In the past I used a different flavor of SDR, the SDR Play RSP1, to receive spacecraft data such as Fox telemetry, ISS packet data, and telemetry from the likes of CAS-4A & CAS-4B.

Routing speaker output to mic input didn't work for me. I had to use a Virtual Audio Cable which is a piece of software such as VBCable, JackAudio, etc. The output of the SDR was the input to the virtual audio cable. The output of the virtual audio cable was used as the input to AGWPE, input to FoxTelem, etc. VBCable included advanced features such as setting audio levels between the virtual input and virtual output.

Also I found that the UZ7HO Soundmodem was able to receive more packets than AGWPE when the signal to noise ratio wasn't so good. UISS and the other packet engines will only pass fully decoded packets with the correct checksum. So even if the the downlink signal sounds "good" just a single bit error will fail the checksum and you'll see nothing on the output.

The latest packaged zipfile for UISS includes the UZ7HO soundmodem plus the UISS terminal program.



On 9/19/2023 4:02 PM, Derrick Lau via AMSAT-BB wrote:

Good evening all:

 

I am trying to listen to packets transmitted from the ISS on 145.825 MHz using both a horizontally and vertically polarized 1m dipole.  I use RTL-SDR blog USB SDR device plugged into my Windows 10 laptop running SDR#, AGW Packet Engine, and UISS.  I configured my SDR# to use WFM, no shift, filter Hamm-Poisson, bandwidth 600 kHz, order 500, no squelch.  I had the output of SDR# sent to my speaker port, which I plugged into the microphone in port of my USB soundcard that AGW Packet Engine was attached to.  I also had QTMM packet reader listening to that soundcard too.  I did not see any packets come through, which makes no sense as receiving data packets when the ISS passes overhead should be easy, right?

 

Would you have any idea offhand as to what I did wrong please?

 

Thanks,

Derrick

VA3LGT

 


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