Implementation method by using digital picked clocking as analog reference source

Abstract

In far end unit, multiplexer / demultiplexer of digital processing board is in charge for picking up clock signal from optical fiber as reference source for first order phase locked loop circuit. Afterthe first order phase locked loop circuit executes phase locking, clock is distributed for each chip in digital processing board to provide synchronized signal. The synchronized signal is as referencesource. After the second order phase locked loop circuit executes phase locking, the reference source is provided for analogy frequency conversion board as local oscillation. Thus, the invention makes reference source of whole system of straight through station possess relativity so as to guarantee smaller frequency error of system. Advantages are: avoiding use of costly thermostatically operatedcrystal oscillator, selecting number of stages of each phase locked loop circuit, crystal oscillator, and frequency of crystal oscillator freely, preventing use of oscillator in high frequency.

Description

【Technical field】 [0001] The invention relates to the field of mobile communication repeaters, in particular to a method for implementing digital extraction clocks as analog reference sources in long-distance digital optical fiber communication equipment. 【technical background】 [0002] see figure 1 , in the traditional digital repeater, in the relay terminal and the remote terminal, there are analog frequency conversion boards and digital processing boards to complete the uplink and downlink transmission and processing of signals. In the relay end machine, the constant temperature control crystal oscillator 1 is used as a reference source to provide the local oscillator and clock for the analog frequency conversion board and the digital processing board. After the signal is transmitted to the remote end machine, the clock is extracted from the signal transmitted by the optical fiber. In order to achieve signal synchronization, but in the analog frequency conversion board o...

AI Technical Summary

Problems solved by technology

Therefore, the traditional method of processing reference sources is difficult to balance between performance and price. On the premise of maintaining high performance, it will lead to high cost of relay terminals and remote terminals, increasing the cost of network operators

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