simple loss and return loss will not catch.
Lester B Veenstra
M0YCM K1YCM M0YCM/6Y5 K1YCM/6Y5
Mail Address:
Lester Veenstra
Dawn Cottage
Norwood, Harrogate
HG3 1SD UK
Telephones:
Office 940-6456
Office +44-(0)1423-846-385
Home: +44-(0)1943-880-963
UK Cell: +44-(0)7716-298-224
-----Original Message-----
<NIP>
John
...... minimise the effects of
residual mismatches at either end of the cable.
Bruce
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I just put a Z3801A on Ebay. This is a Z3801A without an antenna or
power supply
It is a clean unit and powers up and locks on to the satellites
The computer port has options set to RS232. The item no. is 190092049523
Thanks
Bill K7NOM
On Mon, 12 Mar 2007 17:16:49 -0400, "Mike Feher" mfeher@eozinc.com
wrote:
Sounds like Heisenberg :). -
Exactly! I was thinking, "Why? Because it is there, to this current
degree of certainty."
When people are non-plussed by why I would spend time and money on one
of my uncommon hobbies, I try to bring up a more common hobby that soaks
up lots of time, effort and money, like car racing. Most people are
already calibrated to accept that one, even though it serves no useful
purpose. My hobby is just like that, only different.
Dr Bruce Griffiths bruce.griffiths@xtra.co.nz wrote:
At the lab I worked at in the 80's, all the cables hanging on
the wall-racks were calibrated and labeled in nanoseconds.
But... after the ECL signals got turned into TTL, we just didn't
care anymore :-).
Your not quite obsessive enough.
The cable delays (including the antenna to splitter cable) should also
be a multiple of half the signal period to minimise the effects of
residual mismatches at either end of the cable.
Signal period? Periodic signals?
If only we had the luxury!
I was not working on the side of the lab where the experiments were
vaporized, though :-).
Tim.
Tim Shoppa wrote:
Dr Bruce Griffiths bruce.griffiths@xtra.co.nz wrote:
At the lab I worked at in the 80's, all the cables hanging on
the wall-racks were calibrated and labeled in nanoseconds.
But... after the ECL signals got turned into TTL, we just didn't
care anymore :-).
Your not quite obsessive enough.
The cable delays (including the antenna to splitter cable) should also
be a multiple of half the signal period to minimise the effects of
residual mismatches at either end of the cable.
Signal period? Periodic signals?
If only we had the luxury!
I was not working on the side of the lab where the experiments were
vaporized, though :-).
Tim.
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Tim
Sorry I should have said a multiple of half the L1 carrier period
(~634.75 ps).
So the cable delay should be a multiple of 317.375...ps.
Bruce
One is much better to take the filter's delay in
account rather than NOT USING a filter!!! i can hardly
imagine a GPS receiver/antenna without any form of
preselection, and, unfortunately, they're many of
those filterless units on the market!
73 de Normand VE2UM
Montreal, Qc. Canada
--- John Ackermann N8UR jra@febo.com wrote:
I had a chance recently to look at the performance
of the two-port and
eight-port HP GPS antenna splitters on a super-duper
network analyzer.
Screenshots of the results are at
http://www.febo.com/time-freq/pages/gps-splitter.
In short, the minimum delay (at the center of the
passband) from antenna
port to output port is around 15 nanoseconds for the
eight way unit, and
about 22 nanoseconds for the two way one. The delay
seems consistent on
all the ports, with less than 1 nanosecond
variation.
However, there is also a hump in the delay near the
edges of the
passband, about 12 MHz above and below the center.
The delay at the
edges increases by perhaps 5 nanoseconds, though
depending on the port,
it's not always symmetrical.
So, an interesting question for any of you real
GPS experts is what
effect a variation in group delay of the RF input
has on the timing
solution? Is the true "length" of the amp/splitter
some average of the
delay across the passband, or, given the spread
spectrum nature of the
signal, does it not really matter? In fact, is the
"length" of the
splitter even related to the measured group delay?
This also raises the issue that any GPS antenna that
has RF filtering is
likely to have similar delays; I've never seen that
sort of data published.
John
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Get your own web address.
Have a HUGE year through Yahoo! Small Business.
http://smallbusiness.yahoo.com/domains/?p=BESTDEAL
Now that is obsessive!!
:-))
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Dr Bruce Griffiths
Sent: 12 March 2007 22:39
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Delay through GPS antenna splitter/amplifier -- an
answer, and a question
Tim Shoppa wrote:
John Ackermann N8UR jra@febo.com wrote:
But we're time-nuts... we DO worry about those things. :-)
While we were at it with the network analyzer, we did FDR (frequency
domain reflectometry) to measure the cable delay to the antenna, and
I spent yesterday making up six matched cables to go from the
splitter to the receivers -- they all test within about 1 nanosecond of
each other.
Obsessive compulsive? Me?
At the lab I worked at in the 80's, all the cables hanging on the
wall-racks were calibrated and labeled in nanoseconds.
But... after the ECL signals got turned into TTL, we just didn't care
anymore :-).
Tim.
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John
Your not quite obsessive enough.
The cable delays (including the antenna to splitter cable) should also be a
multiple of half the signal period to minimise the effects of residual
mismatches at either end of the cable.
Bruce
time-nuts mailing list
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This is the basic problem with our hobby... I proudly tell people that
I
can measure time to trillionths of a second, but am hard pressed for a
good answer when they ask "why do you need to?"
"For the money, for the glory, and for the fun. But mostly for the
fun..."
(with apologies to Burt Reynolds)
Tom Frank, KA2CDK
On Tue, 13 Mar 2007 20:31:31 -0400, Thomas A. Frank ka2cdk@cox.net
wrote:
This is the basic problem with our hobby... I proudly tell people that
I
can measure time to trillionths of a second, but am hard pressed for a
good answer when they ask "why do you need to?"
"For the money, for the glory, and for the fun. But mostly for the
fun..."
(with apologies to Burt Reynolds)
I'm not at the cesium level of time-nut insanity yet but I have other
nerdy vices. When people ask me why, my usual answer is "for the same
reason I have sex. I can and it feels good". I get funny looks
sometimes.......
John
John De Armond
See my website for my current email address
http://www.neon-john.com
Cleveland, Occupied TN
Don't let your schooling interfere with your education-Mark Twain
I suppose an answer could be "Time will tell"
It's better than "Because I can"
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Thomas A. Frank
Sent: Tuesday, March 13, 2007 7:32 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Delay through GPS antenna splitter/amplifier
--ananswer, and a question
This is the basic problem with our hobby... I proudly tell people that
I
can measure time to trillionths of a second, but am hard pressed for a
good answer when they ask "why do you need to?"
"For the money, for the glory, and for the fun. But mostly for the
fun..."
(with apologies to Burt Reynolds)
Tom Frank, KA2CDK
time-nuts mailing list
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This brings the following story back in my mind:
When I was a student at the university of Bochum/Germany the department
of physics owned an electron synchrotron and storage ring. Not really a
big gun in international terms but with 800 MeV energy also not exactly
a child's toy. Once a year the university had its "open day" when the
public was invited to visit the numrerous research facilities.
There was this old lady who had listened to the lecture that the
scientist responsible for the accelerator had given. Although the
lecture had clearly been public-adressed she had hardly understood a bit
of what it all was about. After the lecture, when the other vistors had
already left the laboratory, she talked to the scientist: "Sir, thank
you for your highly interesting lecture. Its just that I missed one
thing: What do you need it for?"
The scientist, anticipating that explaining it to the old lady might be
a task of hours or perhaps impossible, answered: "Mam, it is kind of a
hobby of mine. You know, other men own model railways and watch the
small trains running in circles. What I do is pretty much the same only
with electrons and at a bit more speed". The old lady went away
completely satisfied because now she had really understood....
Cheers
Ulrich Bangert, DF6JB
-----Ursprüngliche Nachricht-----
Von: time-nuts-bounces@febo.com
[mailto:time-nuts-bounces@febo.com] Im Auftrag von MUELLER,
STEVE (ATTOPS)
Gesendet: Mittwoch, 14. März 2007 18:57
An: Discussion of precise time and frequency measurement
Betreff: Re: [time-nuts] Delay through GPS antenna
splitter/amplifier--ananswer, and a question
I suppose an answer could be "Time will tell"
It's better than "Because I can"
-----Original Message-----
From: time-nuts-bounces@febo.com
[mailto:time-nuts-bounces@febo.com] On Behalf > Of Thomas A.
Frank
Sent: Tuesday, March 13, 2007 7:32 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Delay through GPS antenna
splitter/amplifier --ananswer, and a question
This is the basic problem with our hobby... I proudly tell
people that
I
can measure time to trillionths of a second, but am hard
pressed for a
good answer when they ask "why do you need to?"
"For the money, for the glory, and for the fun. But mostly for the
fun..."
(with apologies to Burt Reynolds)
Tom Frank, KA2CDK
time-nuts mailing list
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The local surplus guy got in a few dozen coax switches. The only markings on
them say "Type DSWA0". Dimensions are about 2.6" H x 2" D x 1" W. There is a
toggle switch on the front and three BNC connectors on the back.
I can't find any information about these. Does anyone know anything about
these?
Thanks.
Just a guess, but SPDT toggle switch ?
How much does he want for them ?
Regards, Dick, W1KSZ
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com]On
Behalf Of Joseph Gray
Sent: Saturday, March 17, 2007 9:15 PM
To: Discussion of precise time and frequency measurement
Subject: [time-nuts] Coax switch
The local surplus guy got in a few dozen coax switches. The only markings on
them say "Type DSWA0". Dimensions are about 2.6" H x 2" D x 1" W. There is a
toggle switch on the front and three BNC connectors on the back.
I can't find any information about these. Does anyone know anything about
these?
Thanks.
time-nuts mailing list
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Just a guess, but SPDT toggle switch ?
How much does he want for them ?
Regards, Dick, W1KSZ
I would assume so. I have one and will have to put a meter on it. I was
curious if anyone knew what frequency range these might be good for.
As for price, he said he would probably put them on ebay for $10 each. If
there is interest, I can see about arranging a group buy with him before he
puts them on ebay.
I just checked with a meter and they are DPDT. I read about 0.2 Ohms from
the center BNC when switched to each outer BNC.
----- Original Message -----
From: "Joseph Gray" jgray@zianet.com
To: "Discussion of precise time and frequency measurement"
time-nuts@febo.com
Sent: Saturday, March 17, 2007 8:27 PM
Subject: Re: [time-nuts] Coax switch
Just a guess, but SPDT toggle switch ?
How much does he want for them ?
Regards, Dick, W1KSZ
I would assume so. I have one and will have to put a meter on it. I was
curious if anyone knew what frequency range these might be good for.
As for price, he said he would probably put them on ebay for $10 each. If
there is interest, I can see about arranging a group buy with him before
he
puts them on ebay.
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I assume these are signal switches, as opposed to power switches?
Didier
Joseph Gray wrote:
I just checked with a meter and they are DPDT. I read about 0.2 Ohms from
the center BNC when switched to each outer BNC.
----- Original Message -----
From: "Joseph Gray" jgray@zianet.com
To: "Discussion of precise time and frequency measurement"
time-nuts@febo.com
Sent: Saturday, March 17, 2007 8:27 PM
Subject: Re: [time-nuts] Coax switch
Just a guess, but SPDT toggle switch ?
How much does he want for them ?
Regards, Dick, W1KSZ
I would assume so. I have one and will have to put a meter on it. I was
curious if anyone knew what frequency range these might be good for.
As for price, he said he would probably put them on ebay for $10 each. If
there is interest, I can see about arranging a group buy with him before
he
puts them on ebay.
time-nuts mailing list
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https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
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I assume these are signal switches, as opposed to power switches?
Didier
Well, as I said, they have BNC connectors on them. Also, from the markings
on the panel they were mounted in, they were part of some type of telemetry
system.
I was going to try hooking the one I have up to a signal generator and
comparing the input/output at various frequencies (using my scope) to see if
there is any noticeable degradation. I don't have anything fancier to test
these with.
DPDT ??
73, Dick, W1KSZ
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com]On
Behalf Of Joseph Gray
Sent: Saturday, March 17, 2007 10:34 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Coax switch
I just checked with a meter and they are DPDT. I read about 0.2 Ohms from
the center BNC when switched to each outer BNC.
----- Original Message -----
From: "Joseph Gray" jgray@zianet.com
To: "Discussion of precise time and frequency measurement"
time-nuts@febo.com
Sent: Saturday, March 17, 2007 8:27 PM
Subject: Re: [time-nuts] Coax switch
Just a guess, but SPDT toggle switch ?
How much does he want for them ?
Regards, Dick, W1KSZ
I would assume so. I have one and will have to put a meter on it. I was
curious if anyone knew what frequency range these might be good for.
As for price, he said he would probably put them on ebay for $10 each. If
there is interest, I can see about arranging a group buy with him before
he
puts them on ebay.
time-nuts mailing list
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https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
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Dick: you got my message re: the TDS 544, right? (Apologies for the misuse
of bandwidth but I have had a lot of trouble emailing Earthlink users
lately, and wanted to make sure I got through.)
-- john, KE5FX
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com]On
Behalf Of Richard W. Solomon
Sent: Saturday, March 17, 2007 8:15 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Coax switch
DPDT ??
73, Dick, W1KSZ
Hi Richard,
DPDT ??
double pole, double throw, which could be drawn like this:
-----o
-----o ---- o ----- (pole 1)
-----o
-----o ---- o ----- (pole 2)
^
|
Two "throws" each.
Chris
Interesting, I only have one problem with Earthlink users: absolutely
nothing gets through :-)
Didier
John Miles wrote:
Dick: you got my message re: the TDS 544, right? (Apologies for the misuse
of bandwidth but I have had a lot of trouble emailing Earthlink users
lately, and wanted to make sure I got through.)
-- john, KE5FX
That's 6 BNC connectors, the switch has only three.
73, Dick, W1KSZ
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com]On
Behalf Of Christian Vogel
Sent: Sunday, March 18, 2007 5:35 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Coax switch
Hi Richard,
DPDT ??
double pole, double throw, which could be drawn like this:
-----o
-----o ---- o ----- (pole 1)
-----o
-----o ---- o ----- (pole 2)
^
|
Two "throws" each.
Chris
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Lately, Earthlink has been treating my jpeg and zip attachments
as a "virus" !! Especially if they are over 1 MB.
Big Brother is helping you.
73, Dick, W1KSZ
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com]On
Behalf Of Didier Juges
Sent: Sunday, March 18, 2007 7:04 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Coax switch
Interesting, I only have one problem with Earthlink users: absolutely
nothing gets through :-)
Didier
John Miles wrote:
Dick: you got my message re: the TDS 544, right? (Apologies for the
misuse
of bandwidth but I have had a lot of trouble emailing Earthlink users
lately, and wanted to make sure I got through.)
-- john, KE5FX
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The first time I heard of "all-pass" filters, I said to myself: what's
the point?
I could say the same about Earthlink's filter (all-reject): what's the
point?
Didier KO4BB
Richard W. Solomon wrote:
Lately, Earthlink has been treating my jpeg and zip attachments
as a "virus" !! Especially if they are over 1 MB.
Big Brother is helping you.
73, Dick, W1KSZ
The grounds are also switched.
----- Original Message -----
From: "Richard W. Solomon" w1ksz@earthlink.net
To: "Discussion of precise time and frequency measurement"
time-nuts@febo.com
Sent: Sunday, March 18, 2007 6:54 AM
Subject: Re: [time-nuts] Coax switch
That's 6 BNC connectors, the switch has only three.
73, Dick, W1KSZ
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com]On
Behalf Of Christian Vogel
Sent: Sunday, March 18, 2007 5:35 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Coax switch
Hi Richard,
DPDT ??
double pole, double throw, which could be drawn like this:
-----o
-----o ---- o ----- (pole 1)
-----o
-----o ---- o ----- (pole 2)
^
|
Two "throws" each.
Chris
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On Sun, 18 Mar 2007 11:56:44 -0600, "Joseph Gray" jgray@zianet.com
wrote:
The grounds are also switched.
Really!? I don't think I have ever seen a coax switch or relay where all
the grounds (shields) weren't always connected together.
Unless I suddenly forgot how to use a meter, the grounds are isolated. There
is also a visible plastic (teflon?) ring at the base of each coax.
----- Original Message -----
From: "Rex" rexa@sonic.net
To: "Discussion of precise time and frequency measurement"
time-nuts@febo.com
Sent: Sunday, March 18, 2007 5:18 PM
Subject: Re: [time-nuts] Coax switch
On Sun, 18 Mar 2007 11:56:44 -0600, "Joseph Gray" jgray@zianet.com
wrote:
The grounds are also switched.
Really!? I don't think I have ever seen a coax switch or relay where all
the grounds (shields) weren't always connected together.
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Hi,
This is not unusual, it's common with units that have transformer
isolated inputs, have a look at an old thin Ethernet card and it's BNC
socket.
Robert.
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Joseph Gray
Sent: 19 March 2007 00:45
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Coax switch
Unless I suddenly forgot how to use a meter, the grounds are isolated.
There
is also a visible plastic (teflon?) ring at the base of each coax.
----- Original Message -----
From: "Rex" rexa@sonic.net
To: "Discussion of precise time and frequency measurement"
time-nuts@febo.com
Sent: Sunday, March 18, 2007 5:18 PM
Subject: Re: [time-nuts] Coax switch
On Sun, 18 Mar 2007 11:56:44 -0600, "Joseph Gray" jgray@zianet.com
wrote:
The grounds are also switched.
Really!? I don't think I have ever seen a coax switch or relay where
all
the grounds (shields) weren't always connected together.
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The unauthorised use, disclosure, copying or alteration of this message is strictly forbidden. This mail and any attachments have been scanned for viruses prior to leaving Genetix network. Genetix will not be liable for direct, special, indirect or consequential damages as a result of any virus being passed on, or arising from alteration of the contents of this message by a third party.
This is kind of on the same topic as the government surplus chit-chat...
Just curious but has anyone bought stuff from the website:
????
I just started looking at it last night, they have a ton of stuff and right
now everything has zero bids. I don't know if people all snipe at the last
second or what.
Thoughts / Opinions?
Jason
Some interesting goodies on offer!!
Rob
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Jason Rabel
Sent: 19 March 2007 15:12
To: 'Discussion of precise time and frequency measurement'
Subject: [time-nuts] Government Liquidation
This is kind of on the same topic as the government surplus chit-chat...
Just curious but has anyone bought stuff from the website:
????
I just started looking at it last night, they have a ton of stuff and right
now everything has zero bids. I don't know if people all snipe at the last
second or what.
Thoughts / Opinions?
Jason
time-nuts mailing list
time-nuts@febo.com
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
At 16.12 19/03/2007, you wrote:
This is kind of on the same topic as the government surplus chit-chat...
Just curious but has anyone bought stuff from the website:
????
I just started looking at it last night, they have a ton of stuff and right
now everything has zero bids. I don't know if people all snipe at the last
second or what.
Thoughts / Opinions?
Jason
Jason,
No snipe allowed... if you bid the expiry time is prolonged.
Any kind of bad stories; you must be there and see the equipment and
remove it personally, or you get a lot of scrap. At least, this is
true buying from Europe! Too many people involved, misdescriptions,
extremely bad packaging, and so on. I bought four or five times years
ago, then I had enough. The European office was managed by good
people, but unable to help. Now it's closed.
73 - Marco IK1ODO
Interesting. Yes, I noticed that 'you' have to pick it up (or find some
service to do it for you).
I'm in Houston so I wouldn't mind driving around to the few locations here
in Texas. Though it seems like most of the good test equipment stuff is
located in Norfolk VA... Anyone live near there?
It looks like San Antonio has some good stuff coming up, several HP 5370B's,
Tek scopes, Austron 2000C, etc... I think I might sign up and 'watch' some
items, just to see what prices close at.
Jason
Jason,
No snipe allowed... if you bid the expiry time is prolonged.
Any kind of bad stories; you must be there and see the equipment and
remove it personally, or you get a lot of scrap. At least, this is
true buying from Europe! Too many people involved, misdescriptions,
extremely bad packaging, and so on. I bought four or five times years
ago, then I had enough. The European office was managed by good
people, but unable to help. Now it's closed.
73 - Marco IK1ODO
At 11:26 AM 3/19/2007, you wrote:
At 16.12 19/03/2007, you wrote:
This is kind of on the same topic as the government surplus chit-chat...
Just curious but has anyone bought stuff from the website:
????
I just started looking at it last night, they have a ton of stuff and right
now everything has zero bids. I don't know if people all snipe at the last
second or what.
Thoughts / Opinions?
Jason
Jason,
No snipe allowed... if you bid the expiry time is prolonged.
Any kind of bad stories; you must be there and see the equipment and
remove it personally, or you get a lot of scrap. At least, this is
true buying from Europe! Too many people involved, misdescriptions,
extremely bad packaging, and so on. I bought four or five times years
ago, then I had enough. The European office was managed by good
people, but unable to help. Now it's closed.
73 - Marco IK1ODO
Bidding on the T&M equipment doesn't open until tomorrow. And most of
it is export restricted - it is only available for domestic sale so
those of use anywhere else have to wait for the dealers to get hold
of it and make their teensy weensy little bit of profit.
John
Jason,
This source has some serious limitations.
-
Most of the stuff is REALLY tired. You certainly should check each item
before bidding. -
While all items are available for inspection prior to the auction close,
you are not allowed to
do anything more than pick stuff up & look at it (they really prefer
that you don't handle things).
I tried taking a portable 120V source with me to see what would
power-up & they nearly
threw me out of the place! -
Check final bid prices for the type of stuff you want. You may be
surprised at how high the
bidding goes.
Pete Rawson
Hi,
I have bought items from this site on and off over the years as well as
directly form military DRMO. You really need to go to the site to preview
the item prior to purchase. You will be surprised how good the items looks
in the picture as opposed to what it actually looks like in person. Be
prepared to spend several hours getting into and out of some bases with the
current security in place. On a recent purchase of two 2465b which were
advertised as "powering up" I found that neither would display a trace, in
fact one was completely gutted of all the hybrid chips. Even if I would
have previewed these scopes I would have been unable to look inside as
usually when viewing items you are escorted by a security personal, look but
don't touch.
It is incredible how high these items go when consideration all of the risks
of buying. As little as ten years ago you could regularly pick up bargains
and if the unit worked it was a great deal and if it did not it was a fair
price for a parts unit.
Hope my experiences help.
Jeff
----- Original Message -----
From: "Jason Rabel" jason@extremeoverclocking.com
To: "'Discussion of precise time and frequency measurement'"
time-nuts@febo.com
Sent: Monday, March 19, 2007 11:12 AM
Subject: [time-nuts] Government Liquidation
This is kind of on the same topic as the government surplus chit-chat...
Just curious but has anyone bought stuff from the website:
????
I just started looking at it last night, they have a ton of stuff and
right
now everything has zero bids. I don't know if people all snipe at the last
second or what.
Thoughts / Opinions?
Jason
time-nuts mailing list
time-nuts@febo.com
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Like jshank, it is a real "buyer beware "sort of deal even if you can
inspect things in person. If you have a problem, the customer service is
the worst! You have to wait two weeks for an answer sometimes. Even if
your dispute is serious, you may not even have a chance to appeal their
decision. The last I checked, you'll loose 25% of what you pay (which is
10% to 18% higher than what your winning bid is because of taxes and auction
fees) if you show up and the lot isn't what you thought it was and you
decide not to take it.
Another time, I've seen their employees remove items from a lot AFTER the
auction closed but before the winning bidder picked them up. When I
questioned them about it, they said that some pieces were incorrectly
classified and had to be removed. So I asked them what they would do when
the buyer sees those items missing, the guy actually told me that IF the
buyer sees them missing, that they would work out some sort of deal! (IF
buyer noticed)
There is all sorts of paperwork that's a pain if you buy classified sales
where the stuff they get is from classified projects. Many of the items
have been sitting on the shelves for years. I bought one piece a while ago,
it was classified as a "working" item, but when I opened it up, everything
inside was corroded from exposure to salty sea air. Another big thing to
watch out for is if something is listed in one place in the auction but not
in the auction title, it may not necessarily be in that lot!
My advise to the brave at heart, real ALL the contract docs and fine print
all over the website to understand the fees and auction rules. AND you MUST
inspect the pieces. They keep a log of who inspected what lot, and if you
didn't inspect that lot in person and you have a problem--you won't have a
leg to stand on when trying to file a complaint.
Like jshank says, this was a good deal a few years ago, but people are
willing to pay way too much for stuff they have no idea if it works
-Flavio
----- Original Message -----
From: "jshank" j-shank@comcast.net
To: "Discussion of precise time and frequency measurement"
time-nuts@febo.com
Sent: Monday, March 19, 2007 12:24
Subject: Re: [time-nuts] Government Liquidation
Hi,
I have bought items from this site on and off over the years as well as
directly form military DRMO. You really need to go to the site to preview
the item prior to purchase. You will be surprised how good the items
looks
in the picture as opposed to what it actually looks like in person. Be
prepared to spend several hours getting into and out of some bases with
the
current security in place. On a recent purchase of two 2465b which were
advertised as "powering up" I found that neither would display a trace, in
fact one was completely gutted of all the hybrid chips. Even if I would
have previewed these scopes I would have been unable to look inside as
usually when viewing items you are escorted by a security personal, look
but
don't touch.
It is incredible how high these items go when consideration all of the
risks
of buying. As little as ten years ago you could regularly pick up
bargains
and if the unit worked it was a great deal and if it did not it was a fair
price for a parts unit.
Hope my experiences help.
Jeff
----- Original Message -----
From: "Jason Rabel" jason@extremeoverclocking.com
To: "'Discussion of precise time and frequency measurement'"
time-nuts@febo.com
Sent: Monday, March 19, 2007 11:12 AM
Subject: [time-nuts] Government Liquidation
This is kind of on the same topic as the government surplus chit-chat...
Just curious but has anyone bought stuff from the website:
????
I just started looking at it last night, they have a ton of stuff and
right
now everything has zero bids. I don't know if people all snipe at the
last
second or what.
Thoughts / Opinions?
Jason
time-nuts mailing list
time-nuts@febo.com
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
time-nuts mailing list
time-nuts@febo.com
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
I bought from DRMS directly before they contracted to govliquidation
and also from GL. I can say that it was smart of the govt. since they
(GL) are getting a lot more for each lot. That being said, it's
always been a case of caveat emptor. They have lots of interesting
stuff that doesn't normally see the light of day. If you buy
remotely, then you'll have to pay a shipper: my experience with this
has been good but pricey. Plan on $100 per package.
On 3/19/07, jshank j-shank@comcast.net wrote:
Hi,
I have bought items from this site on and off over the years as well as
directly form military DRMO. You really need to go to the site to preview
the item prior to purchase. You will be surprised how good the items looks
in the picture as opposed to what it actually looks like in person. Be
prepared to spend several hours getting into and out of some bases with the
current security in place. On a recent purchase of two 2465b which were
advertised as "powering up" I found that neither would display a trace, in
fact one was completely gutted of all the hybrid chips. Even if I would
have previewed these scopes I would have been unable to look inside as
usually when viewing items you are escorted by a security personal, look but
don't touch.
It is incredible how high these items go when consideration all of the risks
of buying. As little as ten years ago you could regularly pick up bargains
and if the unit worked it was a great deal and if it did not it was a fair
price for a parts unit.
Hope my experiences help.
Jeff
----- Original Message -----
From: "Jason Rabel" jason@extremeoverclocking.com
To: "'Discussion of precise time and frequency measurement'"
time-nuts@febo.com
Sent: Monday, March 19, 2007 11:12 AM
Subject: [time-nuts] Government Liquidation
This is kind of on the same topic as the government surplus chit-chat...
Just curious but has anyone bought stuff from the website:
????
I just started looking at it last night, they have a ton of stuff and
right
now everything has zero bids. I don't know if people all snipe at the last
second or what.
Thoughts / Opinions?
Jason
time-nuts mailing list
time-nuts@febo.com
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
time-nuts mailing list
time-nuts@febo.com
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Thanks for all the information and feedback, I figured some of you guys
would have bought stuff from them before.
I was going to just 'wait and see' what some items went for on this big
upcoming auction at the beginning of April, unless there is some rare
obscure item that I see and just have to have.
Interesting to hear that things are selling so high, I too would be very
wary for something of unknown condition and probably only bid what would be
a scrap or parts value for an item.
They do have some neat things, you could spend days on end sifting through
all the pages and looking at pictures. At least it doesn't cost anything to
browse though, just have to refrain from clicking the 'bid' button. ;)
Jason
I was planning on mounting one of those Lucent 26dB antennas in my attic,
and was wondering what the signal strength would be like through the asphalt
shingles. If I do that then it's just pretty much a straight drop down the
wall into the computer room. Would that work (have acceptable signal
strength and be able to track multiple satellites), or should I just suck it
up and mount it outside?
I guess another thing I should look at is the temp specs, since attics get
pretty hot down here in Houston during the summer.
Jason
Hi Jason:
I don't recommend GL as a source unless:
- you understand the exact meaning of the Condition Codes, and
- you physically go to the location and preview the lot, and
- you know the product you are looking at, and
- you have the self control to not get into a bidding war (no sniping,
they just extend the closing time), and - you personally pick up the items, and
- you're willing to gamble that you won't have to return any or all of
what you purchased.
If you fail at any step then there's a chance you'll end up with junk,
something else or nothing. Maybe they get some of this stuff from a
dumpster.
With diligence it's possible to overcome the first 5 provisos, but the
last one can be a problem. On more than one occasion GL has mistakenly
sold an item that was not supposed to be sold. In that case the
government (not GL) comes and get the items. If they required an End
User Certificate then you are on the hook to account for all items
including the contact information of any buyers. If you sold an item
your buyer will expect a refund from you. You may expect a refund from
GL, but how long you wait for it is not specified.
The same problem exists with eBay. In my case after purchasing and
receiving a GPS receiver I was contacted by the DOD and they sent a
couple of people to my house to collect the GPS receiver and gave me a
receipt. I got to sign a chain of evidence form to be used at the trial
of the eBay seller on his way to jail. I'm out what I paid. After the
trial I'm free to sue the seller.
Although I'm signed up and have the EUC, I no longer even look at the
auctions with the intent of buying anything. I do use GL to see what's
being sold.
Have Fun,
Brooke Clarke
w/Java http://www.PRC68.com
w/o Java http://www.pacificsites.com/~brooke/PRC68COM.shtml
http://www.precisionclock.com
Jason Rabel wrote:
This is kind of on the same topic as the government surplus chit-chat...
Just curious but has anyone bought stuff from the website:
????
I just started looking at it last night, they have a ton of stuff and right
now everything has zero bids. I don't know if people all snipe at the last
second or what.
Thoughts / Opinions?
Jason
time-nuts mailing list
time-nuts@febo.com
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Jason,
I'm using 4 VIC-100s inside, under a flat concrete roof in my single story
office. Tracking 8 satellites on each receiver module on both my CommSync
units. Each one connected to Rx via a coiled up 50 ft length of RG-59.
Yours should work OK. What cable and what length are you planning on using?
Temp specs on my antennae are -40 to +85C operating which is typical for
this type of product. Don't think it gets that hot in Houston!!
Cheers
Rob K
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Jason Rabel
Sent: 19 March 2007 17:56
To: 'Discussion of precise time and frequency measurement'
Subject: [time-nuts] GPS Signal Strength Through Roof?
I was planning on mounting one of those Lucent 26dB antennas in my attic,
and was wondering what the signal strength would be like through the asphalt
shingles. If I do that then it's just pretty much a straight drop down the
wall into the computer room. Would that work (have acceptable signal
strength and be able to track multiple satellites), or should I just suck it
up and mount it outside?
I guess another thing I should look at is the temp specs, since attics get
pretty hot down here in Houston during the summer.
Jason
time-nuts mailing list
time-nuts@febo.com
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Rob,
I was just going to use some RG-58, and if I can mount it in the attic then
I probably won't need to run more than 15-20ft at most. Loss along the cable
should be minimal since the run will be short, I just didn't know how much
the roof would block the signal.
Jason
Jason,
I'm using 4 VIC-100s inside, under a flat concrete roof in my single story
office. Tracking 8 satellites on each receiver module on both my CommSync
units. Each one connected to Rx via a coiled up 50 ft length of RG-59.
Yours should work OK. What cable and what length are you planning on using?
Temp specs on my antennae are -40 to +85C operating which is typical for
this type of product. Don't think it gets that hot in Houston!!
Cheers
Rob K
Jason,
Loss in the cable will be in the range of 5 - 7 dB plus connector losses.
Let's say about 10dB max.
Looks OK to me.
Good luck!!!
Rob
----- Original Message -----
From: "Jason Rabel" jason@extremeoverclocking.com
To: "'Discussion of precise time and frequency measurement'"
time-nuts@febo.com
Sent: Monday, March 19, 2007 6:41 PM
Subject: Re: [time-nuts] GPS Signal Strength Through Roof?
Rob,
I was just going to use some RG-58, and if I can mount it in the attic
then
I probably won't need to run more than 15-20ft at most. Loss along the
cable
should be minimal since the run will be short, I just didn't know how much
the roof would block the signal.
Jason
Jason,
I'm using 4 VIC-100s inside, under a flat concrete roof in my single story
office. Tracking 8 satellites on each receiver module on both my CommSync
units. Each one connected to Rx via a coiled up 50 ft length of RG-59.
Yours should work OK. What cable and what length are you planning on
using?
Temp specs on my antennae are -40 to +85C operating which is typical for
this type of product. Don't think it gets that hot in Houston!!
Cheers
Rob K
time-nuts mailing list
time-nuts@febo.com
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Hi,
Just for any UK lurkers, GL also sell in the UK and I've bought from them. There are a few issues,
1 Very poor descriptions a photo of a cardboard box doesn't tell yell you much!
2 Tender only, not an auction, so you really need to know how much you want to pay. There is no way of knowing what the lot finally sold for unless you win it. They do have minimums, sometimes listed, sometimes your bid is just rejected.
3 Viewing is a pain
4 payment and collection deadlines are a pain, all biased to their convenience.
5 Items "disappear" from lots, if you argue they sometimes reappear, sometimes not. If you use a collection agent it's a lucky dip.
6 Items get pulled after you spent time and money viewing them.
7 Lot sizes vary from one worthless metal bracket with a £50 minimum to 10 tons of scrap metal with a couple of nice bits of T&M thrown in. Lot descriptions on size and weight can be inaccurate.
Generally it's hardly worth the bother, I think a few dealers, scrap merchants and people with time on their hands who are local to the Sale site do OK but otherwise I think they need to improve the service.
Robert.
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On Behalf Of Brooke Clarke
Sent: 19 March 2007 17:57
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Government Liquidation
Hi Jason:
I don't recommend GL as a source unless:
- you understand the exact meaning of the Condition Codes, and
- you physically go to the location and preview the lot, and
- you know the product you are looking at, and
- you have the self control to not get into a bidding war (no sniping,
they just extend the closing time), and - you personally pick up the items, and
- you're willing to gamble that you won't have to return any or all of
what you purchased.
If you fail at any step then there's a chance you'll end up with junk,
something else or nothing. Maybe they get some of this stuff from a
dumpster.
With diligence it's possible to overcome the first 5 provisos, but the
last one can be a problem. On more than one occasion GL has mistakenly
sold an item that was not supposed to be sold. In that case the
government (not GL) comes and get the items. If they required an End
User Certificate then you are on the hook to account for all items
including the contact information of any buyers. If you sold an item
your buyer will expect a refund from you. You may expect a refund from
GL, but how long you wait for it is not specified.
The same problem exists with eBay. In my case after purchasing and
receiving a GPS receiver I was contacted by the DOD and they sent a
couple of people to my house to collect the GPS receiver and gave me a
receipt. I got to sign a chain of evidence form to be used at the trial
of the eBay seller on his way to jail. I'm out what I paid. After the
trial I'm free to sue the seller.
Although I'm signed up and have the EUC, I no longer even look at the
auctions with the intent of buying anything. I do use GL to see what's
being sold.
Have Fun,
Brooke Clarke
w/Java http://www.PRC68.com
w/o Java http://www.pacificsites.com/~brooke/PRC68COM.shtml
http://www.precisionclock.com
Jason Rabel wrote:
This is kind of on the same topic as the government surplus chit-chat...
Just curious but has anyone bought stuff from the website:
????
I just started looking at it last night, they have a ton of stuff and right
now everything has zero bids. I don't know if people all snipe at the last
second or what.
Thoughts / Opinions?
Jason
time-nuts mailing list
time-nuts@febo.com
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
time-nuts mailing list
time-nuts@febo.com
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Genetix Limited - Queensway, New Milton, Hampshire, BH25 5NN Registered in England No. 2660050 www.genetix.com
Any opinions expressed in this email are those of the individual and not necessarily Genetix Ltd (Genetix) or any company associated with it. This email and any files transmitted with it are confidential and solely for the use of the intended recipient. If you are not the intended recipient or the person responsible for delivering to the intended recipient, be advised that you have received this email in error and that any use is strictly prohibited. If you have received this email in error please notify Genetix by telephone on +44 (0)1425 624600.
The unauthorised use, disclosure, copying or alteration of this message is strictly forbidden. This mail and any attachments have been scanned for viruses prior to leaving Genetix network. Genetix will not be liable for direct, special, indirect or consequential damages as a result of any virus being passed on, or arising from alteration of the contents of this message by a third party.
Thanks for the info. I won't be bothering - my time is precious!!
:-))
Rob (in the UK)
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Robert Atkinson
Sent: 20 March 2007 09:02
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Government Liquidation
Hi,
Just for any UK lurkers, GL also sell in the UK and I've bought from them.
There are a few issues,
1 Very poor descriptions a photo of a cardboard box doesn't tell yell you
much!
2 Tender only, not an auction, so you really need to know how much you want
to pay. There is no way of knowing what the lot finally sold for unless you
win it. They do have minimums, sometimes listed, sometimes your bid is just
rejected.
3 Viewing is a pain
4 payment and collection deadlines are a pain, all biased to their
convenience.
5 Items "disappear" from lots, if you argue they sometimes reappear,
sometimes not. If you use a collection agent it's a lucky dip.
6 Items get pulled after you spent time and money viewing them.
7 Lot sizes vary from one worthless metal bracket with a £50 minimum to 10
tons of scrap metal with a couple of nice bits of T&M thrown in. Lot
descriptions on size and weight can be inaccurate.
Generally it's hardly worth the bother, I think a few dealers, scrap
merchants and people with time on their hands who are local to the Sale site
do OK but otherwise I think they need to improve the service.
Robert.
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Brooke Clarke
Sent: 19 March 2007 17:57
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Government Liquidation
Hi Jason:
I don't recommend GL as a source unless:
- you understand the exact meaning of the Condition Codes, and
- you physically go to the location and preview the lot, and
- you know the product you are looking at, and
- you have the self control to not get into a bidding war (no sniping, they
just extend the closing time), and - you personally pick up the items, and
- you're willing to gamble that you won't have to return any or all of what
you purchased.
If you fail at any step then there's a chance you'll end up with junk,
something else or nothing. Maybe they get some of this stuff from a
dumpster.
With diligence it's possible to overcome the first 5 provisos, but the last
one can be a problem. On more than one occasion GL has mistakenly sold an
item that was not supposed to be sold. In that case the government (not GL)
comes and get the items. If they required an End User Certificate then you
are on the hook to account for all items including the contact information
of any buyers. If you sold an item your buyer will expect a refund from
you. You may expect a refund from GL, but how long you wait for it is not
specified.
The same problem exists with eBay. In my case after purchasing and
receiving a GPS receiver I was contacted by the DOD and they sent a couple
of people to my house to collect the GPS receiver and gave me a receipt. I
got to sign a chain of evidence form to be used at the trial of the eBay
seller on his way to jail. I'm out what I paid. After the trial I'm free
to sue the seller.
Although I'm signed up and have the EUC, I no longer even look at the
auctions with the intent of buying anything. I do use GL to see what's
being sold.
Have Fun,
Brooke Clarke
w/Java http://www.PRC68.com
w/o Java http://www.pacificsites.com/~brooke/PRC68COM.shtml
http://www.precisionclock.com
Jason Rabel wrote:
This is kind of on the same topic as the government surplus chit-chat...
Just curious but has anyone bought stuff from the website:
????
I just started looking at it last night, they have a ton of stuff and
right now everything has zero bids. I don't know if people all snipe at
the last second or what.
Thoughts / Opinions?
Jason
time-nuts mailing list
time-nuts@febo.com
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
time-nuts mailing list
time-nuts@febo.com
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
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time-nuts mailing list
time-nuts@febo.com
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Hi I am new to this group, my background; electronics, amateur radio
and clocks.
I am developing a free pendulum and to analyse its operation I
compare it to WWV
on 5 or 10 MHz, the only available radio frequency standard on air in
Australia.
To examine the phase drift and jitter I compare it with a 1MHz rock
in an oven.
I have a HP 5328A which is not stable. It is marked as having option 010
but when I look inside there is only one crystal, 10mhz, which looks
like an el cheapo,
and no sign of an oven.
Can anyone tell me what option 010 looks like?
I intend to buy a $20, better than average, 10mhz rock and put it in
an oven.
Any advice would be appreciated,
Neville Michie
Here is a link to a photo of an HP 10811
http://www.slack.com/images/TE/HP10811A.jpg
Jamie
--- Neville Michie namichie@gmail.com wrote:
Hi I am new to this group, my background;
electronics, amateur radio
and clocks.
I am developing a free pendulum and to analyse its
operation I
compare it to WWV
on 5 or 10 MHz, the only available radio frequency
standard on air in
Australia.
To examine the phase drift and jitter I compare it
with a 1MHz rock
in an oven.
I have a HP 5328A which is not stable. It is marked
as having option 010
but when I look inside there is only one crystal,
10mhz, which looks
like an el cheapo,
and no sign of an oven.
Can anyone tell me what option 010 looks like?
I intend to buy a $20, better than average, 10mhz
rock and put it in
an oven.
Any advice would be appreciated,
Neville Michie
time-nuts mailing list
time-nuts@febo.com
Fedora Core 4 Linux
8:00? 8:25? 8:40? Find a flick in no time
with the Yahoo! Search movie showtime shortcut.
http://tools.search.yahoo.com/shortcuts/#news
It looks like this
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=280095458978
If it doesn't look very similar to this, buy this one and have done with it!
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Neville Michie
Sent: Tuesday, March 20, 2007 7:28 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Hello
Hi I am new to this group, my background; electronics, amateur radio
and clocks.
I am developing a free pendulum and to analyse its operation I
compare it to WWV
on 5 or 10 MHz, the only available radio frequency standard on air in
Australia.
To examine the phase drift and jitter I compare it with a 1MHz rock
in an oven.
I have a HP 5328A which is not stable. It is marked as having option 010
but when I look inside there is only one crystal, 10mhz, which looks
like an el cheapo,
and no sign of an oven.
Can anyone tell me what option 010 looks like?
I intend to buy a $20, better than average, 10mhz rock and put it in
an oven.
Any advice would be appreciated,
Neville Michie
time-nuts mailing list
time-nuts@febo.com
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Neville,
I am old to this group. I remember when we could go for days
without a message. My background is BSME in 1960, lifetime
interest in electronics and computing (tho I don't write code
anymore) applied to chemical process control. Always interested
in precision time, intensified after a visit to Greenwich and
the British Science Museum's exhibit on clocks.
The Shortt pendulum was of great interest - what could 70 years
of relentlessly advancing technology have to improve on it?
That is a top priority, behind consulting commitments, financial
management, home maintenance, building computers and looking for
business. Which is to say, I've bought things but haven't had any
time to do anything with them, like the Invar rod.
Many years later, I've been able to buy much more than I've been
able to do. My dear and patient wife wants to know when she will
be able to move about the basement again. We approach 70 now, so
it's not like we'll be searching for alternative partners.
But I digress. My research has shown that a free pendulum would be
doing well to approach 10E-8 in accuracy. The folks on this list
are going for 10E-12.
Can you afford a GPS disciplined receiver, like the HP Z3801? That
is all the accuracy you will ever need, better that 10E-10. Crystals
(undisciplined) do not go that low. Satellites do fly over Oz, no?
I no longer think that I will assemble a vacuum pump, tube, zero-loss
pivot, and electrostatic detection and excitation mechanisms in my
lifetime. Especially since I live 100 meters from a low-speed freight
railroad track. Pity, really. Too soon old, too late smart.
Hope I haven't depressed you.
Best regards,
Bill Hawkins
P.S. Visited Melbourne and Sydney, crossing the bridge on foot, in the
mid 80's. Went to Healsville in a 60 MPH wind, unforgettable. Joeys not
just standing around. Got back from a rainy visit to the Fairy Penguins,
no lights in the bathroom or shower, called the desk, "No worries, mate.
The electrician will set it straight in the morning."
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Neville Michie
Sent: Tuesday, March 20, 2007 7:28 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Hello
Hi I am new to this group, my background; electronics, amateur radio and
clocks.
I am developing a free pendulum and to analyse its operation I compare
it to WWV on 5 or 10 MHz, the only available radio frequency standard on
air in Australia.
To examine the phase drift and jitter I compare it with a 1MHz rock in
an oven.
I have a HP 5328A which is not stable. It is marked as having option 010
but when I look inside there is only one crystal, 10mhz, which looks
like an el cheapo, and no sign of an oven.
Can anyone tell me what option 010 looks like?
I intend to buy a $20, better than average, 10mhz rock and put it in an
oven.
Any advice would be appreciated,
Neville Michie
time-nuts mailing list
time-nuts@febo.com
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Hello!
It looks like this
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=280095458978
If it doesn't look very similar to this, buy this one and have done with it!
I have got some HP units with that kind of oscillator instead of the
'original' HP unit... I wonder if this was an aftermarket cheaper option
(my guess) or if HP ever provided it (don't think so!)
Regards,
JOSE
73 EB5AGV / EC5AAU - JOSE V. GAVILA
La Canyada - Valencia (SPAIN) - Loc: IM99SM
Vintage Radio: http://jvgavila.com
Vintage Test Equipment: http://jvgavila.com/testeq.htm
European Boatanchors List: http://groups.yahoo.com/group/euro_ba_swap
The Shortt pendulum was of great interest - what could 70 years
of relentlessly advancing technology have to improve on it?
That is a top priority, behind consulting commitments, financial
management, home maintenance, building computers and looking for
business. Which is to say, I've bought things but haven't had any
time to do anything with them, like the Invar rod.
I would be interested if others of you time-nuts are also
involved with pendulum clocks. At the surface it might
seem odd that with today's technology that anyone would
want to spend time with pendulum clocks. But there are
several hundred guys around the world who are spending
a great deal of time working on modern pendulum clocks.
The history, science, and technology of these things is
far, far deeper than you might think. Here I can make a
plug for Jim's website:
http://www.clockvault.com/heritage/index.htm
and also have a look at Bill's amazing creations:
http://www.precisionclocks.com/
I really like my cesium clocks, but you've got to admit
these old (Riefler and Shortt) and new (Q1 and Q2)
are much better eye candy and old HP or FTS clock.
Many years later, I've been able to buy much more than I've been
able to do. My dear and patient wife wants to know when she will
be able to move about the basement again. We approach 70 now, so
it's not like we'll be searching for alternative partners.
But I digress. My research has shown that a free pendulum would be
doing well to approach 10E-8 in accuracy. The folks on this list
are going for 10E-12.
Right, the best ADEV you can do with a pendulum clock
is about 5e-9 for a tau on the order of days. I should send
you the plots.
I no longer think that I will assemble a vacuum pump, tube, zero-loss
pivot, and electrostatic detection and excitation mechanisms in my
lifetime. Especially since I live 100 meters from a low-speed freight
railroad track. Pity, really. Too soon old, too late smart.
Yes, others working with pendulums have also discovered
that they end up making crude thermometers, barometers,
or seismometers instead of a good clock. Still, not a reason
to give up. But you know you have a world-class pendulum
clock when, after having solved every other perturbation, you
can see the effects of lunar tides in your data (as your good
pendulum clock demonstrates it is also a fair gravimeter).
Tom Van Baak wrote:
The Shortt pendulum was of great interest - what could 70 years
of relentlessly advancing technology have to improve on it?
That is a top priority, behind consulting commitments, financial
management, home maintenance, building computers and looking for
business. Which is to say, I've bought things but haven't had any
time to do anything with them, like the Invar rod.
I would be interested if others of you time-nuts are also
involved with pendulum clocks. At the surface it might
seem odd that with today's technology that anyone would
want to spend time with pendulum clocks. But there are
several hundred guys around the world who are spending
a great deal of time working on modern pendulum clocks.
The history, science, and technology of these things is
far, far deeper than you might think. Here I can make a
plug for Jim's website:
http://www.clockvault.com/heritage/index.htm
and also have a look at Bill's amazing creations:
http://www.precisionclocks.com/
I really like my cesium clocks, but you've got to admit
these old (Riefler and Shortt) and new (Q1 and Q2)
are much better eye candy and old HP or FTS clock.
Stuff snipped
There was a series of articles in The Home Shop Machinist starting in the
September/October 2000 issue that described construction of a Free
Pendulum clock
I think I can find all of the articles if some one wants them
Bill K7NOM (not really nutty about time)