CML Semiconductor Products
4-Level FSK Modem Data Pump
Advance Information
FX929B
D/929B/1 May 1997
Features
Applications
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4800 to 19200 b/s Operation
Full Packet Data Framing
4-Level FSK Data Modulation
Low Power, 2.5mA at 3.3V
Flexible Operating Modes
Powersave Option
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RCR STD-47 and RD-LAP* Systems
Two-Way Paging Equipment
Mobile Data Systems
Wireless Telemetry
DataTAC
®
Terminals
Portable Wireless Data Equipment
*Radio Data-Link Access Procedure (RD-LAP) is a data communications air interface protocol developed by Motorola Inc.
1.1
Brief Description
The FX929B 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 FX929B is backwards compatible
with the FX929A but offers better performance during radio link fading and selectable Tx symbol shapes.
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. After adding symbol and
frame synchronisation codewords, it converts the packet into a filtered 4-level analogue baseband signal for
modulating the radio transmitter.
In receive mode, the FX929B performs the reverse function using the analogue baseband 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 FX929B uses data block sizes and FEC/CRC algorithms compatible with the RD-LAP and RCR STD-47
over-air standards. The device is programmable to operate at most standard bit-rates from a wide choice of
Xtal/clock frequencies.
D2
D5
P4
©
1997 Consumer Microcircuits Limited
CMLMICRO [ CML MICROCIRCUITS ]
