[amsat-bb] Re: ARISSAT-1 TLM Problem
fjamesa at telstra.com
Tue Aug 30 06:54:02 PDT 2011
Make sure you have any audio or DSP filters switched off, IF shift to
centre etc. I found the 'tone' control on the FT736 affects the decode
(eventually, by accident).. Also I found that I had a dirty contact on
the soundcard input to my PC's motherboard! After I fixed some of these
things, the decode was okay, mind you I suspect shielded cable would
also be better - I'm using twin speaker lead.. :( . Put the CW at the
marker (as close as possible and adjust for doppler) in USB mode and you
should get some good frames eventually. I've found usually the high
elevation passes are reliable, the low ones at 3-5 degrees just don't
give me enough of a chance to get telemetry sometimes.
The soundcard is usually part of the issue also. My old P-4 shuttle
mainboard AC97 codec style soundcard I think only samples at 48KHz or
something and uses software drivers to pretend the sampling is at other
rates - a proper PCI soundblaster style card or high quality SDR style
soundcard would probably work better. At some stage I might try a better
PC but for now it works some of the time straight from the headphone
socket to line-in on the soundcard.
On 30/08/2011 2:00 AM, Mark L. Hammond wrote:
> Hi Randy,
> Some people have reported that some types of "soundcard interfaces" don't
> work with this telemetry format. Some reports are even from reliable
> sources ;)
> All kidding aside---where are you getting audio out of the radio; what is
> the path to the sound card (straight wire? some type of interface, either
> homebrew or assembled?); and what sound card input are you using?
> This is a case of "simple is better."
> Mark N8MH
> On Mon, Aug 29, 2011 at 1:38 PM, Randy<rswart1 at twcny.rr.com> wrote:
>> Hi all ..
>> I am receiving the CW and TLM ok signal wise ..
>> I tune in the CW to the mark in the CW / BPSK window..
>> But I don't ever receive any telemetry ..
>> Using USB, FT897D ..
>> I use the rig and computer for BPSK31 all the time ..
>> Any ideas or suggestions ?? I even watched the You tube
>> Video that was posted ..
>> It seems like I am doing it correctly .. but must be missing something ..
>> Randy - N2CUA
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