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Mystery Signals

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DPD1

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Someone else told me about this a while back, and I've become curious about it... On a 780, if you go to 345.0, you will hear what sounds like little TM signals at various strengths. I don't believe these are actually on 345.0. My guess is that they are bleeding over from somewhere else, and the 780 happens to pick it up on 345.0. But what it sounds like are devices in various locations, that randomly send out a little packet every so often. I could be totally wrong, but that's what it sounds like to me. I'm guessing it must be some sort of widely used product. The person that discovered this lives well away from me, so it would appear to be wide spread. Take a listen and see what you think... This is actually about 5 minutes worth, edited down. It's funny, because it sounds like a little population of them kind of talking to each other.

http://www.dpdproductions.com/temp/signals.mp3

Dave
http://www.dpdproductions.com
- Custom Scanner, Aviation, MURS, GMRS, Marine & Ham Antennas -
 

wa8vzq

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Sounds very similar to conventional telephone pulse dialing. Used to be very common to hear that as crosstalk on the telephone. Could be similar from a cordless telephone although I can't imagine why someone would be using pulse mode today - also all of the cordless ones that I remember hearing in the past used FSK for the pulse signaling. Perhaps could still be that but if your 780 is not on the exact frequency you can't hear the FSK and that's what it sounds like.

Dan
 

nexus

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Erik, sounds like he has it on AM mode... and 302HO not far off. It has the spacing of an M-60. Oddly. When I was listening to it, that was what popped into my head. Someone firing an M-60. I've never heard anything like that before. I have a 785, I'll have to put it down on 345.0 and see if I hear anything from here.
 

302HO

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HEY GUYS>>>>>>>

i tuned my icom r20 to 345.000 AM, and i got some noise. Mine doesnt sound like an M60 or a 16. It sounds like an MP5 or an Uzi. Real fast. Alot faster than DPD1! This is of course with the squelch open.

I am using the telescoping antenna that came from my radio. I took it off and tried my Maldol AL-500. The maldol brought it in a little more. The maldol is actually broke right now so maybe i could come in better when i get my new one.

Hopefully in the next couple of weeks, i will receive my Scantenna from univeral radio. It was on back order of course. They dont tell you that crap on their website.

Anyhow, i'll keep monitoring this.


**for the record, i tried this in FM, WFM, CW and both sidebands. Couldnt hear it unless it was in AM.
 

eorange

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Mystery possibly solved

I heard it too on 345.0 AM.

A Google search on "345.0 MHz" telemetry revealed this result:

http://www.atmel.com/dyn/resources/prod_documents/doc4841.pdf

It looks like they make a FSK transceiver that can be used for telemetry, among other applications. On page 1, the operating frequency of 345 MHz is shown almost at the bottom of the page. We hear it on AM because AM picks up all kinds of noise!

I am also hearing it on 315, and another type of data signal on 433.92, just like the document says. :cool:
 

DPD1

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Well I'll be darned... Excellent sleuthing. So it actually is on that freq. Weird. So all those you can hear out there, are running all kinds of stuff probably. I hear a couple on 315, but they're different sounding, and there's not as many.

Dave
http://www.dpdproductions.com
- Custom Scanner, Aviation, MURS, GMRS, Marine & Ham Antennas -
 

eorange

Secret Agent Man
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I was surprised I found the answer that easily, to be honest. I bet there's a lot of those devices out there in various applications.
 

CSL126

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I have it fairly clear from West Alabama, I had to open up the squelch though. Sounds just like the mp3 file above; however, I can only hear what sounds like one transmission. I didn't hear the faint broadcast and then a louder one, I just heard the one broadcast.

I am using a Scantenna mounted up about 40ft, and a RS PRO 2052.
 

kc4jgc

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Virginia Beach, VA
I hear the same thing at my listening post at 345.0. So far nothing on 315.0.

Question still remains... who/what is it? USCG has already ben mentioned as a possibilty but if the same thing is being heard in Arizona it may not be Coast Guard.
 

DPD1

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I would have to assume that how much of it you hear (or don't hear) probably has a lot to do with how urban your area is. For instance, my area is as urban as it gets... That's probably why there's a whole chorus of them out there for me. If you live in the country, you might not get any at all.

Dave
http://www.dpdproductions.com
- Custom Scanner, Aviation, MURS, GMRS, Marine & Ham Antennas -
 
R

Rayjk110

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I live in what can be considered the "country", and signals are still fairly strong over here. But that could be due to the fact that I'm 40 miles out from Lake Michigan, where Great Lakes Naval Base is.
 
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