| 摘要 |
A local area network is described based on a ring of twisted pair cable links (UTP), each carrying at least 1.4 Mbps gross data rate. Each station on the network includes an encoder and following station includes a decoder for PSK (phase shift keying) modulated serial data. The encoder comprises an analogue sine wave oscillator and inverter (310, 312) for generating antiphase analogue sine wave signals (PHI, PHIB) at a carrier frequency and a switching circuit (314) for selecting between the carrier signals according to the data signal to be transmitted. The decoder (318) may comprise a simple integrator and comparator arrangement (U13, U14). The encoder and decoder may be provided in the form of an adapter circuit (210), such that a network based on optical fibre can be replaced by a network based on twisted pair cable using the same digital circuits. Generation of the PSK waveform by analogue circuitry rather than digital synthesis reduces radio frequency emissions to a level suitable for use in an automotive audio/video communications network. |
