User's Manual

SBS-900 Shore Based Radar Systems
Chapter 10: Corrective maintenance
KH-1602-2 issue 1: Standard SBS900 Systems Operator & Maintenance Handbook
Page 201 of 240
10.8.10 NTX-A477-1 radar I/O module
Modular interface system module (MISM) Type 9 (radar I/O module Mk 2)
Part number NTX-A477-1
Backplane locations: A3 (service display output)
A4 (Track extractor output)
B3 (Spare output)
Overview: The radar I/O module interfaces the following signals with the backplane:
- Analogue radar input (video, sync, azimuth and heading line)
- Analogue radar output (video, sync, blanking, azimuth and heading line)
- An auxiliary video channel is used for an ESM Blanking pulse input from
the Tx/ Rx
- A blanking output is used to output an ESM blanking pulse
The board is controlled by the backplane which selects the radar input from
one of many input channels and route the data to the output channels using
the video switching circuitry.
Video IN: Radar video is received on SKA at +1.0V to +6.0V peak-to-peak with an input
impedance of 75ohms and is routed to the radar I/O PCB.
The video is applied to an operational amplifier which provides a 2.0V peak-
to-peak output which is dropped to 1.0V peak-to-peak (TP5) for application to
the backplane. The video amplifier gain and offset is manually set and
controlled from the backplane at 1.0V peak-to-peak ensuring the correct input
level. The offset circuit allows the amplifier to compensate for any DC offset in
the input signal, thus providing the correct signal level to the backplane.
LED D5 flashes when the video input is detected by the backplane.
Video OUT: Video out of the radar I/O PCB is sent to the backplane terminated at 75ohms
to provide an output of between +1.0V to +5.0V peak-to-peak to SKD which
can be measured at TP9.
Sync IN: Radar sync is input on SKB at 3.0V to 15V pulses and an input impedance of
75ohm and is routed to the radar I/O PCB. The sync is processed and passed
via a high speed differential comparator to the backplane as an LVTTL signal
(TP8).
LED D4 is lit when the sync input is detected by the backplane.
Sync OUT: The sync output from the radar I/O PCB is amplified by to provide sync
pulses between 3.0V and 14V on SKE and TP11. The sync level is controlled
from the backplane and an operational amplifier.
Aux video/ blanking: The auxiliary video input/ blanking from the radar I/O PCB is amplified to
provide blanking pulses between 3.0V and 14V on SKF and TP10. The
blanking pulse level is controlled from the backplane and an operational
amplifier.
Azimuth: The Azimuth inputs (Az1 and Az2) utilises the same circuitry as for a pulsed
format, but are all terminated by a link selectable 120| resistor (links 1, 2 & 6
for RS422). Azimuth can be received as pulsed, quadrature, RSS422 or
+5.0V to +17.5V peak-peak (adjustable during system configuration/ factory
set to +15V).