Low-rate spread spectrum communication transmission base band system

A technology of baseband system and spread spectrum communication, which is applied in baseband system components, transmission systems, digital transmission systems, etc., and can solve problems such as error correction and error detection, spread spectrum chip spread code rate and spread code length limitation, etc. , to achieve the effect of flexible use, short design cycle and fast frequency conversion

Active Publication Date: 2011-06-22
ZHONGKE KAIPU TIANJIN SATELLITE NAVIGATION COMM TECH CO LTD
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  • Abstract
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AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to overcome the limitations of the current spreading code rate and spreading code length of the current spreading chip, and the shortcom

Method used

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  • Low-rate spread spectrum communication transmission base band system
  • Low-rate spread spectrum communication transmission base band system
  • Low-rate spread spectrum communication transmission base band system

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Embodiment Construction

[0050] The present invention will be described in further detail below in conjunction with the accompanying drawings.

[0051] Such as figure 1 In the functional block diagram of the present invention shown, except signal modulation and D / A conversion, other functions are all realized in FPGA. The central control module controls the work of each functional module in the FPGA. The spread spectrum method adopts the direct sequence spread spectrum method, and the information rate, code rate, code length and modulation method are all controlled by the program, which can be applied to the direct sequence spread spectrum communication system with low rate (serial port communication rate up to 20Kbps).

[0052] The method of realization of the present invention is as follows:

[0053] The conversion between the TTL level and the positive and negative voltage specified by the RS-232 standard is completed through the serial port level conversion chip, so that the baseband system can ...

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Abstract

The invention relates to a low-rate spread spectrum communication transmission base band system. The system is characterized by using an FPGA (field-programmable gate array) and a DDS (direct digital synthesizer) to realize the low-rate spread spectrum transmission base band system with settable parameters. The system specifically comprises an FPGA chip, a DDS chip and a peripheral module, wherein the FPGA chip comprises a clock signal generating module, an RS (recommended standard)-232 serial communication module, a central control module, a framing module, a channel coding module, a PN (pseudo noise) code generator module, a digital shaping filter module and a DDS working condition controller; the DDS chip comprises a phase accumulator module, a waveform ROM (read only memory) module, aD/A conversion module and a lowpass filtering module and is used for D/A conversion and signal modulation; the input/output port of the FPGA chip is connected with the input port of the DDS chip; andthe FPGA chip inputs the data to be modulated and the condition control signal to the DDS chip and controls the working mode of the DDS chip.

Description

technical field [0001] The invention relates to a communication transmitting baseband system, in particular to a low-rate spread spectrum communication transmitting baseband system. Background technique [0002] Spread spectrum communication is a method of information transmission, and its basic feature is to use a pseudo-random code that is many times higher than the transmitted information data rate to expand the spectrum of the baseband signal carrying information data to form a broadband low power spectral density. The signal is transmitted, and the frequency bandwidth occupied by the signal is much larger than the minimum bandwidth necessary for the transmitted information. Because spread spectrum communication has the advantages of good anti-interference performance, security and confidentiality, multi-access communication, good anti-fading and anti-multipath, etc., it has widely penetrated into all aspects of communication, such as satellite communication, mobile comm...

Claims

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Application Information

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IPC IPC(8): H04B1/707H04L25/02H04L1/00
Inventor 马冠一李婧华范江涛张杰
Owner ZHONGKE KAIPU TIANJIN SATELLITE NAVIGATION COMM TECH CO LTD
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