[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

Fwd: Working the FM birds: memory channels for doppler compensation



Henk asked that I share this with the whole -bb. My first reply went just to
him.

---------- Forwarded message ----------
From: Iain McFadyen <ki4hlv@gmail.com>
Date: Jan 2, 2006 10:51 PM
Subject: Re: [amsat-bb] Working the FM birds: memory channels for doppler
compensation
To: Henk - PA3GUO <pa3guo@amsat.org>

There's just one thing missing from your message:

You don't mention the influence that the geometry of the ISS pass with
respect to the observer's station has on the doppler, and hence the sequence
and speed that you switch from one memory to the next:

An overhead pass, (85-90degrees at max elevation) means that the observing
station should stay on channel A till the ISS is directly overhead, and then
switch directly to channel G.

An average pass where the max elevation is around 30degrees, requires a
gradual switch from A to B to C to D etc through to G.

A low pass might mean that the observer should switch from C to D to E only,
during the whole pass, as the doppler observed for a satellite grazing the
horizon is virtually nil.

Best wishes,

Iain McFadyen     KI4HLV   (& G4JMM)



On 1/2/06, Henk - PA3GUO <pa3guo@amsat.org> wrote:
>
> Dear all,
>
> We have discussed in the past days extensively how to improve the
> change of successfully getting over the FM satellites. One of the basic
> requirements is to compensate for Doppler. This can be done by a PC,
> but also much more simple: I use for the FM birds memory channels:
>
> For each of them I have programmed a series of channels. During the
> pass I start with channel A, and then end with channel G. I simply select
> during the pass for the best/strongest receive signal, and by doing so I
> will
> have automatically the correct transmit frequency selected.
>
> I use this for both my TS2000 and the THD7. Honestly, ISS does not need
> the detailed steps below (A,B,C,D,E,F,G), only channels B,D and F would
> also do fine. Nevertheless, I thought maybe someone would be interested to
>
> try this out. For starters on these satellites I have written down my
> memory
> settings for AO51 & ISS.




ISS Voice Repeater
> A 145.803 437.791
> B 145.802 437.794
> C 145.801 437.797
> D 145.800 437.800 (center)
> E 145.799 437.803
> F 145.798 437.806
> G 145.797 437.809
----
Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
Not an AMSAT member? Join now to support the amateur satellite program!
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org



AMSAT Top AMSAT Home