User's Manual

Single Point of Fail ure
13 In systems with multiple Radar Sensors and Radar Displays, the Radar Sensors are
interfaced with the Radar Displays via a Radar Interswitch Unit (RIU). The RIU is the
critical point in the configuration as all signals are routed via the RIU.
14 If any one of the Radar Sensors or Radar Displays fails, the system will remain
operational with reduced capability, i.e. loss of one Radar Sensor or one Radar Display.
15 If the RIU fails, each Radar Sensor will be allocated to a specific Radar Display (this is
carried out in hardware and is determined on installation. The allocation cannot be
changed by the user. Radar Sensor 1 is assigned to Radar Display 1, Radar Sensor 2 is assigned to
radar Display 2 etc.). This limits each user position (Radar Display) to its allocated Radar
Sensor, thus providing operation with reduced capability. An alarm is generated to warn the user
that the radar sensor will revert to the default radar sensor assigned in the event of RIU failure.
16 In systems with a single Radar Sensor and Radar Display, failure of any critical unit may
prevent the system from operating. There is no means of reconfiguring the system to
provide some level of functionality.
Per for mance Check Deg ra da tion - Mag ne tron Trans ceiv ers
17 If the performance of the radar has deteriorated, and there are no failure messages, carry
out the performance monitor check detailed above and compare the readings with those
documented on installation and at the last routine check.
18 If the Tx Monitor Plume is <50% of the original logged value (the reading taken at
installation), the Rx Monitor Sun (X-band) is <80% of the original logged value or the Rx
Monitor Fingers (S-band) is <50% of the original logged value (the reading taken at installation)
a fault is present in the radar sensor. Lower levels of degradation may also cause performance
problems.
19 Note the following:
(1) Whether the degradation is in the 'plume' or the 'fingers'/'sun' or both.
(2) If there is a significant degradation in the 'plume', the transmitter power has
reduced. The most likely cause of this is aging of the magnetron, and this will
need to be replaced. Note that magnetrons are lifed items and as soon as
significant degradation is detected, a visit to the ship by a service engineer should
be arranged to check the transceiver, and if necessary replace the magnetron.
(3) If there is significant degradation in the 'fingers' or 'sun', there is likely to be a
fault in the receiver circuits.
20 Contact the Kelvin Hughes Service Control Centre or the agent with full details of the
degradation recorded to obtain advice.
Issue 5 (Jan 09) Page 4.9
KH2060-4