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A Very Long Baseline Interferometry Processing Method Based on Digital Signals

A technology of very long baseline interference and processing method, which is applied in the field of VLBI processing for digital signals, which can solve the problems of affecting accuracy, spacecraft broadcast time and accuracy limitations of a priori model, and achieve the effect of delay estimation.

Inactive Publication Date: 2014-06-25
BEIJING AEROSPACE CONTROL CENT
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Problems solved by technology

If the above two preconditions cannot be satisfied, the accuracy of VLBI processing will be seriously affected, which makes the interferometric measurement of spacecraft limited by the broadcast time of VLBI beacons and the accuracy of prior models

Method used

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  • A Very Long Baseline Interferometry Processing Method Based on Digital Signals
  • A Very Long Baseline Interferometry Processing Method Based on Digital Signals
  • A Very Long Baseline Interferometry Processing Method Based on Digital Signals

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Embodiment Construction

[0044] Compared with the VLBI beacon signal, the digital signal is used as the signal carrier for the spacecraft to communicate with the ground station. The broadcast is more frequent and the broadcast time is longer; and the digital signal is a spread spectrum signal with a bandwidth of the MHz level. So it can be used for VLBI interferometry. At the same time, the biggest feature of the digital signal compared with the VLBI beacon signal is that its autocorrelation function is periodic (suppose its period is T c ), according to this characteristic of the digital signal, the design of its VLBI processing flow is as follows.

[0045] Suppose that the sampling rate of the intermediate frequency digital signal received by the two measuring stations is f s After digitization, it has the following form:

[0046]

[0047]

[0048] Where x(n) represents the modulated data signal, f 0 Represents the intermediate frequency, Indicates the initial phase of the carrier after down-conversion,...

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Abstract

The invention discloses a very long baseline interferometry processing method based on digital transmission signals. The method is to obtain the part whose time delay is less than one cross-correlation period of digital transmission signals. The specific steps are as follows: 1) Receive signals through two stations The time-domain cross-correlation of the time domain to obtain the time delay of the integer sampling interval; 2) After the compensation of the integer sampling interval delay of the two received signals, the streak rate search is carried out to obtain the time delay rate of the two signals; 3) The integer sampling interval of the two signals is obtained Sampling interval time delay and fringe rate compensation, using cross-spectrum phase to calculate time delay less than one sampling interval. Then the whole-period ambiguity is estimated using the rough relative positional relationship between the spacecraft and the station. Based on the above processing, the required time delay from the spacecraft signal to the two stations can be obtained. In the case that no special VLBI beacon signal is received and no real-time a priori model is available, the present invention utilizes the most frequently broadcast data transmission signal of the spacecraft to carry out independent VLBI processing, and realizes the time delay estimation of the spacecraft arriving at the ground station .

Description

Technical field: [0001] The invention relates to the technical field of signal processing, and is a VLBI processing method for digital signals. technical background: [0002] VLBI (Very Long Baseline Interferometry) measurement technology is a new radio astronomy measurement technology developed on the basis of traditional radio interference. Its essential feature is that there is no direct, real-time connection between the local crystal oscillators and received signals of the two measuring stations. The high-stability hydrogen atomic clock signal is used as the frequency standard, and the sampled data is recorded by broadband tape equipment for post-related processing. Therefore, the baseline length of VLBI technology can reach tens of thousands of kilometers, which greatly improves the measurement accuracy. VLBI technology has been widely used in the fields of astrometry, geodynamics, deep space exploration and tracking in recent years. [0003] figure 1 It is a schematic diagr...

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01S19/45G01S19/43G01C21/24
Inventor 刘荟萃陈宏敏陈明陈略周率李黎
Owner BEIJING AEROSPACE CONTROL CENT
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