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

Sat Tracking, doppler and CAT control

For some time I have been trying to get the radios to track the beacon on
AO-40 automagically using this CAT interface.  Due to the age of the radios
I have been limited to using the WiSP DDE client since the source is
available and I have been able to modify it to control the radios I have.

I have tried it with both WiSP and WinOrbit.

Now the problems.

WiSP - the orbital calculation problems and the doppler problems of this
program were discussed about a week ago.

WinOrbit - this program seems to "correct" for doppler by the approximately
the right amount but in the wrong direction.  For example AO 40 is moving
AWAY from me at present and I am trying to listen to the middle beacon on S2
(2401.323MHz).  I have given this frequency to WinOrbit.  Since it is moving
away from me I would expect the apparent frequency that I am listening to to
be lower that the actual frequency it is transmitting.  I.e. something just
lower than 2401.323 MHz.  (In fact SatPC32 says the transceiver should tune
to about 14kHz below the beacon at present).  The problem is that WinOrbit
tells the radio to tune to 14kHz ABOVE the beacon (i.e. about 2401.337MHz).

The opposite is hapenning to the uplink frequency.  Since it is moving away
from me I would expect to have to transmit on a slightly higher frequency to
make the actual frequency received by the satellite to be what I expect.
SatPC32 confirms this.  WinOrbit tells the transmitter to do the opposite
and transmi on a slightly lower frequency than what I want.

Have these apparent preoblems with WinOrbit been documented in the past???
Or am I doing something wrong??

Michael VK2JXI

Gee I wish I knew how to get the DDE information out of SatPC32.

Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org