Update: 30 September, 2023
74VHC943 is a full duplex low speed modem for data communication over telephone lines and other narrow bandwidth channels. It provides a 300 baud bidirectional serial interface and is Bell 103 compatible. The 74VHC943 utilizes advanced silicon-gate CMOS technology. Switched capacitor techniques are used to perform analog signal processing. The modulator section contains a frequency synthesizer and a sine wave synthesizer, producing a phase coherent frequency shift keyed (FSK) output. The line driver and hybrid section are designed to facilitate connection to a 600X telephone line, they can perform two to four wire conversion and drive the line at a maximum of b9 dBm. The demodulator section incorporates anti-aliasing filters, a receive filter, limiter, discriminator, and carrier detect circuit. The nine-pole receive filter provides 60 dB of transmitted tone rejection. The discriminator is fully balanced for stable operation.
File format: PDF
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MD5 Checksum: 536C66B860495E76859F0E935C7F1544
Publication date: 08 June, 2012
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PDF Link: National Semiconductor 74VHC943 300 Baud Modem (5V Supply) handbook PDF