[amsat-bb] Satellite SDR: Seeing IS NOT Hearing

CEE cee at palomarlight.com
Sat Mar 25 19:05:42 UTC 2017


Good topic!

I would suggest that this behavior is not confined to SDR or satellite 
QSOs, but pervades all modes and bands of our hobby. I am guilty of 
this, but more due to excitement than intention. The good advice that is 
not confined just to ham radio, listen first, listen again, always 
applies, or as one local ham suggests, put mind in gear before the 
mouth. Not to sound like Miss Manners, but perhaps one of the unique 
aspects of our hobby is to always be considerate of the other operators. 
I always appreciate those ham's who mentor by example with kindness and 
absence of judgement.

Thanks for mentioning!

Chuck N7BFO

On 3/25/2017 11:29 AM, Clayton Coleman wrote:
> I happen to be a fan of using Software Defined Radio (SDR) to receive
> amateur satellites. It is an inexpensive way to view all the signals
> appearing on a satellite's passband simultaneously.  While I don't
> normally run SDR full time at my station, from time to time I use it
> to monitor activity on busy satellite passes because I can view and
> record all activity.
> As a result of more people using SDR on satellites, I have discovered
> an operating trait that warrants some discussion and evaluation.
> On more than one occasion, I have given a call to a very specific
> station, and instead of my intended target had another SDR-based
> station appear on frequency immediately saying "QRZ? QRZ?" rather than
> wait and listen to who is calling on the frequency. The SDR user saw a
> signal on their waterfall and clicked on it. They "pounced" on what
> they perceived to be another station looking to make contact which
> might not necessarily be the case.
> I've see the same thing happen a few times with pileups.  There is an
> existing pileup in progress when the SDR station comes into the
> footprint. Rather than wait a short period to listen, they click on
> the new signal in their waterfall, and immediately proceed to "QRZ" on
> the frequency of the pileup, sometimes interrupting the flow of
> existing contacts.
> Just today I heard this scenario: Station 1 calls CQ.  Station 2 went
> to answer. The SDR user clicked on the waterfall, heard only part of
> the callsign of Station 2, and proceeded to call Station 2, ignoring
> the possibility that Station 2 was attempting to QSO with someone
> else.
> It seems to me the visual nature of SDR waterfalls is causing a
> temporary lapse in judgement when it comes to a basic ham radio
> principle that we apply to satellite operating -- listen with our ears
> before transmitting.
> SDR is a great listening tool. With great power comes great responsibility.
> 73
> Clayton
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