----- Original Message ----- From: "Jean-François Ménard" [email protected] To: "AMSAT Mailing list" [email protected] 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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