Transmitting And Receiving Circuit - Furuno Felcom 250 Service Manual

IF Module:
An interface between the Antenna unit and the Communication unit, and
consists of the Duplexer, Multiplexer, ASK Modem, and 6.5 V/28 V SMPS
(Switched-Mode Power Supply).
GPS Module:
A GPS antenna, GPS LNA. It transmits the received data to the
Communication unit in 4 MHz ASK signal. It is a module commonly used for
FB-1500 and FB-1250.

2. Transmitting and Receiving Circuit

The Antenna unit and the Communication units are connected with a coaxial cable.
Antenna coaxial cable uses; 8D-FB-CV: 30 m/40 m/50 m, 12D-SFA-CV: 100 m. When
you wish to use any other coaxial cable than the one described above for test purpose,
make sure to have the loss of 9 dB (1.6 GHz) or below.
The coaxial cable has the following signal superimposed.
42 V
4 MHz ASK signal : Control signal between the Antenna unit and the
Transmitting signal : 1626.5 to 1660.5 MHz
Receiving signal
: Power supply for the Antenna unit.
(Approx. 1.5 A at maximum for both FB-1500 and FB-1250)
Communication unit, and is Simplex communication.
The specifications for the ASK interface is;
communication speed: 38400 bps, data length: 8 bit,
parity: non, stop bit: 1 bit, flow control: N/A,
frequency: 4MHz
: 1525.0 to 1559.0 MHz
11-16
11.2 Antenna Unit: FB-1500/1250