Direct digital synthesizer (DDS) chip based Gaussian filtered minimum shift keying (GMSK) signal generation method

A DDS chip and signal generation technology, applied in a variety of modulation transmitter/receiver arrangements, digital transmission systems, electrical components, etc., can solve problems such as increasing the complexity of circuit design, many hardware resources, and complex baseband signal modulation. , to achieve the effect of simple and effective implementation

Inactive Publication Date: 2015-06-03
LEIHUA ELECTRONICS TECH RES INST AVIATION IND OF CHINA
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Problems solved by technology

Although the former is simple to implement, the stability of the center frequency is poor, and it needs to be solved by designing an accurate phase-locked loop technology, which increases the complexity of the circuit design.
Although the latter is currently a more popular modulation method, it also occupies more hardware resources, and the modulation of its baseband signal is more complicated.

Method used

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  • Direct digital synthesizer (DDS) chip based Gaussian filtered minimum shift keying (GMSK) signal generation method
  • Direct digital synthesizer (DDS) chip based Gaussian filtered minimum shift keying (GMSK) signal generation method
  • Direct digital synthesizer (DDS) chip based Gaussian filtered minimum shift keying (GMSK) signal generation method

Examples

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Embodiment

[0028] Using JDDS9910 to generate bt=0.5, the center frequency is F c =100M, code rate is R b =1Mb / s GMSK signal, crystal oscillator F r =1GHz, this method includes the following steps:

[0029] The first step is to set the bt value of the Gaussian filter to 0.5 in the simulation software, and the output parameter is a normalization parameter. The binary data stream is divided into eight groups of 000, 001, 010, 011, 100, 101, 110 and 111 according to the three-bit data group. The data stream is converted into a binary non-return-to-zero code, which is input into a Gaussian filter as an input to generate 8 groups of corresponding response waveforms, such as figure 2 shown. According to the frequency of the intermediate frequency signal to be generated, the frequency waveform data corresponding to each response waveform in the 8 groups of response waveforms is calculated; assuming that a string of binary return-to-zero code streams is 1111001010, the response generated afte...

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Abstract

The invention particularly relates to a Gaussian filtered minimum shift keying (GMSK) signal generation method, belonging to the technical field of radar signal generation. Through utilization of a direct digital synthesizer (DDS) chip and assistance of field programmable gate array (FPGA) control, a Gaussian pulse sequence is divided into eight basic waveforms, frequency waveform data is calculated by tools like matlab and is written in a random access memory (RAM) of the DDS chip through hardware logic. When code streams flow in sequentially, a corresponding frequency curve in the RAM is directly invoked according to a current bit and two adjacent bits, so that the DDS chip plays the signal directly according to the frequency curve and a predetermined play rate so as to complete GMSK modulation.

Description

technical field [0001] The invention belongs to the technical field of radar signal generation, in particular to a GMSK signal generation method. Background technique [0002] GMSK modulation is a partial response CPM modulation (continuous phase modulation), the principle of which is to filter the rectangular frequency pulse characteristics of the MSK (minimum shift keying) signal with a Gaussian impulse response filter before frequency modulation of the carrier , In this way, GMSK modulation not only ensures the continuity of the carrier phase when the symbol is converted, but also ensures the continuity of the carrier frequency pulse at the time of the symbol conversion, which further reduces the signal bandwidth, improves the frequency band utilization, reduces the inter-channel interference, and its The constant envelope characteristic is also suitable for transmission in nonlinear channels, so it has been widely developed in civilian and military fields. [0003] At p...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04L27/12
CPCH04L27/2017H04L27/0008H04L27/12
Inventor 包可佳苏光锋钱厦
Owner LEIHUA ELECTRONICS TECH RES INST AVIATION IND OF CHINA
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