Subject: Advance Communication System

Difficulty: Medium

Marks: 4 marks

Function of -

Block A- Duplexer- The transmitter output is fed to a duplexer or isolator which allows the transmitter and receiver and receiver frequencies to share the same antenna.

RSSI Signal-

The demodulator output filtered and is also applied to a DC amplifier which produceds a DC voltage indicating the strength of the received signal. This indicaor is called as received signal strength indicator (RSSI).

The demodulator output is also applied to a band pass filter (BPF) which selects out the conrol audio tones and digital control data signal which are sent by the cell site.

These signal are then applied to the logic unit which produces the set and control signals for transmitter and receiver.

The RSSI signal is sent back to cell site in order to help MTSO to monitor the received signal from the cell and decide about switching to another cell.