The FX929B is a high-performance CMOS 4FSK wireless packet data modem containing all of the required baseband signal processing and Medium Access Control (MAC) protocol functions supporting RD-LAP.
It interfaces with the modem host processor and the radio modulation/demodulation circuits to deliver reliable two-way transfer of application data over the wireless link.
The FX929B 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.
It then converts the packet into filtered 4-level analogue signals for modulating the radio transmitter. In receive mode, the FX929B performs the reverse function using the analogue signals from the receiver discriminator.
The FX929B 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.
Fade management and 'A' version compatibility