I received from my friend Nicola, and gladly publish it, his work on Russian-Ukrainian Datalink.
When reading these notes, one should be aware that they have been pieced together from numerous sources and then consolidated. Carefully controlled machine translation from Russian and Ukrainian has been used. It should also be taken into consideration that the workings of the protocols and the nature of the application data they transport as well as the composition of the automated, military systems they serve may not have been fully understood. Markings in yellow indicate that translation is not available or that the given translation is tentative or poorly understood. Russian and Ukrainian designations have mostly been transliterated into Latin characters.Summing up: this is a work in progress.
1. Introduction and history
Russian-UkrainianDatalink
(RUSUKRDL) is a fictive designationwhich for the sake of simplicity is used in
these notes to designate a collection of data link and application layer
protocols used in air defense, fire controland automated battle field data networks
of the armed forces of the Russian Federation,Ukraine and probably also of other
former Soviet republics.
The description below will concentrate on the Akkord family of protocols. Akkord seems to be a fairly old family of data transmission protocols.In 1953, the Scientific Research Institute of Electrical Devices (NII ETU) separated from the Krasnaya Zarya plant, the main activity of which was the creation of technical means of data transmission and photo-telegraph equipment. The customers were the Air Defense Forces, the Navy, and the Space Forces. The data transmission protocols and equipment created by the Research Institute of ETU, "Araks", "Aragva", "Pogoda", "Akkord-SS-PD", "Akkord-SS-PS" and a number of others are still in operation in the ministry of defense of the Russian Federation.
The operation of early Akkordprotocols are described in detail in a textbook from 1975. Akkord-50 was one of the first protocols and used ITA-2 with blocks of 12x5 data bits + 2 repetition flag bits + 13 checksum bits in fixed data block mode transmitting at 50 or 100 Baud.
Exchange of traffic works like this: Sending station (PD) sends signal “start of data” (SSSS) and the receiving station acknowledges with ‘I’. Then the sending station sends ‘I’ and data block 1 with the two flag bits set to ‘00’. If the sending station does not receive a receipt (‘I’) within 1.5 s after having transmitted a data block, it retransmits the unacknowledged block, now with the flag bits sets to ‘01’.
Akkord-1200
is a protocol designed to be used for data transmission at 600 or 1200 Baud.
In the figure above, the upper diagram shows the structure of a block at 600 Baud, while the lower diagram shows the structure of a 1200 Baud block. The former has 4 block number bits + 112 data bits + 16 check bits (= 132 bits), while the latter utilizes 4 + 240 + 16 bits (= 260 bits). The generator polynomial is x16+x12+x5+1, CCITT-16, the same as used in laterAkkordprotocols described below. It should be obvious from the above illustration, that the structure of Akkord-1200 is very similar to Akkord-SS-PD.
A
special phasing block initiates the transmission of data:
 |
The block consists of 4 flag bits + 60 bits with an optimal number of bit transitions + 16 bits of a special phasing sequence, totaling 80 bits.
As is obvious from the illustration above, Akkord-1200 transmits a data block adding an ‘A’ to the first block, which is acknowledged by the receiving station. Block B(2) arrives in error, and a request for retransmission is issued. Block C (3) is transmitted. When the sending station receives the request, it retransmits blocks B and C.[1]
2. Protocol stack
The protocols discussed in this document are datalink layer protocols and the data they transport. The physical level network, transport and application layers is consequently not part of this discussion, but most of the intercepted radio links have been characterized by a telegraph speed of 1200 bps FSK with a shift of 800 Hz in the frequency range 5-7 MHz, which suggests short to medium range distances. Sources also mention the use of PSK, both absolute and differential.
|
DATA |
|
APPLICATION |
|
TRANSPORT |
|
NETWORK |
|
DATA LINK |
|
PHYSICAL |
2.1 Datalink layer protocols
|
Protocol name |
Block length [(n, k] bits] |
Speed |
Used with |
Remarks |
|
Akkord-SS-PD (“Akkord-165”) |
(165, 144), (117, 96), (69, 48) |
1200, 2400, 4800, 9600 bps |
AI-010, 55Ts6, R-050 |
|
|
Akkord-SS-PS |
(69, 48) |
2400 bps |
AI-011 |
|
|
Irtysh |
(117, 96), (69, 48)[1] |
|
T-235-1L |
|
|
Aragva |
(126, 110) |
1200 bps |
5Ts55 |
|
|
Araks |
? |
? |
? |
Details unknown |
|
Pogoda |
? |
? |
? |
Details unknown |
|
Almaz |
? |
50 Baud |
KSA 5D72, 88E8 |
|
|
? |
(20, 15) |
|
5Ts49 |
ITA-2 (MTK-2) |
|
Pautina-1M |
(32, 28) |
60 |
? |
2 channels |
|
STA-2M |
15 … 26 characters |
|
STA-2M |
ITA-2 without check bits |
|
RB |
? |
? |
? |
Details unknown |
|
ASPD-U |
(40, 36) |
234, 468 |
|
|
2.1.2 Akkord-SS-PD
This protocol appears to be the main protocol used. The packet structure of this protocol is as follows:
The 4 m-bits are so called service bits which are used to signal various modes of operation at link level. The C-bit – also a service bit - indicates the address mode used, and the CRC is the cyclic redundancy check protecting the preceding bits. The protocol is transparent and may transport various types of information.
2.1.2.1 m-bits
These bits indicate the various operation modes of the protocol.
|
Service bits |
|||||
|
Service bit values |
Type of packet
|
||||
|
m |
C |
||||
|
1st Bit |
2nd Bit |
3rd Bit |
4th Bit |
||
|
X |
X |
X |
X |
1 |
Addressed |
|
1 |
0 |
X |
X |
0 |
Broadcast[1] |
|
1 |
1 |
X |
X |
0 |
Idle[2] |
|
Note - "X" is the arbitrary value of this bit (0 or 1) |
|||||
m1 = Flag for erasure mode operation (in Russian DRS, see below)
m2= Flag for feedback (ARQ) operation (in Russian DRO, see below)
Only for duplex operation:
m3 = Receipt for received data block
m4 = Communication channel status indicator
|
m-bits |
Remarks |
|
1000 |
Observed with (165, 144)and (117, 96) payload packets |
|
1010 |
Observed with (69, 48) payload packets |
|
1100 |
Observed with (117, 96) scrambled idle (‘silence’) packets, and (69, 48)scrambled packets[1] |
|
1101 |
Bit sync packets |
Other sources indicate this for Akkord-165:
|
Digitvalues |
Codagram types |
|
|
m |
C |
|
|
0101 |
1 |
Phasing combination (F1 or F2)[1] |
|
010х |
0 |
Idle combination (х – arbitrary value) |
|
zzz0 |
0 |
Information block, where the value of zzz determine the retransmission delay code |
2.1.2.2 Data bits
Data transmission is carried out in blocks of 48, 96 or 144 data bits structured in a number of – 2, 4, or 6 - 24-bit data words. The data field contains the data payload.
2.1.2.2 C-bit
The C-bit indicates whether the data block isunaddressed (‘0’) or addressed (‘1’) to a single recipient or is a broadcast. The address range is 1 to 15.
2.1.2.3 Checksum
The m-bits, the data bits and the c-bit are protected by a 16-bit cyclic redundancy check with a generator polynomial G(x) = x16+x12+x5+1, which is the standard CCITT CRC-16. This will detect six errors and correct three.
2.1.2.3 Protocol operation
The protocol is able to operate in three connection modes: Simplex, full duplex and half duplex. In duplex two sub-modes are available: Data erasure mode, where packets received in error are dropped, and feedback mode, where packets received in error are requested to be retransmitted by the opposite party by transmitting block repetition requests(RQ). If ‘erasure mode’ is disabled, packets in error are forwarded to the recipient (DTE) accompanied with an error indication to warn the end consumer. In simplex and half-duplex modes only erasure operation is available.
SIMPLEX (SPX)
Format: Full Akkord format
Initial sync: 2 x block length reversals + sync seq (normal)
Cyclic sync: Each 21th block is sync seq (normal)
No traffic: Idle sequence
FULL DUPLEX (FDX)
OK ODK-1
Format: Full Akkord format
Initial sync: 2 x block length reversals + sync seq (normal)
Cyclic sync: Each 96th block is sync seq (normal)
No traffic: Idle sequence
OK ODK-2
Format: All bits except the 16-bit CRC are used for data.
Initial sync: 2x block length reversals + sync seq (normal) + sync seq (inverted)
Cyclic sync: Each 96th and 97th block is sync seq (normal) + sync seq (inverted)
No traffic: Idle sequence
OK ODK-2-1
Like ODK 2, but connection is closed down, when no traffic is received from the DTE.
HALF DUPLEX (HDX) (Alternate Duplex mode)
PDK-1
Format: Full Akkord format
Initial sync: 2 x block length reversals + sync seq (normal)
Cyclic sync: Each 21th block is sync seq (normal)
No traffic: Connection closed down
Other sources use the terms Simplex-1, Duplex-1, Duplex-2 and Duplex-3:
SIMPLEX-1, DUPLEX-1
Sync seq every 95th block.
DUPLEX-2
Resync is only initiated if a certain number of Block Repeat Requests[1] is received. Resync is attempted until sync is achieved, i.e. when the exchange of sync seqs with F1 and F2 flags takes place. This happens when the opposite party responds with F2 when sync seqs with F1 are received[2].
DUPLEX-3
Sync every 20th block. After initial sync synchronization is only resumed if a Phase Request[1] signal is received from the opposite party. If sync is not achieved after 96 blocks, then sync seqs are sent every 20th block.
2.1.2.3.1 Synchronization
A special 69-bit synchronization sequence is generated by the polynomial F(x) = x8+x6+x5+x4+1. The start byte of the sequence is 01010000 (0x50) and the final byte is 00000011 (0x03).This 69-bit sync sequence is extended for other block formats so as to cover an entire block, i.e. for (117, 69) 48 bits are added,… 0010 0100 1101 1100 1000 0010 1011 0110 1011 1101 1100 0011, and for (165, 144) another 48 bits are added, … 1110 1101 1110 1011 1010 0010 0001 1011 1111 0011 1001 1000.
Initial synchronization is achieved by transmitting a string of bit reversals. A polarity violation signals that the following string of reversal is the last before an initial sync sequence is transmitted. After this sequence has ended and synchronization achieved, data transmission starts. Depending on the transmission mode, sync sequences are inserted in the data stream at regular intervals (see preceding paragraph).
When the initial phasing codeword 0x50 has been found, the phasing analyzer module of the DCE proceeds to search for the ending codeword 0x03. It the proceeds the sync process, and being synchronized is defined as at least 21matches have been found within 29 bits in any interval of the phasing sequence. At least 21 matches of the corresponding bits must have been detected[1].
2.1.2.3.2 Idle
The idle packet for the (69, 48) and (165, 144) formats is structured like this:
m = 1101 (4 bits)
data = ‘01’ (reversals) (48 | 144 bits)
c-bit (1 bit)
crc (16 bits)
In the idle state the (117, 96) format seems to transmit packets with their contents set to the bits of a pseudo-random bit stream.
2.1.2.3.2. Request for repetition
In duplex mode and with feedback mode selected, the transmitting party stores the already transmitted data blocks and waits for acknowledgement from the opposite party. If an acknowledgement is not received within the time of four data blocks, then the stored data block is retransmitted. This procedure continues until acknowledgement is received.
3. Application protocols
In this document, the term application protocol is used to describe the data transported by the underlying protocol(s).
It seems that the family of Akkord protocols are used for a number of purposes including transmission of defense radio monitoring data and maybe most importantly in automated air defense systems deploying radar stations and altimeters, computation centers, fire control for surface to air missiles (SAM) and control and command for interceptors.
3.1. (69,48)
3.1.2. Irtysh (T-235-1L)
The transfer of information from a radar station via the AI-011 DCE is made automatically using three types of messages with the following priorities:
1. Coordinates of the radar station and information about its operating modes.
2. Target coordinates and bearings for AShP setters.
3. Target coordinates and signs and a flagfor the radar image acquisition channel (automatic or PAS).
Messages of the first priority are sent three times passing the DNA radar direction relative to North.
Messages of the second priority about bearings for AShP setters issued only through the automatic pickup channel.
Messages of the third priority are target information packages sent as they are created.
POP - attention flag (1)
?? (2)
PAS - semi-automatic pickup flag (1)
PG - group target flag (1)
PP - target belonging flag (2)
PT - current review flag (1)
TL - location time (8)
H - target height (for auto-detect and PAS) (8)
ZХ (ZY) - coordinate Х(Y) sign flag (1)
X(Y) - coordinate X(Y) (11)
3.2. Akkord-SS-PS or Akkord-SS-PD?
The messages for the (69, 48) format depicted below – called codograms(KDG) in Russian and Ukrainian – are transmitted between the various components and units of the automated systems. In the sources these messages have been described:
|
Information content |
Form of information submission |
DCE |
|
|
VKP-9S52 |
Computer calculated alerts (20 targets) |
KDG 5, 6, 7, 8 |
AI-011 |
|
Commands to RZ |
KDG 15 |
||
|
Purposed commands (to 2 TsV and 5 ZD) |
KDG 10 |
||
|
General purpose commands |
KDG 12 |
||
|
9S52-VKP |
Information on accompanying targets (up to 24 (96) traces) |
KDG 5, 6, 8, 20 |
AI-011 |
|
Reports onKU, KZ, KRZ |
KDG 11, 12, 15 |
||
|
Reports on the combat capability of individual zrdi |
KDG 5, 6, 8 |
||
|
PORI P1 – 9S52 |
Computer calculated alerts (up to 50 targets) |
KDG 5, 6, 8 |
AI-011 |
|
Bearings |
KDG 9 |
||
|
Reports onKU, KZ |
KDG 11, 12 |
||
|
Coordinates for RLI TS (radar station) |
KDG 12 |
||
|
9S52 – PORI P1 |
Management commands |
KDG 10 |
AI-011 |
|
General purpose commands |
KDG 12 |
||
|
Batch of target numbers |
KDG 7 |
||
|
Coordinates of UT zrbr |
KDG 16, 17 |
||
|
9S470 – 9S52 |
Information on 6 targets accompanying SOU |
KDG 4, 6, 8, 20 |
S23-1 |
|
9S52 – 9S470 |
Reports on KTs |
KDG 11 |
S23-1 |
|
Checkpoint coordinates |
KDG 13 |
||
|
Select computer calculated alerts (up to 15 targets) |
KDG 4, 6, 7, 8 |
||
|
Commands on targets (up to 4 TsV and 5 ZD) |
KDG 10 |
In the following, field explanations will not be repeated after their first occurrence.
 |
|
Message no. 4 –Target coordinates (DCE S-23-1, for DCE AI-011 this message is no. 5) |
ООП – Attention flag (1): 0 = ?,1 = transfer of X, Y coordinates
ПO – Process flag (1): 0 = automatic, 1 = manual
X - Not used (2)
ОЦГ - Group target flag (1): 0 = single, 1 = group
OH – (ЧЖ,СВ, …)- State affiliation (2): 00 = unrecognized,01 = ЧЖ(chuzhiy)- alien, 10 = CB (sviy) - own, 11 = suffer his own misfortune
Озн. наявн. Н.(1) –Flag for height reliability
X -Not used (1)
NСЛ – Trace number (7)
H– Height x200 m (8)
X – X coordinate x100 m(first bit probably sign) (12)
Y – Y coordinate x100 m (first bit probably sign) (12)
 |
| Message no.6 – Target characteristics (DCE AI-011) |
ООП
ТП– ? (6)
X - Not used (2)
NСЛ(NЦ)- Trace (target) number (7)
ТЦ – ? (3)
ПД – ? (2)
ПМ- ? (2)
X - Not used (1)
КС – ? (5)
ТСС - ? (3)
VX – Horizontal velocity along the X-axis(first bit probably sign) (8)
VY – Horizontal velocity along the Y-axis (first bit probably sign) (8)
 |
|
Message no. 8 – End of data transmission (DCE AI-011, S23-1) |
ПOП – ? (1)
ТП
X - Not used (2)
NСЛ(NЦ)
X - Not used (6)
КПТ (траси)–End of data command (2)
X - Not used (24)
 |
|
Message no. 10 – Target command (DCE S23-1) |
ПOП
ТП
X - Not used (2)
NСЛ(NЦ)
КЦ - ? (4)
КЦ - ? (4)
X - Not used (24)
 |
|
Message no. 12 – Various commands (DCE AI-011, S23-1) |
ПOП
ТП
X- Notused (9)
Командазагальноготипу (КЗ)– Generalpurposecommand (4)
Командазагальноготипу (КЗ)– General purpose command (4)
X – X coordinate (12)
Y – Y coordinate (12)
3.3. Akkord-SS-PD
3.3.1.Akkord (69, 48)
The picture above illustrates idle packets mainly containing bit reversals, payload packets (target coordinates (KDG 4 (or 5)), and end of data for given targets (KDG 6)) as well as a sync sequence (marked ‘phasing’) for the (69, 48) format.
This picture show a (69, 48) transmission with scramble or encrypted data blocks and two phasing sequences
3.3.2 Akkord (117, 96)
This format has only been observed used for the transmission of 48 bit data blocks or scrambled idle blocks. The remaining 48 bits are filled up with padding characters (0x0Eh). The blocks of data is initialized with a data block with unknown purpose: 0x7E + 0x45 (or 0x3A)+ bit reversals + 6 x 0xE0.
A transmission in (117, 96) format showing scrambled or encrypted data blocks (probably idles), 48-bit blocks (KDG 4 (5)) with 48bits of padding characters (0x0Eh). Also, notice the initial bit sync string followed by a bit violation in bit 1 in row 3 followed by an initial phasing sequence starting with the codeword 0x50h and ending with 0x03h
Again scrambled (117, 96) data blocks (idles) exhibiting a Pseudo Random pattern (the four ‘belts’ starting in the lower left corner and running diagonally towards the upper right corner.
3.3.2. Akkord (165, 144) (”Akkord-165”)
3.3.2.1. Automated battlefield systems
The messages for the (165, 48) format depicted below are transmitted between the various components and units of the automated systems. In the sources these messages have been described:
|
Direction of information transfer |
Information content |
Form of information submission |
|
I Computer calculated coordinates |
1 x 10 s |
|
|
II Characteristics of computercalculated coordinates |
Immediately after I, then 1 x 2 min |
|
|
III Bearings |
1 x 10 s |
|
|
IV About VP from SAZV |
When updated |
|
|
V Interaction with target |
As needed |
|
|
VI Load of OK and BG DRLI |
1 x 20 s |
|
|
Notification about ET (training) |
|
|
|
KP 1, 2 (about the serviceability of the data channel) or KP 3, 4 |
1 x 10 s |
|
|
73N6 <-> 5N55 (5N55M-O) |
Computer calculated coordinates |
1 x 10 s |
|
Telephone conversation regarding computer calculated coordinates |
One time |
|
|
Bearings |
1 x 10 s |
|
|
Order regarding computer calculated coordinates, 73N6 |
One time |
|
|
KP 1, 2 (about the serviceability of the data channel) or KP 3, 4 |
1 x 10 s |
|
|
73N6 <-> 5K38 |
Interaction commands |
|
|
Guidance information |
|
|
|
Information about the reversal of the VP |
|
|
|
Computer calculated coordinates |
|
|
|
Orders on PN |
|
|
|
KP 1, 2 (about the serviceability of the data channel) or KP 3, 4 |
1 x 10 s |
|
|
73N6 <-> 70R6 |
Order to the database (BD) |
|
|
Orders regadingRLV sectors |
|
|
|
Reference route |
|
|
|
Report on computer calculated coordinates |
|
|
|
Report on database (BD) system |
|
|
|
Report on the ZRK (SAM) database |
|
|
|
Control report |
|
 |
|
Exchange formatfor the link between 73N6 and 5N60, 61K6, 46L6 |
Word no.
1Message header? (24);
2 No. trasi – Trace number (8); +/- - Sign of X (1); X(tsmr – 100 m) –X coordinate (res. 100 m) (14);RP (1)
3 ?(1); ? (7); +/- - Sign of Y (1); Y(tsmr – 100 m)– Y coordinate (res. 100 m) (14); Not used (1);
4 +/- - Sign of VH (1); VH(tsmr- 10 m/s)– Vertical velocity (res. 10 m/s) (7); HH– Fag for height information reliability (0 – H is reliable) ? (1); H(tsmr -100 m)– Height (res. 100 m) (10); Td – Time offset? (5);
5 VZ (2); POM (2); OGP (2); OGP(1); VH (1); +/- - Sign of horizontal velocity along the X-axis (1); Vx(tsmr - 10 m/s) – Horizontal velocity along the X-axis (res. 10 m/s)(8); M (2); Not used (2); KS(Ts) – Something regarding the target (3);
6 TLA (4); IVO (4);+/- - Sign
of horizontal velocity along the Y-axis (1); VY(tsmr res. 10 m/s)
– Horizontal velocity along the Y-axis (res. 10 m/s) (8); TII (4); SOPR(3);
RP – Flag for electronic warfare purposes; HH – flag for reliability of height (0 - H reliable);
VZ - Interaction with target: (00 - none; 01 - VA; 10 - ZRV; 11 – VA and ZRV);
POM– Interference from target: (00 - none; 01 - AZ; 10 - PZ; 11 - both);
OGP– State affiliation: (00 - unrecognized; 01 - alien; 10 - own; 11 - suffer his own misfortune);
OGP - Flag for renewal of state affiliation?;
M–Flag for maneuver (00 - none; 01 - on course, 10 - on height; 11 - on height and course);
TLA- ?: (SB, IB, KR, PRS, …);
IVO - Air object index code;
TII - Type of radar data: (000 - SAZO; 001 - SNR, RPTs, RPN; 010 – radar station (RLS) in meter range; …);
SOPR –Support information:(001 - new target; 011 - coordinates extrapolated; 100 - correction of coordinates X, Y; … 111 - reset route).
 |
| Exchange format for the link between 73N6 and KZA 5N55M |
1Message header? (24)
2No.trasi (8); +/- (1); X(0 – 1638,3) (14); Not used (1)
3No.RTB(strashirozryadi) (8); +/- (1); Y(0 – 1638,3) (14); SN (1)
4No.RTB(molodshirozryadi) (8); Not used (1); H(0 -102,3) (10); Td (5)
5? (2); No. zayavki (22)
6TLA (4); IVO (4); ¿ (9); VNPR (4); ¿ (1); PA (1); ¿ (1)
SN – Flag for connection numbering: (0 –Number is in the number system of the transmitting KP; 1 –Number is not in the number system of the transmitting KP);
№ zayavki- Number of the application aircraft (consists of two digits (letters) and the code of the VP);
VNRP - Type of flight violation: (0000 - none; 0001 - violation of the KS; 0100 - deviation for H; 1000 - by route, …);
3.3.3.2. Radio monitoring data
 |
|
Akkord(4 x 24 bits) used for the transmission of radio monitoring data |
Word no.
1 Шифр (8);Частота(24): x10 МГц (4), x1 МГц (4), x100 кГц(4), x10 кГц(4),
2x1 кГц(4), x100 Гц(4); Пеленги (12): x100 Град (4), x10 Град (4), x1 Град (4); ТЛФ (2); Приoр (2)
3 чатота нажатияFн(12): x1 кГц (4), x100 Гц (4), x10 Гц (4);чатота отжатияFo(12): x1 кГц (4), x100 Гц (4), x10 Гц (4)
4 полоса (4); скоростьТЛГ (боды) (4); Сост. Цели (4); Уровни (4); X (12)
Шифр - Number?
Частота- Frequency: x10 МHz, x1 МHz, x100 kHz, x10 kHz, x1 kHz, x100 Hz
Пеленги- Bearing: x100 degrees, x10 degrees, x1 degrees
ТЛФ- ?
Приoр- Priority
чатотанажатия–?: x1 kHz,x100 Hz, x10 Hz
чатота отжатия- ?: x1 kHz, x100 Hz, x10 Hz
полоса- Band
скорость ТЛГ (боды)– Telegraphspeed (Baud)
Сост. Цели– Target composition?
Уровни– Levels
Not used?
3.3.3.3. Time and time offset data
 |
|
Akkord-SS-PD (2 x 24 bits) used to transmit network time and time offset. The message is meant to be transmitted immediately following a phasing block |
Word no.
1 AM-PM(1); Часы (4); Минуты (4); секунды (4); миллисекунды (7)
2 день (5); месяц (4); Год (7);смещение (8)
AM-PM – Before or afternoon: 0 = AM, 1 = PM(1)
Часы- Hour: 0 – 12
Минуты– Minut: 0 – 60
секунды– Second: 0 – 60
миллисекунды–Milliseconds: 0 – 100
день–Day: 1 – 31;месяц– Month: 1- 12; Год– 0 - 99;смещение–Offset (0 – 4,25 min)
4. Samples
This sample consists of two (69, 48) Akkord-SS-PD or PS messages KDG no. 4 and no. 6 transmitted from a S23-1 DCE, where the data link layer has been removed. These messages seem always to be sent together:
KDG 4: 11000101 00100010 00100000 110111011010 000111111100
KDG 6: 00001010 00100010 01010000 000001000010011100010101
KDG № 4 Coordinates of the target (DCE S23-1, [KDG] No. 5 via DCE AI-011)
11000101 0010001000100000110111011010000111111100
1 = OON (attention flag = transferring X, Y coordinates)
1 = PO (process flag = manual)
00 = X (not used)
0 = OTsG(group target flag = single)
10 = ON(indication of state affiliation = own)
1 = Ozn. Nayavi. H (height information reliability flag = Height unreliable)
0 = X (not used)
0100010 = NTs = 34 (trace/target no.)
00100000 = H (x200 m) = 32 = 6400 m
110111011010 = X (x100 m) = 1 10111011010 = +149800 m
000111111100 = Y (x100 m)= 0 00111111100 = -50800 m
KDG № 6 Characteristics of the target (DCE AI-011)
00001010 00100010 01010000 00000 100 0010011100010101
0 = OON (attention flag = no transfer of coordinates)
000101 = TP = 5
0 0 = X (not used)
0100010 = NTs= 34
010 = TTs = 2
10 = PTs = 2
00 = PM = 0
0 = X = 0 (not used)
00000 = KS
100 = TSS = 4
00100111 = Vx = 0 39 = 390 m/s
00010101 = Vy = 0 = 21 = 210 m/s
KDG № 8 End of data transmission (DCE AI-011, S23-1)
00010010 00100010 00000011 000000000000000000000000
0 = POP
001001 = 9 = TP
0 0 = X (not used)
0100010 = NTs = 34
000000 = X (not used)
11 = 3 = KPT (trasi) = end of tracking command
0…0 = X (not used)
