Re: Stanag 4193 Pdf.zip
Sondra Pevy
The Identification Friend or Foe (IFF) Mode 5 sub-project will provide modern IFF Mode 5 cryptographic devices to be used in conjunction with new IFF Mode 5 transponders and interrogators being implemented in Canadian Armed Forces (CAF) that meet the STANAG 4193 specifications. The primary objective for the IFF cryptographic modernization sub-project is to replace in-service Mode 4 cryptographic devices currently being used in conjunction with the IFF system.
1.SCOPE
This document describes the functional requirement and implementation of blanking pulse generation logic in IFF MKX Transponder, required to Interface the IFF unit with jammer pods of the Sukhoi-30MKI aircraft.
2.INTRODUCTION
Avionics bay of an aircraft comprises various LRUs operating in L-Band. Whenever any L-Band LRU initiates transmission, at the same time it should send a blanking pulse to the other L-band LRUs in order to protect the receiver of the LRU from high power RF and avoid interference. This blanking pulse shall disable the receiver circuitry of other LRU. Blanking pulses from the different LRU are routed to the EMC unit, which has the protocol logic for routing the blanking pulses of various LRUs as per the requirement. This invention claims the blanking pulse generation logic in IFF MKX Transponder for interfacing with jammer PODs in aircraft.
3.DESCRIPTION
Blanking pulse from IFF Transponder should be available to the other L-band LRU a minimum of 0.8us well before the reply is generated from the IFF for the interrogation received from ground station (ATC). If the suppression is generated with a delay of less than 0.8us from the reply, then the blanking of LRU may not be proper, which shall cause the jammer PODs to receive the own aircraft signals (of IFF) and show on the RWR as unknown targets, which can mislead the pilot for some radar target.
So the IFF MKX Transponder should generate and provide the blanking pulse at proper time in order to blank the other L Band LRUs during IFF Transponder reply operation.
BLANKING PULSE GENERATION (DESIGN)
IFF MKX Transponder interfaces to the on-board EMC unit using a co-axial cable, and the output of EMC unit for jammer PODs is also routed through coaxial cables. The blanking pulse generation logic is implemented in an on-board complex logic programmable device (CPLD) in the Encoder card of IFF MKX Transponder. The CPLD is a Xilinx CPLD with 64pins operating on a clock frequency of 2MHz. Its primary function is blanking pulse generation based on the interrogation, emergency and IP functionality implementation.
This blanking pulse generation logic complies to STANAG 4193. The blanking pulse generation logic is depicted in Fig 1 below.
Fig 1. BLANKING PULSE GENERATION LOGIC
Based on the input interrogation, the blanking pulse is started at the falling edge of second pulse of P1P3 pair and then it is made LOW at the falling edge of the encoder gate signal from the decoder card. The timing diagram is shown in fig 2 below. This blanking pulse output from CPLD is a TTL signal which shall be level translated to 24V in the video processor card using transistor logics which is then routed to the output BNC connector on the front panel of the IFF MKX Transponder.
CLAIM:
I claim that this blanking pulse generation logic implemented in IFF MKX Transponder
(1)Maintains the Interface and timing protocol as per STANAG 4193 standard.
(2)Provides efficient and reliable blanking signal to the other L-band LRUs without any intermittency.
(3)Amplitude and pulse width control is implemented using an RC combination at the output of supp_out line.
(4)Spurious pulse elimination logic is implemented to cater for invalid interrogations.
(5)Autonomous generation of blanking pulse during IP and EMERGENCY operation.
(6)Blanking pulse rise time and fall time are matched to the maximum load conditions.
(7)Interface from IFF to EMC unit is through matched coaxial cable.
Models are available that comply with IFF Modes 1, 2, 3A & C, 4, ,5, and Mode S-ELM designed to meet the demanding standards of DoD AIMS97-1000, RTCA/DO-181C, and STANAG 4193. Series 1100 products are in use worldwide in IFF Transponders and in the US Army Model PPX-3 IFF Interrogator.
A similar document to Annex 10 is STANAG 4193 which is published by NATO. This document covers additional specifications concerned with the characteristics of the military Modes 1, 2 and 3, as well as Mode 4.
- Mode 4: For IFF (NOT ONLY AIRCRAFT), ENCRYPTED. So I was curious of how this is works, I looked into the STANAG 4193 (listed as classified -promulg , look for 4193) and AIMS DoD ( -international-aims-program-office---dod-aims) documentation public available, not very useful. Well, one thing that's clear is that there's a communications system which transmits the Mode 4 keys to all "allowed" Military NATO operators in the world. I suppose that in legacy times these Keys were broadcasted encrypted by radio stations and bases, for oceanic keys probably VLF bands. The first time entering the "community of devices that knew the keys" you probably needed a second party already inside it providing the current keys (since key are updated), and once you are in you can update your own keys. With the introduction of GPS those keys were probably transmitted inside navigation message carried Y-code (encrypted P code), and nowadays carried inside M-Codes (GPS) which they can carry more Military information and provide other capabilities related with DataLink, MIDS, etc.
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