Multichannel multipoint distribution service system synchronization using global positioning system clock

Timing and synchronization are critical in the design of any digital communications system. A communication system being studied. The multichannel multipoint distribution services (MMDS), requires a robust synchronization in order to be able to transmit a high speed data stream and to ensure data integrity. In the absence of SONET and SDH, a precise frequency from the global positioning system (GPS) is used for the system reference clock instead of crystals. This frequency and time have an accuracy that is directly and traceable continuously to the coordinates universal time (UTC). A GPS receiver locks onto the GPS frequency and locally regenerates a stable clock. A reference 10 MHz clock with TTL output was generated. This clock is used in the system for clocking and synchronization purposes. Precision timing combined with the word synchronization scheme makes the MMDS system simple, robust, low cost, and reliable.