CN117250619B - Low false alarm high reliable anticollision radar device - Google Patents
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/88—Radar or analogous systems specially adapted for specific applications
- G01S13/93—Radar or analogous systems specially adapted for specific applications for anti-collision purposes
- G01S13/931—Radar or analogous systems specially adapted for specific applications for anti-collision purposes of land vehicles
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
- G01S13/06—Systems determining position data of a target
- G01S13/08—Systems for measuring distance only
- G01S13/32—Systems for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated
- G01S13/34—Systems for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated using transmission of continuous, frequency-modulated waves while heterodyning the received signal, or a signal derived therefrom, with a locally-generated signal related to the contemporaneously transmitted signal
- G01S13/345—Systems for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated using transmission of continuous, frequency-modulated waves while heterodyning the received signal, or a signal derived therefrom, with a locally-generated signal related to the contemporaneously transmitted signal using triangular modulation
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
- G01S13/50—Systems of measurement based on relative movement of target
- G01S13/58—Velocity or trajectory determination systems; Sense-of-movement determination systems
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
- G01S7/41—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00 using analysis of echo signal for target characterisation; Target signature; Target cross-section
- G01S7/415—Identification of targets based on measurements of movement associated with the target
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Abstract
The invention discloses a low false alarm high-reliability anti-collision radar device, and relates to the field of anti-collision radars. The device comprises a transmitting unit and a receiving unit, wherein the transmitting unit comprises a waveform generating module, a time control module, a linear frequency modulation module, a spread spectrum module and a transmitting antenna module; the receiving unit comprises a receiving antenna module, a despreading module, a signal processing module and an alarm prompting module; the time control module divides the cycle time intoNTime slots of different time, saidNEach time slot of the plurality of time slots comprises a rising period and a falling period; the linear frequency modulation module generates an envelope function as follows under the action of the time control signalm(t) Is a linear frequency modulated signal; the spread spectrum module is used for forming broadband frequency modulation signals of each time slot; the signal processing module calculates the distance and speed value of the detected target, eliminates the false target speed value and eliminates the false target. The invention reduces the false alarm probability of the anti-collision radar and improves the reliability.
Description
Technical Field
The invention relates to the field of intelligent traffic control anti-collision radars, in particular to a low false alarm high-reliability anti-collision radar device for intelligent traffic control.
Background
Automobiles have become an indispensable tool in the life of today's society as a main means of transportation and traffic. In recent years, with the development of economy, the traffic volume of highway is increasing, the holding capacity of automobiles is increasing, and the problems are obvious when the automobiles bring convenience to human society.
The automobile anti-collision control technology is an indispensable part of intelligent traffic control technology, and plays a vital role in safe running of automobiles. The research of the anti-collision control of the automobile has the effect of treating the root cause of the collision accident rate. Therefore, research on the anti-collision technology of automobiles is the most urgent and valuable in the field of intelligent traffic control.
However, as a typical representative of the collision avoidance control technology of automobiles, there is a problem in that the probability of collision avoidance false alarm is high. By analysis, the main reasons for causing false alarms are in two aspects; firstly, the anti-collision radar cannot eliminate false points in an R-V plane, so that false alarms are caused; secondly, the anti-collision radar signal has no anti-interference capability and is easy to be interfered, especially is greatly influenced by urban noise and multipath interference, thereby causing false alarm.
Therefore, how to reduce the false alarm probability of the anti-collision radar and improve the reliability is a difficult problem to be solved in the field of the anti-collision radar for intelligent traffic control.
Disclosure of Invention
The invention aims to disclose a low false alarm high-reliability anti-collision radar device so as to reduce the false alarm probability and improve the reliability.
In order to achieve the purpose of the invention, the invention provides a low false alarm high-reliability anti-collision radar device, which comprises a transmitting unit and a receiving unit, wherein the transmitting unit comprises a waveform generating module, a time control module, a linear frequency modulation module, a spread spectrum module and a transmitting antenna module; the receiving unit comprises a receiving antenna module, a despreading module, a signal processing module and an alarm prompting module;
the waveform generation module is used for generating envelope pulsem(t)And output to the chirp module;
the time control module is used for timing, outputting a time control signal to the linear frequency modulation module, and setting the cycle time of the anti-collision radar signalT s Will cycle timeT s Divided intoNEach time length varies from time slot to time slot, and willNEach time slot of the plurality of time slots is divided into a rising period and a falling period;
the linear frequency modulation module generates an envelope function as follows under the action of a time control signalm(t) Is output to the spread spectrum module and the signal processing module; at the position ofNThe generated chirp signal has an envelope function within each rising period of each time slotm(t) Is a positive chirp signal of (a); at the position ofNThe generated chirp signal is envelope function within each falling period of each time slotm(t) Is a negative-going chirp signal of (2); the chirp rate of the positive and negative chirps varies from time slot to time slot;
the spread spectrum module is used for generating a pseudo-random sequence and outputting the pseudo-random sequence to the despreading module; at the position ofNIn each time slot of each time slot, multiplying each chip amplitude of the pseudo-random sequence with the linear frequency modulation signal according to the chip sequence from low to high to form a broadband frequency modulation signal of each time slot, and outputting the broadband frequency modulation signal to the transmitting antenna module;
the despreading module performs despreading processing on the echo signals received by the receiving antenna module based on a pseudo-random sequence to form despread signals and outputs the despread signals to the signal processing module;
the signal processing module processes the despread signal and the linear frequency modulation signal, calculates the distance and the speed value of the detection target, eliminates the false target, and outputs the distance and the speed value of the real target to the alarm prompting module;
the alarm prompting module is used for displaying the distance and speed values of the real target and judging whether to output an alarm signal according to a preset threshold value.
Further, the envelope function generated by the chirp module ism(t) Is:
；
the envelope function generated by the linear frequency modulation module ism(t) Is:
；
wherein,fas a function of the carrier frequency,g i is the firstiFrequency modulation slope of each time slot.
Further, the chirp module generates an envelope function asm(t) Positive and negative chirp signals, carrier frequencies of positive and negative chirp signalsfThe method comprises the following steps:
；
wherein,f 0 is the initial carrier frequency of the chirp signal,for the frequency variation step of the chirp signal,iis the firstiA number of time slots of a time slot,ithe value range of (2) is 1-1%NIs a positive integer of (a).
Further, the time control module is divided intoNThe method for each time slot is as follows:
will cycle timeT s Divided intoNA number of time slots of a time slot,Nthe time lengths of the individual time slots are respectively expressed as:T m1 ,T m2 ,…,T mi ,…,T mN ，ithe value range of (2) is 1-1%NIs a positive integer of (2); and will beNEach time slot of the plurality of time slots is divided into a rising period and a falling period; wherein,
first, theiThe rise time interval of each slot is expressed as:，
first, theiThe fall time interval of each slot is expressed as:，
t i- 1 、t i respectively represent the firstiThe starting time and the ending time of each time slot.
Further, the spreading module is used for forming wideband frequency modulation signals of each time slot, and the firstiThe wideband fm signal for each slot is:
when (when)In the time-course of which the first and second contact surfaces,
；
when (when)In the time-course of which the first and second contact surfaces,
；
wherein,t i-1 、t i respectively represent the firstiStarting time and ending time of each time slot, T mi Represent the firstiThe length of time of the one time slot,e i (t) Represent the firstiA wideband fm signal for a time slot,ithe value range of (2) is 1-1%NIs a positive integer of (a) and (b),Nrepresenting the periodT s The total number of divided time slots,m(t) Representing the envelope pulse(s),ξrepresenting envelope pulsesm(t) Is used for the time period of (a),φ j indicating the number of chips asMPseudo-random sequence of (c)jThe amplitude of the individual chips is determined,f 0 for the initial carrier frequency, deltafFor the step size of the frequency variation,g i is the firstiFrequency modulation slope of each time slot.
Further, the chirp signal generated by the chirp module has a frequency modulation bandwidthB150MHz or more.
Further, the envelope pulse m (t) is a gaussian pulse.
Further, the pseudo-random sequence is a barker code sequence.
Compared with the prior art, the invention has the following beneficial effects:
(1) False alarm probability of anti-collision radar is reduced
In the technical proposal disclosed by the invention, the time control module of the transmitting unitT s Divided intoNTime slots of different time lengths,Neach time slot of the plurality of time slots is divided into a rising period and a falling period; the linear frequency modulation module generates an envelope function as follows under the action of a time control signalm(t) Is a linear frequency modulated signal; at the position ofNIn each rising period of each time slot, the linear frequency modulation signal is a forward linear frequency modulation signal; at the position ofNIn each falling period of each time slot, the linear frequency modulation signal is a negative linear frequency modulation signal; respectively constructing frequency domain symmetrical triangular linear frequency modulation signals with different frequency modulation slopes and different time lengths in each time slot through a linear frequency modulation module; sinusoidal carrier frequency between time slotsThe step length of the frequency change is linearly increased, so that the frequency space of the frequency domain symmetric triangle is further expanded, and the signal processing module of the receiving unit can distinguish true targets from false targets; echo signals of a true target and a false target in the rising period and the falling period of each time slot show different characteristics, the distance and the speed value of the true target are irrelevant to the time width of the time slot, and the distance and the speed value of the false target are relevant to the time width of the time slot; based on the characteristics of the true and false targets, the signal processing module of the receiving unit can successfully reject the false targets, so that the false alarm probability of the anti-collision radar is reduced. In the prior art, the modulation signals transmitted by the prior anti-collision radar are frequency domain symmetrical triangle signals with the same frequency modulation period, so that true targets and false targets cannot be distinguished, and the false alarm probability is high. Compared with the prior art, the technical scheme disclosed by the invention greatly reduces the false alarm probability of the anti-collision radar.
(2) Improving the reliability of the anti-collision radar
In the prior art, a continuous wave system is mainly adopted by the anti-collision radar. The continuous wave system anticollision radar has modulation signal transmitted in fixed frequency, signal energy gathered in relatively narrow frequency spectrum range, easy interference, especially great influence of city noise, multipath interference and other factors, and thus high false alarm probability. In the technical scheme disclosed in the invention, the spread spectrum module of the transmitting unit is used for generating pseudo-random sequences, and in the following stepsNIn each time slot of each time slot, according to the sequence of chips from low to high, multiplying each chip amplitude of the pseudo-random sequence with the linear frequency modulation signal to form a broadband frequency modulation signal of each time slot, so that a high-power spectrum signal is subjected to spectrum broadening through the pseudo-random sequence and is converted into a low-power spectrum signal, the purpose of reducing the power spectrum density of an anti-collision radar signal is achieved, and the concealment of the signal is improved; further, the carrier frequency of the chirp signal generated by the chirp module is between each time slotThe frequency change step length is linearly increased, so that the frequency spectrum width of an anti-collision radar signal is further expanded, and the distance between each detection target in an R-V plane is increased; the despreading module of the receiving unit performs despreading processing on the echo signals received by the receiving antenna module based on good autocorrelation characteristics of the pseudo-random sequence, and converts low-power spectrum signals transmitted by a channel into high-power spectrum signals so as to enhance the receiving signal-to-noise ratio and improve the anti-interference capability; based on the spread spectrum and despreading technology, the concealment capability and the anti-interference capability of the anti-collision radar signal are improved. Therefore, compared with the prior art, the technical scheme disclosed by the invention improves the anti-interference capability of the anti-collision radar.
Additional advantages and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following and practice of the invention.
Drawings
FIG. 1 is a schematic diagram of the apparatus according to an embodiment of the present invention.
Fig. 2 is a schematic diagram of a frequency domain symmetric triangle disclosed in an embodiment of the present invention.
Detailed Description
The principles and features of the present invention are described below in conjunction with fig. 1-2, with examples being provided for illustration only and not for limitation of the scope of the invention.
The present invention is described in further detail below with reference to examples and drawings to enable those skilled in the art to practice the same and to refer to the description.
In the prior art, false targets in an R-V plane cannot be removed by an anti-collision radar, so that false alarms are easy to cause. Further, in the prior art, the anti-collision radar mainly adopts a continuous wave system, a modulation signal of the anti-collision radar is modulated by Frequency Shift Keying (FSK) or Minimum Shift Keying (MSK) or Frequency Modulation Continuous Wave (FMCW) as a typical signal, the signal of the anti-collision radar mainly adopts fixed frequency transmission, and signal energy is gathered in a relatively narrow frequency spectrum range, so that the anti-collision radar is easy to be interfered, especially is greatly influenced by factors such as urban noise, multipath interference and the like, and further causes the rising of false alarm probability.
In order to solve the problems in the prior art, the embodiment of the invention discloses a low false alarm high-reliability anti-collision radar device. As shown in fig. 1, the apparatus includes a transmitting unit and a receiving unit, the transmitting unit includes a waveform generating module, a time control module, a chirp module, a spread spectrum module and a transmitting antenna module; the receiving unit comprises a receiving antenna module, a despreading module, a signal processing module and an alarm prompting module;
the waveform generation module is used for generating envelope pulsem(t) And output to the chirp module;
the time control module is used for timing, outputting a time control signal to the linear frequency modulation module, and setting the period time of the anti-collision radar signalT s Will cycle timeT s Divided intoNEach time length varies from time slot to time slot, and willNEach time slot of the plurality of time slots is divided into a rising period and a falling period;
chirping module is atGenerating an envelope function as a function of the time control signalm(t) Is output to a spread spectrum module and a signal processing module; at the position ofNThe generated chirp signal has an envelope function within each rising period of each time slotm(t) Is a positive chirp signal of (a); at the position ofNThe generated chirp signal is envelope function within each falling period of each time slotm(t) Is a negative-going chirp signal of (2); the chirp rate of the positive and negative chirps varies from time slot to time slot;
the frequency spreading module is used for generating a pseudo-random sequence with good autocorrelation and outputting the pseudo-random sequence to the despreading module; at the position ofNIn each time slot of each time slot, multiplying each chip amplitude of the pseudo-random sequence with the linear frequency modulation signal according to the chip sequence from low to high to form a broadband frequency modulation signal of each time slot, and outputting the broadband frequency modulation signal to a transmitting antenna module; typically, the pseudo-random sequences are M sequences, barker code sequences, etc.;
the despreading module performs despreading processing on the echo signals received by the receiving antenna module based on the pseudo-random sequence to form despread signals and outputs the despread signals to the signal processing module;
the signal processing module processes the despread signal and the linear frequency modulation signal, calculates the distance and speed value of the detected target, eliminates the false target, and outputs the distance and speed value of the real target to the alarm prompting module;
the alarm prompting module is used for displaying the distance and speed values of the real target and judging whether to output an alarm signal according to a preset threshold value. The alarm signal can adopt sound alarm or light alarm. The threshold setting can be performed according to the distance, and an alarm signal can be sent out when the threshold reaches the preset distance threshold, or the threshold setting can be performed comprehensively according to the distance and the speed. The setting of the threshold is a well-known and conventional technical means for those skilled in the art, and will not be described in detail herein.
In the technical scheme disclosed by the embodiment of the invention, the envelope function generated by the linear frequency modulation module is as followsm(t) Is the forward chirp signal of (2)：
；
Envelope function generated by the chirp module ism(t) Is:
；
wherein,fis the carrier frequency;g i is the firstiFrequency modulation slope of each time slot.
Further, in the technical solution disclosed in the embodiment of the present invention, the envelope function generated by the chirp module ism(t) Positive and negative chirp signals, carrier frequencies of positive and negative chirp signalsfThe method comprises the following steps:
；
wherein,f 0 is the initial carrier frequency of the chirp signal,for the frequency variation step of the chirp signal,iis the firstiA number of time slots of a time slot,ithe value range of (2) is 1-1%NIs a positive integer of (a).
Further, in the technical scheme disclosed in the embodiment of the invention, the time control module is divided intoNThe method for each time slot is as follows:
will cycle timeT s Divided intoNA number of time slots of a time slot,Nthe time lengths of the individual time slots are respectively expressed as:T m1 ,T m2 ,…,T mi ,…,T mN ，ithe value range of (2) is 1-1%NIs a positive integer of (2); and will beNEach time slot of the plurality of time slots is divided into a rising period and a falling period; wherein,
first, theiRise of individual time slotsThe period time interval is expressed as:；
first, theiThe fall time interval of each slot is expressed as:；
t i- 1 、t i respectively represent the firstiThe starting time and the ending time of each time slot.
Further, in the technical scheme disclosed in the embodiment of the present invention, the spreading module is used to form wideband fm signals of each time slot, the firstiThe wideband fm signal for each slot is:
when (when)In the time-course of which the first and second contact surfaces,
；
when (when)In the time-course of which the first and second contact surfaces,
；
wherein,t i-1 、t i respectively represent the firstiStarting time and ending time of each time slot, T mi Represent the firstiThe length of time of the one time slot,e i (t) Represent the firstiA wideband fm signal for a time slot,ithe value range of (2) is 1-1%NIs a positive integer of (a) and (b),Nrepresenting repetition periodT s The total number of divided time slots,m(t) Representing the envelope pulse(s),ξrepresenting envelope pulsesm(t) Is used for the time period of (a),φ j indicating the number of chips asMPseudo-random sequence of (c)jChip amplitude，f 0 For the initial carrier frequency to be the same,for the step size of the frequency variation,g i is the firstiFrequency modulation slope of each time slot.
In the technical scheme disclosed by the embodiment of the invention, the time control module of the transmitting unit controls the period timeT s Divided intoNThe time slots of each time are different from each other,Neach time slot of the plurality of time slots is divided into a rising period and a falling period; the linear frequency modulation module generates an envelope function as follows under the action of a time control signalm(t) Is a linear frequency modulated signal; at the position ofNIn each rising period of each time slot, the linear frequency modulation signal is a forward linear frequency modulation signal; at the position ofNIn each falling period of each time slot, the linear frequency modulation signal is a negative linear frequency modulation signal, and the frequency modulation slopes of the positive linear frequency modulation signal and the negative linear frequency modulation signal are different from time slot to time slot; and respectively constructing frequency domain symmetrical triangular linear frequency modulation signals with different frequency modulation slopes in each time slot through a linear frequency modulation module.
According to the detection theory of the anti-collision radar, each detection target can generate echo signals on the ascending side and the descending side of the frequency domain symmetrical triangle, so that two frequencies are obtained. When two targets are detected, two groups of parallel straight lines are generated by the echo signals of the two detected targets in an R-V plane, the horizontal axis R represents the distance of the detected targets, and the vertical axis V represents the speed of the detected targets; because the slopes of the straight lines determined by the rising edge and the falling edge of the frequency domain symmetrical triangle are different, the two groups of parallel straight lines can intersect in the R-V plane to obtain four intersection points, namely two false targets are generated, and therefore false alarms are caused. Similarly, when there are more detected targets, more false targets are generated in the R-V plane, thereby making it difficult to control the accuracy of traffic.
Although both the anti-collision radar and the radio altimeter can range, the anti-collision radar and the radio altimeter have large differences. The altimeter only needs to measure the time delay of the echo signal in the vertical direction so as to achieve the purpose of measuring the vertical height; while anti-collision radar needs to measure all detected target echoes of the beam range, it also has the capability of distinguishing each detected target echo, i.e. the anti-collision radar must have the target resolution capability, whereas the radio altimeter does not need to have the capability.
Through analysis of detection theory of the anti-collision radar, false targets appear due to the fact that modulation signals transmitted by the existing anti-collision radar are frequency domain symmetrical triangle signals with the same time. For a real target, the detection distance and speed values of the real target are irrelevant to the time width of a time slot; whereas for decoys, the detection distance and speed values of the decoys are related to the time width of the time slot.
Based on the analysis, in order to solve the technical problems existing in the prior art, in the technical scheme disclosed by the embodiment of the invention, the time control module of the transmitting unit controls the cycle time byT s Divided into lengths of time differing from each otherNThe time length of each time slot is the time width of the frequency domain symmetrical triangle, and is expressed as:T m1 ,T m2 ,…,T mi ,…,T mN the method comprises the steps of carrying out a first treatment on the surface of the The chirp module of the transmitting unit respectively constructs frequency domain symmetrical triangle chirp signals with different frequency modulation slopes of each time slot, so that echo signals of the detection target on the rising edge and the falling edge of the frequency domain symmetrical triangle received by the receiving unit show different characteristics.
Further, in the technical solution disclosed in the embodiment of the present invention, in order to increase the spacing between each detection target in the R-V plane, the sinusoidal carrier frequency between each time slot is increased by ΔfThe frequency space of the frequency domain symmetric triangle is further expanded for the linear increment of the frequency change step length, and the true and false targets are easier to distinguish.
Further, in the technical scheme disclosed in the embodiment of the invention, after the signal processing module of the receiving unit mixes and filters the despread signal and the chirp signal, the beat signal of the rising edge and the falling edge of the detection target in the frequency domain symmetrical triangle is obtained first, and then the distance and the speed value of the detection target and the time width of each time slot are deducedT mi Is of (3)The correspondence. As can be seen from the detection theory analysis conclusion of the anti-collision radar, for detecting a true target, detection distance and speed values obtained from each frequency domain symmetric triangle are the same, and for a false target, different detection distance and speed values are obtained from each frequency domain symmetric triangle due to different time widths of each frequency domain symmetric triangle; based on this variability, spurious detections can be eliminated. Therefore, in the technical scheme disclosed in the embodiment of the invention, the signal processing module of the receiving unit can detect the distance and speed values of the target and the time width of each time slot according to the true and falseT mi And (3) the false target elimination is realized. Distance and speed values and time width of each time slot as to how to obtain the detected objectT mi The correspondence of (2) is a known and conventional technical means for those skilled in the art, and will not be described here.
Further, in the technical scheme disclosed in the embodiment of the invention, the cycle time is repeatedT s The more time slots are divided, the more frequency domain symmetrical triangles are constructed, and the more detection vehicles can be distinguished when the frequency domain symmetrical triangles are used for intelligent traffic control, but the complexity of an anti-collision radar system is increased at the moment. In combination with the practical application scene and the system complexity of intelligent traffic control, in the technical scheme disclosed by the embodiment of the invention, the time control module controls the cycle time of the anti-collision radar signalT s Divided into 3 time slots, as shown in FIG. 2, three different frequency domain symmetric triangles are constructed, and the time lengths of the 3 time slots are respectively expressed asT m1 、T m2 AndT m3 the time interval of the 1 st time slot is 0-t 1 The time interval of the 2 nd time slot ist 1 ~t 2 The time interval of the 3 rd time slot ist 2 ~t 3 . Further, the 1 st time slot has a rise time interval ofThe falling period time interval isThe method comprises the steps of carrying out a first treatment on the surface of the The rise time interval of the 2 nd time slot is +.>The time interval of the falling period is +.>The method comprises the steps of carrying out a first treatment on the surface of the The rise time interval of the 3 rd time slot is +.>The time interval of the falling period is +.>. Further, the chirp module generatesm(t) The carrier frequency variation step length between each time slot is delta as the linear frequency modulation signal of envelope functionf。
Preferably, in the technical scheme disclosed by the embodiment of the invention, the typical detection distance of the anti-collision radar for intelligent traffic control is 100 meters, and the frequency modulation bandwidths of the positive-direction linear frequency modulation signal and the negative-direction linear frequency modulation signal generated by the linear frequency modulation module are based on the complexity of an anti-collision radar system and the anti-collision performanceB150MHz or more.
Preferably, in the technical scheme disclosed by the embodiment of the invention, the envelope pulse m (t) is a Gaussian pulse, and the pulse waveform is easy to realize, so that the complexity of realization is greatly reduced.
In the prior art, an anti-collision radar mainly adopts a continuous wave system, signals of the system mainly adopt fixed frequency transmission, and signal energy is gathered in a relatively narrow frequency spectrum range, so that the anti-collision radar is easy to be interfered, especially is greatly influenced by factors such as urban noise, multipath interference and the like, and therefore false alarms are easy to be caused.
In order to solve the technical problems in the prior art, in the technical scheme disclosed by the embodiment of the invention, a spread spectrum module of a transmitting unit is used for generating a pseudo-random sequence with good autocorrelation, and in the following stepsNIn each time slot of each time slot, the amplitude of each chip of the pseudo random sequence is respectively and linearly adjusted according to the order of the chips from low to highMultiplying the frequency signals to form broadband frequency modulation signals of each time slot; the spread spectrum module spreads the high power spectrum of the linear modulation frequency modulation signal through a pseudo-random sequence by adopting a spread spectrum technology so as to achieve the purpose of reducing the power spectrum density of the anti-collision radar signal; further, the carrier frequency of the chirp signal generated by the chirp module is between each time slotThe frequency change step length is linearly increased, so that the frequency spectrum width of the anti-collision radar signal is further expanded, and the frequency spreading effect is enhanced. The despreading module of the receiving unit performs despreading processing on echo signals received by the receiving antenna module based on the pseudo-random sequence, and the received echo signals of the detection targets are reconverted from broadband low-power spectrum signals to narrowband high-power spectrum signals by a despreading technology based on good autocorrelation characteristics of the pseudo-random sequence because the pseudo-random sequences adopted by the despreading module and the despreading module are the same, so that the purpose of enhancing the receiving signal-to-noise ratio is achieved, and the anti-interference capability is improved; for the received channel interference signal, the interference signal itself does not contain the same pseudo random sequence, and the channel interference signal is converted into a broadband low-power spectrum signal through a despreading module. Obviously, through the despreading technology, the energy of the detected target echo signals in all chip time can be accumulated, and the power of the channel interference signals is reduced, so that the purpose of improving the signal to noise ratio of the anti-collision radar echo signals is achieved, the capability of influence of distortion factors such as anti-collision radar signals distortion resistance, multipath, diffuse reflection and the like is greatly improved, and the reliability of the anti-collision radar is improved. Therefore, based on the spread spectrum and despreading technology, the concealment capability and the anti-interference capability of the anti-collision radar signal are improved. In summary, compared with the prior art, the technical scheme disclosed by the embodiment of the invention improves the anti-interference capability of the anti-collision radar. How to realize spreading and despreading based on pseudo random sequences is a well-known and conventional technical means for those skilled in the art, and will not be described in detail here.
Preferably, in the technical solution disclosed in the embodiment of the present invention, the pseudo random sequence is a barker code sequence. Compared with an M sequence, the barker code sequence has better autocorrelation property, and is more beneficial to improving the anti-interference capability of signals.
The microwave K wave band has the characteristics of wide available frequency band, less interference and small equipment volume, and is widely applied to the field of anti-collision radars. Preferably, in the technical scheme disclosed in the embodiment of the invention, the transmitting antenna module and the receiving antenna module work in a microwave K band.
Although the embodiments of the present invention have been disclosed above, they are not limited to the modes of use listed in the specification and embodiments. It can be applied to various fields suitable for the present invention. Additional modifications will readily occur to those skilled in the art. Therefore, the invention is not to be limited to the specific details and illustrations shown and described herein, without departing from the general concepts defined in the claims and their equivalents.
The foregoing is only illustrative of the present invention and is not to be construed as limiting thereof, but rather as various modifications, equivalent arrangements, improvements, etc., within the spirit and principles of the present invention.
Claims (4)
1. The low false alarm high-reliability anti-collision radar device is characterized by comprising a transmitting unit and a receiving unit, wherein the transmitting unit comprises a waveform generating module, a time control module, a linear frequency modulation module, a spread spectrum module and a transmitting antenna module; the receiving unit comprises a receiving antenna module, a despreading module, a signal processing module and an alarm prompting module;
the waveform generation module is used for generating envelope pulsem(t)And output to the chirp module, wherein the envelope function generated by the chirp module ism(t) Is:
；
the envelope function generated by the linear frequency modulation module ism(t) Is:
；
wherein,fas a function of the carrier frequency,g i is the firstiFrequency modulation slope of each time slot;
the linear frequency modulation module generates envelope function asm(t) Positive and negative chirp signals, carrier frequencies of positive and negative chirp signalsfThe method comprises the following steps:
；
wherein,f 0 is the initial carrier frequency of the chirp signal,for the frequency variation step of the chirp signal,iis the firstiA number of time slots of a time slot,ithe value range of (2) is 1-1%NIs a positive integer of (2);
the time control module is used for timing, outputting a time control signal to the linear frequency modulation module, and setting the cycle time of the anti-collision radar signalT s Will cycle timeT s Divided intoNEach time length varies from time slot to time slot, and willNEach time slot of the plurality of time slots is divided into a rising period and a falling period;
the time control module is divided intoNThe method for each time slot is as follows:
will cycle timeT s Divided intoNA number of time slots of a time slot,Nthe time lengths of the individual time slots are respectively expressed as:T m1 ,T m2 ,…,T mi ,…,T mN ，ithe value range of (2) is 1-1%NIs a positive integer of (2); and will beNEach time slot of the plurality of time slots is divided into a rising period and a falling period; wherein,
first, theiThe rise time interval of each slot is expressed as: ，
first, theiThe fall time interval of each slot is expressed as: ，
t i-1 、t i respectively represent the firstiStarting time and ending time of each time slot;
the linear frequency modulation module generates an envelope function as follows under the action of a time control signalm(t) Is output to the spread spectrum module and the signal processing module; at the position ofNThe generated chirp signal has an envelope function within each rising period of each time slotm(t) Is a positive chirp signal of (a); at the position ofNThe generated chirp signal is envelope function within each falling period of each time slotm(t) Is a negative-going chirp signal of (2); the chirp rate of the positive and negative chirps varies from time slot to time slot;
the spread spectrum module is used for generating a pseudo-random sequence and outputting the pseudo-random sequence to the despreading module; at the position ofNIn each time slot of each time slot, multiplying each chip amplitude of the pseudo-random sequence with the linear frequency modulation signal according to the chip sequence from low to high to form a broadband frequency modulation signal of each time slot, and outputting the broadband frequency modulation signal to the transmitting antenna module;
the spread spectrum module is used for forming broadband frequency modulation signals of each time slot, the firstiThe wideband fm signal for each slot is:
when (when)In the time-course of which the first and second contact surfaces,
；
when (when)In the time-course of which the first and second contact surfaces,
；
wherein,t i-1 、t i respectively represent the firstiStarting time and ending time of each time slot, T mi Represent the firstiThe length of time of the one time slot,e i (t) Represent the firstiA wideband fm signal for a time slot,ithe value range of (2) is 1-1%NIs a positive integer of (a) and (b),Nrepresenting the periodT s The total number of divided time slots,m(t) Representing the envelope pulse(s),ξrepresenting envelope pulsesm(t) Is used for the time period of (a),φ j indicating the number of chips asMPseudo-random sequence of (c)jThe amplitude of the individual chips is determined,f 0 for the initial carrier frequency, deltafFor the step size of the frequency variation,g i is the firstiFrequency modulation slope of each time slot;
the despreading module performs despreading processing on the echo signals received by the receiving antenna module based on a pseudo-random sequence to form despread signals and outputs the despread signals to the signal processing module;
the signal processing module processes the despread signal and the linear frequency modulation signal, calculates the distance and the speed value of the detection target, eliminates the false target, and outputs the distance and the speed value of the real target to the alarm prompting module;
the alarm prompting module is used for displaying the distance and speed values of the real target and judging whether to output an alarm signal according to a preset threshold value.
2. The low false alarm high reliability anti-collision radar apparatus according to claim 1, wherein the chirp signal generated by the chirp module has a frequency modulation bandwidthB150MHz or more.
3. The low false alarm high reliability anti-collision radar device of claim 1, in which the envelope pulse m (t) is a gaussian pulse.
4. The low false alarm high reliability anti-collision radar apparatus of claim 1, in which the pseudo random sequence is a barker code sequence.
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