CN105281806A - FPGA-based direct sequence spread spectrum system range finding positioning method - Google Patents
FPGA-based direct sequence spread spectrum system range finding positioning method Download PDFInfo
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- CN105281806A CN105281806A CN201510760119.3A CN201510760119A CN105281806A CN 105281806 A CN105281806 A CN 105281806A CN 201510760119 A CN201510760119 A CN 201510760119A CN 105281806 A CN105281806 A CN 105281806A
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Abstract
The invention discloses an FPGA-based direct sequence spread spectrum system range finding positioning method. A radio frequency line fault is localized and monitored by using a radio frequency signal. With direct sequence spread spectrum communication, the wireless communication performance reliability can be improved because of excellent anti-interference capability and anti-multi-path interference capability as well as high timing and range finding precision of the direct sequence spread spectrum communication; and radio frequency line fault positioning and range finding can be realized well based on the direct sequence spread spectrum communication. Radio frequency fault detection equipment mainly includes a baseband part, a digital intermediate frequency part, a radio frequency part, and a control part. An FPGA completes the baseband part, up conversion, and down conversion; and the FPGA consists of a processor interface unit, an information processing unit, a spread spectrum modulator, a spread spectrum demodulator, a DDC, a DUC, an AD interface, and a DA interface and the like.
Description
Technical field
The present invention realizes a kind of fault detect of radio-frequency line, specifically a kind of Fault Locating Method based on Resistant DS Spread Spectrum System.
The present invention FPGA realizes spread spectrum modulator, extended frequency demodulator, pseudo-code information process unit, radio-frequency line fault detection algorithm.
Background technology
The design adopts spread spectrum transmitting radio frequency signal, and spread spectrum is that the information frequency spectrum that will send is widened in a very wide bandwidth and launched, and receiving terminal by its bandwidth reduction, recovers original narrow band signal by correlation reception principle.Spread spectrum has two large features: the first, transmission bandwidth is greater than by the original signal bandwidth transmitted.The second, transmission bandwidth determines primarily of spread-spectrum function.In spread spectrum mode, the design adopts the spread spectrum communication mode of direct sequence spread spectrum, and spreading code and baseband digital signal waiting for transmission are carried out mould 2 and add by direct sequence spread spectrum, thus complete spreading operations.
Radiofrequency signal transmission speed in test line is constant, if the time difference that radiofrequency signal transmits to fault point can be measured, and just can measuring distance.If spread-spectrum is very wide in spread spectrum communication, then mean that adopted pseudo random sequence speed is very high, the time shared by each chip is just very short.Reflect when radiofrequency signal runs into fault point, demodulate pseudo random sequence at receiving terminal, then compare the difference of transmitting-receiving two pseudo-code sequence phase places, just accurately can measure the time difference that spread-spectrum signal comes and goes, thus calculate distance between the two.Certainty of measurement depends on the width of chip, and chip is narrower, and precision is higher.Current radio-frequency line fault monitoring device adopts linear frequency modulation technology mostly, and the design adopts the mode realizing the higher direct sequence spread spectrum of difficulty.
Summary of the invention
The object of the present invention is to provide a kind of line fault detection system based on radio frequency, to solve the problem proposed in above-mentioned background technology.In order to realize online radio-frequency line fault location, solve prior art fault location apart from short, that precision is not high shortcoming, the direct sequence spread spectrum navigation system that the present invention adopts enhances fault-detecting ability.For achieving the above object, the invention provides following technical scheme:
A kind of line fault detection system based on radio frequency, comprise control section, baseband portion, digital intermediate frequency part and radio frequency, part, described control section adopts ARM to make controller, and described baseband portion completes base band encoding and decoding, filtering, DDC, DUC, information processing by FPGA; Digital intermediate frequency part comprises A/D, D/A and filter; Described radio frequency comprises small signal amplifier, frequency mixer, circulator;
Spread spectrum modulator in described FPGA is modulated pseudo-code, through DUC, filtering, A/D produces digital medium-frequency signal, then through frequency mixer, be mixed to the tranmitting frequency of needs, through circulator access mixer after amplification, be connected with test line, radiofrequency signal in test line in transmitting procedure if any fault point, then produce reflected wave, reflected signal is through mixer, circulator enters radio-frequency line fault test set, reflected signal reduces to digital intermediate frequency after mixing, finally send FPGA to through D/A again, baseband signal is become after DDC, eventually pass extended frequency demodulator by the pseudo-code that demodulates to information process unit.Information process unit, according to the pseudo-code sent and receive, calculates the standing-wave ratio of each fault point of circuit, the information such as return loss.
Compared with prior art, the invention has the beneficial effects as follows: spread spectrum communication can improve the signal to noise ratio of signal, the spread spectrum communication mode of direct sequence spread spectrum has inhibitory action to arrowband interference, has the ability of anti-broadband barrage noise interference performance, anti-multipath jamming simultaneously, and therefore the present invention is applicable to the radio-frequency line detection system of long distance, hi-Fix.
Accompanying drawing explanation
Fig. 1 is the radio-frequency line fault detection system structured flowchart based on FPGA;
Fig. 2 is FPGA internal structure block diagram.
Fig. 3 is the structured flowchart of information process unit.
Embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present invention, be clearly and completely described the technical scheme in the embodiment of the present invention, obviously, described embodiment is only the present invention's part embodiment, instead of whole embodiments.Based on the embodiment in the present invention, those of ordinary skill in the art, not making the every other embodiment obtained under creative work prerequisite, belong to the scope of protection of the invention.
Refer to Fig. 1-3, a kind of line fault detection system based on radio frequency, comprise control section, baseband portion, digital intermediate frequency part and radio frequency part, described control section adopts ARM to make controller, described baseband portion generates baseband modulation code by FPGA, and FPGA comprises information process unit, spread spectrum modulator, DUC and DDC; Digital intermediate frequency part comprises A/D, D/A and filter; Described radio frequency part comprises frequency mixer, amplifier and circulator;
Spread spectrum modulator in described FPGA is modulated pseudo-code, through DUC, filtering, A/D produces digital medium-frequency signal, then through frequency mixer, be mixed to the tranmitting frequency of needs, through circulator access mixer after amplification, be connected with test line, radiofrequency signal in test line in transmitting procedure if any fault point, then produce reflected wave, reflected signal is through mixer, circulator enters Lou cable checkout equipment, reflected signal reduces to digital intermediate frequency after mixing, finally send FPGA to through D/A again, baseband signal is become after DDC, eventually pass spread spectrum modulator by the pseudo-code that demodulates to information process unit.Information process unit, according to the pseudo-code sent and receive, calculates the standing-wave ratio of each fault point of circuit, the information such as return loss.
Operation principle of the present invention is: the design adopts direct sequence spread spectrum skill, direct sequence spread spectrum skill is that the information frequency spectrum that will send is widened in a very wide bandwidth and launched, receiving terminal by its bandwidth reduction, recovers original narrow band signal by correlation reception principle.Spread spectrum has two large features: the first, transmission bandwidth is greater than by the original signal bandwidth transmitted.The second, transmission bandwidth determines primarily of spread-spectrum function.In spread spectrum mode, the design adopts the communication mode of direct sequence spread spectrum, and spreading code and baseband digital signal waiting for transmission are carried out mould 2 and add by direct sequence spread spectrum, thus complete spreading operations.
Spread spectrum modulator in FPGA is modulated pseudo-code, produces digital medium-frequency signal, then through frequency mixer, be mixed to the tranmitting frequency of needs through DUC, filtering, AD, through circulator access mixer after amplification, is connected with test line.Radiofrequency signal in test line in transmitting procedure if any fault point, then produce reflected signal, reflected signal enters Lou cable checkout equipment through mixer, circulator.Reflected signal is reduced to digital intermediate frequency, is finally sent FPGA to through DA, after DDC, become baseband signal again after mixing, eventually passes extended frequency demodulator by the pseudo-code that demodulates to information process unit.Information process unit, according to the pseudo-code sent and receive, calculates the standing-wave ratio of each fault point of circuit, the information such as return loss.
Fig. 2 is the structured flowchart of the inner main modular of FPGA.The sample rate of A/D is 184.32M, and digital intermediate frequency frequency is 138.24M.What ADC inputted is digital medium-frequency signal, and IF spot is 138.24, is positioned at 2Nyquist district, and intermediate-freuqncy signal is moved base band by sample rate 184.32MHz, DDC, then filtering, is drawn into 92.16M.Extended frequency demodulator is given by DDC signal out.The signal that spread spectrum modulator is just modulated sends into DUC, gives DA, become intermediate-freuqncy signal after interpolation, filtering.Information process unit processes according to spread spectrum demodulation output signal, draws the fault point information of radio-frequency line, then reports processor.
Fig. 3 is information process unit block diagram, is utilize the propagation time between radio wave transmitting-receiving to measure with the basic thought of pseudo-random code ranging.For the radiofrequency signal that the design launches, through launching, electric wave plays from x time and receives echo-signal, and propagation delay time is
, then target range d and transmission range
between close be:
C is the light velocity, and range finding mainly measures propagation delay time
, mostly adopt pulse or continuous wave to measure at present, when distance is very greatly no matter be pulse or continuous wave, all have difficulties.Pulse increases transmit power limited, and continuous wave exists range ambiguity.Utilize the acuteness of pseudo-code, and the feature that the periodicity of pseudo-code is very long, adopt correlation reception technology, the phase difference launched pseudo-code and receive pseudo-code can be utilized to measure transmission delay, be measure antijamming capability to strengthen, range accuracy and measuring range also increase greatly.
The expectation index that the present invention can reach: (1) can position line fault such as leakage cable, feeder etc.; (2) can tuning on-line; (3) distance of at least 1500 meters (comprise wire jumper and leak cable) can be reached, the positioning precision of 10 meters; (4) can Long-distance Control; (5) webmaster can Realtime Alerts.
Radio-frequency line fault test process, radio-frequency line fault detection signal accesses radio frequency link by mixer together with radio-frequency line working signal, and detection signal and working signal send in different frequency ranges, are less than-100dBm to working signal frequency band signals is spuious.Detection signal runs into fault point and has reflection in transmitting procedure, and reflected signal enters checkout equipment through circulator.Reflected signal and the time difference transmitted, can the localization of faults.Detection signal can be lossy in radio-frequency line transmitting procedure, wherein the size of fissipation factor is relevant with the physical characteristic of radio-frequency line, when radio-frequency line fault test set receiving sensitivity is constant, the ultimate range that Line Attenuation Summing Factor can detect is inversely proportional to.Radio-frequency line checkout equipment provides Ethernet interface, the RS232 mouth of 100M, namely can be used for local test, program upgrade, also can remote monitoring.Radio-frequency line fault test set can with the fault detect completing both direction, and test line is accessed by mixer in each direction.Radio-frequency line fault test set can carry out star net forming, and monitoring information can by the conversion of optical fiber ether transducer, and be uploaded to monitoring management unit by optical fiber, monitoring management unit is unified radio frequency wireline inspection equipment and controlled.
Radio-frequency line fault test set possesses following function: 1. the monitoring and the alarm function that leak cable standing-wave ratio index.2. fault location function.3. monitor two functions 4. of leaking cables to read from local maintenance interface, store and the function of derived data simultaneously.5. the relevant information of equipment is sent to the function of network management system through data transmission link.6. during equipment fault, do not affect the normal work of existing wireless system.
Claims (1)
1. use radiofrequency signal to locate and monitor a method for radio-frequency line, radio frequency impairments checkout equipment mainly comprises baseband portion, digital intermediate frequency part, radio frequency part, control section.FPGA completes baseband portion and up-conversion, down-conversion, AD interface, DA interface.The parts such as processor interface unit, information process unit, spread spectrum modulator, extended frequency demodulator, DDC, DUC, AD interface, DA interface are mainly comprised in FPGA.Spread spectrum modulator in described FPGA is modulated pseudo-code, through DUC, filtering, A/D produces digital medium-frequency signal, then through frequency mixer, be mixed to the tranmitting frequency of needs, through circulator access mixer after amplification, be connected with test line, radiofrequency signal in test line in transmitting procedure if any fault point, then produce reflected wave, reflected signal is through mixer, circulator enters Lou cable checkout equipment, reflected signal becomes digital medium-frequency signal after frequency mixer, finally send FPGA to through D/A again, baseband signal is become after DDC, eventually pass extended frequency demodulator by the pseudo-code that demodulates to information process unit.Information process unit, according to the pseudo-code sent and receive, calculates the standing-wave ratio of each fault point of circuit, the information such as return loss.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN104993891A (en) * | 2015-06-15 | 2015-10-21 | 中国电子科技集团公司第十研究所 | Multi-carrier signal time delay online calibration system |
| CN117269995A (en) * | 2023-11-24 | 2023-12-22 | 北京凯芯微科技有限公司 | GNSS radio frequency module fault detection circuit, GNSS radio frequency module fault detection method, GNSS radio frequency module fault detection chip and GNSS receiver |
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| US20030118081A1 (en) * | 1995-10-04 | 2003-06-26 | Lieven Philips | Programmable modem apparatus for transmitting and receiving digital data, design method and use method for the modem |
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| CN117269995A (en) * | 2023-11-24 | 2023-12-22 | 北京凯芯微科技有限公司 | GNSS radio frequency module fault detection circuit, GNSS radio frequency module fault detection method, GNSS radio frequency module fault detection chip and GNSS receiver |
| CN117269995B (en) * | 2023-11-24 | 2024-02-23 | 北京凯芯微科技有限公司 | GNSS radio frequency module fault detection circuit, GNSS radio frequency module fault detection method, GNSS radio frequency module fault detection chip and GNSS receiver |
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Application publication date: 20160127 |