Design Of The Key Modules In Multi-aircraft TT&C System

In recent years, the unmanned aerial vehicles and small man-made satellitesconstellation, which collaborate with each other in order to complete complex tasks,have aroused extensive attention from academics. With the constant development ofChinese aerospace industry, it is absolutely necessary and timely to study a newgeneration of aircraft tracking telemetry and command technology.The main content of this paper is to study the key technologies in multi-aircraftTT&C system based on DBF-CDMA theory, and design these key modules. Therefore,this paper studies the following aspects.First, this article describes the development historic and situation of the TrackingTelemetry and Command (TT&C) system, and also points out the deficiencies of theexisting TT&C system in China.In ordre to solve these probelems, this paper introducethe multi-aircraft TT&C system based on the DBF-CDMA theory. Then this paperanalyzes the overall schematic diagram of the system.Second, the paper researches on carrier synchronization of multi-aircraft TT&Csystem technology, and inturduces the principle of synchronous detection module.Inorder to process signal suh as DBF and DMF in baseband,it is necessary to transformthe analog IF signal sent by the RF channel to the digital baseband signal.So the paperresearches and analyzes the carrier synchronization of analog and digital conversiontechnology, and designs analog costas loop and digital costas loop circuit to achievecarrier synchronization.Third, the paper researches on the pseudo-code synchronization of themulti-aircraft TT&C system, and introduces the principle of digital matched filter (DMF)and its application in PN acquisition. After analyzing and comparing some DMFstructures and their performance, this paper designes a PN code acquisition circuit basedon3-bit quantization technonlogy.This kind of DMF circuit is also implemented in theFPGA.Fourth, the paper researches on the digital beam forming (DBF) technology ofmulti-aircraft TT&C system.This paper gives an introduction of the circular array factorand its digital beamforming principle. Finally, the paper realizes digital beam formingcircuit in FPGA.The the simulation waveforms prove that this design is right andfeasible.