CN110988864B - MTI radar speed measuring method with frequency agility - Google Patents

MTI radar speed measuring method with frequency agility Download PDF

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CN110988864B
CN110988864B CN201911262770.2A CN201911262770A CN110988864B CN 110988864 B CN110988864 B CN 110988864B CN 201911262770 A CN201911262770 A CN 201911262770A CN 110988864 B CN110988864 B CN 110988864B
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安政帅
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CETC 20 Research Institute
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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
    • G01S13/581—Velocity or trajectory determination systems; Sense-of-movement determination systems using transmission of interrupted pulse modulated waves and based upon the Doppler effect resulting from movement of targets
    • 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
    • G01S13/006—Theoretical aspects
    • 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
    • G01S7/023—Interference mitigation, e.g. reducing or avoiding non-intentional interference with other HF-transmitters, base station transmitters for mobile communication or other radar systems, e.g. using electro-magnetic interference [EMI] reduction techniques
    • 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
    • G01S7/36—Means for anti-jamming, e.g. ECCM, i.e. electronic counter-counter measures
    • 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
    • G01S7/414—Discriminating targets with respect to background clutter
    • 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
    • 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
    • G01S7/418—Theoretical aspects

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Abstract

The invention provides a frequency agility MTI radar speed measurement method, which utilizes double transmitting and receiving channels to simultaneously transmit and receive signals with different frequencies, then performs signal level fusion on the signals of the two channels through signal processing to improve the detection performance, and simultaneously performs speed calculation by utilizing signal phase information of the two receiving channels without additionally transmitting redundant waveforms for speed ambiguity calculation. The invention adopts the simultaneous dual-frequency transmission, reduces the probability of the reconnaissance receiver intercepting the radar transmission signal, and simultaneously, the dual-frequency reception can effectively resist the narrow-band aiming type interference, overcomes the defect of weak electronic resistance in the existing MTI radar, realizes target detection by adopting dual-channel signal level fusion, does not need redundant waveforms to realize speed ambiguity resolution, overcomes the defect of serious energy loss by transmitting the redundant waveforms in the prior art, and effectively improves the comprehensive detection performance of the target.

Description

MTI radar speed measuring method with frequency agility
Technical Field
The invention relates to the technical field of radar target detection, in particular to a frequency agility MTI radar system structure and a speed measuring method.
Background
The task of the modern radar is increasingly complex, and in order to improve the detection performance of the radar in a complex and variable environment, a plurality of advanced theories and methods are proposed, and a clutter suppression technology is one of key technologies. Moving object display technology, which is one of the earliest technologies for suppressing clutter, uses the doppler shift of the echo signal of a moving object to distinguish between a fixed object and a moving object. The low repetition frequency MTI radar increases the transmission energy by transmitting a long pulse width, and theoretically, if the duty ratio and the total time are the same, the detection power of different repetition frequency radars is the same, because the average power and the energy are the same, and in fact, the actual detection distance of the low repetition frequency radar is farther because no accumulated loss exists. The repetition frequency is low, the unambiguous Doppler frequency of the low repetition frequency radar is low, the velocity ambiguity is serious, the low repetition frequency radar is not suitable for pulse Doppler processing, the clutter resistance is weak, but with the development of the technology, the improvement factor of the current advanced MTI radar can reach 60 decibels, the capability of detecting a moving target in clutter can be effectively improved, and the anti-jamming capability of the radar is improved.
At present, the low-repetition-frequency MTI radar is mainly applied to the fields of remote early warning, space surveying and mapping and the like due to the characteristic of clear ranging, and due to the radar system, the low-repetition-frequency MTI radar has serious speed ambiguity when measuring the speed and is not suitable for measuring the speed. However, if the speed information of the target can be obtained, the point trace filtering can be performed by using the speed difference between the target and the clutter, so that a better clutter suppression effect can be achieved. In addition, the speed information of the target can improve the tracking precision of the target and also can roughly estimate the type of the target.
In recent years, the electromagnetic environment in which radar is located has become increasingly complex. In order to improve the anti-interference capability, the radar mostly adopts a frequency agile working mode. Pulse-to-pulse frequency agility has the important advantage of increasing the detectability of certain targets, and frequency agility also mitigates the deleterious effects of echo flicker in tracking radar, facilitating more accurate target tracking. In military radars, inter-pulse frequency agility will force enemy jamming signal energy to be spread out over a wide bandwidth, rather than concentrating the entire energy within the narrow bandwidth of fixed frequency radars.
At present, the study on MTI radar speed measurement by domestic scholars is less. Domestic treweicheng et al has proposed an MTI radar velocimetry algorithm based on phase unwrapping, this algorithm adopts phase unwrapping and heavy frequency spread solution ambiguity method to realize MTI radar speed measurement, but this algorithm need send six heavy frequency spread cycles for understanding the ambiguity, this compares with not having fuzzy radar, the redundant waveform means serious energy loss, can seriously influence the operating distance of radar, and the waveform of sending same operating frequency for a long time receives narrowband aiming formula interference very easily, thereby can't effectively realize target detection, and it is great to different repetition cycle solution ambiguity effect differences, in order to improve the effect, need to carry out special optimal design to the heavy frequency cycle. In recent years, in the field of radar technology, the development of multi-channel transmitting and receiving technology is rapid, but the current research mainly focuses on transmitting and receiving a single working frequency, that is, all transmitting and receiving channels are consistent, and the structural design is simple to implement, but the anti-interference performance is weak. The li-founded country in 2011 proposes a linear channel and logarithmic channel dual-channel receiver, which not only completely retains the amplitude signal of the signal, but also expands the dynamic range of the receiver, but does not research the electronic impedance performance.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides a speed measuring method of a frequency agile MTI radar, which overcomes the defects of weak anti-interference capability and serious energy loss of transmitted redundant waveform of the MTI radar in the prior art. Because single frequency transmission is adopted and redundant waveforms are transmitted in a repeated frequency staggered mode to solve the real speed of a target, signals of the same frequency are transmitted for a long time and are easily intercepted by a reconnaissance receiver and implement narrow-band aiming type interference, and the redundant waveforms transmitted in the repeated frequency staggered mode mean serious energy loss and can seriously influence the action power of a radar.
The technical scheme adopted by the invention for solving the technical problem comprises the following specific steps:
s1: in order to reduce the interception probability of the transmission signal by the reconnaissance receiver, the waveform generator generates a waveform and divides the waveform into two paths to be respectively sent to two transmission channels, and the two transmission channels respectively receive local oscillation signals f sent by a local oscillation source LO1 And f LO2 Require | f LO1 -f LO2 |>1GHz, respectively radiating signals to a space target through the same antenna at different transmitting frequencies by two paths of signals after up-conversion;
s2: in order to resist narrow-band aiming type interference, an antenna collects a target reflection signal and sends the target reflection signal to two receiving channels, and the two receiving channels respectively receive a local oscillation signal f sent by a local oscillation source LO1 And f LO2 Respectively completing the pretreatment of signal amplification, down-conversion, AD conversion and digital down-conversion, and then sending to a signal processor;
s3: in order to improve the target detection performance, the signals preprocessed by the two receiving channels respectively complete pulse compression and MTI processing, then the signals processed by the MTI processing of the two receiving channels are subjected to non-coherent fusion to improve the signal-to-noise ratio, and target constant false alarm detection is completed, wherein the specific contents of the non-coherent fusion are as follows:
receiving channel-MTI processed signal M 11 (t)、M 12 (t) are respectively:
Figure GDA0003727421450000031
Figure GDA0003727421450000032
wherein, A 1 Representing the amplitude of a signal of the receiving channel, f d1 Representing the Doppler frequency, T r Denotes the pulse repetition period phi 01 Representing an initial phase value;
receiving channel two-MTI processed signal M 21 (t)、M 22 (t) is:
Figure GDA0003727421450000033
in the same way, there are
Figure GDA0003727421450000034
Wherein A is 2 Representing the amplitude of the two signals of the receiving channel, f d2 Representing the Doppler frequency, T r Indicates the pulse weight cycle, phi 02 Representing an initial phase value;
receiving channel-MTI processed signal M 11 (t)、M 12 (t) and reception channel two MTI processed Signal M 21 (t)、M 22 (t) performing modulo value operation to obtain | M 11 (t)|、|M 12 (t)|、|M 21 (t)|、|M 22 (t) |, and then performing non-coherent fusion, namely:
M(t)＝|M 11 (t)|+|M 12 (t)|+|M 21 (t)|+|M 22 (t)|
completing target detection on the non-coherent fused data M (t) by adopting a unit average constant false alarm algorithm to obtain a detection result D;
s4: in order to obtain the speed information of the target, signals processed by two receiving channels MTI in S3 and the detection result of the target constant false alarm are utilized, and the phase information is utilized to complete the resolving of the target speed by adopting a screening method, wherein the specific contents are as follows:
s41: according to the signal M after receiving channel-MTI processing 11 (t) and reception channel two MTI processed Signal M 12 (t), and let initial time t =0, calculate the phase value:
Phase 11 ＝-2πf d1 T r +π-φ 01
Phase 12 ＝-4πf d1 T r +π-φ 01
the phase difference value is:
phase_diff 1 ＝Phase 11 -Phase 12 ＝2πf d1 T r
this gives:
Figure GDA0003727421450000041
s42: according to the cancellation result M of the three pulses in S3 21 (t) and M 22 (t), and let initial time t =0, calculate the phase value:
Phase 21 ＝-2πf d2 T r +π-φ 01
Phase 22 ＝-4πf d2 T r +π-φ 01
the phase difference value is as follows:
phase_diff 2 ＝Phase 21 -Phase 22 ＝2πf d2 T r
this gives:
Figure GDA0003727421450000042
s43: will f is mixed d1 All possible corresponding target speeds are listed, namely:
Figure GDA0003727421450000043
N 1 ＝floor(2V max f R1 /(f r c) Wherein V) is max To target maximum possible speed, f R1 For the transmit channel, a transmit frequency, c the speed of light, f r ＝1/T r Is the pulse repetition frequency;
will f is d2 All possible corresponding target speeds are listed, namely:
Figure GDA0003727421450000044
N 2 ＝floor(2V max f R2 /(f r c) In which V is max To target maximum possible speed, f R2 For the emission channel two emission frequencies, c is the speed of light, f r ＝1/T r Is the pulse repetition frequency;
will be provided with
Figure GDA0003727421450000045
Each value of (1) is respectively
Figure GDA0003727421450000046
The difference value of each value is calculated and the absolute norm is obtained
Figure GDA0003727421450000047
In that
Figure GDA0003727421450000048
Search for the minimum value among
Figure GDA0003727421450000049
Is the minimum value, then k 1 Or k 2 Finally obtaining the target correct speed as the calculated ambiguity
Figure GDA00037274214500000410
S5: the detection result D of the target in S3 and the speed information V of the target in S4 are compared r And sending the data to a subsequent data processing subsystem together for further completing target tracking.
The beneficial effects of the invention are as follows: first, since the present invention employs simultaneous dual-frequency transmission, it is possible to
The probability of a reconnaissance receiver intercepting radar transmission signals is reduced, meanwhile, narrow-band aiming type interference can be effectively resisted through double-frequency receiving, the defect that electronic resisting capacity in the existing MTI radar is weak is overcome, and the method has the advantage of strong anti-interference capacity; secondly, because the invention adopts the dual-channel signal level fusion to realize the target detection and does not need redundant waveforms to realize the speed ambiguity resolution, the defect of serious energy loss caused by transmitting redundant waveforms in the prior art is overcome, and the comprehensive detection performance of the target is effectively improved. Therefore, the invention effectively solves the problems of weak interference resistance and low utilization rate of transmitting energy of the MTI radar, and provides powerful technical support for realizing remote target detection in a complex electromagnetic environment.
Drawings
Fig. 1 is a schematic block diagram of a frequency agile MTI radar according to the present invention.
Fig. 2 is a schematic diagram of the variation of the speed measurement accuracy with the signal-to-noise ratio according to the present invention.
Fig. 3 is a detection probability curve of the present invention and the conventional method under different signal-to-noise ratios under the condition of the same false alarm rate.
Detailed Description
The invention is further illustrated by the following examples in conjunction with the drawings.
The invention utilizes the technology of simultaneously transmitting and receiving signals with different frequencies by two channels, not only effectively improves the detection and speed measurement performance of the target, but also improves the comprehensive anti-interference capability, and provides powerful technical support for the practical use of the method in MTI radar.
The invention provides a frequency agility MTI radar speed measurement method, which not only can effectively detect the speed of a target, but also can obviously improve the detection performance and the comprehensive anti-interference capability of a radar, and lays a technical foundation for improving the comprehensive detection capability of the radar in a defense area.
Referring to fig. 1, a schematic block diagram of a frequency agile MTI radar system structure and a speed measurement method according to the present invention is shown. The invention relates to a method for measuring the speed of a frequency agility MTI radar, which comprises the following steps:
s1: referring to fig. 1, a waveform generator generates four pulse periodic waveforms and divides the waveforms into two paths of signals, one of which is sent to a first transmission channel and a local oscillation signal f sent from a local oscillation source LO1 Performing up-conversion, filtering, amplifying, and processing by circulator at RF frequency f R1 Radiating a signal to a spatial target; at the same time, the other path of signal is sent to the local oscillation signal f sent by the second transmission channel and the local oscillation source LO2 Performing up-conversion, filtering, amplifying, and processing by circulator at RF frequency f R2 Radiating a signal to a target in space, requiring | f LO1 -f LO2 |>1GHz, i.e. | f R1 -f R2 |>1GHz。
S2: the antenna collects the target reflection signal and sends the target reflection signal to two receiving channels through a circulator: receiving a local oscillation signal f sent by a local oscillation source after a target echo signal is received by a first receiving channel and is subjected to amplification and filtering processing LO1 Finishing down-conversion treatment, and obtaining a four-pulse signal set S of a receiving channel I through AD conversion and digital down-conversion filtering treatment after filtering and amplifying r1 (t), namely:
Figure GDA0003727421450000061
T r denotes the pulse repetition period, r 1 Which represents the first channel of the reception channel,
Figure GDA0003727421450000062
indicates the first pulse signal of the receiving channel, and l indicates the pulse number.
The second receiving channel receives the local oscillation signal f sent by the local oscillation source after the target echo signal is amplified and filtered LO1 Performing down conversion treatment, filtering, amplifying, and processingAD conversion and digital down-conversion filtering processing are carried out to obtain a four-pulse signal set of a second receiving channel
Figure GDA0003727421450000063
Namely:
Figure GDA0003727421450000064
here T r Denotes the pulse repetition period, r 2 It is indicated that the receiving channel one,
Figure GDA0003727421450000065
indicates the first pulse signal of the receiving channel, and l indicates the pulse number.
S3: the signals preprocessed by the two receiving channels respectively complete pulse compression and MTI processing, and then the signals preprocessed by the two receiving channels MTI are subjected to non-coherent fusion, and the method is specifically implemented as follows:
s31: receiving channel one according to the preprocessed signal S in S2 r1 (t) respectively completing the pulse compression treatment to obtain the result after the pulse compression
Figure GDA0003727421450000066
The signal model is represented as:
Figure GDA0003727421450000067
Figure GDA0003727421450000068
Figure GDA0003727421450000069
Figure GDA00037274214500000610
wherein A is 1 Representing the amplitude of a signal of the receiving channel, f d1 Representing the Doppler frequency, T r Denotes the pulse repetition period phi 01 Representing the initial phase value.
And (3) three-pulse cancellation MTI treatment:
Figure GDA00037274214500000611
Figure GDA00037274214500000612
s32: the second receiving channel is based on the preprocessed signal S in S2 r2 (t) respectively completing the pulse compression treatment to obtain the result after the pulse compression
Figure GDA0003727421450000071
The signal model is represented as:
Figure GDA0003727421450000072
Figure GDA0003727421450000073
Figure GDA0003727421450000074
Figure GDA0003727421450000075
wherein A is 2 Representing the amplitude of the two signals of the receiving channel, f d2 Representing the Doppler frequency, T r Indicates the pulse-weight cycle, phi 02 Representing the initial phase value.
And (3) three-pulse cancellation MTI treatment:
Figure GDA0003727421450000076
for the same reason, have
Figure GDA0003727421450000077
S33: receiving channel-MTI processed signal M 11 (t)、M 12 (t) and reception channel two MTI processed Signal M 21 (t)、M 22 (t) performing modulo value operation to obtain | M 11 (t)|、|M 12 (t)|、|M 21 (t)|、|M 22 (t) |, and then subjected to non-coherent fusion, i.e.
M(t)＝|M 11 (t)|+|M 12 (t)|+|M 21 (t)|+|M 22 (t)|
S34: and (4) completing target detection on the data M (t) subjected to non-coherent fusion in the step (S33) by adopting a traditional unit average constant false alarm algorithm to obtain a detection result D.
S4: and (3) utilizing the signals processed by the two receiving channels MTI in S31 and S32, the target constant false alarm detection result and the phase information to complete the calculation of the target real speed by adopting a screening method, and specifically implementing the following steps:
s41: according to the signal M after receiving channel-MTI processing 11 (t) and reception channel two MTI processed signal M 12 (t), and let initial time t =0, calculate the phase value:
Phase 11 ＝-2πf d1 T r +π-φ 01
Phase 12 ＝-4πf d1 T r +π-φ 01
the phase difference value is:
phase_diff 1 ＝Phase 11 -Phase 12 ＝2πf d1 T r
this gives:
Figure GDA0003727421450000081
s42: according to the cancellation result M of the three pulses in S3 21 (t) and M 22 (t), and with initial time t =0, calculating the phase value:
Phase 21 ＝-2πf d2 T r +π-φ 01
Phase 22 ＝-4πf d2 T r +π-φ 01
the phase difference value is as follows:
phase_diff 2 ＝Phase 21 -Phase 22 ＝2πf d2 T r
this gives:
Figure GDA0003727421450000082
s43: will f is mixed d1 All possible corresponding target speeds are listed, namely:
Figure GDA0003727421450000083
N 1 ＝floor(2V max f R1 /(f r c) In which V is max To target maximum possible speed, f R1 For the transmit channel, a transmit frequency, c the speed of light, f r ＝1/T r Is the pulse repetition frequency;
will f is d2 All possible corresponding target speeds are listed, namely:
Figure GDA0003727421450000084
N 2 ＝floor(2V max f R2 /(f r c) In which V is max To target maximum possible speed, f R2 For the emission channel two emission frequencies, c is the speed of light, f r ＝1/T r Is the pulse repetition frequency;
will be provided with
Figure GDA0003727421450000085
Each value of (1) is respectively
Figure GDA0003727421450000086
The difference value of each value is calculated and the absolute norm is obtained
Figure GDA0003727421450000087
In that
Figure GDA0003727421450000088
Search for the minimum value among
Figure GDA0003727421450000089
Is the minimum value, then k 1 Or k 2 The target correct speed is finally obtained for the ambiguity
Figure GDA00037274214500000810
S5: the detection result D of the target in S3 and the speed information V of the target in S4 are compared r Composition target detection information R = { D, V r And sending the data to a subsequent data processing subsystem to further complete target tracking.
The effect of the present invention is further explained by simulation experiments.
Simulation experiment contents: setting the transmitting waveform as linear frequency modulation signal with time width of 100 mus, bandwidth of 4MHz and pulse repetition period T r =1000 μ s, target speed [100m/s,1500m/s]Randomly generated, radar transmission channel-transmission frequency f R1 =0.9GHz, two transmitting frequencies f of radar transmitting channel R2 =2GHz, the number of monte carlo tests was 1000. Experiments are carried out in MATLAB13.0a software, and target speed calculation is carried out according to the method provided by the invention to obtain the real speed of the target. Referring to fig. 2, a schematic diagram of speed correct resolution probability variation under different signal-to-noise ratios is shown, in fig. 2, a horizontal axis represents the signal-to-noise ratio (unit: decibel), and a vertical axis represents the detection probability; referring to FIG. 3, areIn fig. 3, the horizontal axis represents the signal-to-noise ratio (unit: decibel) and the vertical axis represents the detection probability.
As can be seen from FIG. 2, the method provided by the invention has a high probability of correctly resolving the target speed under a certain signal-to-noise ratio; from fig. 3, it can be seen that the method provided by the present invention has better detection performance compared with the conventional method, thereby proving the effectiveness of the present invention.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.

Claims (1)

1. A method for measuring speed of a frequency agility MTI radar is characterized by comprising the following steps:
s1: in order to reduce the probability of interception of the transmitted signal by the reconnaissance receiver, the waveform generator generates a waveform and divides the waveform into two paths to be respectively sent to two transmitting channels, and the two transmitting channels respectively receive the local oscillation signal f sent by the local oscillation source LO1 And f LO2 Require | f LO1 -f LO2 |>1GHz, respectively radiating signals to a space target through the same antenna at different transmitting frequencies by two paths of signals subjected to up-conversion;
s2: in order to resist narrow-band aiming type interference, an antenna collects a target reflection signal and sends the target reflection signal to two receiving channels, and the two receiving channels respectively receive a local oscillation signal f sent by a local oscillation source LO1 And f LO2 Respectively completing the preprocessing of signal amplification, down conversion, AD conversion and digital down conversion, and then sending the signal to a signal processor;
s3: in order to improve the target detection performance, the signals preprocessed by the two receiving channels respectively complete pulse compression and MTI processing, then the signals processed by the MTI processing of the two receiving channels are subjected to non-coherent fusion to improve the signal-to-noise ratio, and target constant false alarm detection is completed, wherein the specific contents of the non-coherent fusion are as follows:
receiving channel-MTI processed signal M 11 (t)、M 12 (t) are respectively:
Figure FDA0003727421440000011
Figure FDA0003727421440000012
wherein A is 1 Representing the amplitude of a signal of the receiving channel, f d1 Representing the Doppler frequency, T r Indicating the pulse repetition period, phi 01 Represents an initial phase value;
receiving channel two-MTI processed signal M 21 (t)、M 22 (t) is:
Figure FDA0003727421440000013
in the same way, there are
Figure FDA0003727421440000014
Wherein A is 2 Representing the amplitude of the two signals of the receiving channel, f d2 Representing the Doppler frequency, T r Indicates the pulse weight cycle, phi 02 Representing an initial phase value;
receiving channel-MTI processed signal M 11 (t)、M 12 (t) and reception channel two MTI processed Signal M 21 (t)、M 22 (t) performing modulo value operation to obtain | M 11 (t)|、|M 12 (t)|、|M 21 (t)|、|M 22 (t) |, and then performing non-coherent fusion, namely:
M(t)＝|M 11 (t)|+|M 12 (t)|+|M 21 (t)|+|M 22 (t)|
completing target detection on the non-coherent fused data M (t) by adopting a unit average constant false alarm algorithm to obtain a detection result D;
s4: in order to obtain the speed information of the target, signals processed by two receiving channels MTI in S3 and the detection result of the target constant false alarm are utilized, and the phase information is utilized to complete the resolving of the target speed by adopting a screening method, wherein the specific contents are as follows:
s41: according to the receiving channel-MTI processed signal M 11 (t) and reception channel two MTI processed signal M 12 (t), and with initial time t =0, calculating the phase value:
Phase 11 ＝-2πf d1 T r +π-φ 01
Phase 12 ＝-4πf d1 T r +π-φ 01
the phase difference value is:
phase_diff 1 ＝Phase 11 -Phase 12 ＝2πf d1 T r
this gives:
Figure FDA0003727421440000021
s42: according to the result M of the cancellation of the three pulses in S3 21 (t) and M 22 (t), and with initial time t =0, calculating the phase value:
Phase 21 ＝-2πf d2 T r +π-φ 01
Phase 22 ＝-4πf d2 T r +π-φ 01
the phase difference value is as follows:
phase_diff 2 ＝Phase 21 -Phase 22 ＝2πf d2 T r
this gives:
Figure FDA0003727421440000022
s43: will f is d1 List all possible corresponding target speedsNamely:
Figure FDA0003727421440000023
N 1 ＝floor(2V max f R1 /(f r c) Wherein V) is max To target maximum possible speed, f R1 For the emission channel, an emission frequency, c the speed of light, f r ＝1/T r Is the pulse repetition frequency;
will f is d2 All possible corresponding target speeds are listed, namely:
Figure FDA0003727421440000031
N 2 ＝floor(2V max f R2 /(f r c) Wherein V) is max To target maximum possible speed, f R2 For the emission channel two emission frequencies, c is the speed of light, f r ＝1/T r Is the pulse repetition frequency;
will be provided with
Figure FDA0003727421440000032
Each value of (1) is respectively
Figure FDA0003727421440000033
The difference value of each value is calculated and the absolute norm is obtained
Figure FDA0003727421440000034
In that
Figure FDA0003727421440000035
Search for the minimum value, if
Figure FDA0003727421440000036
To a minimumValue, then k 1 Or k 2 The target correct speed is finally obtained for the ambiguity
Figure FDA0003727421440000037
S5: the detection result D of the target in S3 and the speed information V of the target in S4 are compared r And sending the data to a subsequent data processing subsystem together for further completing target tracking.
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