Furuno FELCOM 15 Service Manual page 33

2) Transmission part
BPSK modulation
The transmission frequency is set at CPU. The data is processed by the data to be
transmitted according to the channel below.
- Transmitting MES signaling channel
Message – Scrambling -- Convolutional encoding -- Adding unique word --
BPSK modulating
- Transmitting MES message channel
Message -- Scrambling -- Convolutional encoding -- Adding unique word --
Interleaving -- Permuting encoder -- Adding pre-ambling -- BPSK modulating
- Transmitting NCS/LES TDM channel
Message -- Scrambling -- Convolutional encoding -- Adding unique word --
Interleaving -- Per-muting encoder -- BPSK modulating
DDS (AD9832) modulates the phase of the DDS output frequency. The BPSK modulating is
made at DDS by the input digital data. PLL oscillation output frequency is 1.6 GHz band
which is BPSK modulated. This signal is the transmitting output of the terminal unit with
amplifying to the output of +14 dBm.
Fig.2.3.6 shows the block diagram of RF CON/CPU transmission frequency control.
Fig.2.3.6 Block diagram of RF CON/CPU transmission frequency control
2-11
2.3 Terminal unit, IC-215