CN111948641A - Frequency modulation continuous wave detection system and method based on time modulation technology - Google Patents

Frequency modulation continuous wave detection system and method based on time modulation technology Download PDF

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CN111948641A
CN111948641A CN202010818141.XA CN202010818141A CN111948641A CN 111948641 A CN111948641 A CN 111948641A CN 202010818141 A CN202010818141 A CN 202010818141A CN 111948641 A CN111948641 A CN 111948641A
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frequency
signal
module
modulation
continuous wave
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CN111948641B (en
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陈靖峰
贺冲
郭家瑞
金荣洪
朱卫仁
梁仙灵
耿军平
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Shanghai Jiaotong University
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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
    • G01S13/583—Velocity or trajectory determination systems; Sense-of-movement determination systems using transmission of continuous unmodulated waves, amplitude-, frequency-, or phase-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
    • G01S13/02—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
    • G01S13/583—Velocity or trajectory determination systems; Sense-of-movement determination systems using transmission of continuous unmodulated waves, amplitude-, frequency-, or phase-modulated waves and based upon the Doppler effect resulting from movement of targets
    • G01S13/584—Velocity or trajectory determination systems; Sense-of-movement determination systems using transmission of continuous unmodulated waves, amplitude-, frequency-, or phase-modulated waves and based upon the Doppler effect resulting from movement of targets adapted for simultaneous range and velocity measurements
    • 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
    • G01S7/35—Details of non-pulse systems
    • G01S7/352—Receivers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00—Reducing energy consumption in communication networks
    • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

Abstract

The invention provides a frequency modulation continuous wave detection system and a method based on a time modulation technology.A frequency modulation continuous wave signal generation module is connected with an input port of a radio frequency power distribution network; the output port I of the radio frequency power distribution network and the power amplifier; the power amplifier is connected with the transmitting antenna; the receiving antenna array is connected with the time modulation module; the time modulation module is connected with the power combiner; the power combiner is connected with the low-noise amplifier; the low-noise amplifier is connected with the radio frequency input port of the frequency mixer; the output port of the mixer is connected with the low-pass filter; the low-pass filter is connected with the analog-to-digital converter; the analog-to-digital converter is connected with the digital signal processing module; the local oscillation input port of the frequency mixer is connected with the second output port of the radio frequency power distribution network; the digital control module is connected with the time modulation module. The invention has the characteristics of single channel, low cost and simple structure, and is suitable for platforms such as miniaturized automobile anti-collision radars, unmanned automobile detection systems and the like.

Description

Frequency modulation continuous wave detection system and method based on time modulation technology
Technical Field
The invention relates to the technical field of antenna engineering, in particular to a frequency modulation continuous wave detection system and a frequency modulation continuous wave detection method based on a time modulation technology, and more particularly realizes distance measurement, speed measurement and direction measurement of a target.
Background
Compared with pulse radar, frequency modulation continuous wave radar has no theory and application in the initial stage because of the problem of isolation of receiving and transmitting. With the development of technology, radars are increasingly used in civil fields, such as automotive radars and the like. At this time, the advantages of compact structure and low cost of the frequency modulation continuous wave radar are highlighted. The direction-finding function of the traditional frequency modulation continuous wave radar mainly uses a multi-channel system, and each antenna needs a separate receiving channel. The system model has good real-time performance, but has a complex structure and high hardware cost.
The single-channel frequency modulation continuous wave radar system can effectively reduce the cost of a radar system. Single channel systems make little difference in the detection of stationary objects from multi-channel systems, but in the detection of moving objects the problem of velocity-azimuth coupling due to object motion arises. The problem is that the phase difference caused by target motion received by adjacent array elements is coupled with the inherent phase difference of a target azimuth, direction-finding errors are caused, and wrong angle estimation is caused, and the problem becomes a key problem in the field of single-channel radar detection.
Patent document CN103176181A (application number: 201110431013.0) discloses a nonlinear node detector of a frequency modulated continuous wave system, which includes: a modulation signal generator generating a modulation signal; the voltage controlled oscillator is controlled by the modulation signal to generate a continuous wave frequency modulation signal; the frequency multiplier is used for multiplying the frequency of the continuous wave frequency modulation signal; the first amplifier amplifies the continuous wave frequency modulation signal; a transmitting antenna; a receiving antenna for receiving an echo signal; a second amplifier for amplifying the echo signal; the mixer is used for mixing the frequency-multiplied continuous wave frequency modulation signal serving as a local oscillation signal with the amplified echo signal to generate a beat signal; a filter for filtering the beat signal; a third amplifier for amplifying the filtered beat signal; and the digital signal processing terminal is used for processing the beat signal, analyzing the frequency and the size of the beat signal, determining whether an electronic target exists in the detection area and calculating the position of the electronic target away from the detector.
The invention discloses a frequency modulation continuous wave detection method based on a time modulation technology. And the amplitude of each order of harmonic signal in the mixed modulation signal is compared, so that the direction of the target is measured. The method has the characteristics of simple structure and low cost, and is suitable for application platforms needing target information detection, such as automobile radars, unmanned driving and the like.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a frequency modulation continuous wave detection system and a frequency modulation continuous wave detection method based on a time modulation technology.
The invention provides a frequency modulation continuous wave detection system based on a time modulation technology, which comprises: the device comprises a signal transmitting module and a signal receiving module;
the signal transmitting module comprises a frequency modulation continuous wave signal generating module 1, a radio frequency power distribution network 2, a power amplifier 3 and a transmitting antenna 4;
the signal receiving module comprises a receiving antenna array 5, a time modulation module 6, a power combiner 7, a low noise amplifier 8, a mixer 9, a low-pass filter 10, an analog-to-digital converter 11, a digital signal processing module 12 and a digital control module 13;
the frequency modulation continuous wave signal generation module 1 is connected with an input port of the radio frequency power distribution network 2; the output port I of the radio frequency power distribution network 2 and the power amplifier 3; the power amplifier 3 is connected with the transmitting antenna 4;
the receiving antenna array 5 is connected with the time modulation module 6; the time modulation module 6 is connected with the power combiner 7; the power combiner 7 is connected with the low noise amplifier 8; the low noise amplifier 8 is connected with the radio frequency input port of the mixer 9; the output port of the mixer 9 is connected with the low-pass filter 10; the low-pass filter 10 is connected with the analog-to-digital converter 11; the analog-to-digital converter 11 is connected with the digital signal processing module 12; the local oscillation input port of the frequency mixer 9 is connected with the second output port of the radio frequency power distribution network 2; the digital control module 13 is connected with the time modulation module 6.
Preferably, the signal transmitting module includes:
the frequency modulation continuous wave signal generation module 1 generates a frequency modulation continuous wave signal, the signal energy is equally divided through the radio frequency power distribution network 2, the signal energy is amplified through the power amplifier 3, and then the signal is radiated to the space through the transmitting antenna 4.
Preferably, the signal receiving module includes:
when the signal sent by the transmitting antenna 4 reaches the target, the target reflects the transmitted signal to form an echo signal; the receiving antenna array 5 receives an echo signal, the time modulation module 6 performs periodic modulation on the echo signal, and the modulated signal is converted into a digital signal through the low-pass filter 10 and the analog-to-digital converter 11 after being subjected to down-conversion and deskew in sequence by the power combiner 7, the low-noise amplifier 8 and the mixer 9; and inputting the digital signals into the digital signal processing module 12 to realize the calculation of the target distance, speed and direction information.
Preferably, the digital control module 13 controls the modulation timing of the time modulation module 6 to perform periodic modulation.
Preferably, the receiving antenna array 5 comprises a plurality of antenna array elements.
Preferably, the calculation of the target distance, speed and direction information by using the digital signal processing module 12 includes:
the target distance includes:
Figure BDA0002633486130000031
the speed calculation includes:
Figure BDA0002633486130000032
wherein r is the distance between the target and the detection system; v is the target velocity; f. of0Is the radio signal carrier frequency; c is the speed of light in vacuum; mu is B/T is the frequency modulation slope of the frequency modulation continuous wave signal, B is the signal bandwidth, and T is the signal rising edge or falling edge duration; Δ fupThe frequency difference is obtained after the frequency mixing of the rising edge signals of the frequency modulation continuous waves; Δ fdownThe frequency difference is obtained after the frequency mixing of the frequency modulation continuous wave falling edge signals;
wherein, Δ fupAnd Δ fdownThe method is obtained by finding a corresponding power peak point in a harmonic reconstruction spectrum Ψ (f), and Ψ (f) is expressed as:
Figure BDA0002633486130000033
wherein f ispTo modulate frequency, [ phi ]kFor modulating the frequency spectrum of the signal at [0, fp/2]A mapping of (2); k represents phi mapped by the k-th harmonickA function;
Figure BDA0002633486130000034
y (f) is the frequency spectrum of the frequency-modulated continuous wave signal of the receiving end after time modulation and frequency mixing; q represents a natural number;
the calculation formula of the direction information is as follows:
Figure BDA0002633486130000041
wherein R isi(theta) is the energy proportional relation of different harmonic signals in the ith region, Ri(theta) with coverage in the current areaDifferent angle values are in one-to-one correspondence; AFi，L(theta) and AFi，R(theta) left and right harmonic directional pattern gains in the i-th region, respectively, thetai，floorAnd thetai，upperRespectively, the lower and upper angular limits of the i-th zone.
Preferably, the time modulation module 6 comprises a modulation frequency f of the time modulation module 6pModulating the frequency modulation slope mu of the frequency modulation continuous wave signal generated by the frequency modulation continuous wave signal generation module 1, and transmitting signal carrier frequency f0And the target distance r and the speed v satisfy the following relation:
4(rμ+f0v)/c≤fp (6)。
preferably, the time modulation module 6 comprises a single-pole single-throw radio frequency switch, a single-pole multiple-throw radio frequency switch, or a digital phase shifter.
Preferably, the radio frequency power distribution network includes a multi-path power distribution network, a reconfigurable power distribution network, or a power divider.
The invention provides a frequency modulation continuous wave detection method based on a time modulation technology, which comprises the following steps: the system comprises a frequency modulation continuous wave signal generation module 1, a radio frequency power distribution network 2, a power amplifier 3 and a transmitting antenna 4; the system comprises a receiving antenna array 5, a time modulation module 6, a power combiner 7, a low noise amplifier 8, a mixer 9, a low pass filter 10, an analog-to-digital converter 11, a digital signal processing module 12 and a digital control module 13;
the frequency modulation continuous wave signal generation module 1 is connected with an input port of the radio frequency power distribution network 2; the output port I of the radio frequency power distribution network 2 and the power amplifier 3; the power amplifier 3 is connected with the transmitting antenna 4;
the receiving antenna array 5 is connected with the time modulation module 6; the time modulation module 6 is connected with the power combiner 7; the power combiner 7 is connected with the low noise amplifier 8; the low noise amplifier 8 is connected with the radio frequency input port of the mixer 9; the output port of the mixer 9 is connected with the low-pass filter 10; the low-pass filter 10 is connected with the analog-to-digital converter 11; the analog-to-digital converter 11 is connected with the digital signal processing module 12; the local oscillation input port of the frequency mixer 9 is connected with the second output port of the radio frequency power distribution network 2; the digital control module 13 is connected with the time modulation module 6;
the frequency modulation continuous wave signal generation module 1 generates a frequency modulation continuous wave signal, the signal energy is equally divided through the radio frequency power distribution network 2, the signal energy is amplified through the power amplifier 3, and the signal is radiated to the space through the transmitting antenna 4;
when the signal sent by the transmitting antenna 4 reaches the target, the target reflects the transmitted signal to form an echo signal; the receiving antenna array 5 receives an echo signal, the time modulation module 6 performs periodic modulation on the echo signal, and the modulated signal is converted into a digital signal through the low-pass filter 10 and the analog-to-digital converter 11 after being subjected to down-conversion and deskew in sequence by the power combiner 7, the low-noise amplifier 8 and the mixer 9; inputting the digital signal into the digital signal processing module 12 to realize the calculation of the target distance, speed and direction information;
the digital control module 13 controls the modulation timing sequence of the time modulation module 6 to perform periodic modulation.
The calculation of the target distance, speed and direction information by using the digital signal processing module 12 includes:
the target distance includes:
Figure BDA0002633486130000051
the speed calculation includes:
Figure BDA0002633486130000052
wherein r is the distance between the target and the detection system; v is the target velocity; f. of0Is the radio signal carrier frequency; c is the speed of light in vacuum; mu-B/T is the frequency modulation slope of the frequency modulation continuous wave signal, B is the signal bandwidth, and T is the rising edge or the falling edge of the signalA duration; Δ fupThe frequency difference is obtained after the frequency mixing of the rising edge signals of the frequency modulation continuous waves; Δ fdownThe frequency difference is obtained after the frequency mixing of the frequency modulation continuous wave falling edge signals;
wherein, Δ fupAnd Δ fdownThe method is obtained by finding a corresponding power peak point in a harmonic reconstruction spectrum Ψ (f), and Ψ (f) is expressed as:
Figure BDA0002633486130000053
wherein f ispTo modulate frequency, [ phi ]kFor modulating the frequency spectrum of the signal at [0, fp/2]A mapping of (2); k represents phi mapped by the k-th harmonickA function;
Figure BDA0002633486130000054
y (f) is the frequency spectrum of the frequency-modulated continuous wave signal of the receiving end after time modulation and frequency mixing; q represents a natural number;
the calculation formula of the direction information is as follows:
Figure BDA0002633486130000061
wherein R isi(theta) is the energy proportional relation of different harmonic signals in the ith region, Ri(theta) corresponds to different angle values covered in the current area one by one; AFi，L(theta) and AFi，R(theta) left and right harmonic directional pattern gains in the i-th region, respectively, thetai，floorAnd thetai，upperRespectively, the lower and upper angular limits of the i-th zone.
Compared with the prior art, the invention has the following beneficial effects:
1. the invention realizes the functions of ranging, measuring speed and measuring direction of a target in a single channel by adding the time modulation module for periodic modulation in the radio frequency channel, thereby reducing the system cost of the frequency modulation continuous wave detection method;
2. the invention carries out amplitude comparison direction finding by utilizing the harmonic waves of the echo signals in different areas, simplifies a direction finding system, reduces direction finding calculated amount and ensures the reaction speed of the system;
3. the invention has the characteristics of single channel, low cost and simple structure, and is suitable for platforms such as miniaturized automobile anti-collision radars, unmanned automobile detection systems and the like.
Drawings
Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:
FIG. 1 is a block diagram of the basic structure of a frequency modulated continuous wave detection method based on a time modulation technique;
FIG. 2 is a diagram of the time-frequency relationship of the transmitted signals in the embodiment;
FIG. 3 is a time-frequency relationship diagram of an echo signal after being modulated in the embodiment;
FIG. 4 is a spectrum diagram of an echo signal after being mixed without modulation in the embodiment;
FIG. 5 is a frequency spectrum diagram of echo signals after frequency mixing and reconstruction by using k ∈ [0, 5] power in the embodiment;
FIG. 6 is a spectrum diagram of the echo signal after being mixed and reconstructed by using the power k ∈ [0, 7] in the embodiment.
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that it would be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit of the invention. All falling within the scope of the present invention.
Example 1
The invention provides a frequency modulation continuous wave detection system based on a time modulation technology, which comprises: the device comprises a signal transmitting module and a signal receiving module;
the signal transmitting module comprises a frequency modulation continuous wave signal generating module 1, a radio frequency power distribution network 2, a power amplifier 3 and a transmitting antenna 4;
the signal receiving module comprises a receiving antenna array 5, a time modulation module 6, a power combiner 7, a low noise amplifier 8, a mixer 9, a low-pass filter 10, an analog-to-digital converter 11, a digital signal processing module 12 and a digital control module 13;
the frequency modulation continuous wave signal generation module 1 is connected with an input port of the radio frequency power distribution network 2; the output port I of the radio frequency power distribution network 2 and the power amplifier 3; the power amplifier 3 is connected with the transmitting antenna 4;
the receiving antenna array 5 is connected with the time modulation module 6; the time modulation module 6 is connected with the power combiner 7; the power combiner 7 is connected with the low noise amplifier 8; the low noise amplifier 8 is connected with the radio frequency input port of the mixer 9; the output port of the mixer 9 is connected with the low-pass filter 10; the low-pass filter 10 is connected with the analog-to-digital converter 11; the analog-to-digital converter 11 is connected with the digital signal processing module 12; the local oscillation input port of the frequency mixer 9 is connected with the second output port of the radio frequency power distribution network 2; the digital control module 13 is connected with the time modulation module 6.
Specifically, the signal transmitting module includes:
when the system signal transmitting module transmits frequency modulation continuous wave, the frequency modulation continuous wave signal generating module 1 generates frequency modulation continuous wave signals, the frequency modulation continuous wave signals pass through the radio frequency power distribution network 2 to equally divide signal energy, pass through the power amplifier 3 to amplify the signal energy, and then the signals are radiated to the space through the transmitting antenna 4.
Specifically, the signal receiving module includes:
when the signal sent by the transmitting antenna 4 reaches the target, the target reflects the transmitted signal to form an echo signal; the receiving antenna array 5 receives an echo signal, the time modulation module 6 performs periodic modulation on the echo signal, and the modulated signal is converted into a digital signal through the low-pass filter 10 and the analog-to-digital converter 11 after being subjected to down-conversion and deskew in sequence by the power combiner 7, the low-noise amplifier 8 and the mixer 9; and then, the digital signal processing module 12 is used for processing the digital signal, and the corresponding harmonic coefficient characteristics after the frequency mixing of the modulation signal are obtained through searching, namely, the digital signal is input into the digital signal processing module 12 to realize the calculation of the target distance, speed and direction information.
Specifically, the digital control module 13 controls the modulation period and the modulation timing of the time modulation module 6. The time modulation module 6 is used for performing time modulation on the frequency modulation continuous wave echo signal,
specifically, the receiving antenna array 5 includes a plurality of antenna array units, the spacing between the antenna array units is half wavelength, and the receiving antenna array units correspond to the modulation devices one to one.
Specifically, the calculation of the target distance, speed and direction information by using the digital signal processing module 12 includes:
the target distance includes:
Figure BDA0002633486130000081
the speed calculation includes:
Figure BDA0002633486130000082
wherein r is the distance between the target and the detection system; v is the target velocity; f. of0Is the radio signal carrier frequency; c is the speed of light in vacuum; mu is B/T is the frequency modulation slope of the frequency modulation continuous wave signal, B is the signal bandwidth, and T is the signal rising edge or falling edge duration; Δ fupThe frequency difference is obtained after the frequency mixing of the rising edge signals of the frequency modulation continuous waves; Δ fdownThe frequency difference is obtained after the frequency mixing of the frequency modulation continuous wave falling edge signals;
wherein, Δ fupAnd Δ fdownThe method is obtained by finding a corresponding power peak point in a harmonic reconstruction spectrum Ψ (f), and Ψ (f) is expressed as:
Figure BDA0002633486130000083
wherein f ispTo modulate frequency, [ phi ]kFor modulating the frequency spectrum of the signal at [0, fp/2]A mapping of (2); k represents phi mapped by the k-th harmonickA function;
Figure BDA0002633486130000084
y (f) is the frequency spectrum of the frequency-modulated continuous wave signal of the receiving end after time modulation and frequency mixing; q represents a natural number;
the calculation formula of the direction information is as follows:
Figure BDA0002633486130000085
wherein R isi(theta) is the energy proportional relation of different harmonic signals in the ith region, Ri(theta) corresponds to different angle values covered in the current area one by one; AFi，L(theta) and AFi，R(theta) left and right harmonic directional pattern gains in the i-th region, respectively, thetai，floorAnd thetai，upperRespectively, the lower and upper angular limits of the i-th zone.
In particular, the time modulation module 6 comprises the modulation frequency f of the time modulation module 6pModulating the frequency modulation slope mu of the frequency modulation continuous wave signal generated by the frequency modulation continuous wave signal generation module 1, and transmitting signal carrier frequency f0And the target distance r and the speed v satisfy the following relation:
4(rμ+f0v)/c≤fp (6)。
specifically, the time modulation module 6 includes a single-pole single-throw radio frequency switch, a single-pole multiple-throw radio frequency switch, or a digital phase shifter.
Specifically, the radio frequency power distribution network includes a multi-path power distribution network, a reconfigurable power distribution network, or a power divider.
The single-pole multi-throw radio frequency switch replaces the time modulation module 6 and the power combiner 7.
The invention provides a frequency modulation continuous wave detection method based on a time modulation technology, which comprises the following steps: the system comprises a frequency modulation continuous wave signal generation module 1, a radio frequency power distribution network 2, a power amplifier 3 and a transmitting antenna 4; the system comprises a receiving antenna array 5, a time modulation module 6, a power combiner 7, a low noise amplifier 8, a mixer 9, a low pass filter 10, an analog-to-digital converter 11, a digital signal processing module 12 and a digital control module 13;
the frequency modulation continuous wave signal generation module 1 is connected with an input port of the radio frequency power distribution network 2; the output port I of the radio frequency power distribution network 2 and the power amplifier 3; the power amplifier 3 is connected with the transmitting antenna 4;
the receiving antenna array 5 is connected with the time modulation module 6; the time modulation module 6 is connected with the power combiner 7; the power combiner 7 is connected with the low noise amplifier 8; the low noise amplifier 8 is connected with the radio frequency input port of the mixer 9; the output port of the mixer 9 is connected with the low-pass filter 10; the low-pass filter 10 is connected with the analog-to-digital converter 11; the analog-to-digital converter 11 is connected with the digital signal processing module 12; the local oscillation input port of the frequency mixer 9 is connected with the second output port of the radio frequency power distribution network 2; the digital control module 13 is connected with the time modulation module 6;
the frequency modulation continuous wave signal generation module 1 generates a frequency modulation continuous wave signal, the signal energy is equally divided through the radio frequency power distribution network 2, the signal energy is amplified through the power amplifier 3, and the signal is radiated to the space through the transmitting antenna 4;
when the signal sent by the transmitting antenna 4 reaches the target, the target reflects the transmitted signal to form an echo signal; the receiving antenna array 5 receives an echo signal, the time modulation module 6 performs periodic modulation on the echo signal, and the modulated signal is converted into a digital signal through the low-pass filter 10 and the analog-to-digital converter 11 after being subjected to down-conversion and deskew in sequence by the power combiner 7, the low-noise amplifier 8 and the mixer 9; inputting the digital signal into the digital signal processing module 12 to realize the calculation of the target distance, speed and direction information;
the digital control module 13 controls the modulation time sequence of the time modulation module 6 to perform periodic modulation;
the calculation of the target distance, speed and direction information by using the digital signal processing module 12 includes:
the target distance includes:
Figure BDA0002633486130000101
the speed calculation includes:
Figure BDA0002633486130000102
wherein r is the distance between the target and the detection system; v is the target velocity; f. of0Is the radio signal carrier frequency; c is the speed of light in vacuum; mu is B/T is the frequency modulation slope of the frequency modulation continuous wave signal, B is the signal bandwidth, and T is the signal rising edge or falling edge duration; Δ fupThe frequency difference is obtained after the frequency mixing of the rising edge signals of the frequency modulation continuous waves; Δ fdownThe frequency difference is obtained after the frequency mixing of the frequency modulation continuous wave falling edge signals;
wherein, Δ fupAnd Δ fdownThe method is obtained by finding a corresponding power peak point in a harmonic reconstruction spectrum Ψ (f), and Ψ (f) is expressed as:
Figure BDA0002633486130000103
wherein f ispTo modulate frequency, [ phi ]kFor modulating the frequency spectrum of the signal at [0, fp/2]A mapping of (2); k represents phi mapped by the k-th harmonickA function;
Figure BDA0002633486130000104
y (f) is the frequency spectrum of the frequency-modulated continuous wave signal of the receiving end after time modulation and frequency mixing; q represents a natural number;
the calculation formula of the direction information is as follows:
Figure BDA0002633486130000105
wherein R isi(theta) is the energy proportional relation of different harmonic signals in the ith region, Ri(theta) corresponds to different angle values covered in the current area one by one; AFi，L(theta) and AFi，R(theta) left and right harmonic directional pattern gains in the i-th region, respectively, thetai，floorAnd thetai，upperRespectively, the lower and upper angular limits of the i-th zone.
Example 2
Example 2 is a modification of example 1
As shown in fig. 1, in an embodiment, the method for detecting a frequency modulated continuous wave based on a time modulation technique includes a frequency modulated continuous wave signal generating module 1, a power divider 2, a power amplifier 3, a transmitting antenna 4, an eight-element receiving antenna array 5, a time modulation module 6, a power combiner 7, a low noise amplifier 8, a mixer 9, a low pass filter 10, an analog-to-digital converter 11, a digital signal processing module 12, and a digital control module 13. The frequency modulation continuous wave signal generation module 1 is respectively connected with the power divider 2, the power amplifier 3 and the transmitting antenna 4; the receiving antenna array 5 is sequentially connected with a time modulation module 6, a power combiner 7, a low noise amplifier 8, a mixer 9, a low pass filter 10, an analog-to-digital converter 11 and a digital signal processing module 12; the digital control module 13 is connected with the time modulation module 6
Frequency modulation continuous wave detection method based on time modulation technology for distance measurement, speed measurement and direction measurement
Assuming that the carrier frequency of the transmitted FM continuous wave signal is f024GHz and bandwidth B50MHz, time length T is 1ms, frequency modulation slope is mu 2B/T is 1 × 1011. The transmitted signal may be expressed as:
Figure BDA0002633486130000111
wherein St，upAnd St，downThe time-frequency relationship diagram of the transmitted signal is shown in fig. 2, and the rising edge and the falling edge of the signal have an ideal linear relationship in the time-frequency domain.
The array element spacing d of the receiving antenna array is lambda/2, and lambda is c/f0C is the speed at which the electromagnetic wave propagates in a vacuum. Assuming that the normal phase direction azimuth angle of the target relative to the array is-25 degrees, when the array antenna receives, all the time modulation modules are sequentially switched on in a unit period for time modulation, and the modulation period is T p1 mus, modulation frequency fp1MHz, each antenna element has an on-time of 0.125 mus during one modulation period. The signal is reflected by the target and then received and modulated by the array, and the receiving period number of the whole frequency modulation continuous wave echo signal is M-T/Tp1000. Fig. 3 is a time-frequency relationship diagram of a received echo signal after modulation. It can be seen that after the reflected signal is time-modulated, the incident frequency-modulated continuous wave echo signal is time-modulated and then decomposed into the sum of infinite harmonic signals in the time-frequency domain, and the difference between the carrier frequencies of adjacent harmonics is the modulation frequency of the switch.
Assuming a target distance of 300 meters and a velocity of 50 meters/second, the normal phase azimuth angle θ to the array is-25 °. After the frequency modulation continuous wave echo signal is subjected to time modulation, the echo signal is subjected to deskew and sampling by the frequency mixer to be converted into a digital signal. And obtaining the frequency spectrum Y (f) after deskewing each order of harmonic in the output signal after FFT of the digital signal. By making the frequency spectrum of different areas of Y (f) in [0, fp/2]And performing up-mapping processing to obtain a mapped signal:
Figure BDA0002633486130000121
again taking the harmonic to map the spectrum phik(f) Performing power reconstruction processing, a harmonic power reconstruction spectrum Ψ (f) can be obtained, which can be expressed as:
Figure BDA0002633486130000122
where k is a mapping of each order of harmonic order, and fig. 4 to 6 are normalized energy graphs of power reconstruction at different k values, it can be seen that the reconstructed power is closer to the original power without modulation as the k value is larger compared with the original power without time modulation. Meanwhile, even if k belongs to the range of [0, 5], the difference between the reconstructed power and the original power without time modulation can still be ensured to be within the range of 1dB, and the power reconstruction better ensures that the energy dispersed in harmonic waves is effectively used in the process of distance measurement and speed measurement. By performing power reconstruction and frequency domain analysis on the deskewed echo signal, a distance calculation formula can be further used:
Figure BDA0002633486130000123
and velocity calculation formula:
Figure BDA0002633486130000124
the distance to the target was 300 meters and the speed was 50 meters/second. At the same time, byk(f) The power calculation between different harmonics in the function can result in normalized energy of minus 2 and minus 1 harmonics of-2.305 dB and-8.501 dB, respectively, so the orientation of the target θ can be obtained as-25 ° from the mapping of the amplitude comparison and the angle.
Those skilled in the art will appreciate that, in addition to implementing the systems, apparatus, and various modules thereof provided by the present invention in purely computer readable program code, the same procedures can be implemented entirely by logically programming method steps such that the systems, apparatus, and various modules thereof are provided in the form of logic gates, switches, application specific integrated circuits, programmable logic controllers, embedded microcontrollers and the like. Therefore, the system, the device and the modules thereof provided by the present invention can be considered as a hardware component, and the modules included in the system, the device and the modules thereof for implementing various programs can also be considered as structures in the hardware component; modules for performing various functions may also be considered to be both software programs for performing the methods and structures within hardware components.
The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention. The embodiments and features of the embodiments of the present application may be combined with each other arbitrarily without conflict.

Claims (10)

1. A frequency modulated continuous wave detection system based on time modulation technique, comprising: the device comprises a signal transmitting module and a signal receiving module;
the signal transmitting module comprises a frequency modulation continuous wave signal generating module (1), a radio frequency power distribution network (2), a power amplifier (3) and a transmitting antenna (4);
the signal receiving module comprises a receiving antenna array (5), a time modulation module (6), a power combiner (7), a low noise amplifier (8), a mixer (9), a low-pass filter (10), an analog-to-digital converter (11), a digital signal processing module (12) and a digital control module (13);
the frequency modulation continuous wave signal generation module (1) is connected with an input port of the radio frequency power distribution network (2); the radio frequency power distribution network (2) has one output port and the power amplifier (3); the power amplifier (3) is connected with the transmitting antenna (4);
the receiving antenna array (5) is connected with the time modulation module (6); the time modulation module (6) is connected with the power combiner (7); the power combiner (7) is connected with the low noise amplifier (8); the low noise amplifier (8) is connected with a radio frequency input port of the mixer (9); the output port of the mixer (9) is connected with the low-pass filter (10); the low-pass filter (10) is connected with the analog-to-digital converter (11); the analog-to-digital converter (11) is connected with the digital signal processing module (12); the local oscillation input port of the frequency mixer (9) is connected with the second output port of the radio frequency power distribution network (2); the digital control module (13) is connected with the time modulation module (6).
2. A frequency modulated continuous wave detection system according to claim 1 wherein said signal transmission module comprises:
the frequency modulation continuous wave signal generation module (1) generates a frequency modulation continuous wave signal, the signal energy is equally divided through the radio frequency power distribution network (2), the signal energy is amplified through the power amplifier (3), and the signal is radiated to the space through the transmitting antenna (4).
3. A frequency modulated continuous wave detection system according to claim 1 wherein said signal receiving module comprises:
when the signal sent by the transmitting antenna (4) reaches the target, the target reflects the transmitted signal to form an echo signal; the receiving antenna array (5) receives an echo signal, the time modulation module (6) performs periodic modulation on the echo signal, and the modulated signal is converted into a digital signal through the low-pass filter (10) and the analog-to-digital converter (11) after being subjected to down-conversion and deskew in sequence by the power combiner (7), the low-noise amplifier (8) and the mixer (9); and inputting the digital signals into the digital signal processing module (12) to realize the calculation of the target distance, speed and direction information.
4. Frequency modulated continuous wave detection system based on time modulation technique according to claim 1 characterized in that the digital control module (13) controls the modulation timing of the time modulation module (6) to be modulated periodically.
5. Frequency modulated continuous wave detection system based on a time modulation technique according to claim 1 characterized in that the receiving antenna array (5) comprises a plurality of antenna array elements.
6. Frequency modulated continuous wave detection system based on time modulation technique according to claim 3 characterized in that said calculation of target distance, speed and direction information with digital signal processing module (12) comprises:
the target distance includes:
Figure FDA0002633486120000021
the speed calculation includes:
Figure FDA0002633486120000022
wherein r is the distance between the target and the detection system; v is the target velocity; f. of0Is the radio signal carrier frequency; c is the speed of light in vacuum; mu is B/T is the frequency modulation slope of the frequency modulation continuous wave signal, B is the signal bandwidth, and T is the signal rising edge or falling edge duration; Δ fupThe frequency difference is obtained after the frequency mixing of the rising edge signals of the frequency modulation continuous waves; Δ fdownThe frequency difference is obtained after the frequency mixing of the frequency modulation continuous wave falling edge signals;
wherein, Δ fupAnd Δ fdownThe method is obtained by finding a corresponding power peak point in a harmonic reconstruction spectrum Ψ (f), and Ψ (f) is expressed as:
Figure FDA0002633486120000023
wherein f ispTo modulate frequency, [ phi ]kFor modulating the frequency spectrum of the signal at [0, fp/2]A mapping of (2); k-meterDenotes phi mapped by the k-th harmonickA function;
Figure FDA0002633486120000024
y (f) is the frequency spectrum of the frequency-modulated continuous wave signal of the receiving end after time modulation and frequency mixing; q represents a natural number;
the calculation formula of the direction information is as follows:
Figure FDA0002633486120000031
wherein R isi(theta) is the energy proportional relation of different harmonic signals in the ith region, Ri(theta) corresponds to different angle values covered in the current area one by one; AFi，L(theta) and AFi，R(theta) left and right harmonic directional pattern gains in the i-th region, respectively, thetai，floorAnd thetai，upperRespectively, the lower and upper angular limits of the i-th zone.
7. Frequency modulated continuous wave detection system based on time modulation technique according to claim 6 characterized in that the time modulation module (6) comprises the modulation frequency f of the time modulation module (6)pModulating the frequency modulation slope mu of the frequency modulation continuous wave signal generated by the frequency modulation continuous wave signal generation module (1), and transmitting signal carrier frequency f0And the target distance r and the speed v satisfy the following relation:
4(rμ+f0v)/c≤fp (6)。
8. frequency modulated continuous wave detection system based on time modulation technique according to claim 1 characterized in that the time modulation module (6) comprises a single pole single throw radio frequency switch, a single pole multiple throw radio frequency switch or a digital phase shifter.
9. A frequency modulated continuous wave detection system according to claim 1 wherein said radio frequency power distribution network comprises a multiplexed power distribution network, a reconfigurable power distribution network or a power divider.
10. A frequency modulation continuous wave detection method based on a time modulation technology is characterized by comprising the following steps: the system comprises a frequency modulation continuous wave signal generating module (1), a radio frequency power distribution network (2), a power amplifier (3) and a transmitting antenna (4); the antenna comprises a receiving antenna array (5), a time modulation module (6), a power combiner (7), a low noise amplifier (8), a mixer (9), a low-pass filter (10), an analog-to-digital converter (11), a digital signal processing module (12) and a digital control module (13);
the frequency modulation continuous wave signal generation module (1) is connected with an input port of the radio frequency power distribution network (2); the radio frequency power distribution network (2) has one output port and the power amplifier (3); the power amplifier (3) is connected with the transmitting antenna (4);
the receiving antenna array (5) is connected with the time modulation module (6); the time modulation module (6) is connected with the power combiner (7); the power combiner (7) is connected with the low noise amplifier (8); the low noise amplifier (8) is connected with a radio frequency input port of the mixer (9); the output port of the mixer (9) is connected with the low-pass filter (10); the low-pass filter (10) is connected with the analog-to-digital converter (11); the analog-to-digital converter (11) is connected with the digital signal processing module (12); the local oscillation input port of the frequency mixer (9) is connected with the second output port of the radio frequency power distribution network (2); the digital control module (13) is connected with the time modulation module (6);
the frequency modulation continuous wave signal generation module (1) generates a frequency modulation continuous wave signal, the signal energy is equally divided through the radio frequency power distribution network (2), the signal energy is amplified through the power amplifier (3), and the signal is radiated to the space through the transmitting antenna (4);
when the signal sent by the transmitting antenna (4) reaches the target, the target reflects the transmitted signal to form an echo signal; the receiving antenna array (5) receives an echo signal, the time modulation module (6) performs periodic modulation on the echo signal, and the modulated signal is converted into a digital signal through the low-pass filter (10) and the analog-to-digital converter (11) after being subjected to down-conversion and deskew in sequence by the power combiner (7), the low-noise amplifier (8) and the mixer (9); inputting digital signals into the digital signal processing module (12) to realize the calculation of target distance, speed and direction information;
the digital control module (13) controls the modulation time sequence of the time modulation module (6) to perform periodic modulation;
the calculation of the target distance, speed and direction information by using the digital signal processing module (12) comprises the following steps:
the target distance includes:
Figure FDA0002633486120000041
the speed calculation includes:
Figure FDA0002633486120000042
wherein r is the distance between the target and the detection system; v is the target velocity; f. of0Is the radio signal carrier frequency; c is the speed of light in vacuum; mu is B/T is the frequency modulation slope of the frequency modulation continuous wave signal, B is the signal bandwidth, and T is the signal rising edge or falling edge duration; Δ fupThe frequency difference is obtained after the frequency mixing of the rising edge signals of the frequency modulation continuous waves; Δ fdownThe frequency difference is obtained after the frequency mixing of the frequency modulation continuous wave falling edge signals;
wherein, Δ fupAnd Δ fdownThe method is obtained by finding a corresponding power peak point in a harmonic reconstruction spectrum Ψ (f), and Ψ (f) is expressed as:
Figure FDA0002633486120000043
wherein f ispIn order to modulate the frequency of the signal,Φkfor modulating the frequency spectrum of the signal at [0, fp/2]A mapping of (2); k represents phi mapped by the k-th harmonickA function;
Figure FDA0002633486120000044
y (f) is the frequency spectrum of the frequency-modulated continuous wave signal of the receiving end after time modulation and frequency mixing; q represents a natural number;
the calculation formula of the direction information is as follows:
Figure FDA0002633486120000051
wherein R isi(theta) is the energy proportional relation of different harmonic signals in the ith region, Ri(theta) corresponds to different angle values covered in the current area one by one; AFi，L(theta) and AFi，R(theta) left and right harmonic directional pattern gains in the i-th region, respectively, thetai，floorAnd thetai，upperRespectively, the lower and upper angular limits of the i-th zone.
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