As there a hobby application of precise time or frequency measurement except for being a time nut?
Maybe the subject line is a bit clickbait but this is a serious question.
Hobby VNA are used to measure impedance for antenna, amplifiers,
filters, PCB's and cables. Many applications for a VNA outside the
professional world.
Hobby spectrum analyzers are user for hunting RFI, measuring harmonics
of active devices, assessing what part of the spectrum is still
available for wireless devices, etc... Again many applications.
But for time and frequency measurement the situation seems to be
different. What are hobby applications for accurate assessment of
stability, time or frequency?
For radio amateurs that operate in the GHz bands the accurate assessment
of the frequencies of their generators is such an application but what
other applications do exist and what are their requirements regarding
accuracy?
I'm purposely excluding the applications where the accuracy is the goal
instead of some usage for accuracy.
Any input is welcome.
Erik.
There are the HAMSCI measurements of path delay variations due to solar
eclipses
amd various other causes.
Dana
On Fri, Apr 11, 2025 at 6:57 AM Erik Kaashoek via time-nuts <
time-nuts@lists.febo.com> wrote:
Maybe the subject line is a bit clickbait but this is a serious question.
Hobby VNA are used to measure impedance for antenna, amplifiers,
filters, PCB's and cables. Many applications for a VNA outside the
professional world.
Hobby spectrum analyzers are user for hunting RFI, measuring harmonics
of active devices, assessing what part of the spectrum is still
available for wireless devices, etc... Again many applications.
But for time and frequency measurement the situation seems to be
different. What are hobby applications for accurate assessment of
stability, time or frequency?
For radio amateurs that operate in the GHz bands the accurate assessment
of the frequencies of their generators is such an application but what
other applications do exist and what are their requirements regarding
accuracy?
I'm purposely excluding the applications where the accuracy is the goal
instead of some usage for accuracy.
Any input is welcome.
Erik.
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
Hi
I’d say that the most common things that pop up here on a regular basis are:
-
I have a stand alone frequency source (XO,TCXO,OCXO,Rb,Cesium,Maser ….) that I bought from (fill in the blank) and I want to see if it works properly.
-
I’ve decided to set up a time server (NTP or something else) and I want to check it out.
-
I’ve bought a GPSDO and want to check it out.
-
I have a mechanical clock (yes the do exist) and want to see how it does
-
I’m monitoring the phase of the local power grid.
-
I’ve decided to design and/or build from scratch items 1, 2, 3 or 4
No, that’s not an exhaustive list. I think it’s enough for right now.
What you need is going to depend a lot on which of those rabbit holes you head down. Inevitably the first step is a “reference source” that is better than (or at least as good as) your “target”. Even there the “better than” depends on what characteristic of the target you are looking at. Then the measurement approach comes in.
Many many many rabbit holes to wander down. Each one of them is a bit unique.
Bob
On Apr 11, 2025, at 6:46 AM, Erik Kaashoek via time-nuts time-nuts@lists.febo.com wrote:
Maybe the subject line is a bit clickbait but this is a serious question.
Hobby VNA are used to measure impedance for antenna, amplifiers, filters, PCB's and cables. Many applications for a VNA outside the professional world.
Hobby spectrum analyzers are user for hunting RFI, measuring harmonics of active devices, assessing what part of the spectrum is still available for wireless devices, etc... Again many applications.
But for time and frequency measurement the situation seems to be different. What are hobby applications for accurate assessment of stability, time or frequency?
For radio amateurs that operate in the GHz bands the accurate assessment of the frequencies of their generators is such an application but what other applications do exist and what are their requirements regarding accuracy?
I'm purposely excluding the applications where the accuracy is the goal instead of some usage for accuracy.
Any input is welcome.
Erik.
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
You build good sources so that you have something to measure.
You build good instruments so that you can measure good sources.
You do these things not because they are easy, but because you thought they would be easy. This is the Tao of Time and Frequency. 😊
-- john
-----Original Message-----
From: Erik Kaashoek via time-nuts time-nuts@lists.febo.com
Sent: Friday, April 11, 2025 3:46 AM
To: time nuts time-nuts@lists.febo.com
Cc: Erik Kaashoek erik@kaashoek.com
Subject: [time-nuts] As there a hobby application of precise time or frequency measurement except for being a time nut?
Maybe the subject line is a bit clickbait but this is a serious question.
Hobby VNA are used to measure impedance for antenna, amplifiers, filters, PCB's and cables. Many applications for a VNA outside the professional world.
Hobby spectrum analyzers are user for hunting RFI, measuring harmonics of active devices, assessing what part of the spectrum is still available for wireless devices, etc... Again many applications.
But for time and frequency measurement the situation seems to be different. What are hobby applications for accurate assessment of stability, time or frequency?
For radio amateurs that operate in the GHz bands the accurate assessment of the frequencies of their generators is such an application but what other applications do exist and what are their requirements regarding accuracy?
I'm purposely excluding the applications where the accuracy is the goal instead of some usage for accuracy.
Any input is welcome.
Erik.
time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe send an email to time-nuts-leave@lists.febo.com
A lot depends on what you consider "precise" of course...
Radio astronomy - more and more people (yeah, probably < 1/2 dozen, but..) are setting up interferometers and precise time knowledge is important.
Radio amateurs on microwave frequencies with narrow band signals need good frequency control (1ppm at 10 GHz is wildly insufficient - you'd like to be within 10 Hz - 1E-9)
There seems to be a bunch of people doing direction finding with a distributed system (perhaps collaborative drone flight) - it's unclear what their requirements are.
There is a hobby radar community with bistatic radars - both at low frequencies (chirp sounders) and at microwave frequencies. The performance of the radar depends on both long term stability (for SAR) and closein (phase noise).
I know a guy with a LTE base station he built in his house - granted he's not putting up multiples, so he doesn't need precise timing (yet).
I suspect none of these are hundreds or thousands of people, but they all have some need to understand time and frequency to a "more than you get with a TinySA or oscilloscope" kind of performance.
On Fri, 11 Apr 2025 12:46:12 +0200, Erik Kaashoek via time-nuts time-nuts@lists.febo.com wrote:
Maybe the subject line is a bit clickbait but this is a serious question.
Hobby VNA are used to measure impedance for antenna, amplifiers,
filters, PCB's and cables. Many applications for a VNA outside the
professional world.
Hobby spectrum analyzers are user for hunting RFI, measuring harmonics
of active devices, assessing what part of the spectrum is still
available for wireless devices, etc... Again many applications.
But for time and frequency measurement the situation seems to be
different. What are hobby applications for accurate assessment of
stability, time or frequency?
For radio amateurs that operate in the GHz bands the accurate assessment
of the frequencies of their generators is such an application but what
other applications do exist and what are their requirements regarding
accuracy?
I'm purposely excluding the applications where the accuracy is the goal
instead of some usage for accuracy.
Any input is welcome.
Erik.
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
Radio astronomy - Check...
Radio amateurs - check...
https://isec.space/wp-content/uploads/2025/02/IMG_0179.jpeg
https://isec.space/wp-content/uploads/2025/04/tlm_18_lens_flare-1024x724-1.jpg
And looking for a decent cesium clock...
Martin
On 4/11/2025 1:26 PM, Jim Lux via time-nuts wrote:
A lot depends on what you consider "precise" of course...
Radio astronomy - more and more people (yeah, probably < 1/2 dozen, but..) are setting up interferometers and precise time knowledge is important.
Radio amateurs on microwave frequencies with narrow band signals need good frequency control (1ppm at 10 GHz is wildly insufficient - you'd like to be within 10 Hz - 1E-9)
There seems to be a bunch of people doing direction finding with a distributed system (perhaps collaborative drone flight) - it's unclear what their requirements are.
There is a hobby radar community with bistatic radars - both at low frequencies (chirp sounders) and at microwave frequencies. The performance of the radar depends on both long term stability (for SAR) and closein (phase noise).
I know a guy with a LTE base station he built in his house - granted he's not putting up multiples, so he doesn't need precise timing (yet).
I suspect none of these are hundreds or thousands of people, but they all have some need to understand time and frequency to a "more than you get with a TinySA or oscilloscope" kind of performance.
On Fri, 11 Apr 2025 12:46:12 +0200, Erik Kaashoek via time-nuts time-nuts@lists.febo.com wrote:
Maybe the subject line is a bit clickbait but this is a serious question.
Hobby VNA are used to measure impedance for antenna, amplifiers,
filters, PCB's and cables. Many applications for a VNA outside the
professional world.
Hobby spectrum analyzers are user for hunting RFI, measuring harmonics
of active devices, assessing what part of the spectrum is still
available for wireless devices, etc... Again many applications.
But for time and frequency measurement the situation seems to be
different. What are hobby applications for accurate assessment of
stability, time or frequency?
For radio amateurs that operate in the GHz bands the accurate assessment
of the frequencies of their generators is such an application but what
other applications do exist and what are their requirements regarding
accuracy?
I'm purposely excluding the applications where the accuracy is the goal
instead of some usage for accuracy.
Any input is welcome.
Erik.
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
Speaking for myself, as a noob to this list, I've seen all these time-related things and never understood how they work.
Especially in media (AES67, SMPTE 2110, genlock, etc) and science, it seems like aspects of time are only growing more important year over year.
If we don't know the fundamentals, how can we advance?
It's also a lot cheaper than cars, guns, etc. (at least that's what I tell myself as I look at masers and old HP gear on eBay...)
-Jeff Geerling
On Apr 11, 2025, at 6:20 PM, Jim Lux via time-nuts time-nuts@lists.febo.com wrote:
A lot depends on what you consider "precise" of course...
Radio astronomy - more and more people (yeah, probably < 1/2 dozen, but..) are setting up interferometers and precise time knowledge is important.
Radio amateurs on microwave frequencies with narrow band signals need good frequency control (1ppm at 10 GHz is wildly insufficient - you'd like to be within 10 Hz - 1E-9)
There seems to be a bunch of people doing direction finding with a distributed system (perhaps collaborative drone flight) - it's unclear what their requirements are.
There is a hobby radar community with bistatic radars - both at low frequencies (chirp sounders) and at microwave frequencies. The performance of the radar depends on both long term stability (for SAR) and closein (phase noise).
I know a guy with a LTE base station he built in his house - granted he's not putting up multiples, so he doesn't need precise timing (yet).
I suspect none of these are hundreds or thousands of people, but they all have some need to understand time and frequency to a "more than you get with a TinySA or oscilloscope" kind of performance.
On Fri, 11 Apr 2025 12:46:12 +0200, Erik Kaashoek via time-nuts time-nuts@lists.febo.com wrote:
Maybe the subject line is a bit clickbait but this is a serious question.
Hobby VNA are used to measure impedance for antenna, amplifiers,
filters, PCB's and cables. Many applications for a VNA outside the
professional world.
Hobby spectrum analyzers are user for hunting RFI, measuring harmonics
of active devices, assessing what part of the spectrum is still
available for wireless devices, etc... Again many applications.
But for time and frequency measurement the situation seems to be
different. What are hobby applications for accurate assessment of
stability, time or frequency?
For radio amateurs that operate in the GHz bands the accurate assessment
of the frequencies of their generators is such an application but what
other applications do exist and what are their requirements regarding
accuracy?
I'm purposely excluding the applications where the accuracy is the goal
instead of some usage for accuracy.
Any input is welcome.
Erik.
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
In order to perform close in phase noise measurements that may take 20+ minutes. I need excellent frequency stability, and in particular, must not have phase jumps.
For amateur radio microwave operation, I also need precise frequency references.
From: Jim Lux via time-nuts time-nuts@lists.febo.com
Sent: Friday, April 11, 2025 12:26:40 PM
To: time-nuts@lists.febo.com time-nuts@lists.febo.com
Cc: Jim Lux jim@luxfamily.com
Subject: [time-nuts] Re: As there a hobby application of precise time or frequency measurement except for being a time nut?
A lot depends on what you consider "precise" of course...
Radio astronomy - more and more people (yeah, probably < 1/2 dozen, but..) are setting up interferometers and precise time knowledge is important.
Radio amateurs on microwave frequencies with narrow band signals need good frequency control (1ppm at 10 GHz is wildly insufficient - you'd like to be within 10 Hz - 1E-9)
There seems to be a bunch of people doing direction finding with a distributed system (perhaps collaborative drone flight) - it's unclear what their requirements are.
There is a hobby radar community with bistatic radars - both at low frequencies (chirp sounders) and at microwave frequencies. The performance of the radar depends on both long term stability (for SAR) and closein (phase noise).
I know a guy with a LTE base station he built in his house - granted he's not putting up multiples, so he doesn't need precise timing (yet).
I suspect none of these are hundreds or thousands of people, but they all have some need to understand time and frequency to a "more than you get with a TinySA or oscilloscope" kind of performance.
On Fri, 11 Apr 2025 12:46:12 +0200, Erik Kaashoek via time-nuts time-nuts@lists.febo.com wrote:
Maybe the subject line is a bit clickbait but this is a serious question.
Hobby VNA are used to measure impedance for antenna, amplifiers,
filters, PCB's and cables. Many applications for a VNA outside the
professional world.
Hobby spectrum analyzers are user for hunting RFI, measuring harmonics
of active devices, assessing what part of the spectrum is still
available for wireless devices, etc... Again many applications.
But for time and frequency measurement the situation seems to be
different. What are hobby applications for accurate assessment of
stability, time or frequency?
For radio amateurs that operate in the GHz bands the accurate assessment
of the frequencies of their generators is such an application but what
other applications do exist and what are their requirements regarding
accuracy?
I'm purposely excluding the applications where the accuracy is the goal
instead of some usage for accuracy.
Any input is welcome.
Erik.
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
Hello, Time-nutters-
A hobby of mine is downloading imagery from the
several NOAA polar-orbit environmental satellites.
These satellites are in a relatively low orbital
altitude of just a few hundred miles. Their downlink
frequency is just under 2 Ghz. Their orbital period
is just under 95 minutes. I track these birds with
an elevation over azimuth 2 meter parabolic dish
antenna which at that frequency has a half-power
beamwidth of just under 2 degrees. Tracking them
requires a relatively accurate time clock. A time
error of just a couple of seconds will result in
loss of signal. If you are interested I can send
a photo of my home-brewed tracking mount.
Mike Baker Micanopy, Florida (just a few miles south
of Gainesville, Florida.
On 4/11/2025 6:46 AM, Erik Kaashoek via time-nuts wrote:
Maybe the subject line is a bit clickbait but this is a serious question.
Hobby VNA are used to measure impedance for antenna, amplifiers,
filters, PCB's and cables. Many applications for a VNA outside the
professional world.
Hobby spectrum analyzers are user for hunting RFI, measuring harmonics
of active devices, assessing what part of the spectrum is still
available for wireless devices, etc... Again many applications.
But for time and frequency measurement the situation seems to be
different. What are hobby applications for accurate assessment of
stability, time or frequency?
For radio amateurs that operate in the GHz bands the accurate
assessment of the frequencies of their generators is such an
application but what other applications do exist and what are their
requirements regarding accuracy?
I'm purposely excluding the applications where the accuracy is the
goal instead of some usage for accuracy.
Any input is welcome.
Erik.
My first exposure to precision timekeeping was by an amateur astronomer who was observing occultations of stars and required a precision clock. This was back in the mid-70’s. He built a WWV receiver and worked with NIST to get estimates of propagation delays to get his best time estimate.
Joe Theobald
jltheobald@cox.net
On Apr 12, 2025, at 5:24 AM, Mike via time-nuts time-nuts@lists.febo.com wrote:
Hello, Time-nutters-
A hobby of mine is downloading imagery from the
several NOAA polar-orbit environmental satellites.
These satellites are in a relatively low orbital
altitude of just a few hundred miles. Their downlink
frequency is just under 2 Ghz. Their orbital period
is just under 95 minutes. I track these birds with
an elevation over azimuth 2 meter parabolic dish
antenna which at that frequency has a half-power
beamwidth of just under 2 degrees. Tracking them
requires a relatively accurate time clock. A time
error of just a couple of seconds will result in
loss of signal. If you are interested I can send
a photo of my home-brewed tracking mount.
Mike Baker Micanopy, Florida (just a few miles south
of Gainesville, Florida.
On 4/11/2025 6:46 AM, Erik Kaashoek via time-nuts wrote:
Maybe the subject line is a bit clickbait but this is a serious question.
Hobby VNA are used to measure impedance for antenna, amplifiers, filters, PCB's and cables. Many applications for a VNA outside the professional world.
Hobby spectrum analyzers are user for hunting RFI, measuring harmonics of active devices, assessing what part of the spectrum is still available for wireless devices, etc... Again many applications.
But for time and frequency measurement the situation seems to be different. What are hobby applications for accurate assessment of stability, time or frequency?
For radio amateurs that operate in the GHz bands the accurate assessment of the frequencies of their generators is such an application but what other applications do exist and what are their requirements regarding accuracy?
I'm purposely excluding the applications where the accuracy is the goal instead of some usage for accuracy.
Any input is welcome.
Erik.
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
Our group (K6MTU) run one of the world wide HF DX propagation beacons, which are
all synced in assigned time slots around the planet. GPS derived. But we
are talking slots in seconds, not nS sync. Credit goes to Kevin Rowett K6TD for building
this. https://www.ncdxf.org/beacon/ I know the ARRL runs a precise
freq test on an assigned schedule too, down to some fractional Hz, which is useful for things like
FT8/JT64 et al (look up Joe Taylor).
and this lash up, we sync/split time slots within each machine, but again, mS
for DMR. https://dmr.wa6ycz.org/ you can get an idea of our sensor networks too.
We sync seismometers against USGS for example. There is a massive sync’d
seismology net here in Calif https://www.cisn.org/ we are trying to join that.
The ham/hobby seismology guys are https://www.seismicnet.com/ all time syncd
tightly.
As hams, we also run a NASA Deep Sky Meteor camera system for meteor
tracking. https://meteorshowers.seti.org/ all NTP syncd.
FYI interesting work going on with
LeoLabs phased array radars, sync’d globally as to
space junk tracking. Alaska vs New Zealand vs Eu and soon mobile. Started
in SRI’s parking lot. Interesting how a ham / research project turned
in to a multi $100M company. All based on precise timing and ranging.
. https://leolabs.space/
Another interesting one is Wayne Rosing’s Las Cumbres Observatory which
runs a global Time Domain Astronomy system, many hams. It is
officially “amateur”, but NSF is now sponsoring some research on event
timing and synchronicity.
https://lco.global/
rgds to all.
g
I have been tinkering around with a wwvb receiver on a teensydino. I feel like it is something that would help me better understand signal processing.
My goal is to better the first lock acquisition of a cheap atomic clock
Get BlueMail for Androidhttps://bluemail.me
On Apr 11, 2025, at 06:56, Erik Kaashoek via time-nuts <time-nuts@lists.febo.commailto:time-nuts@lists.febo.com> wrote:
Maybe the subject line is a bit clickbait but this is a serious question.
Hobby VNA are used to measure impedance for antenna, amplifiers,
filters, PCB's and cables. Many applications for a VNA outside the
professional world.
Hobby spectrum analyzers are user for hunting RFI, measuring harmonics
of active devices, assessing what part of the spectrum is still
available for wireless devices, etc... Again many applications.
But for time and frequency measurement the situation seems to be
different. What are hobby applications for accurate assessment of
stability, time or frequency?
For radio amateurs that operate in the GHz bands the accurate assessment
of the frequencies of their generators is such an application but what
other applications do exist and what are their requirements regarding
accuracy?
I'm purposely excluding the applications where the accuracy is the goal
instead of some usage for accuracy.
Any input is welcome.
Erik.
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
for fun and verification of the common source I built a a phase
comparation circuit for a GPS derived 60kHz and the WWVb, you could see
how the propagation time is changing while the sun is moving
73 KO6exs
Alex
On 4/13/2025 12:38 PM, chris elfpen.com via time-nuts wrote:
I have been tinkering around with a wwvb receiver on a teensydino. I feel like it is something that would help me better understand signal processing.
My goal is to better the first lock acquisition of a cheap atomic clock
Get BlueMail for Androidhttps://bluemail.me
On Apr 11, 2025, at 06:56, Erik Kaashoek via time-nuts <time-nuts@lists.febo.commailto:time-nuts@lists.febo.com> wrote:
Maybe the subject line is a bit clickbait but this is a serious question.
Hobby VNA are used to measure impedance for antenna, amplifiers,
filters, PCB's and cables. Many applications for a VNA outside the
professional world.
Hobby spectrum analyzers are user for hunting RFI, measuring harmonics
of active devices, assessing what part of the spectrum is still
available for wireless devices, etc... Again many applications.
But for time and frequency measurement the situation seems to be
different. What are hobby applications for accurate assessment of
stability, time or frequency?
For radio amateurs that operate in the GHz bands the accurate assessment
of the frequencies of their generators is such an application but what
other applications do exist and what are their requirements regarding
accuracy?
I'm purposely excluding the applications where the accuracy is the goal
instead of some usage for accuracy.
Any input is welcome.
Erik.
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
Hey Mike,
I was using WXTOIMG software but on the 136.5MHz frequencies to capture images from these polar orbiters. I used a home built Quadrifilar Helix antenna (QFH) and an ICOM PCR-1000 @50KHz bandwidth to receive the signals. I think the last image I captured was 15 years ago. With GOES, I think the polar orbiters are going obsolete and not being replaced.
Bob
-----Original Message-----
From: Mike via time-nuts time-nuts@lists.febo.com
Sent: Saturday, April 12, 2025 8:25 AM
To: time-nuts@lists.febo.com
Cc: Mike mpb45@clanbaker.org
Subject: [time-nuts] Re: A hobby application of precise time or frequency
Importance: High
Hello, Time-nutters-
A hobby of mine is downloading imagery from the several NOAA polar-orbit environmental satellites.
These satellites are in a relatively low orbital altitude of just a few hundred miles. Their downlink frequency is just under 2 Ghz. Their orbital period is just under 95 minutes. I track these birds with an elevation over azimuth 2 meter parabolic dish antenna which at that frequency has a half-power beamwidth of just under 2 degrees. Tracking them requires a relatively accurate time clock. A time error of just a couple of seconds will result in loss of signal. If you are interested I can send a photo of my home-brewed tracking mount.
Mike Baker Micanopy, Florida (just a few miles south of Gainesville, Florida.
On 4/11/2025 6:46 AM, Erik Kaashoek via time-nuts wrote:
Maybe the subject line is a bit clickbait but this is a serious question.
Hobby VNA are used to measure impedance for antenna, amplifiers,
filters, PCB's and cables. Many applications for a VNA outside the
professional world.
Hobby spectrum analyzers are user for hunting RFI, measuring harmonics
of active devices, assessing what part of the spectrum is still
available for wireless devices, etc... Again many applications.
But for time and frequency measurement the situation seems to be
different. What are hobby applications for accurate assessment of
stability, time or frequency?
For radio amateurs that operate in the GHz bands the accurate
assessment of the frequencies of their generators is such an
application but what other applications do exist and what are their
requirements regarding accuracy?
I'm purposely excluding the applications where the accuracy is the
goal instead of some usage for accuracy.
Any input is welcome.
Erik.
time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe send an email to time-nuts-leave@lists.febo.com
On 15/04/2025 00:10, rbenward--- via time-nuts wrote:
Hey Mike,
I was using WXTOIMG software but on the 136.5MHz frequencies to capture images from these polar orbiters. I used a home built Quadrifilar Helix antenna (QFH) and an ICOM PCR-1000 @50KHz bandwidth to receive the signals. I think the last image I captured was 15 years ago. With GOES, I think the polar orbiters are going obsolete and not being replaced.
Bob
Actually the next generation of polar orbiters are due to be launched starting
this year. More information:
https://www.eumetsat.int/metop-sg
The newest 137 MHz orbiters are using digital image transmission to obtain about
ten times the ground resolution and more channels.
https://usradioguy.com/meteor-satellite/
Cheers,
David
SatSignal Software - Quality software for you
Web: https://www.satsignal.eu
Email: davidtaylor@writeme.com
BlueSky: @gm8arv.bsky.social, Twitter: @gm8arv
I was using WXTOIMG software but on the 136.5MHz frequencies to capture images from these polar
orbiters. I used a home built Quadrifilar Helix antenna (QFH) and an ICOM PCR-1000 @50KHz bandwidth
to receive the signals. I think the last image I captured was 15 years ago. With GOES, I think the
polar orbiters are going obsolete and not being replaced.
Bob
Actually the next generation of polar orbiters are due to be launched starting this year. More
information:
GOES (or any geostationary satellite) can only image with reasonable resolution up to /-60 degree
latitude, whereas polar regions are fundamental information for modelling weather patterns.
The newer digital polar weather satellite decoding is a bit more involved than the POES analog signals
http://jmfriedt.free.fr/glmf_meteor_eng.pdf but do provide opportunities for spaceborne LEO time
transfer opportunities.
Best, Jean-Michel
OK, I feel better. My images are no worse than yours. I always wondered
how people get those clear top to bottom images. Apparently, it's not so
easy.
Bob
-----Original Message-----
From: David Taylor via time-nuts time-nuts@lists.febo.com
Sent: Tuesday, April 15, 2025 2:33 AM
To: time-nuts@lists.febo.com
Cc: David Taylor david-taylor@blueyonder.co.uk
Subject: [time-nuts] Re: A hobby application of precise time or frequency
Importance: High
On 15/04/2025 00:10, rbenward--- via time-nuts wrote:
Hey Mike,
I was using WXTOIMG software but on the 136.5MHz frequencies to capture
images from these polar orbiters. I used a home built Quadrifilar Helix
antenna (QFH) and an ICOM PCR-1000 @50KHz bandwidth to receive the signals.
I think the last image I captured was 15 years ago. With GOES, I think the
polar orbiters are going obsolete and not being replaced.
Bob
Actually the next generation of polar orbiters are due to be launched
starting this year. More information:
https://www.eumetsat.int/metop-sg
The newest 137 MHz orbiters are using digital image transmission to obtain
about ten times the ground resolution and more channels.
https://usradioguy.com/meteor-satellite/
Cheers,
David
SatSignal Software - Quality software for you
Web: https://www.satsignal.eu
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As Jim (and others) have mentioned: Radio Astronomy.
I'm a volunteer at the historic 25m radio astronomy dish in Dwingeloo,
the Netherlands, and I would consider myself our local 'time nut',
amongst the many hats I wear in this group.
Some of the things we do which require accurate time or frequency signals:
Hydrogen line observing - the Doppler shift of the 21cm line at
1420.40575 MHz can be used to model the spiral arms of our Milky Way. We
also observe the redshift to other galaxies, and other spectral lines
such as the OH lines. Accuracy requirements are quite modest, on the
order of a PPM.
Satellite tracking - Doppler information is crucial to tracking your
spacecraft. We were an official NASA (volunteer!) ground station during
the ARTEMIS I mission, and are planning to join the future missions as
well. The accuracy requirement here is much higher, ideally sub-Hz at
2.5 GHz.
Pulsar timing - measuring the time of arrival of the pulsar signal
allows you to determine many physical parameters, such as the size of
the Earth's orbit, a very precise location of the pulsar in the sky, and
the slowdown of the pulsar as it loses its energy. Here the requirement
is very good stability over many years.
Interferometry: We've participated in VLBI observations, together with
other professional dishes in the European VLBI network, and got great
fringes. For us, this requires phase stability at up to 5 GHz, for
periods of up to 15 minutes (after that, the ionosphere starts to
destroy coherence anyway).
We're putting up a new 3m dish, and are planning to do interferometry
and holography of our big dish this way.
We have several Rubidium clocks, but mostly we use a dark fiber White
Rabbit link of 35km length, which is connected to a 'nearby' Hydrogen
maser at the WSRT radio telescope. We ended up trenching and splicing
the last 250 m of fiber ourselves, in 2018.
Regards, Paul Boven - 73 de PE1NUT.
On 4/11/25 19:26, Jim Lux via time-nuts wrote:
A lot depends on what you consider "precise" of course...
Radio astronomy - more and more people (yeah, probably < 1/2 dozen, but..) are setting up interferometers and precise time knowledge is important.
Radio amateurs on microwave frequencies with narrow band signals need good frequency control (1ppm at 10 GHz is wildly insufficient - you'd like to be within 10 Hz - 1E-9)
There seems to be a bunch of people doing direction finding with a distributed system (perhaps collaborative drone flight) - it's unclear what their requirements are.
There is a hobby radar community with bistatic radars - both at low frequencies (chirp sounders) and at microwave frequencies. The performance of the radar depends on both long term stability (for SAR) and closein (phase noise).
I know a guy with a LTE base station he built in his house - granted he's not putting up multiples, so he doesn't need precise timing (yet).
I suspect none of these are hundreds or thousands of people, but they all have some need to understand time and frequency to a "more than you get with a TinySA or oscilloscope" kind of performance.
On Fri, 11 Apr 2025 12:46:12 +0200, Erik Kaashoek via time-nuts time-nuts@lists.febo.com wrote:
Maybe the subject line is a bit clickbait but this is a serious question.
Hobby VNA are used to measure impedance for antenna, amplifiers,
filters, PCB's and cables. Many applications for a VNA outside the
professional world.
Hobby spectrum analyzers are user for hunting RFI, measuring harmonics
of active devices, assessing what part of the spectrum is still
available for wireless devices, etc... Again many applications.
But for time and frequency measurement the situation seems to be
different. What are hobby applications for accurate assessment of
stability, time or frequency?
For radio amateurs that operate in the GHz bands the accurate assessment
of the frequencies of their generators is such an application but what
other applications do exist and what are their requirements regarding
accuracy?
I'm purposely excluding the applications where the accuracy is the goal
instead of some usage for accuracy.
Any input is welcome.
Erik.
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To unsubscribe send an email to time-nuts-leave@lists.febo.com
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Paul: Are you a member of SARA?
https://radio-astronomy.org/
Lester B Veenstra K1YCM MØYCM W8YCM 6Y6Y W8YCM/6Y 6Y8LV (Reformed USNSG
CTM1)
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Keyser WV 26726 USA
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-----Original Message-----
From: Paul Boven via time-nuts [mailto:time-nuts@lists.febo.com]
Sent: Friday, April 25, 2025 7:34 AM
To: time-nuts@lists.febo.com
Cc: Paul Boven
Subject: [time-nuts] Re: As there a hobby application of precise time or
frequency measurement except for being a time nut?
As Jim (and others) have mentioned: Radio Astronomy.
I'm a volunteer at the historic 25m radio astronomy dish in Dwingeloo,
the Netherlands, and I would consider myself our local 'time nut',
amongst the many hats I wear in this group.
Some of the things we do which require accurate time or frequency signals:
Hydrogen line observing - the Doppler shift of the 21cm line at
1420.40575 MHz can be used to model the spiral arms of our Milky Way. We
also observe the redshift to other galaxies, and other spectral lines
such as the OH lines. Accuracy requirements are quite modest, on the
order of a PPM.
Satellite tracking - Doppler information is crucial to tracking your
spacecraft. We were an official NASA (volunteer!) ground station during
the ARTEMIS I mission, and are planning to join the future missions as
well. The accuracy requirement here is much higher, ideally sub-Hz at
2.5 GHz.
Pulsar timing - measuring the time of arrival of the pulsar signal
allows you to determine many physical parameters, such as the size of
the Earth's orbit, a very precise location of the pulsar in the sky, and
the slowdown of the pulsar as it loses its energy. Here the requirement
is very good stability over many years.
Interferometry: We've participated in VLBI observations, together with
other professional dishes in the European VLBI network, and got great
fringes. For us, this requires phase stability at up to 5 GHz, for
periods of up to 15 minutes (after that, the ionosphere starts to
destroy coherence anyway).
We're putting up a new 3m dish, and are planning to do interferometry
and holography of our big dish this way.
We have several Rubidium clocks, but mostly we use a dark fiber White
Rabbit link of 35km length, which is connected to a 'nearby' Hydrogen
maser at the WSRT radio telescope. We ended up trenching and splicing
the last 250 m of fiber ourselves, in 2018.
Regards, Paul Boven - 73 de PE1NUT.
On 4/11/25 19:26, Jim Lux via time-nuts wrote:
A lot depends on what you consider "precise" of course...
Radio astronomy - more and more people (yeah, probably < 1/2 dozen, but..)
are setting up interferometers and precise time knowledge is important.
Radio amateurs on microwave frequencies with narrow band signals need good
frequency control (1ppm at 10 GHz is wildly insufficient - you'd like to be
within 10 Hz - 1E-9)
There seems to be a bunch of people doing direction finding with a
distributed system (perhaps collaborative drone flight) - it's unclear what
their requirements are.
There is a hobby radar community with bistatic radars - both at low
frequencies (chirp sounders) and at microwave frequencies. The performance
of the radar depends on both long term stability (for SAR) and closein
(phase noise).
I know a guy with a LTE base station he built in his house - granted he's
not putting up multiples, so he doesn't need precise timing (yet).
I suspect none of these are hundreds or thousands of people, but they all
have some need to understand time and frequency to a "more than you get with
a TinySA or oscilloscope" kind of performance.
On Fri, 11 Apr 2025 12:46:12 +0200, Erik Kaashoek via time-nuts
time-nuts@lists.febo.com wrote:
Maybe the subject line is a bit clickbait but this is a serious question.
Hobby VNA are used to measure impedance for antenna, amplifiers,
filters, PCB's and cables. Many applications for a VNA outside the
professional world.
Hobby spectrum analyzers are user for hunting RFI, measuring harmonics
of active devices, assessing what part of the spectrum is still
available for wireless devices, etc... Again many applications.
But for time and frequency measurement the situation seems to be
different. What are hobby applications for accurate assessment of
stability, time or frequency?
For radio amateurs that operate in the GHz bands the accurate assessment
of the frequencies of their generators is such an application but what
other applications do exist and what are their requirements regarding
accuracy?
I'm purposely excluding the applications where the accuracy is the goal
instead of some usage for accuracy.
Any input is welcome.
Erik.
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
On 2025-04-25 07:34, Paul Boven via time-nuts wrote:
As Jim (and others) have mentioned: Radio Astronomy.
I'm a volunteer at the historic 25m radio astronomy dish in Dwingeloo,
the Netherlands, and I would consider myself our local 'time nut',
amongst the many hats I wear in this group.
Some of the things we do which require accurate time or frequency
signals:
Dwingeloo also participated recently in planetary radar, receiving
returns from Venus, which also requires accurate station time.
https://www.camras.nl/en/blog/2025/first-venus-bounce-with-the-dwingeloo-telescope/
Hydrogen line observing - the Doppler shift of the 21cm line at
1420.40575 MHz can be used to model the spiral arms of our Milky Way.
We also observe the redshift to other galaxies, and other spectral
lines such as the OH lines. Accuracy requirements are quite modest, on
the order of a PPM.
Satellite tracking - Doppler information is crucial to tracking your
spacecraft. We were an official NASA (volunteer!) ground station during
the ARTEMIS I mission, and are planning to join the future missions as
well. The accuracy requirement here is much higher, ideally sub-Hz at
2.5 GHz.
Pulsar timing - measuring the time of arrival of the pulsar signal
allows you to determine many physical parameters, such as the size of
the Earth's orbit, a very precise location of the pulsar in the sky,
and the slowdown of the pulsar as it loses its energy. Here the
requirement is very good stability over many years.
Interferometry: We've participated in VLBI observations, together with
other professional dishes in the European VLBI network, and got great
fringes. For us, this requires phase stability at up to 5 GHz, for
periods of up to 15 minutes (after that, the ionosphere starts to
destroy coherence anyway).
VLBI famously requires a very good local oscillator - you need phase
stability to << a wavelength over the VLBI integration interval
(typically, 1 second). At cm wavelengths that means something like
10^-13 at one second is the goal, which
is tough to do with cell or beam atomic clocks, and which is why most
VLBI networks use hydrogen masers as their frequency standards.
I have done X band VLBI with a Rb standard, and the data were OK, but
with a noticeable increase in short term frequency noise.
However, not only do the atmosphere (water vapor!) and ionosphere cause
a loss of coherence at periods of tens of minutes (at cm wavelengths -
it's tens of seconds at 1 mm) but longer term clock instabilities can be
estimated from the VLBI data itself.
That has led to interest in using things like active optical fibers
(without frequency stabilization) as local oscillators.
Regards
Marshall Eubanks
We're putting up a new 3m dish, and are planning to do interferometry
and holography of our big dish this way.
We have several Rubidium clocks, but mostly we use a dark fiber White
Rabbit link of 35km length, which is connected to a 'nearby' Hydrogen
maser at the WSRT radio telescope. We ended up trenching and splicing
the last 250 m of fiber ourselves, in 2018.
Regards, Paul Boven - 73 de PE1NUT.
On 4/11/25 19:26, Jim Lux via time-nuts wrote:
A lot depends on what you consider "precise" of course...
Radio astronomy - more and more people (yeah, probably < 1/2 dozen,
but..) are setting up interferometers and precise time knowledge is
important.
Radio amateurs on microwave frequencies with narrow band signals
need good frequency control (1ppm at 10 GHz is wildly insufficient -
you'd like to be within 10 Hz - 1E-9)There seems to be a bunch of people doing direction finding with a
distributed system (perhaps collaborative drone flight) - it's unclear
what their requirements are.There is a hobby radar community with bistatic radars - both at low
frequencies (chirp sounders) and at microwave frequencies. The
performance of the radar depends on both long term stability (for SAR)
and closein (phase noise).I know a guy with a LTE base station he built in his house - granted
he's not putting up multiples, so he doesn't need precise timing
(yet).I suspect none of these are hundreds or thousands of people, but they
all have some need to understand time and frequency to a "more than
you get with a TinySA or oscilloscope" kind of performance.On Fri, 11 Apr 2025 12:46:12 +0200, Erik Kaashoek via time-nuts
time-nuts@lists.febo.com wrote:Maybe the subject line is a bit clickbait but this is a serious
question.
Hobby VNA are used to measure impedance for antenna, amplifiers,
filters, PCB's and cables. Many applications for a VNA outside the
professional world.
Hobby spectrum analyzers are user for hunting RFI, measuring harmonics
of active devices, assessing what part of the spectrum is still
available for wireless devices, etc... Again many applications.
But for time and frequency measurement the situation seems to be
different. What are hobby applications for accurate assessment of
stability, time or frequency?
For radio amateurs that operate in the GHz bands the accurate
assessment
of the frequencies of their generators is such an application but what
other applications do exist and what are their requirements regarding
accuracy?
I'm purposely excluding the applications where the accuracy is the
goal
instead of some usage for accuracy.
Any input is welcome.
Erik.
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe send an email to time-nuts-leave@lists.febo.com