FX919B Datasheet, PDF (1/47 Pages) CML Microcircuits – Excellent Radio Fading Performance

CML Semiconductor Products
FX919B 4-Level FSK Modem Data Pump
D/919B/1 July 1997
Features
• 4-Level FSK Data Modulation
• Half Duplex, 4800 to 19.2k bits/sec
• Excellent Radio Fading Performance
• Error Detection and Error Correction
• Low Power 3.3V to 5V Operation
Advance Information
Applications
• Wireless Data Terminals
• Two Way Paging Systems
• Digital Radio Systems
• Wide Area Wireless Data Broadcasts
• Point to Point Wireless Data Links
1.1 Brief Description
The FX919B 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 FX919B is backwards compatible
with the FX919A but offers better performance during radio link fading and selectable Tx symbol shapes.
The FX919B 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 FX919B 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 FX919B uses data block sizes and FEC/CRC algorithms suitable for 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.
D2
D5
P4
© 1997 Consumer Microcircuits Limited