My comment would be that some gps receivers want to see a particular antenna
current.
Maybe thats low.
Further if the battery backup for the gps unit has failed it can easily take
4-6 hours to figure life out on older receivers. Unless like odetics you can
tell it what sat to look for, not likely since these were intended for
un-attended sites. If you power down it has to start all over again....
Good luck and we will all learn from your effort.
Paul
WB8TSL

On Fri, Oct 7, 2011 at 10:12 AM, Peter Bell bell.peter@gmail.com wrote:

On Sun, Oct 9, 2011 at 3:31 AM, k4cle@aol.com k4cle@aol.com wrote:

Hi, Doug

I don't have any documentation at all - just the actual box.  The
antenna is one that originally came with a Furuno marine GPS, but the
spec looks plausible (+5V @ 40mA, Internal L1 preamp with 26dB gain -
and it has worked with several other GPS units without problems.

I just pulled the oncore out, and connected it up outside the box -
and it doesn't work.  It passes the self test with a response code of
0000 (or 8000 with the antenna disconnected / 4000 with a short on the
antenna socket - so it seems the current consumption is OK) - but no
matter how long you leave it it still says it's tracking 0 satellites,
although it happiy generates status reports.

I wonder if this UT+ version is expecially sensitive to the antenna?
I remember that the oncore VP would work with pretty much anything you
hooked up to it.  Of course, it's equally possible that the GPS module
is defective.

I'm tending towards broken - I also got an RTFG-m-RB with this unit,
and that has a faulty LPRO-101 in it (it's probably fixable - it looks
like the FET that heats up the Rb cell had gone open circuit) - and
the two units together only cost me $40 supplied on a "status unkown,
but likely defective" basis. I should get at least $40 of
entertainment out of trying to fix them :)

Peter,

My UT+ works ok with common antennas, I tested it with a Trimble
28367-00 and with a  INPAQ AAF-03B 5V.  Both are quite old garden
variety GPS antennas intended for car navigators so your problem can be
in the receiver.
I bought mine from fluke.l and he still have some available on his other
shop:
http://www.ebay.com/itm/130303889204?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649
http://www.ebay.com/itm/130303889204?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649
They are cheap enough to buy one as a spare just in case.  Also you can
try with another antenna anyway, because the receiver checks only that
an antenna is connected (that is, the current range is right) but your
antenna could became defective.

Regards,
Ignacio

On 09/10/2011 7:52, Peter Bell wrote:

On Sun, Oct 9, 2011 at 6:55 AM, EB4APL eb4apl@cembreros.jazztel.es wrote:

I found one of these:

http://www.frys.com/product/5342178

to be more sensitive than the egg shaped antenna from fluke.l (fluke.l is a
good seller and I've bought a couple of things from him).  Whether the
GILSSON draws enough current is another matter - Frys claim 12 +/-1 mA.

Orin.

On 10/9/2011 6:55 AM, EB4APL wrote:

That's the route I had to go to fix my RTFG pair.  I replaced the
receiver with one of a pair I purchased from *-Bay. They seem to be working.

Randy, KI6WAS

Hi Peter, yes it sounds like the UT+ is defective if it never gets any sats.  You can probably find one on eBay.  Someone probably fired RF into the receiver front-end and zapped it.  I think the antenna you are using should be OK.

I will look for my drawings on this unit and send copies to you.  And I know I have the software too, just need to find it!

I have read in some of the notes here on time-nuts that people may be able to use RS232 for communicating with the RFTG units.  But it was designed for RS422 and I would suggest you use RS422 for best results.  I use a little RS422-4S232 converter which has worked fine for me.

The early units had FRS rubidiums in them.  The LPRO was used in the newer units.  So, you have the more recent design.
Connected by DROID on Verizon Wireless

-----Original message-----
From: Peter Bell bell.peter@gmail.com
To: Discussion of precise time and frequency measurement time-nuts@febo.com
Sent: Sun, Oct 9, 2011 05:52:25 GMT+00:00
Subject: Re: [time-nuts] Lucent RFTG-m-XO GPSDO

On Sun, Oct 9, 2011 at 3:31 AM, k4cle@aol.com k4cle@aol.com wrote:

Hi, Doug

I don't have any documentation at all - just the actual box.  The
antenna is one that originally came with a Furuno marine GPS, but the
spec looks plausible (+5V @ 40mA, Internal L1 preamp with 26dB gain -
and it has worked with several other GPS units without problems.

I just pulled the oncore out, and connected it up outside the box -
and it doesn't work.  It passes the self test with a response code of
0000 (or 8000 with the antenna disconnected / 4000 with a short on the
antenna socket - so it seems the current consumption is OK) - but no
matter how long you leave it it still says it's tracking 0 satellites,
although it happiy generates status reports.

I wonder if this UT+ version is expecially sensitive to the antenna?
I remember that the oncore VP would work with pretty much anything you
hooked up to it.  Of course, it's equally possible that the GPS module
is defective.

I'm tending towards broken - I also got an RTFG-m-RB with this unit,
and that has a faulty LPRO-101 in it (it's probably fixable - it looks
like the FET that heats up the Rb cell had gone open circuit) - and
the two units together only cost me $40 supplied on a "status unkown,
but likely defective" basis. I should get at least $40 of
entertainment out of trying to fix them :)

time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

As to me, too.

TIA,
Randy, KI6WAS

On 10/9/2011 4:02 PM, Bill Hawkins wrote:

On Mon, Oct 10, 2011 at 2:41 AM, k4cle@aol.com k4cle@aol.com wrote:

Any documentation you can provide would be very helpful - I'm pretty
much sure, based on the comments made by yourself and the other people
on the list, that my GPS Rx is broken - I just found my other oncore
(a VP) and that works correctly in the same test setup that the UT+
out of the RFTG failed to track in.  I also tried the little Motorola
antenna on both boards, with the same results.  I tried plugging the
VP into the Lucent box, but it doesn't seem to like it (the fault
light just stays on), so I have ordered a replacment UT+ board.

I assume the units that had a FRS in them had different PCBs?  The
LPRO is plugged directly into the baseboard on my RB unit (KS-24019
L105B, if that means anything) and it seems to be pretty clearly
designed around it.  The XO (KS-24019 L106C) has the same PCB in it,
except that there is an extra section of PCB with an Efratom OCXO
mounted on it where the LPRO is in the RB unit.

It's sort of a pity it's not an FRS - I've fixed some of those in the
past, and they were pretty straightforward things to work on - all
standard parts and it had the schematic in the manual - all the LPRO
manual says is "not user-servicable; send it back to us" - but that
lamp heater circuit looks fairly simple anyway, so I guess I can have
a go at that while I'm waiting for the GPS board to arrive.

And thank you to everyone that offered suggestions.

Regards,

Pete

There are scans of the L-Pro service manual out there.  Google should help here.

Randy

From: Peter Bell bell.peter@gmail.com
To: Discussion of precise time and frequency measurement time-nuts@febo.com
Sent: Sun, October 9, 2011 9:13:14 PM
Subject: Re: [time-nuts] Lucent RFTG-m-XO GPSDO

On Mon, Oct 10, 2011 at 2:41 AM, k4cle@aol.com k4cle@aol.com wrote:

Any documentation you can provide would be very helpful - I'm pretty
much sure, based on the comments made by yourself and the other people
on the list, that my GPS Rx is broken - I just found my other oncore
(a VP) and that works correctly in the same test setup that the UT+
out of the RFTG failed to track in.  I also tried the little Motorola
antenna on both boards, with the same results.  I tried plugging the
VP into the Lucent box, but it doesn't seem to like it (the fault
light just stays on), so I have ordered a replacment UT+ board.

I assume the units that had a FRS in them had different PCBs?  The
LPRO is plugged directly into the baseboard on my RB unit (KS-24019
L105B, if that means anything) and it seems to be pretty clearly
designed around it.  The XO (KS-24019 L106C) has the same PCB in it,
except that there is an extra section of PCB with an Efratom OCXO
mounted on it where the LPRO is in the RB unit.

It's sort of a pity it's not an FRS - I've fixed some of those in the
past, and they were pretty straightforward things to work on - all
standard parts and it had the schematic in the manual - all the LPRO
manual says is "not user-servicable; send it back to us" - but that
lamp heater circuit looks fairly simple anyway, so I guess I can have
a go at that while I'm waiting for the GPS board to arrive.

And thank you to everyone that offered suggestions.

Regards,

Pete

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and follow the instructions there.

Have you got any pointers?  The only document I could find was a
"repair guide" prepared by PE1FBO - and whiile it's certainly useful
(especially for the specific purpose of getting my unit running), it's
not the original Efratom info.  Maybe it's my history in the avionics
business, but I really like to use official docs if possible :)

Regards,

Pete

On Mon, Oct 10, 2011 at 1:01 PM, randy hunt randy_hunt960@yahoo.com wrote:

The Rx was defective - I just got the new one, hooked it up to my
little test rig anf the antenna, and it happily picked up satellites
and got a position fix.

Swapped it into the box, and found a TTL level copy of the RX data
stream from the encore on pin 2 of the interface connector, so hooked
that up to a TTL->RS232 converter so I could monitor what was
happening.  It all seemed to be tracking OK, although the "No GPS" LED
was still on, so I just left it and after a couple of hours the LED
went out.

Next step is getting the Rb working :)

On Mon, Oct 10, 2011 at 2:41 AM, k4cle@aol.com k4cle@aol.com wrote:

If I recall, the firmware in the RFTGm collects about an hours worth of position info and does an average to establish a self-survey.  The next time you cycle power, it will check the new position against the stored one and if within 50 feet or so, it will use the stored position.  That's probably why it took a while for the LED to extinguish.

Connected by DROID on Verizon Wireless

-----Original message-----
From: Peter Bell bell.peter@gmail.com
To: Discussion of precise time and frequency measurement time-nuts@febo.com
Sent: Tue, Oct 11, 2011 12:49:45 GMT+00:00
Subject: Re: [time-nuts] Lucent RFTG-m-XO GPSDO

The Rx was defective - I just got the new one, hooked it up to my
little test rig anf the antenna, and it happily picked up satellites
and got a position fix.

Swapped it into the box, and found a TTL level copy of the RX data
stream from the encore on pin 2 of the interface connector, so hooked
that up to a TTL->RS232 converter so I could monitor what was
happening.  It all seemed to be tracking OK, although the "No GPS" LED
was still on, so I just left it and after a couple of hours the LED
went out.

Next step is getting the Rb working :)

On Mon, Oct 10, 2011 at 2:41 AM, k4cle@aol.com k4cle@aol.com wrote:

time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

For some reason, the "No GPS" LED is back - although the GPS is
tracking 8 satellites in 3D mode and according to the TRAIM status the
timing error is below the alarm threshhold (alarm = 1300ns, current =
43ns) - I guess the uinit has it's own standards for the GPS quality,
and they are being violated in some way.

Still. at ;least I have seen it running with that LED off, which is a
positve sign :)

On Wed, Oct 12, 2011 at 5:42 AM, k4cle@aol.com k4cle@aol.com wrote:

For some reason, the "No GPS" LED is back - although the GPS is
tracking 8 satellites in 3D mode and according to the TRAIM status the
timing error is below the alarm threshhold (alarm = 1300ns, current =
43ns) - I guess the uinit has it's own standards for the GPS quality,
and they are being violated in some way.

Still. at ;least I have seen it running with that LED off, which is a
positve sign :)

On Wed, Oct 12, 2011 at 5:42 AM, k4cle@aol.com k4cle@aol.com wrote:

On Tue, Oct 11, 2011 at 6:17 PM, Peter Gottlieb nerd@verizon.net wrote:

What level of accuracy do you need on the server.  If "a few milliseconds"
is good enough then you can use internet pool servers as you reference and
you don't need GPS.  If you need a microsecond or better then you are
pushing the state of the art  GPS can work between those limits.        The
hardest part will be finding a computer that can run Linux or BSD UNIX and
an run on 12 or 24 volts DC. I'd guess and older used notebook computer
would be best.  "Old" is best too because you will need a "real" serial
port, not a USB converter.  Use real serial port for best accuracy when
connecting to GPS.    The software NTP, will come with linux or BSD.

Chris Albertson
Redondo Beach, California

Much as I hate to follow up on my own post, I just power cycled the
unit and it quickly went from 2D->3D->Position Hold with the "No GPS"
LED out. So maybe it just ended up in slighly confused state after
doing the site survey and now it's got the position stored it's doing
the right thing.

Looking at the "negative sawtooth" page in WinOncore it's showing
about +/- 40ns of jitter and tracking nicely.

So I guess i had better start working on the Rb :)

On Wed, Oct 12, 2011 at 9:33 AM, Peter Bell bell.peter@gmail.com wrote:

I would like to get better than 100 uSec so I can get a couple of degrees
resolution on a synchrophasor project.

Peter

On 10/12/2011 12:48 AM, Chris Albertson wrote:

On 10/11/2011 6:28 PM, Peter Bell wrote:

The 'no gps light' on mine comes on periodically (usually around
midnight) then goes off after a while.  My antenna is not in the best
location, on window sill in corner.  But, for the most part, it stays
off most of the time. . .

Randy

On Wed, Oct 12, 2011 at 4:33 AM, Peter Gottlieb nerd@verizon.net wrote:

You are in luck 100uS is is the range of "easy to do".    Setting up
an NTP servers is a different task from setting up a GPSDXO.  One
does not need a GPSDXO for NTP.  The Thunderbolt is likely the lowest
price GPSDXO but by the time you get an antenna and power suply and
cables you will have spent abot $300.  It will drive an NTP server to
bette than your 100uS requirement.

But you can also buy a Motorola "Oncore" series GPS for as little as
$18 on ebay and it will run NTP just as good as the Thunderbolt.  For
$60 you can buy a brand new Oncore with warenty and tech suport and it
is an order of magnitude better.

If budget is important be sure an look at the cost of electric power.
It is easy to burn up $250 per year of power or even more.  Those
"junker" PCs you find indumpsters are not cheap if you run then 24x7.
I found a brand new intel Atom powerd machine pays for itself.  Use
a 16GB flash drive or even have it boot off the network and have zero
local storage.

Chris Albertson
Redondo Beach, California

Now this is some very wise advice indeed.
Its the ole power cost.
Great reply and solution.
I like things that draw zip power and can live on a basement wall for 10
years just doing there job.

On Wed, Oct 12, 2011 at 2:14 PM, Chris Albertson
albertson.chris@gmail.comwrote:

Hi Paul!

On 12 October 2011 20:36, paul swed paulswedb@gmail.com wrote:

One of my current NTP servers is running on a Alix 1D motherboard from
PC Engines. Software is FreeBSD 7.4 (nanoBSD).

It's a NTP pool server and it has been serving around 30-40 packets
per second of NTP traffic during the last days.

It consumes around 5W of power, boots of a Compact Flash and runs
completely in memory.

I have two of these units: one with a Garmin 18 LVC and another with a
Motorola Oncore UT+.

Hope this helps.

Cheers,
Miguel

Peter, that's good news.  Sounds like you have a plan.  I am sending a CD to KO4BB to put the drawings and softwre on his site where everyone can download it.  Regards, Doug, K4CLE

Connected by DROID on Verizon Wireless

-----Original message-----
From: Peter Bell bell.peter@gmail.com
To: Discussion of precise time and frequency measurement time-nuts@febo.com
Sent: Wed, Oct 12, 2011 08:02:24 GMT+00:00
Subject: Re: [time-nuts] Lucent RFTG-m-XO GPSDO

Much as I hate to follow up on my own post, I just power cycled the
unit and it quickly went from 2D->3D->Position Hold with the "No GPS"
LED out. So maybe it just ended up in slighly confused state after
doing the site survey and now it's got the position stored it's doing
the right thing.

Looking at the "negative sawtooth" page in WinOncore it's showing
about +/- 40ns of jitter and tracking nicely.

So I guess i had better start working on the Rb :)

On Wed, Oct 12, 2011 at 9:33 AM, Peter Bell bell.peter@gmail.com wrote:

time-nuts mailing list -- time-nuts@febo.com
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and follow the instructions there.

Thank you for making this information available - trying to work on
something without docs can be interesting, but can also end up
sometimes being frustrating.

The ultimate aim is to put my spare Oncore UT+ and a little MCU inside
the RB unit so it can be directly GPS disciplined without having to
use the XO.- but I guess this will require a little reverse
engineering to figure out exactly what messages the RB is looking for,
and what mode the GPS needs to be in to do this.

I've logged the data from power up to with the unit in it's expected
position and it doesn;t look like there are that many commands being
sent to the receiver - my next step is taking the unit to my friends
house and running it there to force it to trigger another site survey
so I can log the messages under those conditions.

I guess it all passes the time :)

Regards,

Pete

On Thu, Oct 13, 2011 at 11:01 AM, k4cle@aol.com k4cle@aol.com wrote:

.. and for the convenience of a board which includes USB and serial
connectors:

http://www.sureelectronics.net/goods.php?id=99
http://www.satsignal.eu/ntp/Sure-GPS.htm

Some assembly required.  US $34.90 + P&P

Cheers,
David

SatSignal software - quality software written to your requirements
Web:  http://www.satsignal.eu
Email:  david-taylor@blueyonder.co.uk

Nice box David. I confirm that results with FreeBSD are better and are,
for shorter periods, even better than a usec and that is for a very
unfavourable view of the north sky. Attached, a couple of shots from
this morning.

Mike

All that's interested, KO4BB now has my RFTGm information on his manuals
section under GPS Timing.  Please let me know if you have questions about
it.  73's, Doug, K4CLE

Connected by DROID on Verizon Wireless

-----Original message-----
From: "Randy D. Hunt" randy_hunt960@yahoo.com
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Sent: Wed, Oct 12, 2011 16:53:04 GMT+00:00
Subject: Re: [time-nuts] Lucent RFTG-m-XO GPSDO

On 10/11/2011 6:28 PM, Peter Bell wrote:

position info and does an average to establish a self-survey.  The next time
you cycle power, it will check the new position against the stored one and
if within 50 feet or so, it will use the stored position.  That's probably
why it took a while for the LED to extinguish.

measurementtime-nuts@febo.com

sats.  You can probably find one on eBay.  Someone probably fired RF into
the receiver front-end and zapped it.  I think the antenna you are using
should be OK.

know I have the software too, just need to find it!

able to use RS232 for communicating with the RFTG units.  But it was
designed for RS422 and I would suggest you use RS422 for best results.  I
use a little RS422-4S232 converter which has worked fine for me.

newer units.  So, you have the more recent design.

measurementtime-nuts@febo.com

supposed

AT&T

provided by

GPS

the

me

https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts

https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts

https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts

https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts

https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts

The 'no gps light' on mine comes on periodically (usually around
midnight) then goes off after a while.  My antenna is not in the best
location, on window sill in corner.  But, for the most part, it stays
off most of the time. . .

Randy

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and follow the instructions there.

Thank you - I've downloaded it and it looks very interesting - I guess
I need to dig out my RS232-RS422 converter and have a play.

Regards,

Pete

On Tue, Oct 18, 2011 at 7:35 AM, k4cle@aol.com k4cle@aol.com wrote:

On Wed, Oct 12, 2011 at 07:33:29AM -0400, Peter Gottlieb wrote:

Once one gets into that region with OSes one gets into a kind of

relativity...

It all depends on what you intend to do with the time of day... 

and where.

Do you intend to schedule events with some required absolute

time accuracy as to when they occur ?  Or time stamp an event with  a
time it occurred ?  Or read something that purports to be the current
absolute time of day in the midst of some code path. Or do one of several
other time related things...

All involve fairly deep questions about what assumptions you

make about both software and processor and system hardware behavior.

Modern processors with multiple pipelines and even multiple

cores and (especially multi level cache) memory systems have layers and
layers of not all that deterministic behavior which introduce
microsecond level jitter in the relationship of the time anything
happens and the time the system reacts to it...

And that is usually dwarfed by the various thread and process

scheduling and interrupt processing latencies in almost any OS - some
versions, properly configured, being much more hard real time than
others.

Most OSes can most readily schedule something on a particular

clock interrupt of a multi KHz rate real time clock interrupt stream -
usually (with normal hardware) based on a not very accurate or terribly
stable crystal.    Whether that something actually happens close to the
time of that clock tick depends very much on thread priorities (usually
set by the user as well as the kernel)  and CPU load and interrupt
activity and how well tuned that particular kernel is with respect to
minimizing long lockouts due to critical regions in kernel code or
contention for locks and resources.  And on top of this there may be
contention and lockouts in the actual hardware...

And most all CPUs have high rate time of day counters that can

be read by the OS - also typically based on a relatively poor frequency
reference - almost always the same one used for the RTC interrupts.
This can be used to establish with high precision the counter time the
counter was read, but the relationship of this to an external event
depends on how the kernel detects the event and with what priority and
latency. And of course the counter time of day is always somewhat off
due to the drift of the frequency reference behind it.

NTP and various related kernel PPS code attempt to use an

accurate stream of 1 PPS (or whatever)  interrupts from a highly stable
and accurate external ticker somewhere to measure and predict the
behavior of the drifting unstable CPU clock so it is possible to compute
a running estimate of  offset between the time of day counter on the CPU
(and the real time clock interrupts) and some external idea (from the 1
PPS) of the real world time of day.  This allows conversion of a
reading from the time of day counter to some notion of real world
time... and in most OSes the kernel does this for you and returns a time
of day rather than time counter reading (or more properly does so if
asked).

And depending on the OS there may also be an ability to attempt

to determine the real world times at which the regular RTC interrupts
happen so an event can be scheduled as close to some absolute time of
day as possible.

However the magnitude of jitter can be significant, and

its statistics not always easy to predict...

And most important if there are multiple sequences of events

occurring it may not be possible to predict or ensure that events that
have a particular time sequence in the outside world appear to have the
same  ordering in time to the software... or even the same sequence to
different threads...

All of which means that using such tools to control or measure

60 Hz (I assume) phase within a degree or so depends very much on system
and software choices - certainly readily possible if done right but at
least on a very slow or heavily loaded or poorly configured platform
also quite possible to occasionally have significant transient error.

Most folks who have played with measuring kernel time base

performance with modern *nix kernels and PPS sync find low microsecond
timing jitter is pretty much the limit... though lots depends on
hardware and software implementation details.

One suspects if one needs anything down in that low us area or

below a FPGA based much more deterministic approach might make sense...
with software and OS only configuring, supervising  and monitoring.

--
Dave Emery N1PRE/AE, die@dieconsulting.com  DIE Consulting, Weston, Mass 02493
"An empty zombie mind with a forlorn barely readable weatherbeaten
'For Rent' sign still vainly flapping outside on the weed encrusted pole - in
celebration of what could have been, but wasn't and is not to be now either."