Installation Manual
THALES Communications
OIM
AHV1600-SYSTEM
Page 106
July 16/09
B. INTERNAL SUB-ASSEMBLIES
The AHV1600 Transceiver contains the following sub-assemblies:
– The Digital chassis:
Performs the High Intensity Radiated Field (HIRF) protection, internal module interconnection,
digital and management processor capacity and power supply distribution,
Provides the helicopter with the mechanical and electrical interfaces,
Provides the hardware support of the downloaded software’s.
– The radio module:
Performs the Radio Frequency (RF) signal emission, the Radio Frequency (RF) signal reception
and the Beat Frequency (BF) signal extraction.
C. FUNCTIONAL CHARACTERISTICS
(1) OPERATION DATA
Output signals characteristics : ARINC 429 standard
Radar Altimeter height : ARINC word label 164 and 165 (BNR and BCD)
Radar Altimeter Status : ARINC word label 272
Timing between both word labels is described hereafter:
First ARINC 429 output (serial) : IRS1 TX HI (+) / IRS1 TX LO (-)
Second ARINC 429 output (serial) : IRS2 TX HI (+) / IRS2 TX LO (-)
ARINC 429 specification:
Exchange: unidirectional asynchronous
Word format: 32 bits data transfer with LSB transmitted in first
Label format: 8 bits in octal coding from LSB position of the word
Parity format: 1 odd parity bit at MSB position of the word
Inter word gap: 4 bits minimum
Note: on each word, the odd parity bit is always computed from the first 31 data bits of the word.
Bit duration : 80 µs 2 µs
Bit form factor : 40 µs
2 µs
Note : the bit duration corresponds to a low speed operation at 12.5 kbps.
ARINC signals Transmission speed : 12.5 kbps
Input signals : AID0, AID1, AID2, AID_P
Low level voltage + 3.5 VDC with sink current < 2mA (logic state 1).
High level voltage
+15.3 VDC with sink current < 1 mA (logic state 0).
Maximum level voltage
+32.2 V
DC
.