Unid VLF 19khz Data Signal?

[Shortwavewave]

Ive been playing around with my sound card as a VLF Rcvr and don't hear quite alot except for the occasional odd tones, whistles(not the real "whistlers" I assume) static, and lightning crashes.

Now this morning was a bit different.

4am Central Time
SoundCard and SAQrx, and Winrad
75ft Longwire

I got this weird data signal I thought was RTTY but Sigmira, and Digipan(decoding software) just gave me a bunch of mumbo jumbo, of course thats what it could very well be.

I was hopeing someone here might know what it is, I know theres sample sites out there but good lord theres like what????...20 different types of PSK and RTTY each?

Anyways heres a sample of what I cought.

[N2DLX]

Sounds like RTTY of some kind. MixW wasn't returning any useful data but it seemed to freely decode garble. I tried changing the character set and baudrate and again nothing useful seemed to be there. Could be heavily coded, a non-standard baudrate, a different format (RTTY derivative), or could be too weak to get a good copy. Who knows..

Great find though!

[ka3jjz]

I understand there's a lot of USN submarines in this area of the band - understandably heavily encrypted...73 Mike

[Bill_White]

Originally Posted by Shortwavewave

Ive been playing around with my sound card as a VLF Rcvr and don't hear quite alot except for the occasional
odd tones, whistles(not the real "whistlers" I assume) static, and lightning crashes.

Now this morning was a bit different.

4am Central Time
SoundCard and SAQrx, and Winrad
75ft Longwire

I would like to hear some more on this setup.

[Shortwavewave]

Well Its basiclly Just a longwire plugged into my 2nd Soundcards Mic/or Line Input, the mic gives a louder signal.

Using this Program, SAQrx (based off the original SAQ settings from Spectrum Lab)

First off just do a google, for Soundcard as VLF rcvr to get some basic info.

SAQrx
SAQ Receiver

Spectrum Lab
DL4YHF's Audio Spectrum Analyser

Winrad (as well as others)
This winrad can be used also for Higher resolution on the waterfall display but requires some fiddleing around with.
The Weaksignals Home Page

Aside from the fact a desktop computer produces a heck of a lot of noise, the "Sound Card" is a very sensitive Rcvr.

This is how I understand it depending on your sound card

44,100khz (actual RX is 0-22khz)
96,000khz (actual RX is 0-48khz)
192,000khz (actual RX is 0-96khx)

This software converts the signal to audio to which you can better understand "Hear"

Now I have been building some filters and pre-selectors to which might actully do away with the software, but the fall back is you can see the displayed freq (waterfall, and scope).

BEWARE to not plug more than 100ft of wire directly into the sound card, Due to static charges and other things.

DISCLAIMER: I will not take resposabilly for this but I have observed that on my second sound card I have plugged 250ft of wire WITHOUT diodes or resistors, for a period of 4days during a ThunderStorm and no harm was done to the Card, this of course might have to do with the ACTUAL BUILD quality of the Sound Card.

[MSM_Maria]

attached files pic.1.gif and and pic.2.gif

As it was said above this signal is really RTTY.

Parameters if this signal:

Baud rate ~ 111 Hz,
Shift between frequencies of manipulation ~ 165 Hz, one bit as Start, 7 bits as data and two bits as Stop.

The interesting momement that the 7th bit is the controll bit. Baud rate and shift are Rare enough and interesting for VLF.

[LarryMax]

I gave the setup a shot last night and I was getting data also. Not sure what freq, I was just messing around with it. Besides a very bad " hum. I heard some crackles and very short whistlers. We had T-storms a few hundred miles a way so I think thats what the crackles were. I did get some very strong very loud, high pitched tones. I'm assuming those were coming from the pc. Pretty cool way to listen to VLF. Thanks for posting the details

[n2nov]

http://en.wikipedia.org/wiki/Anthorn...itting_station

This is from the following webpage:
http://dl4yhf.ssl7.com/frequencies/default.txt

kHz Call ITU Act Station Locator Lang. Remarks
================================================== ===================
19.6 GBZ G Y Anthorn or Skelton ? IO84nr also GQD ?

[MSM_Maria]

Maybe of course it is and GBK, but GBK use MSK mode FSK, GFSK, MSK, GMSK and some other modes. in here FSK-2 RTTY with non standard parameters.

[ka3jjz]

As I mentioned in another thread, if you get into this really low stuff, you want to belong to the Longwave Club of America This club specializes in this kind of stuff - a lot of very smart folks here. Well respected organization....73 Mike