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Sequence cross correlation property-based spectrum spreading and modulating as well as spectrum despreading and demodulating method and device

A spread spectrum modulation and despreading technology, applied in electrical components, transmission systems, etc., can solve problems such as the reliability of power line carrier communication, and achieve the effect of omitting synchronization loops and reducing implementation costs.

Inactive Publication Date: 2016-07-27
MIARTECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The technical problem to be solved by the present invention is to provide a spread spectrum modulation and despreading demodulation method and device based on sequence cross-correlation characteristics to solve the reliability problem of power line carrier communication without any synchronization loop

Method used

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  • Sequence cross correlation property-based spectrum spreading and modulating as well as spectrum despreading and demodulating method and device
  • Sequence cross correlation property-based spectrum spreading and modulating as well as spectrum despreading and demodulating method and device
  • Sequence cross correlation property-based spectrum spreading and modulating as well as spectrum despreading and demodulating method and device

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no. 1 example

[0050] In the actual application of this embodiment, according to the consideration of the data rate, the selection of the working clock and the implementation complexity and cost, etc., a pair of m-sequence optimal pairs with a length of 31 are selected as the spreading codewords, and the generator polynomials are respectively G a (x)=x 5 +x 2 +1 and G b (x)=x 5 +x 4 +x 3 +x 2 +1.

[0051] Taking the BPSK modulation method as an example, it specifically includes the following processing procedures:

[0052] figure 2 A structural block diagram of a communication system transmitter according to the first embodiment of the present invention is shown. refer to figure 2 As shown, the transmitter 200 includes a spreading unit 201 , a spreading code generator 202 , a baseband shaping filter 203 , a modulating unit 204 and a carrier generator 205 . The spreading unit 201, the baseband shaping filter 203 and the modulating unit 204 are connected in sequence. The spreading...

specific Embodiment approach

[0076] We noticed that the complete expressions of the two despread signals M(t) and N(t) of I and Q mentioned above contain two orthogonal factors of cos and sin respectively. When the carrier is fully synchronized, the correlation energy after despreading Concentrate on the I-way (in-phase branch); when the carrier is not synchronized, the energy will "leak" to the Q-way (orthogonal branch) to varying degrees. Therefore, through the squarers 309, 310 and the adder 311, the sum of the squares of M(t) and N(t) can be obtained to obtain a total correlation energy value independent of the carrier phase-frequency error:

[0077]

[0078] At the same time, according to the dual-code spread spectrum and single-code despreading strategies provided in this embodiment, there are:

[0079] C ss = C a , ...

no. 2 example

[0086] Figure 4 A structural block diagram of a communication system receiver according to the second embodiment of the present invention is shown. refer to Figure 4 As shown, the receiver 400 of this embodiment includes demodulation units 401 and 403, local carrier generator 402, low-pass filters 404 and 405, despreading units 406 and 408, local despreading code generator 407, despreading unit 409 and 410 , an adder 411 , and a threshold decision unit 412 . The transmitter of this embodiment may be the same as the transmitter 200 of the first embodiment.

[0087] On the basis of the first embodiment, based on the consideration of reducing the cost of circuit implementation, when the receiver 400 of this embodiment calculates the total value of the relevant energy E(t), through the absolute value units 409, 410 and the adder 411, use The sum of absolute values ​​operation approximates the sum of squares operation, namely:

[0088]

[0089] make It can be seen ...

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Abstract

The invention relates to a sequence cross correlation property-based spread spectrum modulation as well as spectrum despreading and demodulating method and device. The spectrum spreading and modulating method comprises the following spectrum spreading steps: a sequence pair which is high in autocorrelation and small in cross correlation is generated; a first numerical code of original information is subjected to spectrum spreading operation with a first sequence of the sequence pair being used as a spectrum spreading code word, and a second numerical code of the original information is subjected to the spectrum spreading operation with a second sequence of the sequence pair being used as the spectrum spreading code word. The first numerical code of the original information data is subjected to the spectrum spreading operation with the first sequence being used as the spectrum spreading code word via a transmitter, and the second numerical code of the original information data is subjected to the spectrum spreading operation with the second sequence being used as the spectrum spreading code word. According to the spectrum despreading and demodulating method, correlation operation can be conducted with the first sequence being used as a local spectrum despreading code word, and two spectrum despreading states that are a correlated state and an uncorrelated state can be obtained. The sequence cross correlation property-based spectrum spreading and modulating as well as spectrum despreading and demodulating method and device can help solve a problem of reliability in power line carrier communication, and no synchronization loop is needed.

Description

technical field [0001] The invention relates to the field of power line carrier communication (PLC), in particular to a spread spectrum modulation and despreading demodulation method and device based on sequence cross-correlation characteristics. Background technique [0002] As one of the key technologies for smart grid and Internet of Things applications, power line carrier communication (PLC) technology has attracted worldwide attention in recent years. How to realize low-cost and high-reliability communication in harsh power line channel environments has always been a technical problem in this field . Due to the complex topology of the low-voltage power line network, the electrical appliances (called loads) connected to the power grid are diverse and random, making the noise environment of the power line channel harsh and time-varying. On the other hand, a major advantage of using the existing grid as a carrier for communication lies in its lower implementation cost. T...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04B1/709H04B1/7097
Inventor 孙鉴熊泉
Owner MIARTECH