Name that niose...

[rbellows]

... this is a no-brainer for someone, but it confused me: A transmission on 121.500, unintelligible followed by what sounds exactly like an old car or home invasion alarm...for several minutes. :?: :?: :?:

 

[jlh]

rbellows, sounds like a plane's ELT ( emergency locator transmitter ). Sometimes they are triggered by accident. Heard one a few years ago, called the local airport, they tracked it down to a plane that was being worked on.

And then there is the chance that it actually a downed plane.

 

[rbellows]

Thanks. I haven't heard anything local about a crash.

 

[pocho]

Or the pilot made a VERY hard landing (enough to set off the ELT). :lol:

 

[CLB]

9 G's are what's required to trigger an ELT.

If it was a rough landing, the dude has no landing gear anymore :lol:

I track these and EPIRBs in CAP all the time. Fatal crashes are to say the least, messy.

 

[blutarsky]

... this is a no-brainer for someone, but it confused me: A transmission on 121.500, unintelligible followed by what sounds exactly like an old car or home invasion alarm...for several minutes. :?: :?: :?:

i was wondering the same thing, actually. a couple weeks ago i was hearing the same thing, and it's since stopped (i locked out that channel for a while as my scanner kept stopping on it).

as i type this now, however, i'm picking up the same thing on 243.000 (though it's a little more faint, it's the same "whooping" sound). :?

 

[jhooten]

Trivia question

Why was 243.00 chosen for the aircraft UHF Guard/ELT beacon freq?


This comment contains a clue:

as i type this now, however, i'm picking up the same thing on 243.000 (though it's a little more faint, it's the same "whooping" sound).

 

[jlh]

I cheated and looked it up, pretty cool idea.

 

[ECPD279]

Trivia question

Why was 243.00 chosen for the aircraft UHF Guard/ELT beacon freq?

Because 243.000 is the first harmonic of 121.5 (ie 121.5x2=243) so 121.5 can be heard on 243 if military aircraft are involved in the search.

 

[jhooten]

The same reason the original 5 amateur bands were allocated in the spectrum they were BTW.

3.5X2=7
3.5X4=14
3.5X6=21
3.5X8=28
7X2=14
7X3=21
7X4=28
And so on.

 

[rtripp]

9 G's are what's required to trigger an ELT.

If it was a rough landing, the dude has no landing gear anymore :lol:

I track these and EPIRBs in CAP all the time. Fatal crashes are to say the least, messy.

Hmm... The ELT's we used to use didn't take 9 g's. They would go off even in a sharp in-air maneuver. But, it was also made before 1975 8) .

 

[Freeski]

Our's is set for 5 g's.