Soviet IFF system Parol

система опознавания пароль

Cold War Airfields, by Bert Kondruss


Parol is a Soviet / Russian system for identification, friend or foe (IFF) and is the successor to Kremnij-2 system. Using cryptographic methods, a much better imitation security is achieved. In the late 1980s, introduction to the East German forces began.

For compatibility reasons, many Parol ground systems still support Kremnij in the frequency range III. A new addition is the frequency range VII:
- 1532 Mcs: Interrogation
- 1470 Mcs: Response
- 1458 Mcs: Response
So in this range, two response frequencies are used /2/

Mode I: General Identification (frequency range VII)

This mode is similar to the general identification of the system Kremnij-2 (mode I in the frequency range III). It does not use cryptographic methods, so security must be ensured by code changes /3/. Furthermore, it seems that there is also a check code in this mode /11/. The mode is intended for jammed environments and when interrogated by many interrogating systems /3/.

The interrogation is done with three pulses and a further pulse for side lobe suppression. Pulse diagram of the interrogation according to /3/:

The transponder can reply with 6 different codes. The response consists of two pulses, one on each of the response frequencies. The code is determined by the time interval T between the pulses and by the response frequency fB or fC on which the first pulse is sent /3/

On the screen, a target with identification is shown with a parallel bar /3/, /8/

Codes are different for aircraft and ships /11/.

Mode II: Imitation Protected General Identification ("Guaranteed Identification") (frequency range VII)

For a day, there are 911 possible interrogation codes available. From this large amount, a code is randomly selected and sent for an interrogation. The transponder must receive the code and select and send the matching response code from a set of 16 possible codes. The result is received by the interrogating station and verified. If the response code matches to the sent interrogation code, the target is considered as "own" /3/

Pulse diagram of the interrogation according to /3/:

The response consists of two pulses. The 16 possible response codes are formed by the time interval T between the two pulses (8 possibilities) and by the response frequency fB or fC on which the first pulse is sent (2 possibilities). /3/

Pulse diagram of the response according to /3/:

A target with guaranteed identification is displayed on the screen with a bar parallels with hook. /3/, /8/

Mode III: Individual Identification, distress and alarm (frequency range VII)

According to /3/, the individual identification and distress are marked by a third pulse in the response signal. In contrast, /11/ is saying that the individual identification is defined by a three-digit code.

A ground station can receive the distress signal as an alarm signal and display it with a lamp on the control panel, even if they do not make own interrogations /3/, /8/. The ground stations then have to scan their sector for the target /11/.

Mode IV: Individual identification (frequency range VII)

Interrogation of the 5-digit bord number, requires device IO-4M.

Mode VI: Altitude and fuel (frequency range VII)

Requires device IO-4M.

See also ...

Soviet IFF systems: Overview and sources

IFF system Kremniy-2

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