Doppler and Radio.


log in

Advanced search

Questions and Answers : Wish list : Doppler and Radio.

Author Message
Mike Therrien
Send message
Joined: 12 Aug 09
Posts: 1
Credit: 76,177
RAC: 0
United States
Message 926521 - Posted: 16 Aug 2009, 14:25:01 UTC

I get why your looking for doppler shifts. Can you or are you even interested in what that base frequency is of the source? I suspect that this would be needed to isolate the distance and movement of the transmission source. In addition if ET is transmitting radio waves are we looking for Carrier waves with AM or FM signals? Or is that something that will be considered once a viable source is found?

Aurora Borealis
Volunteer tester
Avatar
Send message
Joined: 14 Jan 01
Posts: 2975
Credit: 4,957,972
RAC: 1,323
Canada
Message 926531 - Posted: 16 Aug 2009, 15:28:34 UTC - in response to Message 926521.
Last modified: 16 Aug 2009, 15:38:32 UTC

I get why your looking for doppler shifts. Can you or are you even interested in what that base frequency is of the source? I suspect that this would be needed to isolate the distance and movement of the transmission source. In addition if ET is transmitting radio waves are we looking for Carrier waves with AM or FM signals? Or is that something that will be considered once a viable source is found?

Seti is not looking for doppler shift as much as compensating for doppler shift around the hydrogen frequency. It is looking for any kind of persistent signal that can be differentiated from the normal radio noise of space or astronomical source. We are a long ways from worrying about the actually type of carrier or a deciphering a message. That would be an entirely different project if anything is ever found.

John McLeod VII
Volunteer developer
Volunteer tester
Avatar
Send message
Joined: 15 Jul 99
Posts: 24104
Credit: 518,020
RAC: 150
United States
Message 926565 - Posted: 16 Aug 2009, 19:06:08 UTC - in response to Message 926521.

I get why your looking for doppler shifts. Can you or are you even interested in what that base frequency is of the source? I suspect that this would be needed to isolate the distance and movement of the transmission source. In addition if ET is transmitting radio waves are we looking for Carrier waves with AM or FM signals? Or is that something that will be considered once a viable source is found?

SETI Enhanced is looking for narrow band signals that rise and fall with the rotation of the antenna at Aricebo. The code has to compensate for dopler shifts to see if there is a narrow band signal that is shifted because of rotations and orbits of both the transmitter and receiver.

AstroPulse is looking for broad band signals.

Once a signal is found, then we might aim an antenna full time to try to decipher the signal. But first we have to find the signal.
____________


BOINC WIKI

Profile JLDun
Volunteer tester
Avatar
Send message
Joined: 21 Apr 06
Posts: 307
Credit: 51,623
RAC: 51
United States
Message 934466 - Posted: 19 Sep 2009, 6:12:52 UTC - in response to Message 926521.
Last modified: 19 Sep 2009, 6:14:16 UTC

In addition if ET is transmitting radio waves are we looking for Carrier waves with AM or FM signals? Or is that something that will be considered once a viable source is found?

From what I understand, the AM/FM split in terrestrial broadcasts is split "artificially":
If a signal is centered below a certain frequency, then it uses amplitude changes to transmit information [AM]; otherwise it's frequency mod [FM]. But that's just us...
____________

John McLeod VII
Volunteer developer
Volunteer tester
Avatar
Send message
Joined: 15 Jul 99
Posts: 24104
Credit: 518,020
RAC: 150
United States
Message 934529 - Posted: 19 Sep 2009, 15:54:54 UTC - in response to Message 934466.

In addition if ET is transmitting radio waves are we looking for Carrier waves with AM or FM signals? Or is that something that will be considered once a viable source is found?

From what I understand, the AM/FM split in terrestrial broadcasts is split "artificially":
If a signal is centered below a certain frequency, then it uses amplitude changes to transmit information [AM]; otherwise it's frequency mod [FM]. But that's just us...

Actually, we are looking for any signal, and we will work at interpreting it later.
____________


BOINC WIKI

Questions and Answers : Wish list : Doppler and Radio.

Copyright © 2014 University of California