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Author Topic: Am I hearing ACARS and RTTY on the same frequency?  (Read 4146 times)

WrongwayCorrigan

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Am I hearing ACARS and RTTY on the same frequency?
« on: July 23, 2010, 0707 UTC »
Once again I am unable to identify a data mode. The closest I can think of is ACARS and RTTY ...an aircraft happened to be transmitting ACARS on a frequency where an RTTY signal was present. I have caught Gander Oceanic frequencies with ACARS signals, but never on 5340 kHz

Receiver: Grundig G6 Aviator
Anntenna: Telescoping Rod
Place of Reception: Northeastern United States
Date: 07/22/2010
Time: 0510 UTC
Frequency: 5340 kHz

http://www.zshare.net/audio/78596407220a9d8a/

cmradio

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Re: Am I hearing ACARS and RTTY on the same frequency?
« Reply #1 on: July 23, 2010, 2239 UTC »
5340? I know on 5344 there's an encrypted military RTTY station in Montana. Booms in here at 30 over usually.

Peace!

WrongwayCorrigan

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Re: Am I hearing ACARS and RTTY on the same frequency?
« Reply #2 on: July 25, 2010, 1815 UTC »
My radio has a digital display, so it's fairly accurate. Could the signal have drifted off frequency that far?

WrongwayCorrigan

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Re: Am I hearing ACARS and RTTY on the same frequency?
« Reply #3 on: July 25, 2010, 1818 UTC »
Is it worth attempting to decode any of this signals with software?

Offline SW-J

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Re: Am I hearing ACARS and RTTY on the same frequency?
« Reply #4 on: July 25, 2010, 1926 UTC »
My radio has a digital display, so it's fairly accurate. Could the signal have drifted off frequency that far?

Chances are, you were tuned above the signal (and BFO'd to audible) whereas normally the rcvr LO is tuned below (and then BFO'd audible) ... the difference being about 4 kHz (high).

A 'consumer'/entry-level radio like the Grundig is a lot like the Degen in performance a couple of us have, and unless the IF filter is swapped out the IF (Intermediate Frequency) BW (Bandwidth) is about 6 kHz wide (maybe even a bit more) ...

A good, normal communications receiver IF BW is around 2.3 or 2.4 kHz wide. Modern ham rigs (like an Icom IC-756ProII ) are adjustable from 3 kHz to less than 1.6 kHz (and also shiftable and infinitely variable) and then the CW filters range from 400 or 500 Hz down to 250 Hz wide.

o Icom IC-756ProII, ProIII, Alinco DX-70, Kenwood TS-680s
o WinRadio G303e, Degen/Kaito 1103/DE1103, Stoddart NM-25
o 1/2 wave 80m Dipole used with several tuners
o Tuned loops from 2' thru 16' diam. capable of 160m thru 10m

WrongwayCorrigan

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Re: Am I hearing ACARS and RTTY on the same frequency?
« Reply #5 on: July 25, 2010, 1941 UTC »
That would explain it. I had no idea the intermediate frequency bandwidth was so wide on this little radio.

So if its likely a military RTTY signal, there is really no point in attempting to decode it.

Offline SW-J

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Re: Am I hearing ACARS and RTTY on the same frequency?
« Reply #6 on: July 25, 2010, 1949 UTC »
That would explain it. I had no idea the intermediate frequency bandwidth was so wide on this little radio.

So if its likely a military RTTY signal, there is really no point in attempting to decode it.

And - they don't say in the official docs from the company either ... from their website:

Specs - http://www.etoncorp.com/upload/contents/307/G_G6spec.pdf

Manual - http://www.etoncorp.com/upload/contents/307/G6_Manual_US_010308_low.pdf

So, you can get close, but there will always be some minor 'ambiguity' ... I would take close in these circumstances as being close enough, as I do when I use the Degen 1103 (DE1103) ... compared to the Icom IC-756ProII -

Brief view of its specs:

  http://www.universal-radio.com/catalog/hamhf/4019spec.html

  http://k0swi.microlnk.com/REVIEW/ICOM/ICOM_756PRO/ICOM%20756%20PRO%20REVIEW.htm


As to decoding, it may be nothing more than what appears to be random 5-letter/number code groups ... I don't know, I have never looked.


« Last Edit: July 25, 2010, 1951 UTC by SW-J »
o Icom IC-756ProII, ProIII, Alinco DX-70, Kenwood TS-680s
o WinRadio G303e, Degen/Kaito 1103/DE1103, Stoddart NM-25
o 1/2 wave 80m Dipole used with several tuners
o Tuned loops from 2' thru 16' diam. capable of 160m thru 10m

WrongwayCorrigan

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Re: Am I hearing ACARS and RTTY on the same frequency?
« Reply #7 on: July 25, 2010, 2013 UTC »
Quote
As to decoding, it may be nothing more than what appears to be random 5-letter/number code groups ... I don't know, I have never looked.

I have used software to decode CW, which usually results in 'cut numbers' groups. I do not know morse code well enough to copy it by hand.