CN102647241A - 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, because sky wave can cause the decline of signal and frequency to scatter behind ionospheric reflection, and the interference of surrounding environment electromagnetic noise, make short wave channel not have the cellular system channel so stable.Under this environment, it is necessary that short wave channel is carried out real-time detection.
At present, the mode of frequency sweep is generally adopted in the short wave channel detection, presses frequency step emission detection signal successively at whole or section H F-band, and each detectable signal 3dB scans this detectable signal of reception again successively at receiving terminal.This scanning detection method is the blind scanning to short wave channel, and the scan period is long, can not satisfy the requirement of quick link setup fully; And in the existing short wave communication, all being under the situation of arrowband, to carry out to the detection of channel, all is to scan through changing centre frequency, causes the chronic of channel detection, can not meet consumers' demand.
Summary of the invention
For remedying above-mentioned defective, the objective 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 adopts following technical scheme to be achieved.
Technical scheme one:
A kind of short wave bandwidth channel non-coherent detection system comprises: front end analogue means and energy testing apparatus, and said front end analogue means is used for filtering, the processing and amplifying of signal; Signal after said energy testing apparatus is handled said front end analogue means is monitored and is obtained this signal frequency, it is characterized in that said front end analogue means comprises the AGC module, is used for the rangeability of control signal; Said energy testing apparatus comprises non-coherent demodulation device, FFT frequency spectrum detection module, signal to noise ratio index thresholding setting module, behavioral characteristics coefficient extracting module; Said non-coherent demodulation device comprises down conversion module and bandwidth tunable filter group, and said down conversion module is carried out real-time detection through regulating the behavioral characteristics coefficient to short wave channel; When being used for input, said bandwidth tunable filter group regulates channel width; Result that said FFT frequency spectrum detection module detects and said signal to noise ratio index thresholding setting module are set the frequency that threshold value relatively obtains channel; Said behavioral characteristics coefficient extracting module is used for extracting the behavioral characteristics coefficient that said system detection process obtains, and regulates channel width automatically through regulating the behavioral characteristics coefficient.
The characteristics of technique scheme are with further improving:
(1) said energy testing apparatus also comprises the frequency detecting and the evaluation module of channel, and the frequency detecting of said channel and evaluation module detect the frequency of channel, and combines said this channel of behavioral characteristics coefficient analysis assessment.
(2) said FFT frequency spectrum detection module is converted to frequency-region signal with time-domain signal through FFT, asks the mould quadratic sum to obtain accumulated energy to frequency-region signal then.
(3) said non-coherent demodulation device also comprises Direct Digital frequency synthesis module DDS, said DDS be used for producing carrier wave just, the signal mixing respectively after cosine signal and the said AGC resume module.
(4) said behavioral characteristics coefficient comprises mixing range coefficient, filtering amplification coefficient at different levels and AGC amplification coefficient.
The function that channel non-coherent detection device in the technical scheme of the present invention is mainly accomplished is down-conversion, filtering, and the gained result gets into the FFT energy detection module and detects, and through relatively, extracts characteristic coefficient and carries out the frequency detecting and the assessment of channel again.For fear of omission takes place, in the time of will in the 1M bandwidth channel, detecting greater than certain threshold value, it is regarded as the input that needs bandwidth narrower, as channel width is become 500kHz, or lower.For realizing this function, introduce bandwidth tunable digital filter group and realize.Improve the sensitivity of system's detection signal, then need AGC to control realization.
Technical scheme two:
A kind of short wave bandwidth channel non-coherent detection method is characterized in that, after the filtering of short-wave signal process, the processing and amplifying; Carry out acquisition of signal after getting into the demodulation of non-coherent demodulation device; When having detected signal, signal accumulated energy and signal-noise ratio threshold set point are compared, if during greater than this threshold value; Automatically regulate channel width, carry out trickle detection; Above-mentioned repeatedly detection method when the signal accumulated energy is not more than the signal-noise ratio threshold set point, finishes to survey.
The characteristics of technique scheme are with further improving:
(1) said automatic adjusting channel width is to regulate channel width through automatic adjusting behavioral characteristics coefficient.
(2) a signal mode square summation of said non-coherent demodulation device output result being carried out after FFT changes obtains the signal accumulated energy.
(3) said signal accumulated energy and signal-noise ratio threshold set point compare and obtain channel frequency number, and the computing formula of said channel frequency number is: f
N=(| f-f
c| * 1024)/f
s, wherein f is the RF signal, f
cBe centre frequency, f
sBe sample frequency.
(4) said behavioral characteristics coefficient comprises mixing range coefficient, filtering amplification coefficient at different levels and AGC amplification coefficient.
The detection method that the present technique scheme adopts is an incoherent detection, need not know the concrete condition of each frequency in the sweep bandwidth, and its approach is the local observation signal through the perception user, the electromagnetic environment situation around detecting.The non-coherent detection method mainly is to extract the behavioral characteristics coefficient of detectable signal; And regulate automatically by the channel width of detectable signal; Size according to actual conditions adjustment resolution bandwidth and detectable signal; Realize the quick detection of short wave bandwidth channel quality, for further channel detection provides strong support.Technical scheme design complexities of the present invention is low, and technology maturation is easy to realize; Signal is not made any hypothesis, is a kind of Blind Detect Algorithm, need not to know any priori of detection signal; Speed of detection is very fast, helps user experience.
Description of drawings
Below in conjunction with accompanying drawing and embodiment technical scheme of the present invention is done further explain.
Fig. 1 is an embodiment of the invention intermediate waves broad-band channel non-coherent detection system construction drawing;
Fig. 2 is the schematic diagram of the module integrated chip of multiband harmonic filter and AGC in the embodiment of the invention;
Fig. 3 is a down conversion module fundamental diagram in the embodiment of the invention;
Fig. 4 is an embodiment of the invention intermediate waves broad-band channel non-coherent detection method flow diagram.
Embodiment
The total thought of technical scheme of the present invention is: in the short wave channel band limits, through the channel detection to the 1M bandwidth, can survey the situation that takies of channel, and realize the real-time assessment to short wave channel.For the short wave channel bandwidth of being surveyed, can adjust the channel width of being surveyed according to the 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 the designated frequency band.Through this technology, the real-time detection assessment of channel can be provided, for the quick link setup of shortwave provides effective solution route.
The embodiment of the invention realizes Digital Signal Processing through software radio; Adopt the EP3C40F484 of altera corp to realize; Its function of mainly accomplishing is down-conversion, filtering, FFT frequency spectrum detection; And the extraction of behavioral characteristics coefficient, and then to realization short wave bandwidth frequency detecting of the signal in the 100dB dynamic range and assessment.Adopt novel chip ADRF6516, its function and adjustable gain amplifier function with programmable filter is integrated, makes the front end analogue means of shortwave realize miniaturization.The LPF cut-off frequency of ADRF6516 is that integer is adjustable in 0～31MHz scope, and the adjustable extent of this amplifier is-and 5dBm～+ 45dBm.Analog-to-digital conversion adopts the ADC AD9269 of 16bit in the present embodiment, and power consumption is 200mW, is digital signal with analog signal conversion, for the sensitivity of hardware platform provides guarantee.
Short wave bandwidth channel non-coherent detection system configuration is as shown in Figure 1, comprises front end analogue means, on-site programmable gate array FPGA energy monitor and foreign frequency control module.The front end analogue means comprises multiband harmonic filter, AGC module and analog-to-digital conversion module ADC, is used for filtering, the processing and amplifying of signal; Signal after said FPGA energy monitor is handled said front end analogue means is monitored and is obtained this signal frequency, comprises the frequency detecting and the evaluation module of non-coherent demodulation device, FFT frequency spectrum detection module, signal to noise ratio index setting module, behavioral characteristics coefficient extracting module and channel; The 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.
At first; The RF radiofrequency signal is through the AGC resume module; Carry out again ADC conversion back generate data signal rate at a high speed and DDS produce carrier wave just, cosine signal mixing respectively, get into down conversion module after the mixing, down conversion module is carried out real-time detection through adjusting behavioral characteristics coefficient to short wave channel; Secondly, regulate channel width by bandwidth tunable filter group, and will regulate the result and give FFT frequency spectrum detection module, result that FFT frequency spectrum detection module will detect and signal to noise ratio index thresholding setting module are set the frequency that threshold value relatively obtains channel; Once more, the behavioral characteristics coefficient extracting module is extracted the behavioral characteristics coefficient that obtains in the detection system detection process, and regulates channel width automatically through regulating the behavioral characteristics coefficient; At last, the frequency that detects channel by the frequency detecting and the evaluation module of channel, and combine this channel of behavioral characteristics coefficient analysis assessment.
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.The foreign frequency control module through be provided with the correspondent frequency word control DDS partly produce the corresponding frequencies carrier wave just, cosine signal so that accomplish follow-up Frequency mixing processing.Compare with traditional frequency synthesizer, DDS has 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 integrated chip of multiband harmonic filter and AGC.
For avoiding Harmonic Interference to have influence on the frequency spectrum detection of back, the HF signal that needs antenna is inserted is handled through multiband filter; For the short-wave signal of 100dB dynamic range, need computing, i.e. front end amplifier signal 3dB/6dB through AGC; After controllable filter, controlled amplifier are handled; After the amplifier of rear end, signal is amplified to 6dB/12dB again, at last this amplifying signal is exported to ADC and carries out analog-to-digital conversion.
In conjunction with accompanying drawing 3, be down conversion module fundamental diagram in the embodiment of the invention.
The RF radiofrequency signal generates data signal rate at a high speed through ADC conversion back, with DDS produce just, the realization carrier wave is moved behind the cosine carrier signal mixing.In the processing procedure of down-conversion; Coefficient through regulating low pass filters at different levels in mixing range coefficient, the down-conversion and the amplification coefficient of regulation and control AGC improve the detectivity of system; Regulate through sample rate extraction, bandwidth tunable digital filter group, signal gets into follow-up FFT frequency spectrum detection module at last.
Short wave bandwidth channel non-coherent detection method need directly to signal demodulation and detection, and not regulated channel width by carrier wave automatically, can realize the channel quick detection.Concrete implementation method is as shown in Figure 4, embodiment of the invention intermediate waves broad-band channel non-coherent detection method flow, and flow process is following:
S401: short-wave signal carries out the multiband harmonic filter and AGC module amplifier is handled;
The cut-off frequency of multiband harmonic filter is provided with relevant parameters according to the residing frequency band of current FFT frequency spectrum detection module through the foreign frequency control module.
S402: the signal to after the processing of AGC amplifier carries out analog-to-digital conversion;
S403:DDS is just producing, cosine signal;
The foreign frequency control module through be provided with the correspondent frequency word control DDS partly produce the corresponding frequencies carrier wave just, cosine signal.
S404: the signal that step S402 and step S403 are obtained carries out Frequency mixing processing respectively;
The RF radiofrequency signal generates data signal rate at a high speed through ADC conversion back, with DDS produce just, the mixing respectively of cosine carrier signal, the realization carrier wave is moved.
S405: down-converted;
Improve the sensitivity of system's detection signal, make the signal to be detected can smooth working in the scope of 100dB, then need AGC to control realization.In the processing procedure of down-conversion, come the real-time monitoring sensitivity of raising system through the coefficient of regulating low pass filters at different levels in mixing range coefficient, the down-conversion and the amplification coefficient of regulating and control AGC.In the downconversion process, assessing extractible behavioral characteristics coefficient for channel detection has: mixing range coefficient, filtering amplification coefficient at different levels and AGC amplification coefficient.
S406: regulate by bandwidth tunable filter group;
For limited short wave channel bandwidth, when having large-signal, when detecting, can make small-signal generation omission; For fear of omission takes place, will in the 1M bandwidth channel, detect greater than in certain threshold value, it is regarded as the input that needs bandwidth narrower; As channel width is become 500kHz, or lower, survey repeatedly; Constantly regulate channel width automatically, up to detecting signal.For realizing this function, can realize through bandwidth tunable digital filter group.It is exactly in 1M channel width that kind of an opposite extreme situations is arranged, and the signal of each frequency is a lot, and corresponding signal is also big, then must convert narrow band channel into and survey.
S407: carry out the FFT frequency spectrum detection;
The present invention utilizes software radio to build hardware platform; The detection method that uses is an incoherent detection; Need not know the concrete condition of each frequency in the sweep bandwidth, its approach is the local observation signal through the perception user, the electromagnetic environment situation around detecting.During energy measuring time-domain signal is converted to frequency-region signal through FFT, asks the mould quadratic sum can obtain energy accumulative total to frequency-region signal then.
S408: set signal-noise ratio threshold;
Frequency spectrum detection is in certain frequency band range, to do energy accumulation, if the energy of accumulation is higher than certain thresholding, then explanation has signal to exist, if be lower than certain thresholding, then explanation only has noise.When the bandwidth of signal to be detected is big more, when detecting large-signal and existing,, must realize trickleer channel detection through changing centre frequency and bandwidth to be detected for the detection of small-signal.
S409: extract the behavioral characteristics coefficient;
In this leaching process, can obtain the coefficient of low pass filters at different levels in mixing range coefficient, the down-conversion and the amplification coefficient of regulation and control AGC.
S410: Multiple Channel Analysis and result of detection.
If f
sBe the sample frequency of FFT, N is the sampling number of FFT, and then the frequency resolution of FFT is f
s/ N.The frequency resolution of FFT and sample frequency and sampling number big or small closely bound up, and what adopt is the over-sampling frequency here.In FPGA, after the I that generates after the FFT processing, square summation processing of Q two paths of signals, the generation energy accumulation.Control signal is overflowed in output according to FFT, sets different energy size detection threshold value simultaneously, draws frequency number f after comparing with the energy accumulation signal of importing
N, and this frequency corresponding energy grade, 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 then
NComputing formula be: f
N=(| f-f
c| * 1024)/f
sFor the assessed value of channel, can be according to counter the pushing away of down signals range coefficients at different levels, the contrast of tabling look-up provides corresponding valuation.
Technical scheme design complexities of the present invention is low, and technology maturation is easy to realize; Signal is not made any hypothesis, is a kind of Blind Detect Algorithm, need not to know any priori of detection signal; Speed of detection is very fast, helps user experience.
The present invention also has numerous embodiments, in every case in spirit of the present invention and essential scope, any change of being done, is equal to replacement, improvement, all within protection scope of the present invention.
Claims (10)
1. short wave bandwidth channel non-coherent detection system comprises: front end analogue means and energy testing apparatus, and said front end analogue means is used for filtering, the processing and amplifying of signal; Signal after said energy testing apparatus is handled said front end analogue means is monitored and is obtained this signal frequency, it is characterized in that said front end analogue means comprises the AGC module, is used for the rangeability of control signal; Said energy testing apparatus comprises non-coherent demodulation device, FFT frequency spectrum detection module, signal to noise ratio index thresholding setting module, behavioral characteristics coefficient extracting module; Said non-coherent demodulation device comprises down conversion module and bandwidth tunable filter group, and said down conversion module is carried out real-time detection through regulating the behavioral characteristics coefficient to short wave channel; When being used for input, said bandwidth tunable filter group regulates channel width; Result that said FFT frequency spectrum detection module detects and said signal to noise ratio index thresholding setting module are set the frequency that threshold value relatively obtains channel; Said behavioral characteristics coefficient extracting module is used for extracting the behavioral characteristics coefficient that said system detection process obtains, and regulates channel width automatically through regulating the behavioral characteristics coefficient.
2. short wave bandwidth channel non-coherent detection as claimed in claim 1 system; It is characterized in that; Said energy testing apparatus also comprises the frequency detecting and the evaluation module of channel; The frequency detecting of said channel and evaluation module detect the frequency of channel, and combine said this channel of behavioral characteristics coefficient analysis assessment.
3. short wave bandwidth channel non-coherent detection as claimed in claim 1 system is characterized in that, said FFT frequency spectrum detection module is converted to frequency-region signal with time-domain signal through FFT, asks the mould quadratic sum to obtain accumulated energy to frequency-region signal then.
4. short wave bandwidth channel non-coherent detection as claimed in claim 1 system; It is characterized in that; Said non-coherent demodulation device also comprises Direct Digital frequency synthesis module DDS, said DDS be used for producing carrier wave just, the signal mixing respectively after cosine signal and the said AGC resume module.
5. short wave bandwidth channel non-coherent detection as claimed in claim 1 system is characterized in that said behavioral characteristics coefficient comprises mixing range coefficient, filtering amplification coefficient at different levels and AGC amplification coefficient.
6. a short wave bandwidth channel non-coherent detection method is characterized in that, after the filtering of short-wave signal process, the processing and amplifying; Carry out acquisition of signal after getting into the demodulation of non-coherent demodulation device; When having detected signal, signal accumulated energy and signal-noise ratio threshold set point are compared, if during greater than this threshold value; Automatically regulate channel width, carry out trickle detection; Above-mentioned repeatedly detection method when the signal accumulated energy is not more than the signal-noise ratio threshold set point, finishes to survey.
7. short wave bandwidth channel non-coherent detection method as claimed in claim 6 is characterized in that, said automatic adjusting channel width is to regulate channel width through automatic adjusting behavioral characteristics coefficient.
8. short wave bandwidth channel non-coherent detection method as claimed in claim 6 is characterized in that, the signal mode square summation that said non-coherent demodulation device output result is carried out after FFT changes obtains the signal accumulated energy.
9. short wave bandwidth channel non-coherent detection method as claimed in claim 6 is characterized in that, said signal accumulated energy and signal-noise ratio threshold set point compare and obtain channel frequency number, and the computing formula of said channel frequency number is: f
N=(| f-f
c| * 1024)/f
s, wherein f is the RF signal, f
cBe centre frequency, f
sBe sample frequency.
10. short wave bandwidth channel non-coherent detection method as claimed in claim 6 is characterized in that said behavioral characteristics coefficient comprises mixing range coefficient, filtering amplification coefficient at different levels and AGC amplification coefficient.
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| CN112769506A (en) * | 2021-01-20 | 2021-05-07 | 成都理工大学 | Rapid radio detection method based on frequency spectrum |
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