I was hoping to get a partial decode on the camera test this am, but because it was a low pass (6deg) for me, the stronger signal from CAS-4B (also overhead at the time) high speed telemetry signal captured the telem decoder. Is there a way to prevent these stronger signals from over-powering the telem decoder AO-92 target frequency? (Don't read this as a complaint as having too many satellites)
thanks, 73 Christy KB6LTY DM14
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I have a FT847. Anyone have a suggested list of Sats to input in the memory?? Hal/WB4AEG
Hi Hal,
I too have an FT-847, however instead of programming satellites into the memories, I let SatPC32 'get it right' for me, along with tuning for doppler and handling tones etc. It's a far easier solution.
Otherwise, you could go through the AMSAT OSCAR Status page, and grab all the birds you're likely to want to work from that list.
73, John (XLX)
-----Original Message----- From: AMSAT-BB amsat-bb-bounces@amsat.org On Behalf Of Hal Dale Sent: 12 July 2018 19:09 Cc: amsat-bb@amsat.org Subject: Re: [amsat-bb] AO-92 1626UTC 7/12 PASS CAMERA TEST
I have a FT847. Anyone have a suggested list of Sats to input in the memory?? Hal/WB4AEG _______________________________________________ Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
We also experienced a good bit of QRM on the the AO-92 downlink towards the end of the pass previous to the one mentioned in the subject line (~1450 UTC) during our demo yesterday. We had the same problem (though less of an effect) the day prior during testing of our setup, but slightly offset in time (the QRM showed up just before the 7/11 ~1515 UTC AO-92 pass). Definitely had the doppler shift features indicating it was another satellite in the 2m band and close to the AO-92 downlink. On the 7/12 1450UTC pass, the interferer was strong enough that it 'edged out' the AO-92 downlink and was captured by our doppler correction loop (ending the demo, but that was OK because we already got a few images direct, and then I jumped to the website to show them more images recovered by the community).
We used GNU Radio married to FoxTelem for the passes. I have the recorded IQ files for both passes where the , but haven't had a chance to go back and investigate what exactly was going on or hunt for which bird was the 'culprit' though now it seems CAS-4B is a good suspect......If I get a chance I'll play around with the flowgraph and see if I can manually tune in the AO-92 signal and filter out the interferer to see if I can recover any more telemetry/camera pieces.
Just offering another data point and similar experiences...
-Zach, KJ4QLP
Research Associate Aerospace Systems Lab Ted & Karyn Hume Center for National Security & Technology Virginia Polytechnic Institute & State University Work Phone: 540-231-4174 Cell Phone: 540-808-6305
On 7/13/2018 4:29 AM, John wrote:
Hi Hal,
I too have an FT-847, however instead of programming satellites into the memories, I let SatPC32 'get it right' for me, along with tuning for doppler and handling tones etc. It's a far easier solution.
Otherwise, you could go through the AMSAT OSCAR Status page, and grab all the birds you're likely to want to work from that list.
73, John (XLX)
-----Original Message----- From: AMSAT-BB amsat-bb-bounces@amsat.org On Behalf Of Hal Dale Sent: 12 July 2018 19:09 Cc: amsat-bb@amsat.org Subject: Re: [amsat-bb] AO-92 1626UTC 7/12 PASS CAMERA TEST
I have a FT847. Anyone have a suggested list of Sats to input in the memory?? Hal/WB4AEG _______________________________________________ Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Christy,
Nice problem, usually, to have a crowded sky. ;) That is a tough geometry. I had a similar problem with my earlier pass due to a thick stand of trees which attenuated the AO-92 signal.
You didn't mention your equipment. The typical Elk/Arrow has a wide beamwidth, which is normally ideal, but makes it hard to reject a second signal in the same general area. If you have an antenna with a narrower beamwidth, you can sometimes reduce the interfering signal while still getting a usable signal for the target by careful pointing. FoxTelem with a FCD does a great job, but as you know it can be "spoofed" by a much stronger but similar signal. You can manually "steer" it a bit.
I have a system where the dongle feeds SDR#, and then audio to FoxTelem. This does allow you to narrow the RX passband, and tune precisely to the desired signal. You can ignore CAS-4B so long as it is near but not overlapping AO-92, which sometimes happens due to Doppler. You do need to keep AO-92 carefully centered, either manually or with computer control. This general approach is discussed in the FoxTelem manual.
While not hard, this approach is a bit more complicated, and may not be justified for very occasional work. Fortunately CAS-4B seldom causes a problem with the normal transponder downlink.
73,
Alan WA4SCA
<-----Original Message----- <From: AMSAT-BB [mailto:amsat-bb-bounces@amsat.org] On Behalf Of christy <hunter <Sent: Thursday, July 12, 2018 12:36 PM <To: amsat-bb@amsat.org <Subject: [amsat-bb] AO-92 1626UTC 7/12 PASS CAMERA TEST < <I was hoping to get a partial decode on the camera test this am, but <because it was a low pass (6deg) for me, the stronger signal from CAS-4B <(also overhead at the time) high speed telemetry signal captured the <telem decoder. Is there a way to prevent these stronger signals from <over-powering the telem decoder AO-92 target frequency? (Don't read this <as a complaint as having too many satellites) < <thanks, 73 Christy KB6LTY DM14 < < <--- <This email has been checked for viruses by AVG. <https://www.avg.com < <_______________________________________________ <Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available <to all interested persons worldwide without requiring membership. Opinions <expressed <are solely those of the author, and do not reflect the official views of AMSAT- <NA. <Not an AMSAT-NA member? Join now to support the amateur satellite <program! <Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
What Alan said for sure. The previous pass they crossed paths very near to TCA. 91 was a bit stronger, but there was QRM. If it makes you feel better, no one got any images or pieces even on that last pass.
73, Drew KO4MA
-----Original Message----- From: AMSAT-BB amsat-bb-bounces@amsat.org On Behalf Of Alan Sent: Thursday, July 12, 2018 2:49 PM To: 'christy hunter' cchunter3@mindspring.com; amsat-bb@amsat.org Subject: Re: [amsat-bb] AO-92 1626UTC 7/12 PASS CAMERA TEST
Christy,
Nice problem, usually, to have a crowded sky. ;) That is a tough geometry. I had a similar problem with my earlier pass due to a thick stand of trees which attenuated the AO-92 signal.
You didn't mention your equipment. The typical Elk/Arrow has a wide beamwidth, which is normally ideal, but makes it hard to reject a second signal in the same general area. If you have an antenna with a narrower beamwidth, you can sometimes reduce the interfering signal while still getting a usable signal for the target by careful pointing. FoxTelem with a FCD does a great job, but as you know it can be "spoofed" by a much stronger but similar signal. You can manually "steer" it a bit.
I have a system where the dongle feeds SDR#, and then audio to FoxTelem. This does allow you to narrow the RX passband, and tune precisely to the desired signal. You can ignore CAS-4B so long as it is near but not overlapping AO-92, which sometimes happens due to Doppler. You do need to keep AO-92 carefully centered, either manually or with computer control. This general approach is discussed in the FoxTelem manual.
While not hard, this approach is a bit more complicated, and may not be justified for very occasional work. Fortunately CAS-4B seldom causes a problem with the normal transponder downlink.
73,
Alan WA4SCA
<-----Original Message----- <From: AMSAT-BB [mailto:amsat-bb-bounces@amsat.org] On Behalf Of christy <hunter <Sent: Thursday, July 12, 2018 12:36 PM <To: amsat-bb@amsat.org <Subject: [amsat-bb] AO-92 1626UTC 7/12 PASS CAMERA TEST < <I was hoping to get a partial decode on the camera test this am, but <because it was a low pass (6deg) for me, the stronger signal from CAS-4B <(also overhead at the time) high speed telemetry signal captured the <telem decoder. Is there a way to prevent these stronger signals from <over-powering the telem decoder AO-92 target frequency? (Don't read this <as a complaint as having too many satellites) < <thanks, 73 Christy KB6LTY DM14 < < <--- <This email has been checked for viruses by AVG. <https://www.avg.com < <_______________________________________________ <Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available <to all interested persons worldwide without requiring membership. Opinions <expressed <are solely those of the author, and do not reflect the official views of AMSAT- <NA. <Not an AMSAT-NA member? Join now to support the amateur satellite <program! <Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
_______________________________________________ Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
participants (6)
-
Alan -
Andrew Glasbrenner -
christy hunter -
Hal Dale -
John -
Zach Leffke