Method for converting ASI code stream into SPI code stream and interface circuit for realizing same

Abstract

The invention belongs to the field of digital television exciters, in particular to a method for converting an ASI code stream into an SPI code stream and an interface circuit for realizing the same. The method comprises the following steps: utilizing a special chip CY7B933 to convert the ASI code stream into the SPI code stream to be input to an FPGA chip; utilizing FPGA programming to realize automatic conversion of A / B path code streams; monitoring the current code inputting rate; finding out synchronization, and then sending data to a buffer; finding out corresponding payload code stream rate requirements according to the relevant information of channel coding in a control channel; sending a control signal to a DDS; regulating the output of the DDS to the needed frequency of a clock, and carrying out specified code rate regulation on the code stream by inserting a hollow bag under the action of the clock; in order to ensure PCR jitter to be in a specified standard range, carrying out PCR correction; and finally converting the output code stream into the SPI synchronous parallel code stream received by a digital modulator. The invention has the advantages that the output frequency is stable, interface hardware resources are saved, and the system cost is lowered; and the novel PCR correction method has simple algorithm and easy realization and reduces the occupancy of system resources.

Description

technical field [0001] The invention belongs to the field of digital television exciters, in particular to a method for converting an ASI code stream into an SPI code stream and an interface circuit for realizing the method. Background technique [0002] With the development of digital TV technology, the MPEG2 standard has been widely accepted. It is the basic standard for digitization of sound and image, and can be used in digital TV and digital sound broadcasting, transmission of digital image and sound signals, and multimedia. In the transmission interface of the present broadcast television system, there are two MPEG-2 video transmission interface standards: asynchronous serial interface standard ASI and synchronous parallel interface SPI. The SPI code stream has a total of 11 useful signals. Each signal is differentially divided into two signals to improve the anti-interference performance of the transmission. The physical link is transmitted by DB25, so the connection ...

AI Technical Summary

Problems solved by technology

This is because the data stream coming in from ASI is usually extremely uneven after decoding, and the digital modulator requires the code stream to be output uniformly at a specified code rate, so it is necessary to adjust the code rate of the input code stream, and the code rate adjustment will inevitably Jitter causing Program Clock Reference (PCR)

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