[Elecraft] Aircraft Doppler shift

Fred Jensen k6dgwnv at gmail.com
Mon Jul 24 14:17:22 EDT 2023


We're just a bit west of the approach to KRNO 17R.  A/C normally land 
south and I can just barely discern doppler spreading on 40 m on the P3 
at 4 kHz span.  Last winter when there was FTx on 10, the spreading was 
more pronounced.  I guess Christian Andreas Doppler would tell me ... "Duh!"

73,

Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

Jim Brown wrote on 7/23/2023 7:45 PM:
> Andy,
>
> My observations here are consistent with yours -- I regularly see 
> Doppler on either side of a signal, sometimes even both sides, which 
> would be consistent with multiple aircraft. And without Doppler, I 
> always see low level sidebands on locals that are approximately 
> symmetrical with the P3/SVGA cranked to minimum span. Last season, 
> Trey and I were seeing a neighbor being much wider than normal. Trey 
> went to his shack to help him figure it out while I watched on the P3. 
> It was coming from his Expert amp, and we managed a modest 
> improvement. If I'm remembering correctly, he was running the amp on 
> the low voltage setting.
>
> 73, Jim K9YC
>
>  On 7/23/2023 6:30 PM, Andy Durbin wrote:
>> The aircraft that can be expected to cause Doppler shifted reflection 
>> in the Phoenix Class B airspace are transport aircraft following 
>> Standard Instrument Departures (SID) and Standard Terminal Arrival 
>> Route (STAR) routings.   My QTH is about a mile from a KPHX STAR 
>> (BRUSR ONE).  On a busy day with winds out of the East they go by at 
>> about one per minute.  As they approach from the North I would expect 
>> reflections with a higher frequency.  After they pass and move to the 
>> South I would expect  reflections with a lower frequency. With 
>> multiple aircraft following  the same route I would expect a mix of 
>> reflected signal frequencies spread on each side of the transmitted 
>> signal frequency.
>
>
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