[Lowfer] Flight 370 and 37.5 KHz.

[Warren K2ORS]

Craig,
     Yes they are looking at the repetition rate etc.
Here is summary:
   The signal processing and analysis package Spectrum Laboratory 
written by Wolf DL4YHF that was recently used for the first amateur 
transatlantic VLF detection of WH2XBA on 29kHz is being used by the U.S. 
Navy to analyze the 37.5kHz pings from the Malaysian airliner.  Wolf's 
package is  very first rate software and I know  that there have been 
other professional uses but this was quite an interesting one!
    Some screenshots of  Spect Lab aboard the Navy SHip Ocean Shield as 
shown on BBC TV:

https://www.dropbox.com/s/ahwiput1t3l5shd/Screenshot%202014-04-07%2012.48.31.png

https://www.dropbox.com/s/qo57o3f1oyoful4/Screenshot%202014-04-07%2012.47.30.png

Spectrum Lab "Home Page":
http://www.qsl.net/dl4yhf/spectra1.html

    I've pasted in some e-mails from Wolf below where he talks about his 
support of the Navy effort and his thoughts on the signals received.

73 Warren K2ORS/WH2XBA


---------------------------------------------------------------------------------------------------------------------------------------------------------------

Hello Mike,

Thanks for the info. Indeed I am in contact with two members (actually 
from the US) who are recently 'guests' on board of the Ocean Shield.
Guess what... there was a bug in the NMEA decoder in old versions of SL 
which caused problems when entering the southern hemisphere !  Not a 
mission-critical problem though, it could have been fixed by 
post-processing the recorded files (wave file + aux files which contain 
the ship's position along with the recorded "audio" / spectra). But 
their satellite link was stable enough to download and install a fixed 
version :-)

73,
   Wolf DL4YHF


Hi Pete, Mike, Alan, and all,

I was also sceptic about the first "detection" (by the Malaysian or was 
it a Chinese search vessel).

But to me, the spectrograms taken by the US team aboard Ocean Shield is 
convincing.

The screenshot at ABC is a bit blurred but one can nicely see the 
"bipp-bipp-bipp-..." periodic ultrasonic bursts (aka "pings"), just as 
they should look like:

http://www.abc.net.au/news/2014-04-07/ocean-shield-detects-possible-mh370-black-box-signal/5372616

It's not just a wobbly carrier that comes and goes. In slow-CW-terms, it 
would be an "outstanding signal". The signal is picked up by a towfish 
pulled on a long cable, to get away from the QRM (vessel) as far as 
possible.

Now keeping fingers crossed that the batteries last a bit longer than 
specified. The experts say the pinger's battery usually degrades slowly, 
instead of "going QRT" abruptly.

73,
    Wolf  DL4YHF
---------------------------------------------------------------------
   On 4/7/2014 1:44 PM, N6IO wrote:
> 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
>>
>>
>>


---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com