System clock feeding and recovering method for railway television single frequency network

Abstract

A system clock feed and recovery method in the railway television single frequency network, comprising the following steps: the adapter configuration of the railway television single frequency network can generate the GPS of the second pulse, the local high stability system clock counter is cleared by the second pulse, and the adapter is in the The clock stamp is periodically inserted into the TS stream, and the current value of the counter is written; the synchronizer in the railway TV single frequency network is also equipped with a GPS that can generate second pulses, and the local system clock uses a voltage-controlled crystal oscillator to drive the local counter. The pulse is cleared; the synchronizer extracts the clock stamp and count value in the TS stream, and at the same time calculates the relative difference between the mark and the previous delay count, and drives the D / A conversion chip after certain processing of the difference The analog voltage is output, and the voltage passes through the analog filter circuit to control the local clock of the synchronizer, so that the output frequency is synchronized with the local system clock of the adapter, so as to achieve the purpose of unifying the clock of the whole network of the railway TV single frequency network.

Description

technical field [0001] The invention relates to a method in the field of information technology, in particular to a system clock feeding and recovery method in a railway television single frequency network. Background technique [0002] Single frequency network technology (SFN) is the best way to expand the coverage of digital TV technology. The so-called single frequency network means that in a certain geographical area (city, province, or even a country), several transmitters transmit the same wireless signal on the same frequency band at the same time to achieve reliable coverage of the area. Multipoint transmission is complex and harsh multipath to the receiver. The analog TV system has the problem of ghosting, so the multi-frequency network (MFN), which is extremely resource-intensive and complex in spectrum planning, can only be used to isolate signals in frequency and avoid overlapping coverage areas. Due to the strong anti-interference ability and the support of co...

AI Technical Summary

Problems solved by technology

If the received signal is interfered by irresistible factors such as lightning strikes and solar storms, the reference clock output by the GPS receiver will be affected, which will directly lead to coverage problems in the service area of ​​the entire SFN

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