Turning On The Performance Monitor - Furuno FAR-2107 Series Service Manual

2. Turning on the performance monitor

1. Set "[MENU] -> 1: [ECHO] -> 4: PM" to ON. Adjusted setting conditions are
automatically set up.
2. Check the transmission/reception performance by observing the strength of ring
echoes. If ring echoes look pale, the transmit/receive gain is reduced.
3. After checking is complete, set "[MENU] -> 1: [ECHO] -> 4: PM" to "OFF". The
screen returns to the original display.
Note:
Why the second ring should be pale?
In the PM unit, the diference in gain between the 1
nd
Being pale the 2
st
1 ring echo is adjusted 10 dB higher than the noise level. If the 1
is known that the transmit, receive or transmit/receive gain is reduced by 10 dB. For
this reason, you can find the radar sensitivity from the status of the ring echoes.
Previous PM echo
For exmple, the figure below show the FAR-2805 PM picture, which allows
individual determination of degradation in reception and transmission performance
based on the PM echo.
st
The 1 ring echo is set to 12 NM and shows the degradation of reception and
transmission output according to its distance. Output is degraded by -3 dB/3 NM. The
interval between ring echoes is 3 dB. If the 4th ring disappears, for instance, you can
find that receive sentences have reduced to 3 dB.
ring and making it the same level as the noise level means that the
12NM
Fig. 4.4.10 Previous PM Echo
st
and 2
0dB
-3dB
-6dB
-9dB
4-29
Initialize Setting Initialize Setting
Initialize Setting Initialize Setting
4.4
nd
rings is set to 10 dB.
st
ring disappears, it