Positioning method and system based on CDMA (Code Division Multiple Access) downlink signal and digital television signal

Abstract

The invention provides a positioning method and system based on CDMA (Code Division Multiple Access) downlink signals and digital television signals. The positioning method comprises the following steps: step 1, downloading digital broadcast television tower position information tables of different cities to a user receiver in advance; step 2, the user machine receives the digital television signal, obtains the television tower position information of the city according to the digital broadcasting television tower position information table, carries out frame header capturing on the digital television signal, obtains the frame header time sequence of different television tower signals through the frame header, and calculates the transmission time delay of the television tower; step 3, a user receiver receives CDMA downlink signals at the same time, demodulates the signals, and extracts time difference information of each base station and position information of the base station; and 4, resolving the position of the user receiver according to the time difference information of each base station, the position information of the base station, the transmission delay of the television tower and the position information of the television tower. According to the scheme, when an existing satellite navigation signal cannot be normally received, the requirement of a user for navigation positioning in an urban building dense environment or a satellite navigation signal rejection environment can be quickly met.

Description

technical field [0001] The invention relates to the field of navigation and positioning, in particular to a positioning method and system based on CDMA downlink signals and digital television signals. Background technique [0002] At present, the existing navigation and positioning technology mainly uses the satellite navigation positioning signal, but the average power of the satellite navigation signal reaching the ground is about -125dBm (-155dBw), while the average power of the noise signal within the working bandwidth of the navigation receiver is about -110dBm ( -140dBw), it can be seen that when the satellite navigation signal reaches the receiving antenna of the ground receiver, the useful signal is submerged below the noise. The reason why the satellite navigation receiver can correctly capture and demodulate is because the satellite navigation signal adopts spread spectrum modulation In this way, the spread spectrum gain of civil navigation signals is more than 42d...

AI Technical Summary

Problems solved by technology

[0002] At present, the existing navigation and positioning technology mainly uses the satellite navigation positioning signal, but the average power of the satellite navigation signal reaching the ground is about -125dBm (-155dBw), while the average power of the noise signal within the working bandwidth of the navigation receiver is about -110dBm ( -140dBw), it can be seen that when the satellite navigation signal reaches the receiving antenna of the ground receiver, the useful signal is submerged below the noise. The reason why the satellite navigation receiver can correctly capture and demodulate is because the satellite navigation signal adopts spread spectrum modulation In this way, the spread spectrum gain of civil navigation signals is more than 42dB, so correct navigation information can be obtained through despreading, but when the satellite navigation receiver is in a tunnel, underground garage, deep mountain canyon, etc. or there is strong electromagnetic signal interference in the surrounding environment , the navigation receiver cannot complete the reception and demodulation of satellite signals within the line-of-sight, which makes the satellite navigation and positioning equipment invalid and unable to perform navigation and positioning

[0003] The existing satellite navigation and positioning methods have the following defects: (1) the signal level is extremely weak, and is easily blocked or interfered; (2) coarse positioning requires at least 4 satellites to be able to receive normally, if high-precision positioning is required At least 6 satellites are required to receive normally. In densely populated cities, the number of received satellites is likely to be insufficient, resulting in inability to locate or a decrease in positioning accuracy.

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