TB9100 Reciter Service Manual Digital Circuitry 23
© Tait Electronics Limited January 2006
■ RSSI measurement for monitoring and RSSI signal voltage output
■ SINAD measurement
■ measurement and detection for control of the audio mute
■ calibration parameter estimation
■ line level monitoring.
3.2.3 Serial Ports
The DSP has three synchronous serial ports. Serial port 1 is connected to
the DDC and receives base band samples. Serial port 2 is connected to the
three CODECs (encoder/decoder). Serial port 3 is not used.
3.2.4 CODECs
The three CODECs provide the audio frequency analog interface to the
reciter. There are six analog input and six analog output paths. The sample
rate on all paths is 25kSPS and the sampling resolution is 16 bits.
The CODEC inputs are as follows:
■ two input signals from the frequency control loop (FCL)
■ balanced line input
■ unbalanced line input
■ microphone input
■ synthesizer loop control voltage.
The CODEC outputs are as follows:
■ VCO voltage control line
■ VCXO voltage control line
■ balanced line output
■ unbalanced line output
■ speaker output
■ RSSI voltage indicator.
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