Doppler tracking

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Marcus PY2PLL

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Jul 9, 2025, 2:53:20 PMJul 9
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Hi all. I installed V1.15 w/o problems, testing RX only with a RTL SDR V4, set PPM using a few references I have at home. For now just testing some CW beacons and a couple of BPSK telemetries and I noticed that Doppler correction is a bit delayed.

Is there any extra config I need to do? The VFOs shows some correction and I don't know if those RTL devices does not follow 1Hz steps.

73!

Alex VE3NEA

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Jul 9, 2025, 10:00:45 PMJul 9
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If Doppler correction is delayed in time, this usually means that either your TLE data are outdated, or your system clock is not accurate. Please see this page for a discussion of all factors affecting the accuracy of Doppler tracking.

Thomas Schuessler

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Jul 9, 2025, 10:14:01 PMJul 9
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Here you go.  Use SkyRoof pushing audio via virtual audio cables to the SSTV software of your choice for decoding.  Information is at Upcoming SSTV events 

Enjoy!



 

Alex VE3NEA

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Jul 10, 2025, 6:14:16 PMJul 10
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Has anyone had success receiving sstv from iss? My rx antenna is only for 70 cm, so I cannot receive these transmissions, but in April when they transmitted on 437.8 MHz I did receive a few images.

Thomas Schuessler

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Jul 10, 2025, 6:36:15 PMJul 10
to SkyRoof, Alex VE3NEA
145.8 is the normal frequency for ISS SSTV.  ARISS is looking at using the format that the Fram2 mission used as it would speed up image transmissions  

The Service Module radio is usually set to 25 watts so with any form of decent antenna, you can pick up signals horizon to horizon.

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