|
|
Thread Tools | Display Modes |
#1
|
|||
|
|||
Radio Transmissions
Can someone refresh my memory on wave interference? I've been out of
school too long to remember any details. As I recall, at least all similar waves interfer with each other to some degree. How similar in frequency and type do those waves have to be to cause some interference? How does that afect what you would be able to detect at one light year? Would those signals retain enough of their original form to be easly detected? We do know that we are still able to pick out the signals from our most distant still working probes because of receiver improvements. However that is a weak transmission, and it is the only signal in that area. -- Ed http://www.geeks.org/~ed/Usenet_Servers.html strip to reply |
#2
|
|||
|
|||
Ed wrote:
Can someone refresh my memory on wave interference? I've been out of school too long to remember any details. As I recall, at least all similar waves interfer with each other to some degree. How similar in frequency and type do those waves have to be to cause some interference? I think your first sentence pretty much sums it up ... Technically I guess it would depend on items such as signal to noise ratios, signal coherence, and correlation coefficients, but there is no need to get in to all that ... How does that afect what you would be able to detect at one light year? Would those signals retain enough of their original form to be easly detected? The more frequencies you have the more information you can store of course. On the other hand given an equal amount of power a signal at one frequency will be detectable to much greater range than a signal with the same power spread out over a bunch of frequencies ... Some trade offs (assumptions) have to be made ... We do know that we are still able to pick out the signals from our most distant still working probes because of receiver improvements. However that is a weak transmission, and it is the only signal in that area. Yes, and since one knows what the signal is exactly (the transmitted waveform) then one can tune the reciever to optimize the detection of that signal alone ("matched filters" for example) .... a signal with unknown properties is much more difficult to detect ... of course if it has alot of power then regardless of other things, one will detect it probably (one has to look too --- if one doesn't look then it won't be detected of course) ... Al |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Update: "Will amateur radio astronomers be the first to directly detect extrasolar planets?" | Robert Clark | Astronomy Misc | 1 | October 16th 04 01:15 PM |
Update: "Will amateur radio astronomers be the first to directly detect extrasolar planets?" | Robert Clark | Policy | 0 | October 9th 04 08:58 PM |
Radio Transmissions for SpaceShipOne | Mike Shafer | Policy | 1 | June 24th 04 09:29 PM |
Cosmic Radio Signals can be polarized at 91 mhz, 160 mhz and UHF TV 78 | rev dan izzo | Astronomy Misc | 2 | September 26th 03 01:16 AM |
Einstein's Gravitational Waves May Set Speed Limit For Pulsar Spin | Ron Baalke | Astronomy Misc | 1 | July 3rd 03 08:49 AM |