Relative Newbie to Oscar Satellite Telemetry using SDR's, and need some help from the masters.
*Problem:* Output audio is distorted, although sig strength is relatively strong. Over the past few days, I succeeded in decoding nine packets on AO-95, both on two strong overhead passes, but now have slipped backward. I’ve tried to duplicate my settings used during the successful decodes, but no luck, must be some small, obscure (but critical) setting that I am missing. Setup details follow below:
*Antenna:* 2M and 70CM WIMO X-Quads on 6ft boom (no rotor, both fixed at 35deg). Boom is attached to an aluminum mast and elevated @ 30ft.
*Feedlines:* Both antennas have WIMO factory-made Phasing Cables attached (verified polarity of cables) providing RHCP. Phasing Cables are connected to a CF-4160 Comet Duplexor, then fed to the shack on 70ft of LMR-400. I use the same antennas with my FT-847 for Satellite QSO’s, and it works fine; the setup also works efficiently (despite RHCP) on local repeaters.
*SDR Device:* SDRPlay RSP1A ( I have two, the problem is the same on both) SDR S/W: SDRUNO V1.41
*SDRUNO MAIN WINDOW: *
- Notch: MW/FM Enabled (ON) - FINAL SR: 2000000 - IFBW: 1.536MHz (LIF)
- GAIN: DECIMATION 1 - USB Transfer Mode: ISOCH - IF AGC: Unchecked (OFF)
- OUT: (output device) – VB CABLE-OUT - LOCK OUTPUT & AUDIO LIMITERS – Checked
*SDRUNO RX CONTROL WINDOW: *
- MODE: FM FM MODE: NFM - FILTER: 12K
- ALL ELSE UNCHECKED (OF)
*AMSAT Telemetry Analysis Tool:* V1.11g
- INPUT: -Mode DUV Selected Input: VB CABLE 4800 (AF)
- DUV FILTER: Raised Cosine - Cutoff Freq: 200 Filter: 448
*Virtual Cable CODECS: * Set to 16 Bit 48,000 (Dvd Quality) - Audio Enhancements are OFF
*PC:* Windows 10 Latest Version - Computer has Fast Gaming level CPU and lots of RAM
I can feed downloaded telemetry files into the AMSAT S/W, which decodes fine. The Antennas could be a problem if the polarization is off, but the signal strength is good. I’m convinced the problem is an S/W setting clipping the audio, but hoping to get someone to chime in with a possible solution.
I’ve attached links to three MP3 files of the distorted carrier heard on AO-95 SAFE MODE.
Thanks in advance to anyone that can help me dial in the settings.
Brian, AA5H
MP3 Soundfile Links (Dropbox):
https://www.dropbox.com/s/soqg8m5ub5odcfm/AO95_PASS1.mp3?dl=0
https://www.dropbox.com/s/m9v5q576bqgnw11/AO95_PASS2.mp3?dl=0
https://www.dropbox.com/s/1d92agkvidthcjh/AO95_PASS3.mp3?dl=0