[Lowfer] Flight 370 and 37.5 KHz.

[N6IO]

I was wondering about using something like Spectrum Lab to find signals
like this.  Seems like a very similar task to pulling a weak NDB out of the
noise.

More important than detecting a signal at 37.5 Khz is detecting a pulse
repetetion frequency near the expected rate from these "pingers".   I'm not
sure what features Spectrum Lab has for this.  I've been trying to do a
similar thing to correlate repeating signals like QRSS beacons or NDBs.

In a loosely related area - my PCs are using the setiathome "astropulse"
software to look for repeating pulses - it seems that this kind of software
is even more likely to be useful for a search for these black boxes since
it looks for 3 or more peaks at the target spectrum over an identical
period.

Hopefully the people doing these searches have already thought about this
and are using similar software.  Since looking for 3 pulses in a row is
pretty cpu intensive - I wonder if they could record this data and submit
it to a global network like Boinc to take advantage of very deep levels of
inspection using the vast amount of CPU time available.

If these "pingers" can be heard for a few miles using fairly typical
listening techniques - I would think that adding 30 or 40 or more db of
gain using these kinds of signal processing would increase that range quite
a bit.


Doesn't the US Navy still run a network of ocean sensors that should have
recorded the initial impact when the plane went down?  I remember that
network being used long ago to detect where a Russian sub broke up so we
could go back with the Glomar Explorer to pick up the crypto gear from
it.   Maybe that was retired when the cold war ended?

Craig - N6IO







On Mon, Apr 7, 2014 at 12:55 PM, Warren K2ORS <k2ors at verizon.net> wrote:

> FYI
>    There is an interesting thread on the RSGB reflector. The U.S. Navy is
> actually using the same software Spectrum Laboratory by DL4YHF  to analyze
> the pings as was used in the 29kHz T/A work.
>
> 73 Warren
>
>
>
> On 4/6/2014 10:35 PM, Dexter McIntyre W4DEX wrote:
>
>> Tom "Doc" Gruis wrote:
>>
>>> ASn interesting article on one of our local TV station's website this
>>> morning.
>>>
>>> http://www.kcci.com/national/scanners-scour-ocean-depths-
>>> for-flight-370/25336098?treets=des&tid=265847210813&
>>> tml=des_natlbreak&tmi=des_natlbreak_1_06570104052014&ts=H
>>>
>>>
>>> Just passing it along because of the frequency of 37.5 KHz. involved.
>>>
>> The pinger frequency caught my attention also Doc.   That would be a
>> good frequency for Bob to avoid.  Some non technical reporter may cause
>> a stir if that hit the media.
>> Dex
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