COMPONENT MAINTENANCE MANUAL
C17004
34-57-96
Page 20
COPYRIGHT
SEXTANT Avionique 1995
c
(b) Signal processing
This function is designed to make the signals received usable by the
central processing unit.
The signal is processed on PCBs Z3 and Z4.
The HF PCB, Z4, pre-processes the signal.
The CPU PCB, Z3, processes the signal.
On the Z4 PCB, the Asic T100 performs common pre-processing of the
GPS signals.
The Asic T100 functions in association with two Asic TS25 circuits,
installed on the CPU PCB, Z3.
The two TS25 circuits process the GPS signals; each circuit may pro-
cess 5 parallel channels i.e., a total of ten channels, eight of
which are used.
Each separate channel receives a different satellite, chosen by the
central processing unit according to the satellite code.
Each TS25 circuit serves to interface commands and data acquisition
from the central processing unit. The fact that the TS25 circuits
and the central processing unit are grouped together on the CPU PCB
means that the signal is completely processed on this PCB.
(c) Central processing unit
The central processing unit comprises a 68020 microprocessor and a
68822 coprocessor, associated with the memory circuits.
The following buses are used for communication between the various
Asic circuits, the central processing unit and the input/output
interface:
- 32-bit data bus: D (0/31),
- 32-bit address bus: A (0/31),
- Service bus, SB;
(d) Input/output interface
This interface, installed on the CPU PCB Z3, is used for:
- Matching program pin input signals on the data bus,
- Managing ARINC 429 input/outputs, using the Asic circuit COMA,
- Managing RS422 input/outputs, using the Asic circuit GLU .
(e) Filtering input/outputs
The various input/output signals transit through the Z2 filter PCB,
which is directly connected to functional connector J1 using a flat
cable.
OCT 16/95
The document reference is online, please check the correspondence between the online documentation and the printed version.
