Furuno FM-8800D Service Manual page 194

4.4.2 RX IF LEVEL
This indicates IF signal level of 37.5 kHZ from TX/RX board which is its
amplitude. It changes according to the level of signal. When the signal increases,
RX IF LEVEL increases as well.
4.4.3 RX AF NOISE
This indicates out-off-band noise (over 37.5 kHz ± 12.5 kHz). It changes
according to the level of signal. When the signal increases, RX AF NOISE
decreases.
4.4.4 CH70 RX IF LEVEL
This indicates IF signal level of 37.5 kHz from CH70 RX board which is its
amplitude. It changes according to the level of signal. When the signal increases,
CH70 RX IF LEVEL increase as well.
4.4.5 CH70 RX AF NOISE
This indicates the out-of-band noise (over 37.5kHz ± 12.5 kHz). It changes
according to the level of signal. When the signal increases, CH70 RX AF
NOISE decreases.
4.4.6 PLL 1 UL LEVEL
This indicates the state (Q21 output) of PLL UN-LOCK on TX/RX board. PLL
frequency data inputted into TX/RX board is the channel set up in this display.
- The state of PLL LOCK: UL LEVEL indicates below 50 which is normally ''
"0".
- The state of PLL UNLOCK: UL LEVEL indicates over 51 which is
normally "1023".
4.4.7 PLL 2 UL LEVEL
This indicates the state (Q10 output) of PLL circuit on DUP RX board. PLL
frequency data inputted into DUP RX board is the channel set up in this display.
When FM-8800D is in SIMP mode, ''155'' is normally indicated.
- The state of PLL LOCK: UL LEVEL indicates below 50 which is normally
"0".
- The state of PLL UNLOCK: UL-LEVEL indicates over 51 which is
normally "1023".
CAUTION:
When FM-8800S is in use, ''155'' is indicated as PLL2 UL LEVEL.
8-14
8.3 T/A, TEST, RESET DSP