[amsat-bb] Doppler Tracking Discontinuity at TCA - Problem Solved

[Bruce Perens]

Well I guess it could be used in geosynchronous orbit, although it hasn't
been tested to operate with all of the satellites under it :-) wrong unit
and scale selection are a common user error. Not really your fault.

On Sat, Aug 29, 2020, 11:16 AM Hasan N0AN <hbasri.schiers6 at gmail.com> wrote:

> Hi Bruce,
> I'm sure it should be error trapped when an absolutely crazy value is
> input, but I'm not pointing the finger at any programmer, when I, in fact,
> input the wrong, really wrong, value.
>
> I'm just glad I found it and now doppler tracking is perfectly even on an
> 89 degree overhead pass.
>
> Considering all the things done right in the software, way beyond any
> other program I've seen, I'm not going to complain.
>
> The program auto-schedules, tracks, prioritizes and presents for decoding
> AO-73, EO-88, JO-97, AO-91 and AO-92, with no operator intervention
> whatsoever. Any number of birds can be added or deleted.
>
> I can let it run overnight and come down and see every bird's TLM
> perfectly decoded.
>
> If I chose to, I could have it IQ record every pass and go back and decode
> it again later.
>
> The program is absolutely amazing. The fact that it accepted a ridiculous
> input value from me without warning me, is to my way of thinking, small
> potatoes. :-)
>
> (SDR-Radio Console v 3.x )
>
> 5 EL Yagi > 60' Hardline > Duplexer > ARR GasFET > Funcube Pro+ SDR >
> SDRConsole v3
>
> Rotor control by SDRC > PSTrotator
> 15 deg uptilt yagi (5 EL on 2m, 8 EL on 70cm, interlaced, common feedpoint)
>
> Anyone using an SDR that has not used SDRC for controlling it, for
> satellite work, has no idea how enriching an SDR setup with good software
> can be.
>
> 73, N0AN
> Hasan
>
>
> On Sat, Aug 29, 2020 at 12:52 PM Bruce Perens <bruce at perens.com> wrote:
>
>> It's a software bug when the software quietly accepts an impossible
>> parameter.
>>
>> On Sat, Aug 29, 2020, 6:17 AM Hasan N0AN via AMSAT-BB <amsat-bb at amsat.org>
>> wrote:
>>
>>> Over the last week or two, I have been getting a 200 Hz discontinuity
>>> jump
>>> in my uplink frequency at TCA (Time of Closest Approach), also known as
>>> the
>>> zero doppler point. This happened on every bird, every pass. (all mode B,
>>> 70cm up, 2m down)
>>>
>>> AOS was early, LOS was late, and doppler tracking was non-linear and had
>>> the bad jump at TCA.
>>>
>>> Today, thanks to K5GZR and KB7IJ, the problem source was identified and
>>> corrected.
>>>
>>> It was caused by a terrible error in the definition of my Home Altitude.
>>> I
>>> typed in, 350 meters. The program took it 35,000 meters.
>>>
>>> I corrected it and now doppler tracking in SDRC v3.x is perfect.
>>>
>>> If anyone else ever gets a set of symptoms like mine, take a look at your
>>> Home QTH altitude setting. Being off by a factor of 100:1 makes a
>>> difference.
>>>
>>> 73, N0AN
>>>
>>> Hasan
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>>