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Long-period spreading code frequency folding time frequency parallel searching method

A search method and frequency search technology, applied in the field of spread spectrum code acquisition, can solve the problems of limiting the performance of parallel search methods

Active Publication Date: 2009-10-21
TSINGHUA UNIV
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Problems solved by technology

Therefore, this method has to divide the carrier frequency range to be searched into multiple frequency cells for searching even in the case of a high signal ratio, which limits the performance of multiple code phase parallel search methods

Method used

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  • Long-period spreading code frequency folding time frequency parallel searching method
  • Long-period spreading code frequency folding time frequency parallel searching method
  • Long-period spreading code frequency folding time frequency parallel searching method

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Embodiment Construction

[0059] Here, the FFT length is 2048 points, the number of frequency units to be searched is 20, and the number of non-coherent accumulation is 10, briefly describe the implementation steps of the "long-period spreading code frequency folding method":

[0060] 1. Select 1024 points of signals sampled by the front-end A / D, and map these signals to 20 different frequency grid units. Add up the mapped signals correspondingly, and get 1024 new signals in total;

[0061] 2. Fill the new signal of 1024 points with zero to 2048 points, perform FFT operation and take complex conjugate;

[0062] 3. Generate 2048 local pseudo-code signals and perform FFT operation;

[0063] 4. Multiply the results of 2 and 3, and perform IFFT processing on the obtained 2048 point data;

[0064] 5. Store the result obtained in step 4 of 1025 points;

[0065] 6. Repeat the above steps 1 to 5 for a total of 10 times;

[0066] 7. Non-coherently accumulate the 10 results obtained in step 6, and perform po...

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Abstract

Characters of the method are that carrying out folding operation for mapping same segment of received signal into different frequency cells to implement parallel searching frequency cells; next, using parallel searching method for multiple code phases to implement parallel searching multiple code phase units; when implementing, the method determines number of frequency unit to be searched based on frequency range and step length for searching frequency, and then carries out folding operation for same segment of received signal mapped to different frequency cells; afterwards, using FFT technique for implementing parallel correlation between the folded signals and local pseudo code so as to realize parallel searching multiple code phases. Under condition of not increasing complexity of algorithm and hardware markedly, realizing parallel searching carrier frequency unit and multiple code phase units, the method raises searching speed, and reduces time for capturing pseudo code.

Description

technical field [0001] The invention belongs to the technical field of spread spectrum code acquisition in spread spectrum communication. Background technique [0002] Spread spectrum communication has many advantages and is widely used. Spread spectrum signals can counter or suppress the harmful effects of interference, such as interference caused by other users in the channel; spread spectrum signals are sent at low power to conceal signals, making them difficult for eavesdroppers to detect; secure communications can be achieved. Spread spectrum communication technology is widely used in military, civilian and other fields. [0003] The three main standards of 3G communication, WCDMA, TD-SCDMA, and CDMA-2000, are all based on spread spectrum communication technology. Currently the most widely used satellite navigation system, the Global Positioning System (GPS), is also based on spread-spectrum communication technology. The acquisition of spread spectrum code is the bas...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04B1/707H04B7/26G01S5/02H04B1/7075
Inventor 李洪陆明泉冯振明
Owner TSINGHUA UNIV
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