PUBLIC SERVICE TRUNKING SIMULCAST SYSTEM

摘要

45MR00576 PUBLIC SERVICE TRUNKING SIMULCAST SYSTEM In a multiple site radio frequency simulcasting RF/ transmission system, data transmitted from a control point to the RF transmitter sites exhibits random time delay skew because multi-phase modems recover clock signals from an arbitrary one of the multiple phases. The outputs of the modems are temporarily stored at the sites by memory buffers. The control point derives resynchronization signals from a source data clock, this signal containing frequency and timing information. The resynchronization signal is distributed to the various sites via additional phase-stable, delay compensated channels. Each site is provided with a clock recovery circuit that recovers the original source data clocking signal from the resynchronization signal and also extracts read-out timing information from the resynchronization signal. The recovered data clocking signal and the readout timing information are used to synchronize the readout from the FIFO memory buffers --providing approximately simultaneous (coherent) readout of the same data bits from the respective buffers of the different simulcasting transmitter sites.