Hi Derrick,

First problem is with SDR#.
Way back in 2017, I wrote a paper on how to set up SDR#, VB-Cable, and FoxTelem with an RTL-SDR dongle.
It is in the September/October 2017 issue available here. https://launch.amsat.org/The-AMSAT-Journal-2017.

1. Note the settings for SDR# are: Radio: NFM, Filter: Blackman Harris 7, Bandwidth: 16000, Order: 500, Snap to grid: ticked, Step Size: 2.5 KHz, Audio Tab: Sample rate 48000 sample /sec (preset), Input: [MME] Microsoft Sound (Mapper) (preset), Output: [MME] CABLE Input (VB Audio Virtual C, Note: this output setting is required to pipe demodulated signal to the decoder in the next section of this document. Latency (ms): 100, Unity Gain: unticked, Filter Audio: unticked.

As JoAnne says, you will need VB-Cable and Soundmodem. Soundmodem decodes better than AGWPE and Direwolf is pretty good as well. QTMM will work also but you need VB-Cable for any of the decoders.

Next problem: Computer Noise. Once you have SDR# running, check the noise floor on the SDR# spectrum display. If it is not at the bottom of the display, then you need to separate the dongle and laptop via a long USB cable.

Next problem: The RTL-SDR receiver is not very sensitive and you will need a gain antenna (3 Element yagi or similar) to receive much. A 1 M dipole is too short. See: https://www.work-sat.com/antennas.html for some antenna ideas. You may also need a preamp.

Finally, unless there is some ISS packet activity in your region, you may not find many packets. When I have been listening in New Zealand, I only hear about 1 packet per pass. (the beacon when there is no activity).

If anyone is interested, I can write a version using Soundmodem for the journal.

73,
Terry Osborne ZL2BAC

On 20/09/2023 9:01 am, 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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