[time-nuts] Re: A hobby application of precise time or frequency

[rbenward at verizon.net]

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 at lists.febo.com> 
Sent: Saturday, April 12, 2025 8:25 AM
To: time-nuts at lists.febo.com
Cc: Mike <mpb45 at 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.
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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.
> _______________________________________________
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