Furuno FR-7062, FR-7252, FR-7112 manual Selecting Pulsewidth, Suppressing Radar Interference

3.3Suppressing Radar Interference

Radar interference may occur when near another shipborne radar operating in the same frequency band as your radar. Its on-screen appearance is many bright dots either scattered at random or in the form of dotted lines extending from the center to the edge of the display. Figure 3-4 il- lustrates interference in the from of curved spokes. Interference effects are distinguishable form normal echoes because they do not ap- pear in the same place on successive rotations of the antenna.

Figure 3-4 Radar interference

Four levels of interference are available, includ- ing off; IR1, IR2, IR3 and OFF. IR3 provides the highest level of rejection.

1.Press the [MENU] key.

2.Select “INT REJECT” and press the [ACQ/ ENTER] key.

3.Select level desired by pressing the [ACQ/ ENTER] key.

4.Press the [MENU] key to close the menu.

IR and level selected appears at the bottom right corner on the display when the interference re- jection circuit is turned on.

3.4 Selecting Pulsewidth

Pulsewidth is the transmission time of a single radar pulse. The longer the pulsewidth the greater the direction range capability, however range accuracy and range resolution are re- duced.

Pulsewidth can be selected to short or long on the 1.5 and 3 nautical mile ranges.

1.Press the [MENU] key.

2.Select “OTHER MENU” and press the [ACQ/ENTER] key.

[ OTHERS ]	TX
Select item by T-ball

and press ENTER key.

1	. Panel Dimmer				1				2				3					4
2	. Mark Brill				1				2				3
																	4
3	. HD Mark				1				2				3
																		4
4	. Characters				1				2				3
																	4
5	. Trail Tone									Multi
					Single
6	. Pulselength				Short
										Long
7	. Noise Reject									On
					Off
8	. Trail Time									30sec			1min
					15sec
		3min			6min				15min				30min					Cont
9	. Tune									Manual
					Auto
10. WPT Mark										On
					Off
11.		EBL Ref								True
					Rel
12. VRM Unit †					nm					km			sm
13.		Watchman								5min			10min			20min20min
					Off
14. STBY Disp										Econo			Nav
					Norm
15.		Guard Mode			In					Out
16.		Own Position								TD
					L/L
17.		Cursor Posi								L/L
					R/B
18. Alm Sense LV										Med			Hig
					Low
19.		Dead Sector								On
					Off
20.		Range											1
						1/8		1/4		1/2		3/4			1.5				* *		*
		2		4				8			16
			3				6			12			24	36		48			72	96
21.		2nd Rej								On
					Off

22.Self Test

23.Installation Setup

†: Not displayed on N-type radar; VRM unit is fixed for nm.

*Max. range is; FR-7062: 64 FR-7112: 72 FR-7252: 96

Figure 3-5 OTHER MENU

3.Select “6. Pulselength” by operating the trackball.

4.Select Short or Long by operating the trackball.

5.Press the [ACQ/ENTER] key.

6.Press the [MENU] key to close the menu.

3-2