Furuno FELCOM 12 Service Manual

6-8
REF Offset Freq NG
CPU1 (U49) receives offset data generated by the DEMOD and finely adjusts the
frequency of the reference oscillater VCXO. Based on the received signal, the oscillation
frequency of TX/RX PLL synthesizer is adjusted to 15.6 MHz ±150Hz. When the offset
frequency is more than 150Hz, “REF Offset Freq. NG” appears, indicating that CPU
and/or RF CON board may be defective.
DEMOD
CPU 1
(U49)
CPU 2
(U23)
D/A
(U12)
RX sig. RX
sig.
C/N data (8bit)
J10-4
CPU (16P0148)
TX
ANT
DIPLEXER
Antenna unit
Communication unit
50kHz
1530 - 1545MHz
RX freq.
offset data
U10
VCXO
J2-1 J10-1
RF CON (16P0147)
TX/RX PLL SYN
J2-4
2ndLoRXLo
RFE CNT
S-DATA (TX)
TXLo
15.6MHz

Furuno FELCOM 12 Specifications

General

Brand	Furuno
Model	FELCOM 12
Category	Marine GPS System
Language	English