CN111183750B

CN111183750B - Long-short code combined spread spectrum system unmanned aerial vehicle data link receiver

Info

Publication number: CN111183750B
Application number: CN201518003467.7A
Authority: CN
Inventors: 李涛护; 王育红; 周侃; 保巍巍
Original assignee: CETC 54 Research Institute
Current assignee: CETC 54 Research Institute
Priority date: 2015-07-17
Filing date: 2015-07-17
Publication date: 2017-11-10
Anticipated expiration: 2035-07-17

Abstract

The invention discloses a long and short code combined spread spectrum system unmanned aerial vehicle data link receiver. The method adopts a short code direct sequence spread spectrum signal and a long code direct sequence spread spectrum signal orthogonal modulation system, short code modulation information is time synchronization information guiding a long code capture mode, and long code modulation information is user data information. The receiver firstly captures the short code synchronous information and then completes the capture and tracking of the long code information with the assistance of the synchronous information. Compared with a short-period direct sequence spread spectrum system data link, the invention adopts long-period pseudorandom sequence spread spectrum, obviously improves the anti-interception capability of the unmanned aerial vehicle link, also has the advantages of high digitization degree, small volume, easy debugging, stable and reliable performance and the like, and is suitable for information transmission in complex electromagnetic environment with higher requirement on the safety degree of instruction information.

Description

Long-short code combined spread spectrum system unmanned aerial vehicle data link receiver

Technical Field

The invention relates to an unmanned aerial vehicle data link receiver with a long code and short code combined spread spectrum system in the field of unmanned aerial vehicle measurement and control, which is particularly suitable for interception-resistant wireless transmission with higher requirement on the safety degree of instruction information in a complex electromagnetic environment.

Background

In order to deal with complex electromagnetic threats and improve the information security degree of wireless data transmission in the field of measurement and control, a necessary anti-interception technology is adopted. At present, the uplink and the downlink of a medium-speed data chain of an unmanned aerial vehicle at home and abroad have widely adopted a short-period pseudorandom sequence direct sequence spread spectrum technology, but no report of an anti-interception technology adopting a long-short code combined spread spectrum system exists. The signal period characteristics of the current short-period pseudorandom sequence direct sequence spread spectrum system data link are obvious, the pseudorandom sequence is easy to be decoded by a non-cooperative party through the period characteristics, strong information safety hazards exist, and the data link cannot meet the requirement of military communication confidentiality.

Disclosure of Invention

The invention aims to make up for the defects in the background technology, and effectively improves the information safety by utilizing the characteristic that the non-periodic sequence has no periodicity and adopting a certain section of the long-period pseudorandom sequence to spread the frequency of data. The invention solves the key problems of phase synchronization, synchronous information assisted long code capture and the like which need to be solved when a long-period pseudorandom sequence is applied as a receiver, can be compatible with most of unmanned aerial vehicle data link hardware flat additions, greatly improves the interception resistance of a data link, and simultaneously has the advantages of high digital integration degree, simple circuit, small volume, easy debugging, stable and reliable performance and the like.

The invention is realized by the following steps:

a long and short code united spread spectrum system unmanned aerial vehicle data link receiver is characterized in that: the device comprises a digital down converter 1, a short code acquisition tracking module 2, a short code generation module 3, a short code de-spreading demodulation module 4, a long code tracking module 5, a long code generation module 6, a long code de-spreading demodulation module 7 and a power supply 8; the digital down converter 1 performs down conversion on an input spread spectrum signal, converts the input spread spectrum signal into a zero intermediate frequency signal and respectively outputs the zero intermediate frequency signal to the short code capturing and tracking module 2, the short code despreading and demodulating module 4, the long code tracking module 5 and the long code despreading and demodulating module 7; the short code capturing and tracking module 2 captures and tracks the zero intermediate frequency signal output by the digital down converter 1 by using the specified phase short code output by the short code generating module 3, and then outputs a short code state control signal to the short code generating module 3; the short code generating module 3 generates a short code with a specified phase according to the short code state control signal and respectively outputs the short code to the short code capturing and tracking module 2 and the short code despreading and demodulating module 4; the short code de-spreading demodulation module 4 de-spreads and demodulates the zero intermediate frequency signal output by the digital down converter 1 by using the specified phase short code output by the short code generation module 3, recovers the long code synchronization information modulated on the short code and outputs the long code synchronization information to the long code generation module 6; the long code tracking module 5 tracks the long code of the zero intermediate frequency signal output by the digital down converter 1 by using the long code signal within one chip of the phase offset output by the long code generating module 6, and then outputs the long code phase information after accurate tracking to the long code generating module 6; the long code generating module 6 presets the long code phase according to the long code synchronization information output by the short code despreading and demodulating module 4, provides the long code signal with phase shift within one chip to the long code tracking module 5, generates the long code signal according to the long code phase information after accurate tracking output by the long code tracking module 5, and outputs the long code signal to the long code despreading and demodulating module 7; the long code de-spreading demodulation module 7 performs de-spreading demodulation on the zero intermediate frequency signal output by the digital down converter 1 by using the long code signal output by the long code generation module 6, and recovers data information.

Compared with the background technology, the invention has the following advantages:

1. the receiver of the long-period pseudorandom sequence spread spectrum system is realized, has strong anti-interception performance, can be suitable for most unmanned aerial vehicle uplink data chains, and improves the anti-interception capability of the uplink remote control command.

2. The invention has two working modes: the long and short code combined spreading mode and the long and short code alternate spreading mode can adapt to different application occasions.

3. All parts of the invention are made of large-scale programmable integrated circuits, and the invention has the advantages of simple circuit, small volume, low cost, easy debugging, stable and reliable performance, strong practicability in engineering, and popularization and application value.

Drawings

Fig. 1 is an electrical schematic block diagram of the present invention.

Detailed Description

The present invention will be further described with reference to fig. 1.

A long and short code combined spread spectrum system unmanned aerial vehicle data link receiver comprises a digital down converter 1, a short code capturing and tracking module 2, a short code generating module 3, a short code de-spreading and demodulating module 4, a long code tracking module 5, a long code generating module 6, a long code de-spreading and demodulating module 7 and a power supply 8. Fig. 1 is an electrical schematic block diagram of the present invention. Embodiments connect the lines as in fig. 1.

The digital down converter 1 carries out down conversion on an input spread spectrum signal, converts the input spread spectrum signal into a zero intermediate frequency signal and respectively outputs the zero intermediate frequency signal to the short code capturing and tracking module 2, the short code despreading and demodulating module 4, the long code tracking module 5 and the long code despreading and demodulating module 7; the short code capturing and tracking module 2 captures and tracks the zero intermediate frequency signal output by the digital down converter 1 by using the specified phase short code output by the short code generating module 3, and then outputs a short code state control signal to the short code generating module 3; the short code generating module 3 generates a short code with a specified phase according to the short code state control signal and respectively outputs the short code to the short code capturing and tracking module 2 and the short code despreading and demodulating module 4; the short code de-spreading demodulation module 4 de-spreads and demodulates the zero intermediate frequency signal output by the digital down converter 1 by using the specified phase short code output by the short code generation module 3, recovers the long code synchronization information modulated on the short code and outputs the long code synchronization information to the long code generation module 6; the long code tracking module 5 tracks the long code of the zero intermediate frequency signal output by the digital down converter 1 by using the long code signal within one chip of the phase offset output by the long code generating module 6, and then outputs the long code phase information after accurate tracking to the long code generating module 6; the long code generating module 6 presets the long code phase according to the long code synchronization information output by the short code despreading and demodulating module 4, provides the long code signal with phase shift within one chip to the long code tracking module 5, generates the long code signal according to the long code phase information after accurate tracking output by the long code tracking module 5, and outputs the long code signal to the long code despreading and demodulating module 7; the long code de-spreading demodulation module 7 performs de-spreading demodulation on the zero intermediate frequency signal output by the digital down converter 1 by using the long code signal output by the long code generation module 6 to recover data information; the power supply 8 of the invention provides working voltages of all stages of components, the embodiment is made of a universal integrated voltage-stabilized power supply, and the output voltage is + 3.3V.

The invention has the following brief working principle:

the received spread spectrum signal is filtered and amplified, then is subjected to intermediate frequency high-speed sampling, and is sent to a programmable device for digital processing. The spread spectrum intermediate frequency signal received in the programmable device and the local carrier wave are firstly subjected to digital down-conversion and low-pass filtering in the digital down-converter 1 to obtain a baseband signal. The baseband signal is firstly sent to the short code capturing and tracking module 2 for processing, and when the capturing is successful and the tracking is locked, the synchronous short code generated by the short code generating module 3 is used for despreading and demodulating the baseband signal to extract the synchronous information. The long code generating module 6 sets a long code phase according to the synchronization information, searches a maximum correlation peak value for the baseband signal through the matched filter, controls the long code phase within a chip range when the correlation peak value is larger than a threshold value, then shifts the long code phase into the long code tracking module 5 for phase fine adjustment until the correlation peak value is completely matched, and then despreads and demodulates the baseband signal by using the tracked long code signal to obtain original data information.

The installation structure of the invention is as follows: all the components of the circuit components in the invention shown in figure 1 are respectively arranged on a printed board with the length multiplied by the width of 140 multiplied by 127mm, then the printed boards are respectively arranged in two shielding boxes with the length multiplied by the width multiplied by the height of 150 multiplied by 137 multiplied by 12.5mm, the shielding boxes are respectively assembled in a chassis with the length multiplied by 230 multiplied by 220mm, cable sockets of a signal inlet port and a signal outlet port are arranged on the rear panel of the chassis, the cable sockets are connected with external radio frequency components through cables, a power supply input socket is arranged on the rear panel of the chassis, and a power supply switch is arranged on the front panel.

Claims

1. A long and short code united spread spectrum system unmanned aerial vehicle data link receiver is characterized in that: the device comprises a digital down converter (1), a short code acquisition tracking module (2), a short code generation module (3), a short code de-spreading demodulation module (4), a long code tracking module (5), a long code generation module (6), a long code de-spreading demodulation module (7) and a power supply (8); the digital down converter (1) performs down conversion on an input spread spectrum signal, converts the input spread spectrum signal into a zero intermediate frequency signal and respectively outputs the zero intermediate frequency signal to the short code acquisition tracking module (2), the short code despreading and demodulation module (4), the long code tracking module (5) and the long code despreading and demodulation module (7); the short code capturing and tracking module (2) captures and tracks the zero intermediate frequency signal output by the digital down converter (1) by using the appointed phase short code output by the short code generating module (3), and then outputs a short code state control signal to the short code generating module (3); the short code generating module (3) generates a short code with a specified phase according to the short code state control signal and respectively outputs the short code to the short code capturing and tracking module (2) and the short code de-spreading and demodulating module (4); the short code de-spreading demodulation module (4) de-spreads and demodulates the zero intermediate frequency signal output by the digital down converter (1) by using the appointed phase short code output by the short code generation module (3), recovers the long code synchronous information modulated on the short code and outputs the long code synchronous information to the long code generation module (6); the long code tracking module (5) tracks the long code of the zero intermediate frequency signal output by the digital down converter (1) by using the long code signal of the phase offset output by the long code generating module (6) in one chip, and then outputs the long code phase information after accurate tracking to the long code generating module (6); the long code generating module (6) presets the long code phase according to the long code synchronous information output by the short code de-spreading demodulation module (4), provides the long code signal with the phase offset in one chip to the long code tracking module (5), generates the long code signal according to the long code phase information output by the long code tracking module (5) after accurate tracking, and outputs the long code signal to the long code de-spreading demodulation module (7); the long code de-spreading demodulation module (7) utilizes the long code signal output by the long code generation module (6) to de-spread and demodulate the zero intermediate frequency signal output by the digital down converter (1) to recover the data information.