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LINK-11 CLEW, Hamming check matrix
The check of a Link-11 CLEW stream discussed in the end part of this post, can be speed up by using the Hamming check matrix for the H(30,24) coding, ie a 30-bit code word consisting of 24 bits for...
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LINK-11 CLEW, doubts about the generator polynomial x^5+x+1
I have some doubts about the description at page 19 of MIL 188-203-1A (Tadil-A/Link-11) [1]: the document states that the Start Code and the Address Code frames " [...] are equivalent to 60-bit...
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LINK-11 SLEW, Systematic CRC check matrix
In Link-11 SLEW the error detection encoding is applied to all 48-bit data words within each type of field with the exception of the EOM field. The encoding scheme uses Cyclic Redundancy Check (CRC)...
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the unid Kongsfjord OFDM (2)
As said in the previous post, these signals could also belong to a Narrowband (Under 500 kHz) Power Line Communications (NB-PLC) system. Just to investigate this second hypothesis, my friend Bjarne...
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WINB Red Lion to test DRM Single Channel Simulcast (SCS)
Shortwave station WINB has recently started conducting test in DRM directed to Europe on 15670 kHz Monday - Friday from 11:00 -17:00 UTC using a new DRM 18 Kw transmitter, an ASI CE-50000WS, and...
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recent logs
05089.0: ---: Swiss AF, SUI 0610 VFT-TMS430 2x100Bd/170 (channels cf at -500, +500Hz) (10Jul18) (AAI)05689.0: HWK01: Swedish Mil, S 1006 USB 3G-HF 1-way FLSU flwd by 188-110A Serial, Circuit Mode tfc...
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a Rockwell Collins/DHFCS 1536-bit TDM protocol
This afternoon I spotted a STANAG-4285 1200bps/L transmission on 7937.0 KHz/usb carrying the 1536-bit TDM data protocol already seen in some previous records here and here. The most important thing is...
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DHFCS 1536-bit TDM protocol (2)
In the previous post I associated the 1536-bit TDM protocol to the DHFCS network, and that's correct, but I wrongly ascribed this protocol to Rockwell Collins. Indeed, looking carefully at the two...
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LINK-11 SLEW, transmission format
The SLEW waveform transmission format consists of an acquisition preamble followed by two or more fields, each field followed by a reinsertion probe. The first field immediately following the preamble...
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LINK-11 SLEW, properties of the acquisition preamble sequence
(thanks to Christoph for his Octave hints and collaboration) Since some weeks I'm studying the symbols sequence which is used to form the Link-11 SLEW acquisition preamble, the reason is that - quoting...
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Unid FSK 100Bd/500, T-207 encryption
Yet another (unid) FSK 100Bd/500 signal spotted on 9075.0 CF around 0810z (11 Sep) with good SNR. User is likely from Kaliningrad Oblast, contents are encrypted with T-207...
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"Winnie pooh" HF test transmissions
odd wideband signals spotted recently on 9110 KHz (center frequency) and likely related to Russian tests or exercises. Transmissions (Figure 1) consist of a 3xFSK 250bd/500 waveform which occurs as...
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PSK-8 bursts at inconsistent 12800bps data rate, a deepen look at S4539 preamble
These transmissions consist of spread band "cluster bursts" which are sent in sequential order on several frequencies, ie the clusters are not sent simultaneously (Figure 1). Each cluster lasts about...
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CIS FSK 100Bd/1000, prob. Russian AF
FSK transmission heard today on 13994.8 KHz (cf) at 0930z, contents are T-207 encrypted. Possibly from Russian AF.https://yadi.sk/d/ri_lmpC0lMkQlg
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unid FSK 1200Bd/1200 test transmissions
Unid long-run (crtical) FSK 1200Bd/1200 test transmission heard on 13720.0 (cf) around 1320z (26 Sep). The demodulated stream consists of 16-bit frames, each frame consisting of: *) seven bits coded...
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HF Industry website (HFIA)
WARNING: some of the recent posts have links to the "meetings & presentations" section of the High Frequency Industry Association (HFIA) website that end up giving the 404 error "page not found"....
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PSK-8 bursts at inconsistent 12800bps data rate (2)
Some other observations on the weird PSK-8 12800bps STANAG-4539 bursts, which was discussed here. Assumptions rely on the reliability of SA and K500.Preamble & data constellationsLook at the...
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logs
05838.0: ABC7: Croatian Mil, HRV 0742 USB 188-141 2G ALE calling ABH3 (20Sep18) (AAI)05855.0: ---: Unid 0723 USB TADIRAN AutoCall MFSK-4 (20Sep18) (AAI)05859.0: QS00: Unid 0629 USB 188-141 2G ALE...
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S5066 data transfer, scaling from 3200bps (QPSK/PSK8 on-air) up to 9600bps...
13378.0 KHz/USB, 0848z: S5066 data transfer using HF waveforms 110A & S4539 which scale from 3200bps (QPSK/PSK-8 on air) up to 9600bps (QAM-64); unid user/location. Notice in Figure 1 that QAM-32...
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NILE/Link-22 waveform #2 (S4539 Annex D)
STANAG-4539 HF Fixed Frequency TDMA transmission, used by NILE/Link-22, spotted on 7606.0 KHz/usb and followed from 0905z up to 0950z (October, 9). Modem for HFFF TDMA operations are described in Annex...
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