Thursday, May 24, 2018

STANAG 4285 survey

Perhaps not surprisingly, the frame markers described in this blog post were also found in STANAG 4285 the bit streams. The table below summarizes a 30 min scan of STANAG 4285 signals using the excellent KiwiSDR @T4FM. The bitstreams were obtained using this code.

6800 - 13500 kHz, 20180522T0945-1015Z, T4FM KiwiSDR, STANAG 4285 600L and 1200L.
format count remarks
(1) 14 7-bit frames delimited by F1, see here
(3) 14 7-bit frames delimited by F4, see here
CARB 5 ITA1 coded Channel Availability and Receipt Broadcast messages, see Antonio's blog
1536-bit ACF 3 see Antonio's blog
15-bit ACF 1 see Antonio's blog

3 comments:

  1. Well done Christoph! Now, given that:
    1) the HF waveform STANAG-4285 is largely used for NATO naval broadcasts;
    2) the markers consist of the bits of pseudo-random sequence generated by the polynomial x^31+x^3+1, as specified by STANAG-5630 and already seen in FSK 50Bd/850;
    3) those bits (termed "Fibonacci bits") are used by KW-46 cryptographic equipment to provide synchronization;
    we can assume that NATO naval broadcasts are secured with KW-46 encryption.

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  2. Hi Christoph,
    if you still need it, I was able to make the GPS work with my kiwisdr.

    ciao!
    marco / IS0KYB
    http://sibamanna.duckdns.org:8073/

    ReplyDelete
    Replies
    1. Hi Marco,

      this is great and will help a lot with TDoA measurements.

      Thanks a lot.

      73
      Christoph

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