CML Semiconductor Products

4-Level FSK Modem Data Pump

FX929A

© 1996 Consumer Microcircuits Limited

D/929A/4 June 1996

1.0

Features

Advance Information

• Radio Data-Link Access Procedure (RD-LAP) is a data communications air interface protocol developed by Motorola Inc. •

1.1

Brief Description

The FX929A is a CMOS integrated circuit that contains all of the baseband signal processing and Medium

Access Control (MAC) protocol functions required for a high performance 4-level FSK Wireless Packet Data

Modem. It interfaces with the modem host processor and the radio modulation/demodulation circuits to deliver

reliable two-way transfer of the application data over the wireless link.

The FX929A assembles application data received from the processor, adds forward error correction (FEC) and

error detection (CRC) information and interleaves the result for burst-error protection. After adding symbol and

frame sync codewords, it converts the packet into filtered 4-level analogue signals for modulating the radio

transmitter.

In receive mode, the FX929A performs the reverse function using the analogue signals from the receiver

discriminator. After error correction and removal of the packet overhead, the recovered application data is

supplied to the processor. Any residual uncorrected errors in the data will be flagged. A readout of the SNR

value during receipt of a packet is also provided.

The FX929A uses data block sizes and FEC/CRC algorithms compatible with the RD-LAP over-air standard.

The format used is suitable for other private applications which require the high-speed transfer of data over

narrow-band wireless links. The device is programmable to operate at most standard bit-rates from a wide

choice of Xtal/clock frequencies.