1200/2400/4800 Baud FFSK/MSK Modem
CMX469A
1.5
General Description
The CMX469A has two sections, apart from the Xtal oscillator circuit and clock dividers. These
sections may be independently powersaved.
Transmitter
The transmitter is enabled by taking Tx EnableN low. Serial data applied to Tx Data Input is sampled
internally and an FFSK/MSK sequence is generated. After filtering, this is output at
Tx Signal O/P and the transmit clock derived from this signal is output at Tx Sync O/P.
Receiver
The receiver is enabled by taking Rx Enable high. The signal applied to Rx Signal I/P is filtered and
recovered as serial data from the Unclocked Data O/P. A flywheel synchroniser is used to extract a
clock from the recovered serial data stream. The clock is available at Rx Sync O/P and the retimed
serial data is available at Clocked Data O/P.
The integrated peak values of the Rx amplitude are compared with out-of-band noise levels and used
to make a signal-to-noise assessment, which is available at Carrier Detect O/P.
A Bandpass O/P is also available from the output of the first Rx filter stage, but will require buffering
before use.
©
2001 Consumer Microcircuits Limited
8
D/469A/2
CMLMICRO [ CML MICROCIRCUITS ]
