[amsat-bb] FW: Wanted: ARISSat-1 BPSK1000 recordings

[Alan Cresswell]

Hi Douglas,

 

I have some recordings but I am not sure they will be of much use.

However I thought it might be useful to share my experiences with the
telemetry.

 

I monitored the audio downlink on the first two passes and the data downlink
on three passes.   I used the ARISSATtlm-0.47 software for decoding on the
data passes.

On the first pass I could not clearly see the CW signal on the tuning
indicator so no decode of the CW or data.  The next two pass I had good CW
decode and could line up the CW signal OK but no decode.  After the passes
(naturally) I re-read the article in the AMSAT journal and realized the
importance of the 48k, 16 bit sample rate.  The article claims that the
ARISSATtlm configures the sound card to these values but when I checked the
sound card was still at my normal 44.1k sample rate.  Perhaps the software
sets it to 48k and then sets it back to its previous value but I suspect
not.

I re-sampled my recording at 48k but still no decode.  I noticed also that
the CW decode from the recording was not as good as the original so perhaps
the recording was at fault.

To test this re-sampling method I re-sampled the test wave file at 44.1k and
confirmed that it would not decode.  I then re-sampled this file at 48k and
once again it would decode.

(i.e. the re-sampling worked OK.)   This again perhaps pointed to a problem
with the quality of my recording.

 

Some observations.

a  Make sure the sound card output is set to 48k/16bit.

b  I noticed that the live telemetry sounded quite different from the test
wave file.  The data signal was much more obvious.

c  When running the test file Excel complains that data has been lost from
the CSV file because the number of columns exceeded the 256 column limit.
(Excel opens OK and all 256 columns contain data)

d  I notice that when I use the 0.7 software to decode the test file, the
software remains active until I close it.  When I attempt to decode my
recordings the software always closes itself when the file ends.

 

73

Alan

ZL2BX

 

  _____  

From: amsat-bb-bounces at amsat.org [mailto:amsat-bb-bounces at amsat.org] On
Behalf Of Douglas Quagliana
Sent: Saturday, 12 February 2011 23:59
To: amsat
Subject: [amsat-bb] Wanted: ARISSat-1 BPSK1000 recordings

 

If anyone made a recording of ARISSat-1's BPSK1000 signal (either an SDR
recording or just a regular recording), then I'd like to get a copy. 
Please email me if you made a recording of the BPSK1000 signal.
73,
Douglas KA2UPW/5


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