30 September 2015

CISwitching...


September, 30 at 0711z on 15812.0 KHz on USB: on-the-fly switch from CIS-45 to CIS-60, both belonging to HDR (High Data Rate) family modem. Maybe tests or fast (auto) adatpion to the channel conditions ? (recording is available, as well as for the others) 

29 September 2015

Australian MHFCS net


this is a transmission from the Australian MHFCS (Modernised High Frequency Communications System), an HF radio network providing communications services for the operational control of Australian Defence Forces (ADF) and allied aircraft, HF equipped marine craft, and land units.
The signal was heard on September,25 at 1357z on 14790.0 KHz on USB. Waveform is FSK-2: shift frequency of 340 hertz and manipulation speed of 600 baud, probably GFSK (or CPFSK). 

Fig. 1
Fig. 2
MHFCS is a managed, long-range strategic communications system that enables the secure exchange of information, such as voice, e-mail, facsimile, interactive data and organizational messages, between fixed and mobile stations using one integrated system.
MHFCS features automated priority messaging, an assured delivery system, extensive geographic coverage that includes 2,000 nautical miles offshore, and automated frequency-management and traditional-operator tasks.

The network  is controlled remotely by Defence Communications Station Canberra (DCSC) at the Network Management Facility (NMF) located in Canberra and consists of four TX/RX Nodes:
NORTH WEST CAPE, WA (S22.20 E114.30)
DARWIN, NT (S12.22 E130.59)
TOWNSVILLE, QLD (S19.28 E146.25)
RIVERINA, NSW (S35.01 E146.25)

 
DCSC is capable of operating Independent Side Band (ISB) or AM modes, however, the normal mode of operation is Upper Side Band (USB). Digital modes may be employed for encrypted transmissions. It is possible that one of these modes is 2G ALE, ANDVT, or Stanag 5066, however message content is encrypted and it is an offence to decrypt such transmissions. Registered frequencies available on the ADF MHFCS are listed here. As reported, remember to subtract the 1500Hz offset from the listed frequency to obtain proper dial frequencies (Fig. 3)
 
Fig. 3
Sometimes an FSK 50Bd/340Hz transmission has been seen within the 600Bd/340Hz signal so that it seems an ISB system (Fig. 3).

Fig. 3
Unless the simultaneity of the transmissions start/end  points (one of the two may begin before or after) I'm not so positive about the MHFCS source since they use a 1500 Hz offset so, in my opinion, the distance of the two CFs should be 3000 Hz and not ~2700 Hz as measured (Fig. 4).
 

Fig. 4

27 September 2015

Logs

12464.0 RHM80: Russian Navy ship "Yauza" 1206 CW FM-13 report "...99365 10236...22223..." (26Sep15)
14790.0 ---: MHFCS HF net, AUS 1357 USB GFSK 600Bd/340 (25Sep15)
14497.0 ---: Russian Mil 0830 cF CIS-3000 bursts flwd by MFSK-68 (34+34) (25Sep15)
07732.0 CS004A: Macedonian Military, MDN 0717 USB MIL 188-141 ALE calling BS008C1 (25Sep15)
07622.0 CS002: Macedonian Military, MDN 0703 USB MIL 188-141 ALE calling BS007A (25Sep15)
06425.0 D54: Chinese Mil, CHN 2111 proprietary MFSK-8 waveform  (23Sep15)
06350.0 ---: Unid 2015 USB 2400Bd/3000 PSK-8 (prob. 188-141B/App.C BW2 bursts 5.4 mS length) (23Sep15)
17289.0 ---: Russian Mil 1143 USB CIS-48 probe/marker 4 x DBPSK 50Bd (22Sep15)
12165.0 ---: Russian Telegraph, RUS 0720 cf VEZHA-C F1B 100Bd/500 (22Sep15)
12464.0 RMCW: Russian Navy ship "Donuzlav" 1211 CW FM-13 report "...99396 10256...22242..." (21Sep15) 
15878.0 ---: Russian Mil 0748 USB CIS-3000 serial tone PSK-8 3000Bd acf=640mS (21Sep15) 
14490.0 ---: Unid (prob. Czech Diplo) 0720 USB PacTOR-III (21Sep15) 
15871.5 ---: Unid (prob. French Mil) 0703 USB Thales Systeme3000 Robust data (21Sep15)
14556.0 RIW: Russian navy HQ Moscow, RUS 0655 CW "RHM80 DE RIW QSA2 K" (21Sep15)
14386.0 ---: Unid (prob. French Mil) 0640 USB Systeme3000 ALE (21Sep15)
14489.5 ---: Unid (prob. Russian Gov.) 0625 cf F1B 100Bd/2000 // 14969.5 KHz (21Sep15)


RHM80 tracking
(prob.) STANAG-4538/MS 188-141B App.C BW2 waveform

26 September 2015

a CIS-20 variant (37.5Bd, 60Hz)



the so-called CIS-20, in its standard format, is an OFDM 20-tone waveform characterised by π/4-DQPSK modulation at 75 symbols per second and 120Hz channel separation, as described here. CIS-20 is supposed to be the successor of CIS-12.
This variant exhibits the same modulation format but speed and channel separation are exactly the half of the ones of the standard version, i.e. 37.5Bd and 60Hz channel step. The signal bandwidth is unchanged (~2800Hz).

CIS-20 variant - OFDM parameters
CIS-20 single channel analysis

Note, once again, the differences between PSK-8 and π/4-DQPSK constellations (in absolute and relative mode, Diff=0 and Diff=1):

in a real PSK-8 the paths cross the origin of axis

23 September 2015

VEZHA-C (ВЕЖА-С), Russian Telegraph


This is a very old Russian telegraph system carrying information possibly for radio check of lines or for other (uknown) purposes. I could not find news about this signal and Russian monitors too do not have detailed informations about it; asking Karapuz and digging radioscanner forum I found the same signal than mine, and then its name "VEZHA-C", in these pages:
http://www.radioscanner.ru/forum/topic29556.html
Here their recording (you might use this file for your analysis):
http://www.radioscanner.ru/uploader/2005/5440.wav 

The transmission was heard (and monitored for tens of minutes) at 0725z on 12165.0 KHz cf on September 22, and it did not change its format, sending the same "train" of bits and sometimes something like a "sync" signal . My measurements match the ones obtained by the Russian friends: baudrate 100Bd and 500 Hz frequency shift, frame is 162 bits and the the length of the codeword could be 6 bits. It's interesting to notice that - looking at the spectrum as at a Morse code -  the points are exactly 3 times shorter than the dashes so the "message" could be 
  -.-.-.-.-.-.-..... 


As usual, recordings are available, just email me :)

22 September 2015

CIS-48 probe/marker signal


heard today on 17289.0 KHz on USB (on May 21 also, but on 17234.0 KHz there) from 1140z, this is the so-called 'CIS-48 probe/marker of channel' signal, according as defined here in radioscanner forum. 
The probes are sent every ~16 Sec - at least in this sample - in quite long sessions w/out any other signal during the monitored time (more than 1 hour) and consist of 4 x DPSK 50 baud modulated tones, located at 500 Hz, 1250 Hz, 1750 Hz, 2500 Hz and spaced by 750, 500 and 750 Hz, bandwidth is 2000 Hz. A short recording is available.




21 September 2015

Logs

08968.0 CROSPR USAF SIPR-Net Croughton, G 1933 USB MIL 188-141 ALE calling MOBD30DAT (18Sep15)
09200.0 --- Unid NATO stn 1350 ISB/DSB LINK-11 SLEW (18Sep15)
14720.0 006 1309 USB MIL 188-141 ALE calling 011 (18Sep15)
14720.0 006 1305 USB MIL 188-141 ALE calling 011 (18Sep15)
14715.0 --- Unid (prob. Russian Intel/Diplo) 0720 cf MFSK-11 125Bd 250Hz step (18Sep15)
14750.0 --- Russian Intel/Diplo 0650 USB SERDOLIK OFDM 35-tone QPSK and MFSK-34 (CROWD-36) segments (18Sep15)


SERDOLIK OFDM 35-tone QPSK and MFSK-34
MFSK-11 125Bd 250Hz step
MFSK-11 recordings are available.

19 September 2015

about π/4 DQPSK modulation (here in CIS-60 30Bd)

looking deeper at CIS-60 signal reported in the previous post, the relative constellation changes in a symbol by symbol way but always exhibiting a 4-ary constellation although absolute constellation in each-1 mode looks like a PSK-8 modulation. This condition is called "π/4 DQPSK modulation" (Pic. 1).
Pic. 1
The π/4 DQPSK modulation format uses two QPSK constellations offset by 45 degrees (π/4 radians) and transitions occur from one constellation to the other, making the illusion of a PSK-8 modulation (Pic. 2). This guarantees that there is always a change in phase at each symbol, making clock recovery easier. The data is encoded in the magnitude and direction of the phase shift, not in the absolute position on the constellation. One advantage of π/4 DQPSK is that the signal trajectory does not pass through the origin, thus simplifying transmitter design.


Pic. 2 - we see PSK-8 in absolute constellation since the π/4 DQPSK modulation format uses two QPSK constellations offset by 45 degrees and transitions occur from one constellation to the other.
I want mean  that we see two 45 deg shifted QPSK (in relative) constellations:
- the one each 1, 3, 5,... symbols
- the other each 2,4,6,.. symbols
and this also influences the pattern that we see in absolute constellation.

In order to be safe about the main modulation (4 or 8-ary) used in this waveform, I highlighted a single channel from the CIS-60 signal (Pic. 3): if it was a clean QPSK or PSK-8 modulation then we should see three harmonics  in the fourth power while there are only two and this outstands a behavior of a π/4 DQPSK modulation (and OQPSK too). 
Now, looking at the phase plane of this channel, notice that the absolute constellation (Diff-0) exhibits 8-ary, BUT, as said above, there is no transition paths through the center (as in case of a clear PSK-8!) and that the relative constellation (Diff-1) looks like QPSK but 90 degrees rotated: this suggest the π/4 DQPSK modulation.
 
Pic. 3

By the way, the π/4 DQPSK modulation format is also used in CIS-45 v2 HDR modem (Pic. 4).

Pic. 4

The channel-by-channel analysis with the SA phase-plane method should be performed on all the channels, but it requires very good signals/recordings and a lot of time; anyway all the channels have been examintaed using SA OFDM module always getting the same  constellations shown in Pic. 2.

17 September 2015

logs

14259.0 --- Russian Mil, RUS 0710 USB OFDM 60-tone modem 30Bd 44.4Hz π/4 DQPSK (17Sep15)
14633.1 --- Russian Mil, RUS 0818 cf MFSK-68 (34+34) (16Sep15)
14547.0 --- Russian Mil, RUS 0815 USB OFDM 60-tone modem 35.5Bd 44.4Hz π/8 DPSK-8 (16Sep15)
08016.0 NPRDPZ Nat. Protection and Rescue Directorate, HRV 1359 USB MIL 188-141 ALE TWS (15Sep15)
16103.0 --- Russian Mil, RUS 1320 USB OFDM 45-tone HDR modem 33.33Bd 62.5Hz DBPSK (15Sep15)
09098.6 FUG French Navy La Regine, F 1336 USB STANAG-4285 1200/S encrypted (14Sep15)
09270.8 --- French MIL Favières via Vernon, F 1308 USB ARQ-E 184.6Bd/850 no traffic (14Sep15)



during the last days, starting atbout 0700z, around 14200 KHz and 14500 KHz on USB was possible to hear OFDM 60-tone modems (aka CIS-60) running at the same time and in different frequencies, i.e. 14233.0, 14259.0 and 14285.0 KHz, and some other interesting signals as the MFSK-68 reported above in the log. The CIS-60 signals belong to the two known waveforms: 35.5 Bd π/8 DPSK-8 and 30Bd π/4 DQPSK (same channel separation,  44.44 Hz). You can also hear op. chats and sometimes quite long CIS-60 sessions consisting of not-modulated carriers followed by modulated carriers but w/out input data (idling). About the "parallel" emissions, I do not know if we face different transmission sites or different beamings/power, anyway, given that fading is not in all the CIS-60 frequencies, it's my guess that these should not be harmonics but just separate transmissions.

MFSK-68 (34+34) - constellation of the embedded PSK bursts
CIS-60 modem 30Bd π/4 DQPSK
op.chat and CIS-60 start

14 September 2015

MIL 188-110A/B/C 150bps, 66.6mS ACF

(a discussion about the MIL 188-110A/B/C ACF values)


This is a MIL 188-110A waveform: decoder k500 (and others) recognizes this signal just as a 188-110A and 150bps/S data-rate. The curious is that this signal doesn't exhibit the 200mS ACF value but a strong 66,67mS frame (160 symbols) and an equally strong  "superframe" of 200 mS length that meets the expected value (200mS). Me and Angazu tried to clrafify the reasons of this.

ACF of this signal (150 bps data-rate)

 Let's have a look at the 188-110 protocol and frame formations:

 

The reason is that the standard 188-110A/B/C has always a 200 mS ACF, but in case of low data-rate speeds (from 150 up to 1200 bps) four groups of the pairs probe+data count 160 symbols (4 x 40) and they are just in sync with the scrambler length (160 symbols) causing the strong 66.67mS ACF. 


66.6mS frame (note the 20+20 groups for low data-rate)
MIL 188-110A/B/C 150 bps

In case of 2400 bps (data and/or voice) we'll have groups of 48 symbols (32 symbols for data +16 symbols for probe) and this value is not correlated to the the scrambler length, so the "visible" ACF in this mode (and in 4800 uncoded) is the known 200 mS.
In case of the lowest speed (75bps) there are no channel probe so the 66.6mS ACF is just due to the scrambler length (160 symbols).

MIL 188-110A/B/C 600 bps
MIL 188-110A/B/C 2400 bps

 "So...we can state that ACF is 200 mS, but scrambler and group formation size generate the 66,6 mS ACF in user speeds of 1200Bd and lower" Angazu says.

A signal with these same features (modulation, speed and ACF) is also reported in radioscanner.ru site but named as USAF MIL 188-110A Compatible and nothing more precise.

11 September 2015

NVIS (and DX) links predictions

During these times of poor propagation, browsing the web you can find pretty useful and interactive tools to try to predict the probability and the reliability of NVIS (Near Vertical Incidence Skywave) single hop paths, representative of common tactical military HF communications scenarios, as well as of thousands of kilometers (DX) paths, more suitable for strategic back haul links scenarios. 

VOACAP Online can be used for NVIS and DX paths. The diagrams show for each hour the propability and reliability of links required by users:
http://www.voacap.com/prediction.html
 
VOACAP diagram related to Italy - Far East links

analysis for the requested link Italy-Swaziland

For who loves to listen exploiting the NVIS propagation, these URLs provide near real-time high-resolution maps of F2-layer critical frequencies (foF2) which correspond to the maximum radio frequency that can be reflected by the F2-region of the ionosphere at vertical incidence, that is when the signal is transmitted straight up into the ionosphere (NVIS): just choose the location that you are interested from a quite extensive list.


today foF2 statistics form Roquetes (Spain)
foF2 real-time plot from Brisbane (Australia)

If you are more interested in NVIS, well, this pdf document is a good starting point.

9 September 2015

a new Russian OFDM modem: 4-ary start-tones


this is a modded version of the CIS-OFDM3100, a (new) Russian modem/waveform reported here.This is the most recent recording of this signal that we have in our hands and it dates back to September 10, 2014 (just one year ago). The updates made to the signal are related to pre-tones, and more precisely their modulation: in the original version (recording of April 2014) the 5 pre-tones had a 2-ary modulation (DBPSK) and 50 Baud speed while this version exhibits a 4-ary modulation. Although the signal name, for what we know, be "Preliminary DQPSK", it's not easy to say which of 4-ary modulations we are facing (DQPSK vs OQPSK) because there are some unclear nuances about the manipulation speed in these tones .

The baudrate auto-measurement method of SA returns the plain standard value of 50Bd (Pic. 1) but we know that this feature does not always determines the correct baudrate so we looked at the absolute phase changes in order to receive a confirm or a new value for Br.
In Pic. 2 all changes are periodic and the 4 mSec changes (associated with 250 Baud speed) take place near the standard 20 mSec changes (associated with 50 Baud speed). Forcing these two values in the phase-module of SA I get two different 4-ary constellations:
- OQPSK @ 50 Baud (no diagonal transitions), as in Pic. 3
- DQPSK @ 250 Baud, as in PIc. 4

Assuming that "Preliminary DQPSK" be something like an official item, we should conclude for a DQPSK 250 Baud but, as said, not all shadows are gone.

Pic. 1 
Pic. 2
Pic. 3



Pic. 4
The above pictures are related to the pre-tone #4 but the findings also apply to the other pre-tones. Below (Pic. 5) another SA method to receive the baudrate of a signal by the full-wave detector: this method also confirms the 250 Baud.

Pic. 5