Method for estimating single-frequency network digital television terrestrial broadcast signal time delay

Abstract

The invention discloses a method for estimating single-frequency network digital television terrestrial broadcast signal time delay. The method comprises the steps of firstly, sampling and storing received digital television terrestrial broadcast signals after the signals are subjected to down-conversion to zero intermediate frequency; performing channel equalization, demodulation and decoding on the digital zero intermediate frequency signal to obtain a transmission code stream of the digital television terrestrial broadcast signal; according to time mark positions indicated by different digital television standards, sending time information of the frame is extracted from a data information frame header obtained through decoding, and a time sequence which is the same as that of a transmitter is provided for a reconstructed signal frame; and then coding and modulating the reconstructed signal frames frame by frame, which are the same as those of a transmitting end, and carrying out cross-correlation operation on reconstructed transmitting signal samples and stored receiving signal baseband samples, so as to accurately estimate the time delay of all single-frequency network transmitting station broadcast signals reaching a mobile receiver through different transmission paths. The method is high in time delay estimation precision, simple and economical to implement and wide in application range.

Description

technical field [0001] The invention belongs to the composite technical field of digital television broadcasting and radio navigation and positioning, and relates to a time delay estimation method, in particular to a method for estimating the time delay of single frequency network digital TV terrestrial broadcasting signals. Background technique [0002] 1. Insufficiency of the existing positioning system [0003] Positioning technology has been widely used in various fields of the national economy, resulting in huge economic and social benefits. At present, the research hotspots at home and abroad are mostly limited to satellite positioning technology. For example: the United States' Global Positioning System (GPS), Europe's Galileo system (Galileo), Russia's GLONASS system, and my country's Beidou positioning system. [0004] Taking the most widely used GPS as an example, in order to improve the detection performance and secrecy ability of weak satellite signals, GPS ado...

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Problems solved by technology

[0005] However, the main disadvantages of satellite positioning systems such as GPS are: 1) The positioning probability in urban areas is 60%, and positioning can hardly be completed indoors; 2) Due to multipath effects, satellite orbit errors, ionospheric delay effects, etc., the positioning is affected Accuracy; 3) Poor real-time positioning, it takes 30s or more to switch to normal working mode during cold start

[0006] The main disadvantages of the mobile phone positioning system based on the digital terrestrial cellular network are: 1) The signal transmission power of the mobile phone is low, and the reception is greatly affected by noise interference and the location of the base station; 2) The network has an interception effect; 3) Users cannot directly get their own location The location information can only be completed through the central platform and multiple base stations, and the confidentiality of the user's location is affected

[0012] 3. New challenges caused by single frequency network

[0016] Although the SFN broadcast of digital TV or digital sound has greatly improved the coverage performance and reception effect, it has brought confusion in principle to the passive positioning based on the digital TV terrestrial broadcast signal: because the MS digital receiver tuned to a certain channel The received signal may come from several (for example, 3) BS transmitting antennas with completely different geographical locations, and the receiving antennas of the current car radio and car TV are omnidirectional, so if the MS uses this non-directional selection If the antenna receives the SFN digital TV signal without frequency difference, based on the existing principles and technologies, it cannot correctly distinguish the same-frequency TOA from different BSs, especially when the MS does not know its current exact location

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