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A Time Diversity Parallel Synchronization Method Against Helicopter Rotor Shading Based on FPGA

A technology for time diversity and data transmission. It is applied to synchronization devices, synchronization receivers, code division multiplexing systems, etc. It can solve the problems of periodic fading of communication signals, difficult to meet actual needs, and affect normal communication. Good transmission bit error performance, improved frame synchronization rate, and a wide range of effects

Active Publication Date: 2020-06-16
UNIV OF ELECTRONICS SCI & TECH OF CHINA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Since the propagation mode of the satellite communication radio wave is a direct wave, it is required to communicate under the condition of no occlusion. During the flight of the helicopter, the rotor blades will periodically block the antenna, causing the periodic fading of the communication signal and affecting the normal communication.
Using dual time diversity to send data can effectively counteract the influence of rotor occlusion, but there are still some problems to be solved in the process of frame synchronization and data reorganization
[0003] In the helicopter satellite communication system, DSP is often used to achieve frame synchronization, but this method needs to store a large amount of data, and the synchronization rate is slow. As the communication rate increases, it may be difficult to meet actual needs

Method used

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  • A Time Diversity Parallel Synchronization Method Against Helicopter Rotor Shading Based on FPGA
  • A Time Diversity Parallel Synchronization Method Against Helicopter Rotor Shading Based on FPGA
  • A Time Diversity Parallel Synchronization Method Against Helicopter Rotor Shading Based on FPGA

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0039] The simulation platform used in Example 1 is MATLAB R2011b, and the occlusion model used is as follows figure 2 As shown, the occlusion rate is 25%, the occlusion period is 31.25ms, the occlusion drop and occlusion rise time each account for 40% of the occlusion time, the complete occlusion time accounts for 20% of the occlusion time, and the signal energy attenuation is 40dB when fully occluded, without occlusion When the signal energy attenuation is 0dB, the occlusion model curve occlusion decline and rise are linear changes.

[0040] The test block diagram used in Example 1 is as follows Figure 5 As shown, a random 0,1 signal is first generated, and then QPSK (Quadrature Phase Shift Keying) mapping is performed, data is framed in a dual time diversity manner, processed by an occlusion model, and then noise is added to obtain a received signal (Gaussian occlusion channel processing); at the receiving end, the received signal is frame-synchronized, and the frame-syn...

example 2

[0042] The simulation platform used in Example 2 is ISE 14.7 and Modelsim 10.1a, and the processing block diagram is as follows Figure 7 As shown, the data is first framed, processed by the occlusion model, and processed by noise, and then the frame is synchronized, and finally the data obtained by the frame synchronization is merged and reorganized. Figure 8 is the frame synchronization simulation diagram, Figure 9 for right Figure 8 A partial enlargement of the white dotted box marked at the left end of . Depend on Figure 8 , 9 It can be seen that the local ZC sequence performs a sliding correlation operation with the source frame and the copied frame. When the corresponding frame header is detected, its normalized correlation value is much higher than other positions of the frame, that is, the frame synchronization can be synchronized in real time. Synchronize the frame header and get the corresponding subframe index. For example, when the local ZC sequence number...

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Abstract

The present invention relates to the technical field of satellite communication for helicopter anti-rotor occlusion, and discloses an FPGA-based time-diversity parallel synchronization method for anti-rotor occlusion of helicopters. For rotor occlusion, the sending end adopts a dual time-diversity method to form frames, and after occlusion As well as noise processing, the receiving end adopts the parallel synchronization frame detection method for frame synchronization, and at the same time adopts the combination method for reorganization to deframe. The present invention makes full use of the parallelism of the FPGA to quickly synchronize the positions of the subframes. The invention has the characteristics of simplicity, high efficiency, strong expansibility, wide application range, etc., can reduce storage resources, improve frame synchronization rate, and has good transmission error performance.

Description

technical field [0001] The invention relates to the technical field of satellite communication for helicopter anti-rotor occlusion, in particular to an FPGA-based time-diversity parallel synchronization method for anti-helicopter rotor occlusion. Background technique [0002] At present, helicopters play an increasingly important role in non-war military operations such as anti-terrorism, emergency rescue and disaster relief, and handling border emergencies. The helicopter satellite communication system is a point-to-point communication system composed of helicopters and ground fixed stations through synchronous satellites. Since the propagation mode of satellite communication radio waves is direct waves, it is required to communicate under unobstructed conditions. During the flight of a helicopter, the rotor blades will periodically block the antenna, causing periodic fading of communication signals and affecting normal communication. Using dual time diversity to send data...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04L7/00H04J13/00H04L1/00H04B7/185
CPCH04B7/18508H04J13/0062H04L1/0083H04L7/0079
Inventor 何春黄圳姚国强李浩
Owner UNIV OF ELECTRONICS SCI & TECH OF CHINA
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