23 April 2015

Arcotel MAHRS-2400 ALE burst (Telefunken Racoms)

Fast bursts sent every 500 msec, spreading about a 2800 Hz bandwidth. Each burst shows a short preamble of 8 un-modulated carriers, symmetrical with respect to the center frequency of the signal, and a short PSK-2 preamble. The data segment is a serial tone carrier at ~ 1800 Hz with a PSK-8 manipulation at 2400 baud.


The MAHRS protocol, or better the procedure, was described in WUN-10 newsletter, and here reported:
"For establishing the link between two stations there is a call of one dot each second at a length of 500ms. Most of the time the station calls 62 times then changes back to listening for 60 seconds and then selects a new frequency for calling. The selection of freqs happens according to position of both sender and receiver, actual daytime and actual sunspot numbers. The system calculates a prediction model of propagation and decides which line may be the best. When in contact the called station answers after waiting a maximum of 15 seconds by one dot of 500ms and the both stations give their "handshakes" and then the full transmission starts using a high speed ARQ like transmission system at a speed of 4800 bps" [http://www.udxf.nl/WUN-v10.pdf]

Sometimes you find the MAHRS protocol reported along with the names EADS/RADCOM and Arcotel: the former is the name of the HW producer, TELEFUNKEN Radio Communication Systems - TELEFUNKEN RACOMS (http://www.army-guide.com/eng/firm3787.html) while the latter (Arcotel) is the name of the modem (now indicating the radio processor).
The source should be the German Mil, as reported in the above link to WUN newsletter http://www.udxf.nl/WUN-v10.pdf

21 April 2015

Japanese Military 8 frequencies: 2 FSK channels, cross-schema reduntant

This signal was seen on 16553.5 KHz/USB around 1900z  and - at that same time - on 12384.5 KHz/USB by my friend Mauro IK2GFT from Milano:

It is composed of 8 distinct channels, 300 Hz spaced and 100 Baud as symbol rate. The signal uses about a 2400 Hz bandwidth.
The signal consists of two independent FSK-2 channels which are doubled according to a cross-schema (tones separation too is doubled), so the 4 FSK-2 channels (8 traces) that are visible in the sonogram/spectrum. According to the analysis performed by radioscanner group, all the four channels use the Manchester code and, since the time offset between the first and second channel, they are formed using OFDM technology.

more info here (signals.radioscanner.ru) 

9 April 2015


the signal shows an OFDM part followed by the usual Serdolik MFSK-34: this is one of the several variants of the Russian system SERDOLIK.

As the 35-tone OFDM mode, this variant shows a 40-samples lenght for LG, 35 tones and spreads a about 3000 Hz bandwidth.
This mode has an easily distinguishable pilot tone at the lower channel so the used channels count to 60 and they are PSK-4 manipulated at 40 Hz (aggregate speed 2400 bps). Separation among channels is 50 Hz, since the presence of CP. The other parameters of the correlation triangle are Br-40, Sh-50 and 'magic K' = 1/4.

4 April 2015

Logs: 31 Mar - 03 Apr

08968.0 ---:
USAF HFGCS SIPRNET-GW 0745 MIL 188-110A 1200/Short encrypted messages (01Apr15) (AAI)
11476.5 ---:
Czech embassy Moscow, RUS 0635 PacTOR-III encrypted message "$pa $x$B $Y" (01Apr15) (AAI)
12857.0 6WW: French Navy Dakar, SEN 1855 STANAG-4285 600L (calling ?) "FS DE 6WW IMI KKKKKKKKKKKK" (31Mar15) (AAI) 
15622.2 ---: Russian Mil, RUS 1335 CIS-128, 128-tone PSK-8 OFDM modem 20.9Br/23.46 (03Apr15) (AAI) 
15812.0 ---: Russian Mil, RUS 0705 CIS-45, 45-tones PSK-2 OFDM modem v1 33.33Bd/62.5 bursts (01Apr15) (AAI)
18046.8 ---: MFA Cairo, EGY 1205 ARQ/SiTOR-A message to Islamabad Embassy (31Mar15) (AAI)

08759.0 AB1: Navy Malta patrol boat P21, MLT 0558 MIL 188-141A sndg-Twas (02Apr15) (AAI)
09073.0 5CIN2D:
French Navy (OMAR HF NG) 0730 MIL 188-141A clg-Tis 5CIN1D (03Apr15) (AAI)
09073.0 5CI:
French Navy (OMAR HF NG) 0728 MIL 188-141A clg-Tis 5CIN1D then into MIL 188-110A (03Apr15) (AAI)
09200.0 13081: Moroccan Civil Protection, MRC 0620 MIL 188-141A sndg-Tws (01Apr15) (AAI)
09234.0 GW01: Algerian Mil, ALG 2035 MIL 188-141A LQA REQUEST RESPONSE to PY01 (01Apr15) (AAI)
09240.0 3341: Turkish Civil Defence Istanbul, TUR 0629 MIL 188-141A sndg-Tws (01Apr15) (AAI)
09300.0 SNB813: Polish Military, POL 0623 MIL 188-141A LQA REQUEST RESPONSE to SPT424 (01Apr15) (AAI)
09300.0 SPT424: Polish Military, POL 0623 MIL 188-141A LQA REQUEST RESPONSE to SNB813 (01Apr15) (AAI)
14406.0 CENTR3: MFA Bucharest, ROU 1221 MIL 188-141A clg-Tis FOL then into MIL 188-110A (01Apr15) (AAI)
14430.0 CM6: Algerian AF, ALG 0647 MIL 188-141A LQA REQUEST RESPONSE to HE2 (01Apr15) (AAI) 
14550.0 JP1: Moroccan Military, MRC 1243 MIL-188-41A clg-Tis G2 then into MIL 188-110A (03Apr15) (AAI)
14550.0 JP1: Moroccan Military, MRC 1245 MIL-188-41A clg-Tws O5 (03Apr15) (AAI)
15708.0 CAOFEM001: FEMA San Juan, PTR 0657 MIL-188-41A sndg (01Apr15) (AAI)
15880.0 CM2: Algerian AF Oran, ALG 0710 MIL 188-141A LQA REQUEST RESPONSE to COF (01Apr15) (AAI)

1 April 2015

CIS-45 v1 HDR modem 33.33 Bd BPSK bursts

CIS-45 Ch, Russian 45 tones HDR modem, version 1 http://signals.radioscanner.ru/base/signal46/
This is a Russian 45 tones HDR modem, version 1, formed using the principles of OFDM and here running in burst-mode. Most likely it is a lightweight version of the Russian 93 tone modem. The HDR name is just an abbreviation of High Data Rate.
The transmission heard on 15812.0 KHz USB at 0705z, is composed of two bursts, sent at irregular intervals. Looking at its features it corresponds to the version 1 of the well known Russian 45-tones PSK-2 OFDM modem (also known as CIS-45), here running in burst mode at 33.33 Baud.
The pilot tone also acts as a sync tone at the beginning of each burst. The 45 sub-carriers in the trailer are un-modulated and followed by a PSK-2 modulated segmen. The data-block after the preamble shows a PSK-2 modulation in the channels at the speed of  33.33 baud.

Bandwidth: ~ 3000 Hz
Number of channels: 45 + 1 pilot tone (~ 3350 Hertz)
Manipulation in the channels: 2-PSK
Step between channels (frequency net/grid): 62.5 Hz
Manipulation speed (Baud rate): 33.33(aggregate 1800)

THALES TRC-1752 Stanag-4285 FEC

I herad this signal on 31 Mar on 12857.0 USB around 1850z. My analysis matches the one by radioscanner.ru shown here: http://signals.radioscanner.ru/base/signal101/

THALES TRC-1752 STANAG 4285 FEC has all the characteristics inherent STANAG-4285 (serial tone carrier 1800 Hz, speed 2400 baud and modulation PSK-8) except for the phase constellation of the preamble.THALES TRC-1752 uses a 'special' preamble with 5-ary constellation maybe for receivers tuning purposes.


I had a bit of luck to (clearly) listen and take the preamble of such transmissions: here the preamble is very short, anyway we can appreciate the 5-ary

TRC-1752 modem seems to be replaced by the HF Multi Mode modem TRC 177X family.