[amsat-bb] Re: uplink & downlink mode question

[i8cvs]

----- Original Message -----
From: "Jean-François Ménard" <jf.va2ss at gmail.com>
To: "AMSAT Mailing list" <amsat-bb at amsat.org>
Sent: Wednesday, December 30, 2009 2:47 PM
Subject: [amsat-bb] uplink & downlink mode question


Hi, I', relatively new to sats and I'm still a bit confused about one
topic and I would like to make this very clear in my mind....

It is regarding "uplink and downlink" mode configured for each satellite.

Ok for FM, SSB and so on.... But...


=> What about NORMAL or REVERSE doppler shift ??

HI  JEAN, VA2SS
I CANNOT UNDESTAND EXACTLY THE MEANING OF YOUR QUESTION
BUT  SINCE THE TRANSPONDER IS MADE "INVERTING" THEN THE
TOTAL  DOPPLER SHIFT BECOMES THE DIFFERENCE BETWEEN THE
UPLINK FREQUENCY AND DOWNLINK FREQUENCY AND IF THE
TRANSPONDER IS NOT INVERTING THE TOTAL DOPPLER SHIFT IS
THE SUM OF BOTH.
THE TRANSPONDER IS MADE INVERTING TO PARTIALLY COMPENSATE
AND REDUCE THE TOTAL DOPPLER SHIFT.


=> When using SSB on transponder, what about when to use USB on uplink
and LSB on downlink ??

SINCE THE TRASPONDER ARE NORMALLY MADE INVERTING IF YOUR
UPLINK IS USB THEN YOU RECEIVE A LSB DOWNLINK BUT THIS IS IN
CONTRAST WITH THE CONVENTIONAL TERRESTRIAL MODE OF
OPERATION THAT IS USB MODE

=> When using SSB on transponder, what about when to use LSB on uplink
and USB on downlink ??

SINCE THE TRANSPONDER IS INVERTING IF YOU TRANSMIT A LSB
UPLINK THEN YOUR DOWLINK WILL BE RECEIVED USB ACCORDING
TO THE CONVENTIONAL MODE OF OPERATION FOR TERRESTRIAL
COMMUNICATION THAT IS OK BECAUSE ANY OTHER AMATEUR STATION
CAN RECEIVE YOU WITHOUT TO SWITCH THE RECEIVER BETWEEN USB
TO LSB

I'm very confused if my doppler.sqf file is properly configured and a
short explanation would be really appreciated.

I know this is a basic and fundamental question, but I really need to
free my mind with this one.

Thank for your patience guys !

73 and Happy New Year 2010 !!!

I wish you health, health, health and more sats to come !!!

BEST 73" DE

i8CVS DOMENICO
--
Jean-François Ménard
VA2SS

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