pseudo-random frequency hopping

Frequency Hopping Spread Spectrum (FHSS) is a method of transmitting radio signals by rapidly switching the carrier among many frequency channels using a pseudo-random sequence known to both transmitter and receiver(s). The heard packets in this sample have a duration of 2520 ms, frequency shift ~ 20 Hz and 20 data bits carried (other similar transmission have been noted with 2460 ms and 24 data bits, same shift) and span up a 2 MHz bandwidth, this recording has been on 13 MHz band.

playing with MS-DMT (MIL-STD Data Modem Terminal)

The MS-DMT application is a software defined modem based communications terminal tool developed as a Microsoft Foundation Class (MFC) based Multi-threaded 32 bit application. It is currently designed to run under MSWindows XP SP3 and later versions of both 32 and 64 bit MS-Windows operating systems. The tool is written in C++ using the Microsoft Visual Studio 2008 compiler and requires the installation of the VS2008 C++ runtime redistribution libraries which are part of the full MS-DMT install distribution only.

The MS-DMT tool functions as both a MIL-STD modem and basic data communications terminal and provides MARS a MIL-STD-188-110A (MS110A) compliant Serial Tone (ST) waveform modem based Message Terminal capability providing message composition and automated message storage to simplify MARS MS110A Forward Error Correction (FEC) message handling.
The software’s terminal provides numerous features to aid in message handling and the software also supports the use of more fully featured external asynchronous terminal applications. Additional features such as Data Link Protocol, Data Compression, Data Encryption and others may be added to the MS-DMT tool as required and in accordance with the specific standards as requested or left to implementation in external terminal applications.
You may use MS-DMT to build, decode and learn the MIL-STD 188-110 ST wavefvorm, the modem, along with other interesting resources and docs, can be downloaded from here:
MIL-STD Data Modem Terminal (MS-DMT) software and resources 

MFSK-4 (double FSK) 96/100Bd 500Hz, Ukraine Military

This waveform is known as Double FSK 96/100 Baud and 500 Hz shift, a dual channel  mode used by Ukraine Military, spreading about a 1730Hz bandwidth and tones at -750, -250, +250 and + 750 Hz. Actually, there are two versions of this waveform:

96Bd-100Bd/500 heard on August 21th on 8008 KHz/usb (likely F7W mode?)
96Bd/500 heard on December 3rd on 6968 KHz/usb (F7B mode)

Site radioscanner.ru reports the first signal (08/21) as Ukraine Mil 96-100, the two baudrates indication (96 and 100) is due to some difficulties  in determining the speed of manipulation, due to the fact that the two transmission channels are not synchronized  with each other. The "double" speed is not present in the measurement results of the first signal (12/03): most likely the two channels are in sync and transmitted according to the F7B mode.

Fig. 1

Fig. 2

96Bd-100Bd/500 waveform (likely F7W mode?)
https://yadi.sk/d/SvmC1_ajzVzAAw

96Bd/500 waveform (F7B mode)
https://yadi.sk/d/VHJYHLgg7ATdeA

CIS-128 and its ACF discrepancy

Looking at a CIS-128 signal heard this morning, I came across the discrepancy about its ACF value and the the right way to calculate it.
The signal exhibits the well known values of this waveform (64+64 channels, 20.9Bd speed and 23.5Hz step) but the modulation seems a BPSK with the add of 4 service tones: unfortunatelly, it's quite difficult to separate a single tone in order to confirm this mode. As it is common for CIS-128, a special char is sent each 5 symbols (Pic. 1) so that the expected value for the ACF should be ~239ms ...but looking for that value we get strong ~477ms spikes in SA module (Pic. 2): it's just the double, or else 10 symbol periods!
In my opinion, the reason for this double ACF is in the way the special chars are sent. 
By looking at the whole 477ms length frame in Pic. 3, it's visible - straining a bit the eyes - the right ACF period that occurs each 5 symbols (~239ms) just as it was expected: but the spec chars sent each 5 symbols are in some way alternately reversed as illustrated by the white-circled bits (Pic. 3). This way, these special chars seem to appear to the ACF-tool eyes as a sort of sequence like 

:: :: :: :: XY :: :: :: :: YX :: :: :: :: XY :: :: :: :: YX :: :: :: ::

and then the repetition period, according to its point of view, is logically 10 rather 5 symbols. Something like an optical illusion. 

Pic. 1

Pic. 2

Pic. 3

The same situation can be found analyzing the 6000Hz 'broadband version' of this waveform (Pic. 4).

In this case the ACF is ~238 ms BUT here the speed is double, so the special chars, which are sent each 5 symbols, should make ~119ms spikes: using the CCF measurement these chars are visible inside the red-marked circles (Pic. 5) and white-marked in the structure of the frame (Pic. 6).

Pic. 4

Pic. 5

Pic. 6

HFDVL modem tests: sync. preamble

Spanish Universities are still conducting intensive tests of the HFDVL modem (hfdvl-modem-ofdm-73-tone) on 14350.0 KHz on USB, I not tried  to listen on the other 14825.5 KHz test-frequency. While the previous tests consisted of transmission of about 30 and 10 seconds duration, in these samples (at least) a different "test format" is used: it seems to me that one side of the link just sends data (long signals) while the other peer seems just send a sort of ACK (shorter signals). The durations are fixed, ie 1'06'' and 0'11 secs. 

The tests involve two transmitting modems, more likely located at Las Palmas - Canary Islands (14350.0 KHz just belongs to the University of Las Palmas) and Madrid, since the HFDVL waveform is developed by the groups "CeTIC" from the Universidad de Las Palmas de Gran Canaria and "GAPS" from Universidad Politécnia de Madrid, other than Aeropuertos Españoles y Navegación Aérea. As far as I know, the modem manufacturer is MM CICOM Telecomunicaciones from Spain.

Prior to the transmission of data, a three part preamble is transmitted.

Part one consists of an initial unmodulated tone more likely used for Doppler correction. This tone is slighty shifted in the two signals (Pic.1) but just a few hz, so pretty meaningless though some distortion visible in ACK signals which could be due to a falut of modem (Pic. 1b). Looking at the Pic. 2, in 17-Nov recording the initial tone lasts for 
- 633.1/3 ms (19 signal element periods) in ACK signals 
- 433.1/3 ms (13 signal element periods) in DATA signals 
while in the 24-May recording the tone has a duration of 433.1/3 ms (13 signal element periods). Part two consists of  2 signal element periods of (KNOWN) data and part three consists of 1 signal element period of only even carriers followed by 3 signal element periods of only odd carriers: part two and three sum to 6 signals and make a 200ms duration (Pic. 3). 
My friend KarapuZ pointed my attention on the part two: according to his analysis, this is BPSK 2400Bd modulated and carrier is 60 Hz down-shifted in respect of the unmodulated tone frequency. The 60 Hz shift is probably added for the initial synchronization. Following his tips I replicated his results (Pic. 4).
 

Pic. 1

Pic. 1b

Pic. 2

Pic.3

Pic. 4