CN111766443A - Distributed broadband electromagnetic signal monitoring method and system based on narrow-band spectrum stitching - Google Patents
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Abstract
Description
Technical Field
The invention relates to the technical field of frequency spectrum splicing, in particular to a distributed broadband electromagnetic signal monitoring method and system based on narrow-band frequency spectrum stitching.
Background
A Wireless Sensor Network (WSN) is a novel distributed information acquisition system, which is based on a Wireless ad hoc Network technology and puts higher requirements on its functional applications. The WSN can rapidly deploy a large number of nodes to a target monitoring area in a large range, multiple nodes cooperatively work to acquire multiple items of information about a target, and dynamic topology is performed on the network when an individual node dies, so that the fault tolerance and the survivability of the whole system are ensured. Based on the characteristics, the WSN is very suitable for military battlefields, emergency disaster relief, temporary radio control and other occasions.
Systems similar to the distributed broadband electromagnetic spectrum monitoring form have been proposed in 2012 or so, but they do not implement narrowband spectrum splicing, which is a newer theoretical system. Regarding narrow-band spectrum splicing, a spectrum splicing implementation platform based on software radio is constructed in the document "a spectrum scanning technology based on software radio", frequency sweeping type collection is performed by means of a single software radio device and compared with an original spectrum, and feasibility of the spectrum splicing technology is verified. Document "an effective wideband digital reconnaissance receiver signal detection method" proposes a method for detecting the frequency spectrum of a wideband signal, in which a digital channelization method is adopted to divide the frequency spectrum into uniform narrow sub-bands, and the sub-bands are spliced into the frequency spectrum of the whole receiving bandwidth after FFT operation. The two methods are used for directly splicing digitized spectrum data, and the working mode is similar to that of a frequency scanner, so that the performance is relatively general.
In a patent of a multi-sub-band spectrum splicing and synthesizing method of an ultrahigh-resolution spaceborne SAR system with the publication number of CN110988875A, an ultrahigh-resolution imaging result meeting the requirements of imaging indexes is finally realized through processing flows of pulse compression, spectrum splicing, correction of linear phase inconsistency among sub-bands, compensation of amplitude difference and phase difference and spectrum splicing. However, in this method, the subband signals are only spliced in the phase direction, and a high-accuracy spectrum monitoring cannot be realized.
Disclosure of Invention
The purpose of the invention is as follows: the invention discloses a distributed broadband electromagnetic signal monitoring method and system based on narrow-band spectrum stitching, aiming at the defect of low accuracy of continuous wide-band spectrum monitoring in the prior art.
The technical scheme is as follows: in order to achieve the technical purpose, the invention adopts the following technical scheme.
A distributed broadband electromagnetic signal monitoring method based on narrow-band spectrum stitching comprises the following steps:
s1, original broadband signal division: acquiring an original broadband signal to be monitored in a certain range, dividing the original broadband signal into a plurality of sub-frequency bands, wherein the sub-frequency bands comprise a plurality of spectral lines, and the frequency intervals of adjacent sub-frequency bands are mutually overlapped;
s2, monitoring the sub-band signals: inputting the sub-band signals to each monitoring node, wherein the monitoring nodes are down-conversion channels with different local oscillation frequencies; down-converting the sub-band signal to a baseband, filtering out a high-frequency component through a low-pass filter, and outputting a signal with frequency conversion and high-frequency component filtering;
s3, obtaining amplitude and phase data of the sub-band spectral line in each channel: sampling the signals with frequency conversion and high-frequency component filtering, and obtaining amplitude and phase data of all spectral lines in the signals through FFT processing;
s4, splicing the sub-band signals, and reconstructing an original broadband signal: and splicing the sub-band signals in parallel according to the amplitude and phase fitting curve, neglecting the frequency band when encountering the sub-band signal of the dead node, recording amplitude and phase data of all spectral lines, completing splicing, reconstructing the original broadband signal, wherein the frequency band of the dead node is a cavity signal in the reconstructed original broadband signal.
Preferably, in the step S1, when the frequency intervals of the adjacent sub-bands overlap with each other, the number of spectral lines of the sub-bands and the overlapping portion thereof are freely configured according to actual requirements.
Preferably, in step S2, the cut-off frequency of the low-pass filter is the sub-band signal width of each channel.
Preferably, the step S2 of obtaining the frequency-converted signal with the high-frequency component filtered out includes:
s21, selecting the frequency of the local oscillator of the channel i:
wherein, ω issIs the spacing between adjacent frequency points of the frequency spectrum,
the frequency of the starting point of the frequency range of the subband signal in the channel i, K is the number of spectral lines of the subband signal, and P is the number of spectral lines of the frequency intervals of the adjacent subbands which are overlapped with each other;
s22, down-converting the sub-band signal to a baseband through the frequency of the local oscillator of the channel i:
wherein
Is a signal after the frequency conversion, and is a signal,
is the frequency of the local oscillator of channel i, GiFor conversion loss or gain of the mixeriIs the initial phase of the local oscillator signal,
and
are respectively k omegasAnd-k ωsThe amplitude of the frequency point;
s23, filtering the high-frequency component through a low-pass filter:
wherein
Is a frequency-converted signal.
Preferably, the specific process of splicing the sub-bands in step S4 includes:
s41, splicing every two sub-band signals in parallel, if a single residual sub-band signal exists, splicing the signal at the next time, and ignoring the frequency band when encountering the sub-band signal of the dead node;
s42, if the number of the finally obtained sub-band signals is one or other sub-band signals at two ends of the sub-band signal of the death node are spliced, completing all splicing, reconstructing the original broadband signal, wherein the frequency band of the death node is a cavity signal in the reconstructed original broadband signal, and executing the step S43; otherwise, updating the number of the spliced sub-band signal spectral lines, keeping the number of the un-spliced sub-band signal spectral lines unchanged, returning to the step S41, and continuing splicing;
and S43, storing the amplitude and phase data of all spectral lines in the recorded sub-band signals.
Preferably, the specific process of splicing each two sub-band signals in S41 in parallel is as follows:
s411, obtaining amplitude and phase data of spectral lines of the overlapped parts of adjacent sub-band signals, respectively calculating the ratio of the spectral line amplitudes of the overlapped parts, and obtaining the average value of the amplitude ratios of the spectral lines of the overlapped parts; fitting the spectral line phase difference of the overlapped part to obtain the curve slope and intercept of the phase difference;
s412, respectively carrying out amplitude extrapolation and phase extrapolation in two directions according to the positions of adjacent sub-band signals of the overlapped part spectral lines and the overlapped part spectral lines to generate two frequency spectrums;
and S413, performing fusion averaging on the two extrapolation results, and taking the amplitude and phase data after fusion averaging as the amplitude and phase data of all spectral lines of the spliced sub-band signals to finish splicing of the adjacent sub-band signals.
Preferably, the calculation process of the amplitude extrapolation and the phase extrapolation in step S412 is:
wherein
Respectively the amplitude data of the spectral lines of the overlapping parts of adjacent sub-band signals,
phase data, K, of spectral lines of overlapping portions of adjacent sub-band signals, respectivelyi、Ki+1Respectively, the number of spectral lines of adjacent subband signals, and P is the number of spectral lines of the overlapping part of the adjacent subband signals.
A distributed broadband electromagnetic signal monitoring system based on narrow-band spectrum stitching is used for realizing any one of the above distributed broadband electromagnetic signal monitoring methods based on narrow-band spectrum stitching, and comprises a wireless sensor network, wherein the wireless sensor network comprises a plurality of monitoring nodes, a splicing module and a memory, the splicing module is connected with all the monitoring nodes, and the memory is connected with the splicing module; the monitoring node is used for receiving the sub-band signals, the splicing module is used for performing spectrum stitching on the sub-band signals, and the memory is used for storing amplitude and phase data of all spectral lines in the sub-band signals.
Preferably, the splicing module further comprises a mixer, a low-pass filter and a signal sampler which are connected in sequence; the frequency mixer is used for carrying out frequency conversion on the sub-frequency band signals, the low-pass filter is used for filtering high-frequency components of the signals after frequency conversion, and the signal sampler is used for sampling the signals after frequency conversion and high-frequency components filtering.
Has the advantages that:
1. according to the invention, the broadband signal frequency spectrum is divided into a plurality of mutually overlapped narrow-band intervals for monitoring, the data of the overlapped part of adjacent sub-band signals are processed in parallel, two frequency spectrums are respectively generated simultaneously during splicing, the results of the two frequency spectrums are fused and averaged, finally, a spliced frequency spectrum is obtained, the original broadband signal is reconstructed, the accuracy of frequency spectrum monitoring is greatly improved, and the problem of large splicing error of distributed frequency spectrum monitoring is solved;
2. in the invention, when the frequency band of a dead node is encountered, the dead node is automatically ignored, and other sub-band signals are spliced in parallel, so that the problem of clamping in the splicing process is avoided, and other frequency spectrums can still be monitored;
3. the number of monitoring nodes, the number of spectral lines of each sub-band and the number of overlapping spectral lines of adjacent sub-bands can be configured automatically, and flexible splicing is realized under the condition that overlapping is ensured;
4. the invention realizes the distributed broadband electromagnetic signal monitoring in the wireless sensor network and has the characteristics of low power consumption, convenience, flexibility, low cost and the like.
Drawings
FIG. 1 is a general process flow diagram of the present invention;
FIG. 2 is a schematic diagram of the sub-band signal monitoring and processing flow of the present invention;
FIG. 3 is a flow chart of the sub-band signal splicing process of the present invention;
FIG. 4 is a flow chart of splicing adjacent sub-band signals according to the present invention;
FIG. 5 is a diagram illustrating signal splicing in the first embodiment;
FIG. 6 is a schematic diagram of a broadband spectrum and its frequency conversion center frequency in the second embodiment;
FIG. 7 is a diagram illustrating a spectrum stitching process in the second embodiment;
FIG. 8 is a schematic diagram of the system of the present invention.
Detailed Description
The invention discloses a distributed broadband electromagnetic signal monitoring method and system based on narrowband frequency spectrum stitching, and the scheme is further explained and explained by combining the accompanying drawings and embodiments.
As shown in fig. 1 and fig. 2, the original wideband signal to be monitored is divided into multiple paths and input to down-conversion channels with different local oscillator frequencies, where each channel corresponds to a monitoring node in the distributed system. Each channel down-converts the corresponding sub-band signal to a baseband, filters high-frequency components by using a low-pass filter, and performs FFT (fast Fourier transform) processing to obtain the frequency spectrum data of each sub-band signal. The cut-off frequency of the low-pass filter is the width of each channel sub-band, and the adjacent sub-bands are overlapped. The number of monitoring nodes, the number of spectral lines of each sub-band and the number of overlapping spectral lines of adjacent sub-bands can be configured by self, and flexible splicing is realized under the condition of ensuring overlapping.
The original wideband signal can be expressed by equation (1):
wherein, ω issIs the spacing between adjacent frequency points of the frequency spectrum,
and
are respectively k omegasAnd-k ωsAmplitude of frequency points, in general
Or
Dividing an original broadband signal into a plurality of overlapped sub-band signals, mixing the sub-band signals with local oscillation signals after the sub-band signals enter each channel, setting the total monitoring node number as N, and obtaining an intermediate frequency signal of a channel i as follows:
wherein,
is the local oscillator frequency of channel i, GiIs the conversion loss or gain of the mixer, phiiIs the initial phase of the local oscillator signal. The high frequency component of the frequency-converted signal is filtered after passing through the low-pass filter, and the rest signal, namely the frequency-converted signal with the high frequency component filtered is
In pair
Obtaining the amplitude of the spectral line in each sub-band signal by FFT
And phase
And (4) data.
Where each channel is down-converted at a mid-band frequency and the local oscillator frequency is ωsMultiple of (2):
where K is the number of lines in each sub-band,
is the frequency at the beginning of the subband signal range in channel i. The phase difference between the overlapping spectral lines of adjacent channels is:
it can be seen from equation (5) that the phase difference is a linear function with respect to frequency, and the slope is ωsAnd the intercept is the initial phase difference of the local oscillator. For overlapping spectral linesThe phase relation of adjacent channels on corresponding frequency points can be obtained by fitting the phase difference function, and then the phase spectrum of the residual spectral line is extrapolated. And the ratio of the amplitudes between overlapping spectral lines of adjacent channels is
It can be seen from equation (6) that the ratio of the amplitudes is a fixed constant, but in practice may fluctuate slightly due to the influence of noise, so that the average value of the ratios of the overlapping spectral lines is used as the final ratio, and the amplitude spectrum of the remaining spectral lines is extrapolated.
The time for the sub-bands to enter each channel is actually different, namely, time delay exists, fitting needs to be carried out through phase difference, and a least square method is adopted in a fitting algorithm.
When the signal enters each channel, there is a time delay (tau)i+1-τi) And then, the phase difference between the superposed spectral lines of the adjacent channels is as follows:
the slope of the fitted curve is considered to be ωs(τi+1-τi) Then, phase extrapolation is performed:
for the signals with the monitored frequency band only having positive frequency or negative frequency and the signals with the equal positive and negative frequency components, the steps are still adopted for processing, for the signals with the positive and negative frequency components and the unequal components, a complex down-conversion mode is adopted, and the specific formula is as follows:
1) the positive frequency component needs to be monitored (by means of complex down-conversion, the original signal and
multiplication):
i＝1，2，…，N
the low-pass filtered signal is:
2) the negative frequency component needs to be monitored (by means of complex down-conversion, the original signal and
multiplication):
i＝1，2，…，N
the low-pass filtered signal is:
the subsequent extrapolation and stitching process is the same as before.
Distributed spectrum monitoring is similar to a WSN in nature, and therefore the problem of node failure needs to be considered, for example, a monitoring node may be a small wireless signal receiver powered by a battery, the monitoring node is scattered in a wild and unpopular area, the battery cannot be replaced, and therefore the node is dead after the battery is used up. Because this scheme adopts the mode that starts the concatenation from the spectrum middle multiple point is parallel, neglects when meetting the frequency channel of dead node, waits to splice from the frequency channel concatenation of other frequency spectrum regions and meet the back and splice, and some holes appear in the result, other partial frequency spectrums still can monitor, just be the part of piecing together earlier, leave bad part, avoid can only leading to can't skipping the problem of inefficacy frequency channel from a left side to a right side.
Example one
Assuming that there is no time delay when the signal enters each channel, the total number of monitoring nodes is N, and the subband signals are spliced M times,then N is 2M。
As shown in fig. 3, when the frequency spectrums of two adjacent channels are spliced, a channel i is extrapolated to a channel i +1 to obtain a spliced frequency spectrum, and then the channel i +1 is extrapolated to the channel i to obtain a spliced frequency spectrum. The number of lines in the overlapping part is P, and the number of lines in the sub-band signals of the adjacent channels is K, the process can be expressed by the formulas (13) and (14)
Then averaging the two obtained frequency spectrums:
namely, the 2 nd order sub-band after the first splicing is obtained.
The above is the splicing principle of every two adjacent sub-bands, and can be written as follows (assuming that the amplitude and phase data of all sub-band spectral lines are obtained)
)：
(1) Obtaining amplitude information of spectral lines of overlapping parts of adjacent sub-bands
Calculating the average of the ratios of the amplitudes as the extrapolated ratio
(2) The amplitude extrapolation is performed in two directions, according to the position of the overlapping spectral lines in the sub-bands:
(3) obtaining phase information of spectral lines in overlapping portions of adjacent sub-bands
Fitting the phase difference between the overlapped spectral lines to obtain the slope and intercept of a phase difference curve;
(4) phase extrapolation is performed in two directions:
(5) the results of the two direction extrapolations are fusion averaged:
(6) store record | Ak|、
And finishing splicing.
As shown in fig. 4, the whole band stepped splicing method is as follows (assuming that a low-pass signal is obtained):
the first step is as follows: FFT is carried out on the low-pass signals sampled by each branch to obtain the amplitude and phase data of all spectral lines
The second step is that: splicing every two sub-frequency bands into a group from left to right according to the flow of the figure 2, and if the remaining last sub-frequency band exists, remaining the next time for splicing;
the third step: if the number of the obtained sub-frequency bands is 1, completing splicing; if the number of the sub-frequency bands is more than 1, updating the number of the spliced sub-frequency band spectral lines to be K-2K-P, and switching to the second step to continue splicing if the number of the sub-frequency bands is not changed;
the fourth step: and storing and recording the amplitude and phase data of all spectral lines to finish splicing.
According to the method, every two adjacent sub-bands are spliced to obtain a plurality of 2-order sub-bands, the sub-bands are regarded as independent sub-bands, then adjacent two sub-bands are spliced, and circulation is carried out according to the above steps until a complete frequency spectrum is spliced. If the total node number N is 2MThen, M times of splicing are carried out for the first time, and then M/2 times of splicing are carried out for the second time, and M stages of circulation are needed in total. Fig. 5 is a schematic diagram of this process.
According to the invention, the broadband signal frequency spectrum is divided into a plurality of mutually overlapped narrow-band intervals for monitoring, the data of the overlapped part of the adjacent sub-band signals are processed, two frequency spectrums are respectively generated simultaneously during splicing, the results of the two frequency spectrums are fused and averaged, finally, a spliced frequency spectrum is obtained, the original broadband signal is reconstructed, the accuracy of frequency spectrum monitoring is greatly improved, and the problem of large splicing error of distributed frequency spectrum monitoring is solved.
Example two
The method comprises the steps of monitoring a broadband frequency spectrum in the range of 900-941 MHz in practice, wherein time delay does not exist when a signal enters each channel, the signal is divided into 8 sections of narrow sub-bands and is monitored by 8 nodes, the width of each sub-band is 6MHz, the bandwidth of a superposed part between adjacent sub-bands is 1MHz, the monitoring range of each node is 900-906, 905-911, 910-916, 915-921, 920-926, 925-931, 930-936 and 935-941 MHz respectively, and the local oscillation frequency corresponding to each node is 903, 908, 913, 918, 923, 928, 938 and 941 MHz. The number of spectral lines of each frequency band is 60, 10 spectral lines are overlapped between adjacent frequency bands, and the frequency spectrum and the down-conversion center frequency are shown in figure 6.
The dotted arrow in FIG. 6 indicates the center frequency of each sub-band
Converting each sub-band to intermediate frequency according to its central frequency, and low-pass filtering to obtainAnd (3) carrying out FFT on the baseband signal of 3-3 MHz to obtain data of each spectral line of the frequency spectrum. The spectrum splicing process is shown in fig. 7.
First, the first adjacent sub-bands of 1 st order are spliced two by two. Taking splicing ofsub-bands 1 and 2 as an example, the back 10 spectral lines of the sub-band 1 are the same signals represented by the front 10 spectral lines of thesub-band 2, i.e. signals of 905-906 MHz band on the frequency band, according to the relation between the amplitude and the phase of the two common 10 spectral lines, the following equations (7) and (8) can push out 50 spectral lines from the sub-band 1 backwards or push out 50 spectral lines from the sub-band 2 forwards to obtain two frequency spectrums with a width of 11MHz, and then the frequency spectrums are fused and averaged to complete the first splicing to obtain the sub-band 1 of 2 order. Similarly, the 2-order subband 2 is obtained by extrapolation, fusion and averaging the 1-order subbands 3 and 4, then 10 spectral lines are overlapped between the 2-order subbands 1 and 2, and similarly, the 2 nd-order splicing can be performed to obtain the 3-order subband 1. And repeating the steps until the final broadband frequency spectrum data result with the range of 0-41 MHz (900-941 MHz) is spliced.
As shown in fig. 8, a distributed broadband electromagnetic signal monitoring system based on narrowband spectrum stitching is used for implementing any one of the above distributed broadband electromagnetic signal monitoring methods based on narrowband spectrum stitching, and includes a wireless sensor network, where the wireless sensor network includes a plurality of monitoring nodes, a splicing module and a memory, the splicing module is connected to all the monitoring nodes, and the memory is connected to the splicing module; the monitoring node is used for receiving the sub-band signals, the splicing module is used for performing spectrum stitching on the sub-band signals, and the memory is used for storing amplitude and phase data of all spectral lines in the sub-band signals.
The splicing module further comprises a frequency mixer, a low-pass filter and a signal sampler which are sequentially connected; the frequency mixer is used for carrying out frequency conversion on the sub-frequency band signals, the low-pass filter is used for filtering high-frequency components of the signals after frequency conversion, and the signal sampler is used for sampling the signals after frequency conversion and high-frequency components filtering. The invention realizes the distributed broadband electromagnetic signal monitoring in the wireless sensor network and has the characteristics of low power consumption, convenience, flexibility, low cost and the like.
The above description is only of the preferred embodiments of the present invention, and it should be noted that: it will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the principles of the invention and these are intended to be within the scope of the invention.
Claims (9)
1. A distributed broadband electromagnetic signal monitoring method based on narrow-band spectrum stitching is characterized by comprising the following steps:
s1, original broadband signal division: acquiring an original broadband signal to be monitored in a certain range, dividing the original broadband signal into a plurality of sub-frequency bands, wherein the sub-frequency bands comprise a plurality of spectral lines, and the frequency intervals of adjacent sub-frequency bands are mutually overlapped;
s2, monitoring the sub-band signals: inputting the sub-band signals to each monitoring node, wherein the monitoring nodes are down-conversion channels with different local oscillation frequencies; down-converting the sub-band signal to a baseband, filtering out a high-frequency component through a low-pass filter, and outputting a signal with frequency conversion and high-frequency component filtering;
s3, obtaining amplitude and phase data of the sub-band spectral line in each channel: sampling the signals with frequency conversion and high-frequency component filtering, and obtaining amplitude and phase data of all spectral lines in the signals through FFT processing;
s4, splicing the sub-band signals, and reconstructing an original broadband signal: and splicing the sub-band signals in parallel according to the amplitude and phase fitting curve, neglecting the frequency band when encountering the sub-band signal of the dead node, recording amplitude and phase data of all spectral lines, completing splicing, reconstructing the original broadband signal, wherein the frequency band of the dead node is a cavity signal in the reconstructed original broadband signal.
2. The distributed broadband electromagnetic signal monitoring method based on narrowband frequency spectrum stitching according to claim 1, characterized in that: in the step S1, when the frequency intervals of adjacent sub-bands overlap each other, the number of the sub-bands and the number of the spectral lines of the overlapping portion thereof are freely configured according to actual requirements.
3. The distributed broadband electromagnetic signal monitoring method based on narrowband frequency spectrum stitching according to claim 1, characterized in that: in step S2, the cut-off frequency of the low pass filter is the sub-band signal width of each channel.
4. The method according to claim 1, wherein the step S2 of obtaining a frequency-converted and high-frequency component-filtered signal comprises the following specific steps:
s21, selecting the frequency of the local oscillator of the channel i:
wherein, ω issIs the spacing between adjacent frequency points of the frequency spectrum,
the frequency of the starting point of the frequency spectrum range of the subband signal in the channel i, K is the number of spectral lines of the subband signal, and P is the number of spectral lines of the adjacent frequency intervals of the subbands, which are overlapped with each other;
s22, down-converting the sub-band signal to a baseband through the frequency of the local oscillator of the channel i:
wherein
Is a signal after the frequency conversion, and is a signal,
is the frequency of the local oscillator of channel i, GiFor conversion loss or gain of the mixeriIs the initial phase of the local oscillator signal,
and
are respectively k omegasAnd-k ωsThe amplitude of the frequency point;
s23, filtering the high-frequency component through a low-pass filter:
wherein
Is a frequency-converted signal.
5. The method for monitoring distributed broadband electromagnetic signals based on narrowband spectrum stitching according to claim 1, wherein the specific process of splicing the sub-bands in step S4 includes:
s41, splicing every two sub-band signals in parallel, if a single residual sub-band signal exists, splicing the signal at the next time, and ignoring the frequency band when encountering the sub-band signal of the dead node;
s42, if the number of the finally obtained sub-band signals is one or other sub-band signals at two ends of the sub-band signal of the death node are spliced, completing all splicing, reconstructing the original broadband signal, wherein the frequency band of the death node is a cavity signal in the reconstructed original broadband signal, and executing the step S43; otherwise, updating the number of the spliced sub-band signal spectral lines, keeping the number of the un-spliced sub-band signal spectral lines unchanged, returning to the step S41, and continuing splicing;
and S43, storing the amplitude and phase data of all spectral lines in the recorded sub-band signals.
6. The method for monitoring distributed broadband electromagnetic signals based on narrowband spectrum stitching according to claim 5, wherein the specific process of splicing each two groups of sub-band signals in parallel in S41 is as follows:
s411, obtaining amplitude and phase data of spectral lines of the overlapped parts of adjacent sub-band signals, respectively calculating the ratio of the spectral line amplitudes of the overlapped parts, and obtaining the average value of the amplitude ratios of the spectral lines of the overlapped parts; fitting the spectral line phase difference of the overlapped part to obtain the curve slope and intercept of the phase difference;
s412, respectively carrying out amplitude extrapolation and phase extrapolation in two directions according to the positions of adjacent sub-band signals of the overlapped part spectral lines and the overlapped part spectral lines to generate two frequency spectrums;
and S413, performing fusion averaging on the two extrapolation results, and taking the amplitude and phase data after fusion averaging as the amplitude and phase data of all spectral lines of the spliced sub-band signals to finish splicing of the adjacent sub-band signals.
7. The method for monitoring distributed broadband electromagnetic signals based on narrowband spectral stitching according to claim 6, wherein the calculation process of amplitude extrapolation and phase extrapolation in step S412 is as follows:
wherein
Respectively the amplitude data of the spectral lines of the overlapping parts of adjacent sub-band signals,
phase data, K, of spectral lines of overlapping portions of adjacent sub-band signals, respectivelyi、Ki+1Respectively, the number of spectral lines of adjacent subband signals, and P is the number of spectral lines of the overlapping part of the adjacent subband signals.
8. A distributed broadband electromagnetic signal monitoring system based on narrowband spectrum stitching, which is used for implementing the distributed broadband electromagnetic signal monitoring method based on narrowband spectrum stitching according to any one of claims 1 to 7, and is characterized in that: the wireless sensor network comprises a plurality of monitoring nodes, a splicing module and a memory, wherein the splicing module is connected with all the monitoring nodes, and the memory is connected with the splicing module; the monitoring node is used for receiving the sub-band signals, the splicing module is used for performing spectrum stitching on the sub-band signals, and the memory is used for storing amplitude and phase data of all spectral lines in the sub-band signals.
9. The distributed broadband electromagnetic signal monitoring method based on narrowband spectrum stitching according to claim 8, wherein: the splicing module further comprises a frequency mixer, a low-pass filter and a signal sampler which are sequentially connected; the frequency mixer is used for carrying out frequency conversion on the sub-frequency band signals, the low-pass filter is used for filtering high-frequency components of the signals after frequency conversion, and the signal sampler is used for sampling the signals after frequency conversion and high-frequency components filtering.
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| CN111766443B (en) | 2022-11-01 |
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