JRC JMR-92 Series Field Service Manual page 80

it is supplied with power and the CPU operates even if the display unit power is turned off.
Therefore, even if the display unit power is turned off, the GIF circuit can continue to calculate the
true azimuth.
RIF : Radar Interface Circuit mediates radar signals from transmitter-receiver unit or interswitch
unit to CCU. Also, it mediates the power such as 100-220Vac, 48Vdc, and 24Vdc from PSU to
scanner motor and transmitter-receiver unit.
Basic radar operations
In magnetron radar, the preheating of the magnetron of the transmitter-receiver unit is required. It
takes several tens of seconds. When the preheating of the magnetron is complete, the display unit
will be on standby state for transmitting. In solid state radar, no preheating is required. the display
unit will be standby state at the same time as starting up.
By clicking the TX/STBY button in the screen or pressing that button on the KOPU, the system
will be in transmission state. CCU issues a start transmission command to the transmitter-receiver
unit, the transmitter-receiver unit starts transmitting, and the antenna starts to rotate. The radar
signals sent by the transmitter-receiver unit are input to CCU via RIF. Unwanted waves are
suppressed by powerful DSPs and advanced signal processing technologies. The radar image
will always be displayed optimal in every range.
The switches and dials on KOPU can be used to change the settings of the signal processing in
CCU and the screen display, the results of which are immediately reflected in the radar image
display.
Interswitch Function
The interswitch NQE-3141 allows the user to freely switch the connections between multiple
display units and the scanner unit, so that even if there is a problem with one display unit, the
operation of the system as a whole is maintained. For example, without the interswitch function, if
a problem occurred in the No.1: S-band display unit, it would become impossible to use the S
band radar, which would affect maritime safety in adverse weather conditions. With the inter
switch function, however, it is possible to connect the functioning No. 1 scanner unit to the No. 2
display unit, and continue to use S band radar. The inter switch is easily operated from the radar
screen.
CCU automatically detects, when the system is started, whether or not there is an interswitch. If
there is, it operates in the interswitch mode. If there is no inter switch, or if the interswitch or its
cable is damaged, preventing the inter switch from being detected, CCU automatically operates in
the standalone mode.
Chapter 2 System Configuration 2-22