unid BPSK 100Bd & 200Bd

heard on 18255.0 (cf) monday, 26 October around 0830z the signal alternates BSPK segments with 100 and 1200 Baud. Out of these formats, the signal altenates long 11 carriers 150 Hz spaced preamble with a sort of modulated inserts. The signal is partially described in radioscanner.ru (missing the initial BPSK 100/1200 Baud part):
http://signals.radioscanner.ru/base/signal92/

STANAG-4538, LDL BW3-BW4 samples

This is a recording of Low rate Data Link (LDL) protocol BW3, carrying Harris "Citadel" encrypted traffic, + BW4 LDL acknowledgments (ACK) waveforms: transmission was herad on 16716.0 KHz/USB. Both STANAG-4538 and MIL 188-141B/C App.C share these waveforms

pic.1

BW3 and BW4 waveforms, and the Data Link protocol (LDL), are identifiable by their duration as is specified in the STANAG-4538 official documentation "table 13-1":

pic.2 - BW4 lenght

For what concerns the BW3 waveform (pic.3), its ACF of 13.33ms (96 bits lenght, or 32 PSK-8 symbols) is a further test:

pic.3 - 13.33ms ACF of BW3 waveform

Bt the way, the LDL traffic consists of files which are encrypted using the Harris "Citadel" encryption system, as detecte by the analyzing the bistream once removed the Link Layer overhead (pic.4)

pic.4 - detecting Citadel encryption in the secondary protocol (LDL)

STANAG-4538 BW5 sample

waveform BW5

The usual 2G scenario (MIL 188-141 2G-ALE + MIL 188-110A/B 3KHz serial-tone) is replicated here but using 3G waveforms: the sample shows a data transfer, using one of the MIL 188-110C App.D serial-tone waveforms (precisely the waveform-id n.7 15KHz bandwidth, seen in another post), followed by STANAG 4538 FLSU 3G-ALE signal to supposedly close the link. 

To avoid confusions, MIL 188-141C Appendix C third-generation ALE is termed Link Set-Up (LSU) in STANAG 4538. Two non-interoperable protocols for link establishment are specified in STANAG 4538: Fast LSU (FLSU, smaller, lightly-loaded tactical networks) and Robust LSU (RLSU, large networks and heavy traffic).  The specifications previously contained in the Appendix C have been replaced with reference to the essentially identical NATO STANAG 4538: I refer to this document.

The ALE segments have been downsampled and decimated in order to get a better signal to analyze (pic. 2), so it was possible to identify the 3G-ALE as the Fast LSU burst-waveform n.5, or BW5 waveform as indicated in the table shown in picture 3, just from the standard STANG 4538. PSK-8 modulation is analyzed in pic. 4.

Pic. 2 - 3G-ALE signals after downsampling

lenght of the burst: 1013 ms

Pic. 3 - the heard signal mathces the characteristics of the BW5 waveform

Pic. 4

MIL 188-110C App.D: BW18KHz, SR14400 Bd, PSK-8

 Waveform Number 7: PSK-8, 18 KHz bandwidth

 

This waveform (WID7-18Khz) occupies a bandwidth of 18 kHz, providing 28800 bps user data rate. Modulation used is PSK-8 at 14400 symbols/sec. Reading the MIL 188-110C App.D documentation, a frame for this waveform consists of 1536 unkown symbols (data) + 192 known symbols (mini probe), so 1728 symbols. Since the 14400 baudrate , the mini-probes should generate a 120 ms ACF: in this sample I used the CCF function but the obtained 240 ms result is the same as in WID7-15Khz.

MIL 188-110C App.D: BW15 KHz, SR12000 Bd, PSK-8

signals were heard at different days and times, around 1100-1200z, on 18270.KHz (f0) by KarapuZ.

   

Waveform Number 7: PSK-8, 15 KHz bandwidth 

 

The waveform (WID7-15Khz) occupies a bandwidth of 15 kHz, providing 24000 bps user data rate. Modulation used is PSK-8 at 12000 symbols/sec. Reading the MIL 188-110C App.D documentation, a frame for this waveform consists of 1280 unkown symbols (data) + 160 known symbols (mini probe), so 1440 symbols. Since the 12000 symbols/sec of this waveform, the frame should be 120 ms long but I get a 240 ms ACF: just the double of the expected lenght. More likely ACF value is generated by the cyclic rotation of the mini-probes, as specified in the standard, and the interleaving of this sample needs one rotation after 2 data blocks and so the 8640 bits period (240 ms).