Furuno FR-8111, FR-8251 manual Performance Monitor, Operating a performance monitor

Appendix A DESCRIPTION OF OPTIONAL EQUIPMENT

This appendix provides a brief description of op- tional equipment which can be connected to the FR-8051/8111/8251. For more detailed informa- tion, see the respective operator’s manual.

A.1 Performance Monitor

A performance monitor is required for a radar in- stalled on vessels of 300 GT and upward engaged in international voyages. For X-band radars, the FURUNO PM-30 satisfies the requirement cov- ering 9410 ±50 MHz.

The performance monitor is an independent unit, namely, it is not interconnected with any unit of the radar system except for the 100 VAC power cable. In some radars the power cable is not routed via the power switch or other control of the radar and the monitor is operated as completely a sepa- rate device.

Operating a performance monitor

Transmit the radar on the 24 nm range scale and select a long pulse. The radar screen will show several arcs, opposite to the heading marker (pro- vided that the performance monitor is installed behind the radar antenna as is normally the case.) If the radar transmitter and receiver are in good working conditions inasmuch as the original state when the monitor was tuned, the innermost arc should appear at 12 nm and there should be a to- tal of 4 arcs.

The range of the innermost arc reduces 3 nm with every 3 dB loss of transmitted power. The receiver sensitivity can be evaluated from the number of visible arcs; one arc is lost every 3 dB deteriora- tion of the sensitivity.

Transmitter		Receiver
performance		performance
Range to	Loss	No. of	Loss
innermost		arcs
arc
12 nm	0 dB	4	0 dB
9 nm	3 dB	3	3 dB
6 nm	6 dB	2	6 dB
3 nm or	10 dB	1	9 dB
less or none
		0	12 dB

Display	Meaning
	TRANSMITTER: normal
	RECEIVER: normal

12 nm

	TRANSMITTER: 3 db loss
	(Transmitter system has lost
	half of initial power.
9 nm	Suspect magnetron and
	feeder system.)
	RECEIVER: normal
	TRANSMITTER: 3 db loss
	(Transmitter system has lost
	half of initial power.
9 nm	Suspect magnetron and
	feeder system.)
	RECEIVER: 3 db loss
	(Receiver has lost half of
	normal sensitivity. Suspect
	receiver front end, water
	leakage in feeder system,
	etc.

A – 1