CN102647241B - Non-coherent detection system and method for short-wave broad-band channel - Google Patents
Non-coherent detection system and method for short-wave broad-band channel Download PDFInfo
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Abstract
The invention relates to the technical field of communication and discloses a non-coherent detection system and method for a short-wave broad-band channel. According to the system and the method, after being filtered and amplified, a short-wave signal enters into a non-coherent demodulation device so as to be demodulated, and then is subjected to signal detection; when a signal is detected, the signal accumulated energy is compared with a set SNR (Signal to Noise Ratio) threshold value, if the signal accumulated energy is greater than the threshold value, the channel bandwidth is automatically regulated, and fine detection is carried out; and the detection method is repeatedly carried out until the accumulated energy is not greater than the set SNR threshold value, and then detection is finished. According to the technical scheme adopted by the invention, signals are not subjected to any assumption, a blind detection algorithm is adopted, any prior knowledge of detection signals is not required to be known; the technical scheme is low in complexity, mature in technology and easy to realize; and the system and the method can be used for regulating the sizes of the resolution bandwidth and the detection signals, finally realizing the rapid detection on the short-wave broad-band channel quality and meeting the user experience.
Description
Technical field
The present invention relates to communication technical field, relate more specifically to a kind of short wave bandwidth channel non-coherent detection system and detection method.
Background technology
Dispersive Channels when short wave channel is a kind of, scatters because sky wave can cause the decline of signal and frequency after ionospheric reflection, and the interference of surrounding environment electromagnetic noise, makes short wave channel not have cellular system channel so stable.Under this environment, short wave channel is carried out to real-time detection necessary.
At present, short wave channel is surveyed the general mode that adopts frequency sweep, in HF frequency range all or in part by frequency step successively emission detection signal, each detectable signal 3dB, receiving terminal again successively scanning receive this detectable signal.This scanning detection method, is the blind scanning to short wave channel, and the scan period is long, can not meet the requirement of quick link setup completely; And in existing short wave communication, to the detection of channel, being all to carry out the arrowband in the situation that, is all to scan by changing centre frequency, causes the chronic of channel detection, can not meet consumers' demand.
Summary of the invention
For making up above-mentioned defect, the object of the invention is to propose a kind of short wave bandwidth channel non-coherent detection system and detection method.
In order to achieve the above object, the present invention is achieved by the following technical solutions.
Technical scheme one:
A short wave bandwidth channel non-coherent detection system, comprising: front end analogue means and energy testing apparatus, and described front end analogue means is processed for filtering, the amplification of signal; Signal after described energy testing apparatus is processed described front end analogue means is monitored and is obtained this signal frequency, it is characterized in that, described front end analogue means comprises AGC module, for the rangeability of control signal; Described energy testing apparatus comprises non-coherent demodulation device, FFT frequency spectrum detection module, signal to noise ratio index thresholding setting module, dynamic characteristic coefficients extraction module; Described non-coherent demodulation device comprises down conversion module and bandwidth tunable filter group, and described down conversion module is by regulating dynamic characteristic coefficients to carry out real-time detection to short wave channel; Described bandwidth tunable filter group regulates channel width while being used for input; The result that described FFT frequency spectrum detection module detects and described signal to noise ratio index thresholding setting module are set the frequency that threshold value relatively obtains channel; Described dynamic characteristic coefficients extraction module is used for extracting the dynamic characteristic coefficients that described system detection process obtains, and by regulating dynamic characteristic coefficients automatically to regulate channel width.
The feature of technique scheme and further improvement are:
(1) described energy testing apparatus also comprises frequency detecting and the evaluation module of channel, and the frequency detecting of described channel and evaluation module detect the frequency of channel, and in conjunction with described this channel of dynamic characteristic coefficients analysis and evaluation.
(2) described FFT frequency spectrum detection module is converted to frequency-region signal by time-domain signal through FFT, then to frequency-region signal, asks mould quadratic sum to obtain accumulated energy.
(3) described non-coherent demodulation device also comprises Direct Digital frequency synthesis module DDS, and described DDS is used for producing the signal mixing respectively just, after cosine signal and described AGC resume module of carrier wave.
(4) described dynamic characteristic coefficients comprises mixing range coefficient, filter and amplification coefficient at different levels and AGC amplification coefficient.
The function that channel non-coherent detection device in technical solution of the present invention mainly completes is down-conversion, filtering, and acquired results enters FFT energy detection module and detects, then by relatively, extracts characteristic coefficient and carry out frequency detecting and the assessment of channel.Undetected for fear of occurring, will in 1M bandwidth channel, detect while being greater than certain threshold value, be regarded as the input that needs bandwidth narrower, as channel width is become to 500kHz, or lower.For realizing this function, introduce bandwidth tunable digital filter group and realize.Improve the sensitivity of system detection signal, need AGC to control realization.
Technical scheme two:
A kind of short wave bandwidth channel non-coherent detection method, it is characterized in that, short-wave signal after filtering, amplify to process after, after entering the demodulation of non-coherent demodulation device, carry out acquisition of signal, when having detected signal, signal accumulated energy and signal-noise ratio threshold set point are compared, if while being greater than this threshold value, automatically regulate channel width, carry out trickle detection; Above-mentioned detection method repeatedly, until signal accumulated energy while being not more than signal-noise ratio threshold set point, finishes to survey.
The feature of technique scheme and further improvement are:
(1) described automatic adjusting channel width is to regulate channel width by automatic regulation moving state characteristic coefficient.
(2) a signal mode square summation of described non-coherent demodulation device Output rusults being carried out after FFT conversion obtains signal accumulated energy.
(3) described signal accumulated energy and signal-noise ratio threshold set point compare and obtain channel frequency number, and the computing formula of described channel frequency number is: f
n=(| f-f
c| * 1024)/f
s, wherein f is RF signal, f
ccentered by frequency, f
sfor sample frequency.
(4) described dynamic characteristic coefficients comprises mixing range coefficient, filter and amplification coefficient at different levels and AGC amplification coefficient.
The detection method that the technical program adopts is incoherent detection, does not need to know the concrete condition of each frequency in sweep bandwidth, and its approach is the local observation signal by perception user, detects electromagnetic environment situation around.Non-coherent detection method is mainly to extract the dynamic characteristic coefficients of detectable signal, and the automatic channel width that is detected signal that regulates, according to actual conditions, adjust the size of resolution bandwidth and detectable signal, realize the quick detection of short wave bandwidth channel quality, for further channel detection provides strong support.Technical solution of the present invention design complexities is low, and technology maturation is easy to realize; Signal is not made to any hypothesis, is a kind of Blind Detect Algorithm, without any priori of knowing detection signal; Speed of detection is very fast, contributes to user to experience.
Accompanying drawing explanation
Below in conjunction with the drawings and specific embodiments, technical scheme of the present invention is described in further detail.
Fig. 1 is embodiment of the present invention intermediate waves broad-band channel non-coherent detection system construction drawing;
Fig. 2 is the schematic diagram of the module integration chip of multiband harmonic filter and AGC in the embodiment of the present invention;
Fig. 3 is down conversion module fundamental diagram in the embodiment of the present invention;
Fig. 4 is embodiment of the present invention intermediate waves broad-band channel non-coherent detection method flow diagram.
Embodiment
The total thought of technical solution of the present invention is: in short wave channel band limits, by the channel detection to 1M bandwidth, can survey the situation that takies of channel, and realize the real-time assessment to short wave channel.For surveyed short wave channel bandwidth, can adjust surveyed channel width according to actual detection situation, and then the resolution bandwidth of change surveying, and corresponding channel energy size detection precision more, and then realize the channel detection in designated frequency band.By this technology, can provide the real-time detection assessment of channel, for the quick link setup of shortwave provides effective solution route.
The embodiment of the present invention realizes Digital Signal Processing by software radio, adopt the EP3C40F484 of altera corp to realize, its function mainly completing is down-conversion, filtering, FFT frequency spectrum detection, and the extraction of dynamic characteristic coefficients, and then the signal in 100dB dynamic range is realized to short wave bandwidth frequency detecting and assessment.Adopt novel chip ADRF6516, it is integrated by the function of programmable filter and adjustable gain operational amplifier function, makes the front end analogue means of shortwave realize miniaturization.The low-pass filtering cut-off frequency of ADRF6516 is that integer is adjustable within the scope of 0～31MHz, and the adjustable extent of this amplifier is-and 5dBm～+ 45dBm.In the present embodiment, analog-to-digital conversion adopts the ADC AD9269 of 16bit, and power consumption is 200mW, and analog signal is converted to digital signal, for the sensitivity of hardware platform provides guarantee.
Short wave bandwidth channel non-coherent detection system configuration as shown in Figure 1, comprises front end analogue means, on-site programmable gate array FPGA energy monitor and foreign frequency control module.Front end analogue means comprises multiband harmonic filter, AGC module and analog-to-digital conversion module ADC, for filtering, the amplification of signal, processes; Signal after described FPGA energy monitor is processed described front end analogue means is monitored and is obtained this signal frequency, comprises frequency detecting and the evaluation module of non-coherent demodulation device, FFT frequency spectrum detection module, signal to noise ratio index setting module, dynamic characteristic coefficients extraction module and channel; Non-coherent demodulation device comprises Direct Digital frequency synthesis module DDS, down conversion module 1, down conversion module 2, bandwidth tunable filter group 1 and bandwidth tunable filter group 2.
First, RF radiofrequency signal is through AGC resume module, carry out again generating after ADC conversion data signal rate at a high speed and DDS produce carrier wave just, cosine signal mixing respectively, after mixing, enter down conversion module, down conversion module is carried out real-time detection by adjusting dynamic characteristic coefficients to short wave channel; Secondly, regulate channel width, and give FFT frequency spectrum detection module by adjusting result by bandwidth tunable filter group, FFT frequency spectrum detection module sets by the result of detection and signal to noise ratio index thresholding setting module the frequency that threshold value relatively obtains channel; Again, dynamic characteristic coefficients extraction module extracts the dynamic characteristic coefficients obtaining in detection system detection process, and by regulating dynamic characteristic coefficients automatically to regulate channel width; Finally, the frequency that channel detected by frequency detecting and the evaluation module of channel, and in conjunction with this channel of dynamic characteristic coefficients analysis and evaluation.
Direct Digital frequency synthesis module DDS in the present embodiment, its frequency accuracy reaches 0.0168Hz, and the signal generation carrier wave of shortwave is moved.Foreign frequency control module by arrange corresponding frequency word control DDS partly produce corresponding frequencies carrier wave just, cosine signal, to complete follow-up Frequency mixing processing.Compare with traditional frequency synthesizer, DDS has the advantages such as low cost, low-power consumption, high-resolution and quick change-over time.
As shown in Figure 2, the schematic diagram of the module integration chip of multiband harmonic filter and AGC.
For avoiding humorous wave interference to have influence on frequency spectrum detection below, the HF signal of antenna access need be processed through multiband filter; For the short-wave signal of 100dB dynamic range, need the computing through AGC, i.e. front end amplifier signal 3dB/6dB, after controllable filter, controlled amplifier are processed, after the amplifier of rear end, signal is amplified to 6dB/12dB again, finally this amplifying signal is exported to ADC and carries out analog-to-digital conversion.
By reference to the accompanying drawings 3, be down conversion module fundamental diagram in the embodiment of the present invention.
RF radiofrequency signal generates data signal rate at a high speed after ADC conversion, with DDS produce just, realize carrier wave after the mixing of cosine carrier signal and move.In the processing procedure of down-conversion, by regulating the coefficient of low pass filters at different levels in mixing range coefficient, down-conversion and the amplification coefficient of regulation and control AGC to improve the detectivity of system, by sample rate extract, bandwidth tunable digital filter group regulates, signal finally enters follow-up FFT frequency spectrum detection module.
Short wave bandwidth channel non-coherent detection method, need to directly to signal demodulation detection, and not regulate channel width automatically by carrier wave, can realize channel quick detection.Concrete methods of realizing as shown in Figure 4, embodiment of the present invention intermediate waves broad-band channel non-coherent detection method flow, flow process is as follows:
S401: short-wave signal carries out multiband harmonic filter and AGC module amplifier is processed;
The cut-off frequency of multiband harmonic filter arranges corresponding parameter according to the residing frequency band of current FFT frequency spectrum detection module by foreign frequency control module.
S402: the signal after AGC amplifier is processed carries out analog-to-digital conversion;
S403:DDS is just producing, cosine signal;
Foreign frequency control module by arrange corresponding frequency word control DDS partly produce corresponding frequencies carrier wave just, cosine signal.
S404: the signal that step S402 and step S403 are obtained carries out respectively Frequency mixing processing;
RF radiofrequency signal generates data signal rate at a high speed after ADC conversion, with DDS produce just, the mixing respectively of cosine carrier signal, realize carrier wave and move.
S405: down-converted;
Improve the sensitivity of system detection signal, make the signal to be detected can smooth working in the scope of 100dB, need AGC to control realization.In the processing procedure of down-conversion, by regulating the coefficient of low pass filters at different levels in mixing range coefficient, down-conversion and the amplification coefficient of regulation and control AGC to improve the sensitivity of system Real-Time Monitoring.In downconversion process, for channel detection, assessing extractible dynamic characteristic coefficients has: mixing range coefficient, filter and amplification coefficient at different levels and AGC amplification coefficient.
S406: regulated by bandwidth tunable filter group;
For limited short wave channel bandwidth, when there is large-signal, when detecting, can make small-signal occur undetected; Undetected for fear of occurring, by when detecting and be greater than certain threshold value, be regarded as the input that needs bandwidth narrower in 1M bandwidth channel, as channel width is become to 500kHz, or lower, repeatedly survey, constantly automatically regulate channel width, until detect signal.For realizing this function, can realize by bandwidth tunable digital filter group.Having kind of an extreme situation is exactly in 1M channel width, and the signal of each frequency is a lot, and corresponding signal is also large, must be converted to narrow band channel and survey.
S407: carry out FFT frequency spectrum detection;
The present invention utilizes software radio to build hardware platform, the detection method using is incoherent detection, do not need to know the concrete condition of each frequency in sweep bandwidth, its approach is the local observation signal by perception user, detects electromagnetic environment situation around.During energy measuring, time-domain signal is converted to frequency-region signal through FFT, then to frequency-region signal, asks mould quadratic sum can obtain energy accumulative total.
S408: set signal-noise ratio threshold;
Frequency spectrum detection is to do energy accumulation in certain frequency band range, if the energy of accumulation higher than certain thresholding, explanation has signal to exist, if lower than certain thresholding, explanation only has noise.When the bandwidth of signal to be detected is larger, when large-signal being detected and existing, for the detection of small-signal, must, by changing centre frequency and bandwidth to be detected, realize trickleer channel detection.
S409: extract dynamic characteristic coefficients;
In this leaching process, can obtain the coefficient of low pass filters at different levels in mixing range coefficient, down-conversion and the amplification coefficient of regulation and control AGC.
S410: Multiple Channel Analysis and result of detection.
If f
sfor the sample frequency of FFT, the sampling number that N is FFT, the frequency resolution of FFT is f
s/ N.The size of the frequency resolution of FFT and sample frequency and sampling number is closely bound up, and employing herein is over-sampling frequency.In FPGA, the I generating after FFT is processed, square summation of Q two paths of signals generate energy accumulation after processing.According to the output overflow control signal of FFT, set different energy size detection threshold values simultaneously, after comparing with the energy accumulation signal of inputting, draw frequency number f
n, and energy grade corresponding to this frequency, and then realize signal strength signal intensity is given a mark.If the frequency of input rf signal is f, centre frequency is f
c, the sample frequency of FFT is f
s, its corresponding frequency number f
ncomputing formula be: f
n=(| f-f
c| * 1024)/f
s.For the assessed value of channel, can be according to counter the pushing away of signal amplitude coefficient of down-conversions at different levels, the contrast of tabling look-up, provides corresponding valuation.
Technical solution of the present invention design complexities is low, and technology maturation is easy to realize; Signal is not made to any hypothesis, is a kind of Blind Detect Algorithm, without any priori of knowing detection signal; Speed of detection is very fast, contributes to user to experience.
The present invention also has numerous embodiments, in every case in spirit of the present invention and essential scope, any change of doing, is equal to replacements, improvement, all within protection scope of the present invention.
Claims (5)
1. a short wave bandwidth channel non-coherent detection system, comprising: front end analogue means and energy testing apparatus, described front end analogue means for the filtering of signal, amplify and process; Signal after described energy testing apparatus is processed described front end analogue means is monitored and is obtained this signal frequency, it is characterized in that, described front end analogue means comprises AGC module, for the rangeability of control signal; Described energy testing apparatus comprises non-coherent demodulation device, FFT frequency spectrum detection module, signal to noise ratio index thresholding setting module, dynamic characteristic coefficients extraction module; Described dynamic characteristic coefficients extraction module is for extracting the dynamic characteristic coefficients that described system detection process obtains, and described dynamic characteristic coefficients comprises mixing range coefficient, filter and amplification coefficient at different levels and AGC amplification coefficient; Described non-coherent demodulation device comprises down conversion module and bandwidth tunable filter group, and described down conversion module is by regulating dynamic characteristic coefficients to carry out real-time detection to short wave channel; Secondly, by bandwidth tunable filter group, regulate channel width; Described FFT frequency spectrum detection module is converted to frequency-region signal by time-domain signal through FFT, then to frequency-region signal, ask mould quadratic sum to obtain accumulated energy, the accumulated energy result that described FFT frequency spectrum detection module detects and described signal to noise ratio index thresholding setting module are set the frequency that threshold value relatively obtains channel.
2. short wave bandwidth channel non-coherent detection system as claimed in claim 1, it is characterized in that, described energy testing apparatus also comprises frequency detecting and the evaluation module of channel, the frequency of the channel that the accumulated energy result that the described FFT frequency spectrum detection module that detects the frequency detecting of described channel and evaluation module detects and described signal to noise ratio index thresholding setting module setting threshold value relatively obtain, and in conjunction with described this channel of dynamic characteristic coefficients analysis and evaluation.
3. short wave bandwidth channel non-coherent detection system as claimed in claim 1, it is characterized in that, described non-coherent demodulation device also comprises Direct Digital frequency synthesis module DDS, and described DDS is used for producing the signal mixing respectively just, after cosine signal and described AGC resume module of carrier wave.
4. a short wave bandwidth channel non-coherent detection method, it is characterized in that, short-wave signal after filtering, amplify to process after, after entering the demodulation of non-coherent demodulation device, carry out acquisition of signal, when having detected signal, signal accumulated energy and signal-noise ratio threshold set point are compared, if while being greater than this threshold value, automatically regulate channel width, carry out trickle detection; Above-mentioned detection method repeatedly, until signal accumulated energy while being not more than signal-noise ratio threshold set point, finishes to survey;
Wherein, described automatic adjusting channel width is to regulate channel width by automatic regulation moving state characteristic coefficient, and described dynamic characteristic coefficients comprises mixing range coefficient, filter and amplification coefficient at different levels and AGC amplification coefficient.
5. short wave bandwidth channel non-coherent detection method as claimed in claim 4, is characterized in that, the signal mode square summation that described non-coherent demodulation device Output rusults is carried out after FFT conversion obtains signal accumulated energy.
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| CN102843750B (en) * | 2012-08-13 | 2013-08-07 | 北京盈想东方科技发展有限公司 | Short-wave frequency searching device and control method thereof |
| US9772353B2 (en) * | 2013-06-04 | 2017-09-26 | Tektronix, Inc. | Equivalent-time sampling technique for non-coherently modulated signals |
| CN106850104A (en) * | 2016-12-09 | 2017-06-13 | 中国人民解放军重庆通信学院 | The quick frequency-selective systems of NVIS and its method based on passive monitoring |
| CN109474306B (en) * | 2018-09-20 | 2021-01-26 | 中国人民解放军63653部队 | Detection and judgment method based on direct sequence spread spectrum signal capture |
| CN109818695B (en) * | 2019-03-08 | 2021-08-10 | 重庆邮电大学 | Short-wave communication semi-blind frequency selection system and frequency selection method based on CW signal |
| CN110208737B (en) * | 2019-07-08 | 2024-05-14 | 成都爱科特科技发展有限公司 | Ultrashort wave double-channel broadband direction finding system and threshold judgment direction finding method |
| CN110572227A (en) * | 2019-09-19 | 2019-12-13 | 河海大学 | Digital broadcast television signal cognition method for navigation self-positioning |
| CN110996401B (en) * | 2019-12-02 | 2022-04-26 | 锐捷网络股份有限公司 | Method, device and equipment for determining idle channel |
| CN112769506B (en) * | 2021-01-20 | 2023-05-12 | 西安千将云信息科技有限公司 | Quick radio detection method based on frequency spectrum |
| CN117955523B (en) * | 2024-03-27 | 2024-06-21 | 成都讯联科技有限公司 | Anti-interference method based on cluster unmanned aerial vehicle platform in multi-mode ad hoc network scene |
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