ARQ Independent Side Band system

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ARQ Independent Side Band system

Mensaje por ansanto » 14 Oct 2017 12:43

I'm sorry to use English but unfortunately I do not know Spanish (... although very similar to my language)

This is an ARQ ISB system heard on 6231.5 KHz/USB (Maritime Mobile band), 2800Hz offset from carrier, around 0630z on 12 October [1].
Most likely the two 3 KHz side bands are used as follows:
on USB: user data transfer using adaptive 2400 Baud PSK-2 and QPSK burst waveform, according to the channel conditions and the feasible data-rate;
on LSB: link and traffic management (ACKs and mode used for data transfer) using 1500 Baud PSK-2/QPSK waveform;

it is not clear if the adaptive mode is driven by the receive peer.
At least in this sample, data bursts last 2088 msec for PSK-2 and 3144 msec for QPSK, the initial bursts have a duration of 520msec; link management bursts last 310 msec.
I know that KLN Netwkors is testing a proprietary 3GHF system to support the ship traffic in Artic regions [2]. In that high latitudes satcomm links can't be easily used since geostationary satellites do not cover these areas, moreover due to the long dark periods the low portion of HF shall be used (lack of F layers). Perhaps may catches are related to their tests, but it's only my guess (I emailed them to ask a confirm and shed some ligth on this system).

Happy to read your comments :)

[1] signal download



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ARQ Independent Side Band system

Mensaje por ANgazu » 14 Oct 2017 21:01

Thanks Ansanto. Very interesting signal.

There are quite a few new signals in HF. And very interesting, indeed.

Saludos cordiales.
EA4021SWL aka ANgazu

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ARQ Independent Side Band system

Mensaje por Kilo » 14 Oct 2017 22:22

Thank you very much Antonio
Best regards

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ARQ Independent Side Band system

Mensaje por Rapidbit » 15 Oct 2017 00:08

Another very intesting signal, thank you.
Best regards.