A synchronization method for gmsk modulation system
A modulation system and synchronization position technology, applied in the field of digital communication research, can solve the problems of sensitivity to changes in energy intensity and synchronization measurement energy intensity, which is not conducive to engineering implementation, and achieve the effect of facilitating engineering implementation and improving robustness
Active Publication Date: 2017-09-22
GUANGZHOU HAIGE COMM GRP INC
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Problems solved by technology
This method can eliminate the small frequency difference and phase deviation in the signal, but the calculation is complicated, and multiple thresholds need to be set, which is sensitive to the change of energy intensity and does not use the actual engineering
[0014] In summary, the shortcomings of the existing correlation synchronization methods: (1) The interference caused by frequency offset and initial phase is not eliminated
(2) Synchronization metrics are sensitive to changes in energy intensity, which is not conducive to engineering implementation
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Embodiment 1
[0036] Such as figure 1 As shown, a kind of GMSK modulation system synchronization method of the present embodiment, its implementation process specifically comprises the following steps:
[0037] (1), according to the training codes of different burst types stipulated by different systems using GMSK modulation, corresponding GMSK modulation signals are generated respectively, and the modulation process is as follows figure 2 As shown, the modulation process is based on the classic GMSK quadrature modulation signal generation principle, so details are not described here. Then, the differential operation is performed on the generated GMSK modulation signal. From the block diagram of the GMSK signal generation, it can be seen that the signal after the differential operation is restored to the signal after passing through the Gaussian low-pass filter and before integration.
[0038] In the baseband signal after the local carrier performs spectrum shift on the received signal, t...
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The invention discloses a method for synchronizing a GMSK modulation system. When the length of the local reference signal is the same as the length of the local reference signal, the current GMSK data receiving point is marked as the sampling point, and the differential operation is performed on the current GMSK data segment to obtain the GMSK differential signal; according to the local reference signal and the GMSK differential signal under the same burst type signal, to obtain the vector space cosine similarity; judge whether the vector space cosine similarity exceeds the threshold, if not, continue to receive GMSK data, otherwise the burst type is the burst type of the currently received GMSK data, and the current sampling point is Alternative synchronization positions, and then within the preset GMSK data receiving time, select one of the synchronization positions from the alternative synchronization positions for system synchronization. The invention can realize reliable synchronization and meet the requirement of engineering application more.
Description
technical field [0001] The invention relates to the field of digital communication research, in particular to a method for synchronizing a GMSK modulation system. Background technique [0002] The GMSK (Gaussian filtered MSK) signal is pre-modulated by a Gaussian low-pass filter before generating the MSK signal, and it belongs to the constant envelope digital modulation like MSK. Constant-envelope digital modulation allows the use of power-efficient nonlinear amplifiers, avoiding filtered sidelobe regeneration that occurs when non-constant-envelope modulation uses power-efficient nonlinear amplifiers. [0003] The MSK signal can be regarded as a continuous phase FSK signal with a modulation index of 0.5. Although it has the advantages of constant envelope, continuous phase, and relatively narrow bandwidth, its out-of-band radiation still does not meet the requirements for some communication systems. In order to effectively suppress the out-of-band radiation, a pre-modulated...
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IPC IPC(8): H04L27/152
Inventor 刘东辉胡汉武肖纯智
Owner GUANGZHOU HAIGE COMM GRP INC