Motorola V8162, Service Manual

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V8160
piece speaker or head set speaker.
Receive Audio - CDMA Mode
Received CDMA QPSK data (RX I, RX Q) is gain
controlled and converted to digital by CIA IC. The
1.2288 Mb/sec. RX data stream is then decoded by
the Modem IC in casper (The CSP) to produce a sig-
nal containing only the desired data. The digital
speech data is routed through the microprocessor ,
decoded by the DSP CELP Vocoder, and sent to CIA
IC to be converted into analog audio. The audio signal
is then amplified by C CAP Lite and sent to the ear-
piece speaker or head set speaker.
Transmit Audio - AMPS Mode
Audio from the internal microphone is ampli-fied
and converted to data by CIA IC. In AMPS mode, the
digitized microphone audio is then sent to DSP in
casperwhich performs all compression, pre-empha-
sis, limiting, and bandpass filtering functions in the
digital domain. All AMPS signalling (SAT, ST,
DTMF) is also generated in the digital domain by
DSP in casper. The digitized AMPS TX audio signal
is converted back to analog by the CIA ICand sent to
the 154.65 MHz TX Offset VCO to modulate the
transmitter.
Transmit Audio - CDMA Mode
In CDMA mode, the digitized TX audio is processed
by a CELP variable rate vocoder,in casper. The digital
signal is then routed through microprocessor and pro-
cessed by the CDMA Modem IC, in casper(the CSP),
which produces the 1.2288 Mb/sec. CDMA data
stream. This stream is then converted to analog QPSK
signals (TX I, TX Q) by D/A CIA IC. The TX I and
TX Q signals are sent to the IF/Synthesizer IC U700
which modulates the 154.8 MHz TX offset VCO.