CN111722218B - Double-frequency composite waveform high-frequency radar system - Google Patents
Double-frequency composite waveform high-frequency radar system Download PDFInfo
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- CN111722218B CN111722218B CN202010495403.3A CN202010495403A CN111722218B CN 111722218 B CN111722218 B CN 111722218B CN 202010495403 A CN202010495403 A CN 202010495403A CN 111722218 B CN111722218 B CN 111722218B
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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
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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
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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
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Abstract
The invention discloses a dual-frequency composite waveform high-frequency radar system, which is based on a composite waveform combining a frequency modulation interrupted continuous wave system and a linear frequency modulation pulse system, adopts the linear frequency modulation pulse system working at a lower frequency band and a narrower frequency sweep period and the frequency modulation interrupted continuous wave system working at a higher frequency band and a longer frequency sweep period to simultaneously work, ensures that two waveforms simultaneously work not only without mutual interference but also have complementary advantages through reasonable parameter design, simultaneously completes the demodulation of two waveform echo signals at a receiving end echo signal demodulation unit through a matched filtering method and a slope removal method, ensures that the radar has the advantages of sea state parameter real-time monitoring while having the detection capability of moving targets at different distances and different speeds and in low altitude, and greatly improves the detection performance of the radar.
Description
Technical Field
The invention relates to the field of high-frequency beyond visual range radars, in particular to a dual-frequency composite waveform high-frequency radar system.
Background
The high-frequency ground wave radar is a new ocean remote sensing device, has the advantages of large detection area, all-weather working, low operation cost and the like, can realize the monitoring of the dynamic state of the ocean surface for tens of thousands of square kilometers, can also realize the detection and tracking of the moving target on the sea surface and low altitude, and can play a positive role in the aspects of ocean supervision, maritime search and rescue, traffic management and the like. The real-time monitoring information of the ocean surface dynamics state can be used as the basis for sea clutter suppression in the real-time detection of targets, and the sea target detection is used for important links such as channel calibration, clutter suppression and the like in the ocean state monitoring.
However, the traditional high-frequency ground wave radar mostly adopts a single waveform system, is difficult to realize the simultaneous detection of the far and near distance ocean state and the fast and slow speed targets, and cannot give full play to the advantages of the high-frequency ground wave radar. Most high-Frequency ground Wave radars adopt a receiving and transmitting common station, in order to avoid the influence of strong direct waves on a receiver, frequency Modulated Interrupted Continuous Waves (FMICW) are adopted, the high-Frequency ground Wave radar has the advantages of linear Frequency sweeping Continuous waves and a pulse system, the harsh requirements of large difference of strength of echo waves at far and near sea surfaces on the dynamic range of the receiver can be better overcome, sea condition information of a plurality of distance points can be obtained through one-time measurement, however, the Frequency sweeping period needs to be reduced when a high-speed moving target is detected, the maximum distance capable of being detected is limited by receiving and transmitting pulses. A Chirp Pulse (Chirp Pulse) waveform is often used in the detection of a long-distance high-speed moving target of a radar to ensure a longer detection distance and a wider doppler spectrum width, but due to the influence of different times of transceiving required by a transceiving common station, the bandwidth of an echo at a short distance is reduced, so that a short distance is blurred, and when the detection distance needs to be considered far and near, the waveform system has a very high requirement on the dynamic range of a receiver. Therefore, the method for designing the waveform of the high-frequency ground wave radar and realizing the system is researched, a complementary waveform system which does not interfere with each other is constructed and applied to the system, the complementary waveform system is applied to an actual system, and a dual-frequency composite waveform radar high-frequency receiver system is designed, so that the high-frequency radar can realize the simultaneous detection of the near-far distance ocean state and the fast-slow speed target, and has important research significance and application value.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a dual-frequency composite waveform high-frequency radar system which has the capability of simultaneously detecting a far-near distance ocean state and fast and slow targets.
In order to achieve the purpose, the invention provides the following technical scheme: a dual-frequency composite waveform high-frequency radar system is characterized in that a composite waveform system is adopted, a Frequency Modulation Interrupt Continuous Wave (FMICW) system and a Chirp Pulse (Chirp Pulse) system are combined, and waveform parameters are reasonably set to enable the radar to work together, so that the radar has the capability of simultaneously detecting a far-near marine state and a fast-slow target.
The composite waveform system adopts a Chirp Pulse (Chirp Pulse) system working at a lower frequency band and with a narrower Pulse period to realize remote detection; meanwhile, a Frequency Modulation Interrupted Continuous Wave (FMICW) system working at a higher frequency band and a longer frequency sweep period is adopted to realize close-range detection.
The design of the composite waveform system comprises the working frequency f of a Chirp Pulse (Chirp Pulse) system 0L Emission pulse period T L Emission pulse width T pL Receiving a pulse width T BL Selecting; operating frequency f of frequency-modulated interrupted continuous wave (FMICW) system 0M Sweep period T s Gate control pulse period T M Gate control pulse width T pM Receiving a pulse width T BH Selecting; and determining the working time sequence of the two waveform systems. The specific process of designing the composite waveform system comprises the following steps:
step 1: selecting a working carrier frequency of a linear frequency modulation pulse system according to the farthest detection distance required by the radar, determining a transmission pulse period of the linear frequency modulation pulse system according to the maximum speed of a target to be detected, determining a transmission pulse width of the linear frequency modulation pulse system and a receiving pulse width of the linear frequency modulation pulse system to obtain a distance detection range of the linear frequency modulation pulse system, and further constructing a transmission signal model of the linear frequency modulation pulse system;
preferably, the operating carrier frequency of the chirp system in step 1 is f 0L ；
Step 1, determining the transmission pulse period of a linear frequency modulation pulse system according to the maximum speed of the target to be detected, wherein the transmission pulse period is as follows:
emission pulse period T of the chirp system L With the maximum velocity v of the object to be detected max Satisfy the relationship
Wherein, T L The transmission pulse period being a chirp system, c being the speed of light, f dmax Doppler shift, f, corresponding to the maximum velocity of the object to be measured 0L Selecting T for the working carrier frequency of the linear frequency modulation pulse system on the premise of satisfying the formula L ；
Step 1 determining the transmission pulse width T of the chirp system pL It should satisfy:
wherein, T pL Transmission pulse width, B, of a chirp system L Swept bandwidth, Δ R, for signals transmitted over the system L For the range resolution of the system, c is the speed of light, and T is determined according to the detection requirement of the range resolution by combining the relation pL Is selected on the premise of satisfying the formula pL ；
Step 1 receiving pulse width T of said linear frequency modulation pulse system BL It should satisfy:
wherein, T BL Selecting T for the pulse width of the linear frequency modulation pulse system on the premise of satisfying the formula BL ；
Step 1, the distance detection range of the linear frequency modulation pulse system is R minL ～R max ；
Wherein R is minL Lower limit of range detection, R, for a chirp system max The maximum detection range required for the radar;
step 1, the emission signal model of the chirp system is as follows:
wherein k is L ＝B L /T pL For slope of frequency sweep, T pL Transmission pulse width, B, of a chirp system L The sweep bandwidth of the transmitted signal for this system, T being the time, T L Period of transmitted pulse, f, of chirp system 0L Working carrier frequency of linear frequency modulation pulse system;
step 2: determining the working carrier frequency, the frequency sweep period, the frequency sweep bandwidth, the gate control pulse period, the gate control pulse width and the receiving pulse width of a frequency modulation interrupt continuous wave system according to the lower limit of the distance detection range of the linear frequency modulation pulse system, and constructing a transmitting signal model of the frequency modulation interrupt continuous wave system;
preferably, the operating carrier frequency of the frequency modulation interrupted continuous wave system determined in step 2 is f 0H The farthest detection distance of the frequency modulation interrupted continuous wave system is required to be greater than the lower limit of the distance detection range of the linear frequency modulation pulse system, namely R minL. 。
Preferably, the determining of the modulation-interrupted continuous wave system gating pulse period T as described in step 2 L Pulse period T of gate control pulse corresponding to frequency modulation interrupt continuous wave system H Equal and the two pulse edges are aligned to realize simultaneous triggering.
Preferably, the step 2 of determining the pulse width T of the gating pulse of the frequency-modulated interrupted continuous wave system pH Pulse width T of transmission pulse corresponding to linear frequency modulation pulse system PL And are equal.
Preferably, the sweep period T of the frequency-modulated discontinuous continuous wave system in step 2 s It should satisfy:
T s ＝N s *T H ＝N s *T L
wherein, T H 、T pH 、B H The gate control pulse period of the frequency modulation interruption continuous wave system, the gate control pulse width of the frequency modulation interruption continuous wave system and the sweep frequency bandwidth of the frequency modulation interruption continuous wave system are sequentially arranged, c is the light speed, N is the light speed s The number of gated pulses in the sweep frequency period of the frequency-modulated interrupted continuous wave system can be selected according to actual requirements minL The lower limit of the range detection range of the linear frequency modulation pulse system;
preferably, the receiving pulse width T of the FM interrupt continuous wave system in the step 2 BH The following requirements should be satisfied:
wherein, T H 、T pH The gate control pulse period and gate control pulse width of the frequency modulation interrupted continuous wave system, c is the speed of light, R minL The lower limit of the range detection range of the linear frequency modulation pulse system;
preferably, the pulse width T of the received pulse in the FM interrupt continuous wave system BH Pulse width T of received pulse of linear frequency modulation pulse system BL Equal;
step 2, the emission signal model of the frequency modulation interruption continuous wave system is as follows:
wherein f is 0H The working carrier frequency of the continuous wave system is interrupted for frequency modulation; t is a unit of H 、T pH 、T s 、T BH And B H Respectively a gate control pulse period, a gate control pulse width, a sweep frequency period, a receiving pulse width and a sweep frequency bandwidth of a frequency modulation interrupt continuous wave system; k is a radical of H ＝B H /T pH Slope of sweep frequency, T is time, rect (T/T) pH ) Represents a width of T pH And a rectangular window centered at the origin;
and step 3: transmitting signal carrier frequency f according to a chirp system 0L Bandwidth B L Pulse period T of emission pulse L Pulse width T PL Generating a transmission signal of a chirp system, according to a carrier frequency f of the transmission signal of a FM discontinuous continuous wave system 0H Bandwidth B H Gate control pulse period T H Gate control pulse width T pH Sweep period T s Sweep bandwidth B H Generating a transmitting signal of a frequency modulation interrupted continuous wave system;
and 4, step 4: receiving pulse width T according to chirp system BL Controlling the receiving/transmitting switch to receive the echo signal of the system according to the receiving pulse width T of the frequency-modulated interrupted continuous wave system BH And controlling the receiving and transmitting switch to receive the echo signals of the system.
In order to realize a composite waveform system, the dual-frequency high-frequency radar receiver system comprises: the device comprises a synchronous control unit, a transmitting signal synthesis unit, a receiving analog front end, an echo signal demodulation unit, a data transmission unit and an upper computer;
the synchronous control unit is connected with the transmitting signal synthesis unit in a wired mode; the synchronous control unit is connected with the receiving analog front end in a wired mode; the synchronous control unit is connected with the echo signal demodulation unit in a wired mode; the synchronous control unit is connected with the data transmission unit in a wired mode; the receiving analog front end, the echo signal demodulation unit, the data transmission unit and the upper computer are connected in sequence in a wired mode;
the transmitting signal synthesis unit completes the generation of the transmitting signal, and the generated signal is transmitted to the external power amplification unit; the power amplification unit is composed of a first power amplifier and a second power amplifier;
preferably, the transmitting signal synthesizing unit comprises a first transmitting path and a second transmitting path which are parallel, the first transmitting path generates a transmitting signal of a linear frequency modulation pulse system, the second transmitting path generates a transmitting signal of a frequency modulation interrupted continuous wave system, and the first transmitting path and the second transmitting path respectively comprise a signal generating circuit, a filter circuit, a transceiving switch and an amplifying circuit which are sequentially connected; a transmission signal of a chirp system generated by the first transmission channel is accessed to a first transmission antenna through an external first power amplifier and is radiated; the transmission signal of the frequency modulation interrupted continuous wave system generated by the second transmission channel is accessed to a second transmission antenna through an external second power amplifier to be radiated;
the signal generating circuit of the first transmitting channel transmits signal carrier frequency f according to a linear frequency modulation pulse system 0L Bandwidth B L Pulse period T of the emission pulse L Pulse width T PL To set parameters to generate a transmit signal in a chirp regime.
The signal generating circuit of the second transmitting channel transmits signal carrier frequency f according to frequency modulation interrupt continuous wave system 0H Bandwidth B H Gate control pulse period T H Gated pulse width T pH Sweep period T s Sweep bandwidth B H The parameters are set, and the transmitting signals of a frequency modulation interrupted continuous wave system are generated.
The receiving and transmitting switches of the first transmitting path and the second transmitting path are subjected to the pulse period T output by the synchronous control unit L And a pulse width of T PL The switch is closed in the high level of the pulse, the signal is transmitted, the switch is opened in the low level, and the signal is not transmitted;
the central frequency of the filter of the first transmission path is matched with the transmission signal carrier frequency f of the chirp system 0L Consistency;
the central frequency of the filter of the second transmission path follows the transmission signal f of the frequency-modulated discontinuous continuous wave system 0H Consistency;
preferably, the receiving analog front end completes the amplification filtering and the digital-to-analog conversion of the echo signal.
Further, the receiving analog front end includes a transceiving switch, a power divider, a first receiving path, and a second receiving path; the receiving and transmitting switch is connected with the power divider in a wired mode; the power divider is respectively connected with the first receiving channel and the second receiving channel in parallel in sequence in a wired mode;
the pulse period of the receiving and transmitting switch output by the synchronous control unit is T L And a pulse width of T BL The on-off of the signal is realized by the control of the received pulse, the switch is closed in the high level of the pulse, the signal is received, and the switch is opened in the low level and is not received;
the power divider divides the echo signal into two paths of signals with equal power and respectively transmits the two paths of signals to the first receiving channel and the second receiving channel;
the first receiving path and the second receiving path respectively comprise a filter, an amplifier and an analog-to-digital conversion circuit which are connected in sequence;
the filter of the first receive path is the same as the filter in the first transmit path. After the echo signal passes through the filter, the echo signal of the linear frequency modulation pulse system is reserved, and the echo signal of the frequency modulation interrupt continuous wave system is filtered;
the filter of the second receive path is the same as the filter in the second transmit path. After the echo signal passes through the filter, the frequency modulation interrupt continuous wave system echo signal is reserved, and the chirp pulse system echo signal is filtered;
the first receiving channel outputs a chirp system echo digital signal;
the second receiving channel outputs a frequency-modulated interrupted continuous wave system echo digital signal;
preferably, the echo signal demodulation unit includes a first demodulation path and a second demodulation path;
the first demodulation channel demodulates the frequency modulation pulse system echo digital signal to obtain a linear frequency modulation pulse baseband signal; and the second demodulation channel demodulates the frequency modulation interrupted continuous wave body echo digital signal to obtain a frequency modulation interrupted continuous wave baseband signal.
The first demodulation path adopts a matched filtering method for demodulation and comprises a quadrature frequency mixing module, an extraction filtering module and a matched filtering module which are connected in sequence; the matched filtering module comprises an FFT module, a complex multiplier module and an IFFT module which are connected in sequence;
the second demodulation channel adopts a slope removal method for demodulation and comprises an orthogonal frequency mixing module and a decimation filtering module which are connected in sequence;
the data transmission unit completes data transmission of the demodulated baseband signal and transmission of control parameters, and the data transmission interface is connected with the upper computer.
Preferably, said control parameter comprises the operating frequency f of a previously defined chirp system 0L Sweep bandwidth B L Emission pulse period T L Emission pulse width T pL Receiving a pulse width T BL (ii) a Working frequency f of frequency-modulated interrupted continuous wave system 0M Sweep bandwidth B H Sweep period T s Gate control pulse period T M Gated pulse width T pM Receiving a pulse width T BH And the like. The data transmission unit can be controlled by FPGA, and the data transmission can be completed by Ethernet port, USB and other modes.
The synchronous control unit generates a transmitting pulse control signal and a receiving pulse control signal according to the control parameters transmitted by the data transmission unit.
Preferably, the transmission pulse is a transmission pulse of a determined chirp system, and the relevant parameter is a transmission pulse period T L Emission pulse width T pL . Preferably, the received pulse is a received pulse of a determined chirp system, and the relevant parameter is the received pulseWidth T BL . Preferably, the synchronous control unit may be implemented by an FPGA.
Compared with the prior art, the invention has the advantages that:
the dual-frequency composite waveform high-frequency radar system breaks through the limitation of a traditional single waveform system of the series of radars, and combines a Chirp Pulse (Chirp Pulse) system and a Frequency Modulation Interrupt Continuous Wave (FMICW) system through reasonable parameter design to realize the complementary advantages of the two waveforms without mutual influence;
the double-frequency composite waveform high-frequency radar system enables the radar receiver to have the advantages of detecting a long-distance high-speed moving target in real time, detecting a short-distance low-speed target and monitoring an ocean state, and greatly improves the radar detection performance;
the transmitting signal synthesis and signal demodulation processing mechanisms in the two waveform systems of the dual-frequency composite waveform high-frequency radar system are easy to configure, high in flexibility, capable of being changed according to actual requirements and easy to maintain and upgrade.
Drawings
FIG. 1 is a flow chart of the design of the composite waveform system in the method of the present invention;
FIG. 2 is a timing diagram of the Chirp Pulse and FMICW transmit-receive in the composite waveform system designed by the present invention;
FIG. 3 is a block diagram of a dual-frequency complex waveform high-frequency radar system designed by the present invention;
FIG. 4 is a block diagram of a Chirp Pulse echo signal demodulation module and a block diagram of a digital down-conversion module in the invention;
fig. 5 is a block diagram of a FMICW echo signal demodulation module and a digital down-conversion module according to the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
A dual-frequency composite waveform high-frequency radar system is characterized in that the system adopts a composite waveform system, so that the radar has the capability of simultaneously detecting a far-near distance ocean state and fast and slow targets. The composite waveform design is to adopt a Chirp Pulse (Chirp Pulse) system working at a lower frequency band and a narrower sweep frequency period to realize the real-time detection of a high-speed target at a long distance; meanwhile, a Frequency Modulation Interrupted Continuous Wave (FMICW) system working at a higher frequency band and a longer frequency sweep period is adopted to realize the fine detection of the ocean state parameters and the low-speed target at a close distance.
The following describes the embodiments of the present invention with reference to fig. 1 to 5:
according to the design process of the composite waveform system in the method of the present invention as shown in FIG. 1, the farthest detection distance R of the radar is used max For example, 300km and 5km distance resolution are required, and a waveform system is designed.
According to the radar equation, the target echo intensity P of the ground wave over-the-horizon radar propagating along the ocean surface r Generally expressed as:
wherein, P av Represents the average transmitted power of the radar; g t Representing the directional gain of the transmit antenna; g r Represents the directional gain of the receiving antenna; r represents the distance between the target and the radar base station; σ represents a scattering cross-sectional area of the target; l is a radical of an alcohol s Characterizing radar system loss; f (R) represents a Norton attenuation term when the distance is R; λ = c/f denotes the operating wavelength. To achieve detection, the target echo intensity P r Must be greater than the sensitivity of the radar receiver. By combining the two relations and combining the available frequency range of the ground wave radar, the working frequency f of a proper Chirp Pulse (Chirp Pulse) waveform system can be selected 0L . The working carrier frequency of the linear frequency modulation pulse system is f by combining the available distribution frequency of the ground wave radar 0L Take 4.4MHz.
Assuming a maximum velocity v of the object to be detected max 300m/s, the transmission pulse period T of the linear frequency modulation pulse system L Should satisfy the relationship
T is selected on the premise of satisfying the formula L Take 4ms.
According to the requirement of distance resolution ratio, the sweep frequency bandwidth B of the transmitting signal of the linear frequency modulation pulse system is taken L 30kHz, the transmission pulse width T of the chirp system pL The following requirements should be satisfied:
T pL take 0.8ms. R minL Then the lower limit of the range detection range of the system of chirps is greater than or equal to>
Receiving pulse width T of linear frequency modulation pulse system BL It should satisfy:
T BL take 3.18ms.
The transmitted signal model of the chirp system is:
wherein k is L ＝B L /T pL For slope of frequency sweep, T pL 0.8ms of B L 30kHz, T is time, T L Is 4ms 0L Is 4.4MHz;
lower limit R of range detection according to linear frequency modulation pulse system minL Selecting the working carrier frequency f for determining the frequency modulation interrupted continuous wave system 0H The farthest detection distance of the frequency modulation interrupted continuous wave system is required to be more than R minL. Combined with the allocated frequency, f, available for ground-wave radar 0H Taken to be 9.3MHz.
Next, the gating pulse period T of the frequency modulation interrupted continuous wave system is determined H Gated pulse width T pH Sweep period T s Receiving a pulse width T BH Sweep bandwidth B H The number of gated pulses N within the sweep frequency period s Respectively 4ms, 0.8ms, 500ms, 3.18ms, 30kHz and 125, and further determining that a transmitting signal model of the frequency modulation interrupted continuous wave system in the step 2 is as follows:
wherein k is H ＝B H /T pH Slope of sweep frequency, T is time, rect (T/T) pH ) Indicates a width of T pH And the center is located at the rectangular window of the origin;
and combining the parameters to generate a transmitting signal of a composite waveform system, and utilizing the designed receiving pulse control system to receive the echo signal.
Fig. 2 shows a transmitting/receiving timing chart of the designed radar with a composite waveform system, fig. 2 (a) is a transmitting/receiving timing chart of a chirp system, and fig. 2 (b) is a transmitting/receiving timing chart of a frequency modulation interrupt continuous wave system. The pulse periods of the transmission pulse of the chirp system in fig. 2 (a) and the gate pulse of the fm-interrupted continuous wave system in fig. 2 (b) are equal (both are 4 ms), the pulse widths of the transmission pulse of fig. 2 (a) and the gate pulse of fig. 2 (b) are equal (both are 0.8 ms), and the pulse edges of the transmission pulse of fig. 2 (a) and the gate pulse of fig. 2 (b) are aligned and are at T p The inner two waveform systems transmit signals simultaneously. The received pulses of fig. 2 (a) and 2 (b) are equal in pulse width (3.18 ms each), equal in pulse period, and edge aligned, at T B And simultaneously receiving echo signals of two waveform systems. By the mode, the purpose that the two waveform systems work simultaneously and do not interfere with each other can be achieved.
In order to realize a composite waveform system, the dual-frequency high-frequency radar receiver system comprises: the device comprises a synchronous control unit, a transmitting signal synthesis unit, a receiving analog front end, an echo signal demodulation unit, a data transmission unit and an upper computer; the structure of the dual-frequency composite waveform high-frequency radar system is shown in figure 3.
In order to realize the dual-frequency composite waveform work of the system, the transmitting signal synthesis unit comprises a first transmitting path TH L And a second transmission path TH H . First transmission path TH L The carrier wave of the linear frequency modulation pulse system is generated to be 4.4MHz transmitting signal (S) TL ) Second transmission path TH H Generating a transmission signal (S) of 9.3MHz carrier wave of frequency-modulated discontinuous continuous wave system TH ) The two transmission paths comprise a signal generating circuit, a filter circuit, a transceiving switch, an amplifying circuit and the like which are connected in sequence. The signal generating circuit can be realized by an FPGA and a DAC circuit, and can also be realized by an FPGA and a DDS chip. When the signal generating circuit is realized by adopting an FPGA and a DAC circuit, two paths of parallel NCO are needed to set parameters respectively according to the frequency, the bandwidth, the sweep frequency period and the like of two types of transmitting waveforms designed in the prior art by utilizing an NCO IP core in the FPGA and two paths of transmitting signals, two types of digital transmitting signals meeting the requirements are generated, and then the digital-to-analog conversion is realized through a two-channel DAC chip such as an AD 9747. When the FPGA and the DDS chip are adopted for realizing, two DDS chips such as AD9910 or a double-circuit DDS chip such as AD9958 are needed, the FPGA configures the DDS chips according to the frequency, the sweep frequency bandwidth, the sweep frequency period and the like of the two emission waveforms designed in the front, the DDS chips directly synthesize two emission signals, S TL The sweep frequency period is pulse width 4ms TH The sweep period is 500ms.
The filters of the first and second transmission paths often adopt band-pass filters, transmission path TH L The center frequency of the medium filter is 4.4MHz, and the transmission path TH H The center frequency of the middle filter is 9.3MHz.
The transceiving switches of the first transmitting path and the second transmitting path can adopt SA630, the transceiving switches are controlled by the transmitting pulse output by the synchronous control unit to realize the on-off of signals, the switches are closed in a pulse high level to transmit signals, the switches are opened in a low level to not transmit signals;
the receiving analog front end completes the amplification filtering and the digital-to-analog conversion of the echo signal.
The receiving analog front end comprises a receiving and transmitting switch, a power divider, a first receiving path and a second receiving path; the power generation switch is connected with the power divider in a wired mode; the power divider is respectively connected with the first receiving channel and the second receiving channel in parallel in sequence in a wired mode;
the receiving and transmitting switches can adopt SA630, and are controlled by the receiving pulse output by the synchronous control unit to realize the on-off of signals, the switches are closed in the high level of the pulse, the signals are received, and the switches are opened in the low level and are not received;
the power divider divides the echo signal into two paths of signals with equal power and respectively transmits the two paths of signals to the first receiving path and the second receiving path;
the first receiving channel and the second receiving channel respectively comprise a filter, an amplifier and an analog-to-digital conversion circuit which are connected in sequence;
the filter of the first receive path is the same as the filter in the first transmit path. After the echo signal passes through the filter, the echo signal of the linear frequency modulation pulse system is reserved, and the echo signal of the frequency modulation interrupt continuous wave system is filtered;
the filter of the second receive path is the same as the filter in the second transmit path. After the echo signal passes through the filter, the frequency modulation interrupt continuous wave system echo signal is reserved, and the chirp pulse system echo signal is filtered;
the first receiving channel outputs a chirp system echo digital signal;
the second receiving channel outputs a frequency modulation interrupted continuous wave system echo digital signal;
the echo signal demodulation unit comprises a first demodulation channel and a second demodulation channel;
the first demodulation channel demodulates the digital signal of the frequency modulation pulse system echo to obtain a linear frequency modulation pulse baseband signal; and the second demodulation channel demodulates the frequency modulation interrupt continuous wave body modulation echo digital signal to obtain a frequency modulation interrupt continuous wave baseband signal.
The first demodulation path adopts a matched filtering method for demodulation and comprises a quadrature frequency mixing module, an extraction filtering module and a matched filtering module which are connected in sequence; the matched filtering module comprises an FFT module, a complex multiplier module and an IFFT module which are connected in sequence;
the demodulation of the Chirp Pulse echo signal is explained below with reference to fig. 4. The Chirp Pulse echo signal demodulation path adopts a matched filtering method for demodulation and comprises a quadrature frequency mixing module, an extraction filtering module and a matched filtering module which are sequentially connected, wherein the quadrature frequency mixing module also comprises two paths of quadrature local oscillator signal synthesis and a digital mixer, but the local oscillator signals are single-frequency signals, so that carrier waves are removed after frequency mixing, the obtained linear frequency sweeping signals are still linear frequency sweeping signals, the linear frequency sweeping signals with lower data rate are obtained by filtering wave extraction, and the corresponding I/Q signals are sequentially input to the matched filtering module as the real part and the imaginary part of a complex analytic signal. The matched filtering module comprises an FFT module, a complex multiplier module and an IFFT module which are connected in sequence, and the baseband signal with lower data rate can be obtained through matched filtering. The whole processing process is completed in the FPGA, and the parameter setting can be modified according to the change of the actual transmitting waveform parameters.
The second demodulation channel adopts a slope removal method for demodulation and comprises an orthogonal frequency mixing module and a decimation filtering module which are connected in sequence;
the following describes the demodulation of the FMICW echo signal with reference to fig. 5, the FMICW echo signal demodulation path adopts a slope removal method for demodulation, and includes a quadrature frequency mixing module and an extraction filtering module which are connected in sequence, the quadrature frequency mixing module includes two paths of orthogonal local oscillator signal synthesis and digital mixers, the local oscillator is an FMICW signal, and is also realized by using an NCO IP core of an FPGA, the frequency and the frequency sweep slope of the NCO IP core are the same as those of a transmitting signal, and the quadrature frequency mixing completes the slope removal and the carrier removal of the echo signal to become a single-frequency signal. The decimation filtering module comprises a CIC decimation filter and a low-pass FIR filter which are connected in sequence, and the mixed signal can be subjected to decimation filtering to obtain a baseband signal with a lower data rate. The whole processing process is completed in the FPGA, and the parameter setting can be modified according to the change of the actual emission waveform parameters.
The data transmission unit completes data transmission of the demodulated baseband signal and transmission of control parameters, and the data transmission interface is connected with the upper computer. The data transmission unit can be realized by FPGA, and the data transmission can be completed by Ethernet port, USB and other modes.
The control parameters include the operating frequency f of the previously determined chirp system 0L Sweep bandwidth B L Emission pulse period T L Emission pulse width T pL Receiving a pulse width T BL (ii) a Operating frequency f of frequency-modulated interrupted continuous wave system 0M Sweep bandwidth B H Sweep period T s Gate control pulse period T M Gated pulse width T pM Receiving a pulse width T BH And so on. The data transmission unit can be controlled by FPGA, and the data transmission can be completed by Ethernet port, USB and other modes.
The synchronous control unit generates control signals such as a transmitting pulse and a receiving pulse according to the control parameters transmitted by the data transmission unit, such as the transmitting pulse and the receiving pulse in two waveform systems in fig. 2. Preferably, the synchronous control unit may be implemented by an FPGA.
And after the data are uploaded to an upper computer, respectively processing according to a conventional high-frequency ground wave radar target/sea state detection flow to obtain the required target/sea state information.
It should be understood that the above description of the preferred embodiments is given for clarity and not for any purpose of limitation, and that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (6)
1. A method for generating a dual-frequency composite waveform, comprising the steps of:
step 1: selecting a working carrier frequency of a linear frequency modulation pulse system according to the farthest detection distance required by a radar, determining a transmission pulse period of the linear frequency modulation pulse system according to the maximum speed of a target to be detected, determining a transmission pulse width of the linear frequency modulation pulse system and a receiving pulse width of the linear frequency modulation pulse system to obtain a distance detection range of the linear frequency modulation pulse system, and further constructing a transmission signal model of the linear frequency modulation pulse system;
step 2: determining the working carrier frequency, the frequency sweep period, the frequency sweep bandwidth, the gate control pulse period, the gate control pulse width and the receiving pulse width of a frequency modulation interrupt continuous wave system according to the lower limit of the distance detection range of the linear frequency modulation pulse system, and constructing a transmitting signal model of the frequency modulation interrupt continuous wave system;
and 3, step 3: generating a transmitting signal of a linear frequency modulation pulse system according to the carrier frequency and the bandwidth of a transmitting signal of the linear frequency modulation pulse system, the pulse period of the transmitting pulse and the pulse width, and generating the transmitting signal of the frequency modulation interrupt continuous wave system according to the carrier frequency and the bandwidth of the transmitting signal of the frequency modulation interrupt continuous wave system, the gate control pulse period, the gate control pulse width, the frequency sweep period and the frequency sweep bandwidth;
and 4, step 4: controlling a receiving and transmitting switch according to the receiving pulse width of a linear frequency modulation pulse system to realize the receiving of the echo signals of the system, and controlling the receiving and transmitting switch according to the receiving pulse width of a frequency modulation interrupt continuous wave system to realize the receiving of the echo signals of the system;
step 1 the working carrier frequency of the linear frequency modulation pulse system is f 0L ；
Step 1, determining the transmission pulse period of a linear frequency modulation pulse system according to the maximum speed of the target to be detected, wherein the transmission pulse period is as follows:
the transmission pulse period T of the linear frequency modulation pulse system L With the maximum speed v of the target to be detected max Satisfy the relationship
Wherein, T L The period of the transmitted pulse being a chirp system, c being the speed of light, f dmax Is the object to be measuredDoppler shift, f, for large velocities 0L Selecting T for the working carrier frequency of the linear frequency modulation pulse system on the premise of satisfying the formula L ；
Step 1 determining the transmission pulse width T of the chirp system pL It should satisfy:
wherein, T pL Transmission pulse width, B, of a chirp system L Swept bandwidth, Δ R, for signals transmitted over the system L For the range resolution of the system, c is the speed of light, and T is determined according to the detection requirement of the range resolution by combining the relation pL Is selected on the premise of satisfying the formula pL ；
Step 1 receiving pulse width T of said linear frequency modulation pulse system BL It should satisfy:
wherein, T BL Selecting T for the pulse width of the linear frequency modulation pulse system on the premise of satisfying the formula BL ；
Step 1, the distance detection range of the linear frequency modulation pulse system is R minL ～R max ；
Wherein R is minL Lower limit of range detection, R, for a chirp system max The maximum detection range required for the radar;
step 1, the emission signal model of the chirp system is as follows:
wherein k is L ＝B L /T pL Is the slope of the frequency sweep, T pL Transmission pulse width, B, of a chirp system L The sweep bandwidth of the transmitted signal for this system, T being the time, T L Transmission pulse period, f, of a chirp system 0L Working carrier frequency of linear frequency modulation pulse system;
step 2, determining the working carrier frequency of the frequency modulation interrupted continuous wave system as f 0H The farthest detection distance of the frequency modulation interrupted continuous wave system is required to be greater than the lower limit of the distance detection range of the linear frequency modulation pulse system, namely R minL .；
Step 2, determining the gating pulse period T of the frequency modulation interrupt continuous wave system L Pulse period T of gate control pulse corresponding to frequency modulation interrupt continuous wave system H The two pulse edges are aligned to realize simultaneous triggering;
step 2, determining the pulse width T of the gating pulse of the frequency modulation interrupt continuous wave system pH Pulse width T of transmission pulse corresponding to linear frequency modulation pulse system PL Equal;
step 2, the sweep frequency period T of the frequency modulation interrupt continuous wave system s It should satisfy:
T s ＝N s *T H ＝N s *T L
wherein, T H 、T pH 、B H The gate control pulse period of the frequency modulation interruption continuous wave system, the gate control pulse width of the frequency modulation interruption continuous wave system and the sweep frequency bandwidth of the frequency modulation interruption continuous wave system are sequentially arranged, c is the light speed, N is the light speed s The number of gate control pulses in the sweep frequency period of the frequency modulation interrupted continuous wave system can be selected according to actual requirements minL Distance for a chirp systemThe lower limit of the detection range;
step 2 receiving pulse width T of frequency modulation interrupt continuous wave system BH It should satisfy:
wherein, T H 、T pH The gate control pulse period and gate control pulse width of the frequency modulation interrupted continuous wave system, c is the speed of light, R minL The lower limit of the range detection range of the linear frequency modulation pulse system;
pulse width T of received pulse of frequency modulation interrupted continuous wave system BH Pulse width T of received pulse of linear frequency modulation pulse system BL Equal;
step 2, the emission signal model of the frequency modulation interruption continuous wave system is as follows:
wherein, f 0H The working carrier frequency of the frequency modulation interrupted continuous wave system; t is a unit of H 、T pH 、T s 、T BH And B H Respectively a gate control pulse period, a gate control pulse width, a sweep frequency period, a receiving pulse width and a sweep frequency bandwidth of a frequency modulation interrupt continuous wave system; k is a radical of H ＝B H /T pH Slope of sweep frequency, T is time, rect (T/T) pH ) Represents a width of T pH And a rectangular window centered at the origin.
2. A dual-frequency complex waveform high-frequency radar system applied to the dual-frequency complex waveform generation method according to claim 1, comprising:
the device comprises a synchronous control unit, a transmitting signal synthesis unit, a receiving analog front end, an echo signal demodulation unit, a data transmission unit and an upper computer;
the synchronous control unit is connected with the transmitting signal synthesis unit in a wired mode; the synchronous control unit is connected with the receiving analog front end in a wired mode; the synchronous control unit is connected with the echo signal demodulation unit in a wired mode; the synchronous control unit is connected with the data transmission unit in a wired mode; the receiving analog front end, the echo signal demodulation unit, the data transmission unit and the upper computer are connected in sequence in a wired mode;
the transmitting signal synthesis unit completes the generation of the transmitting signal, and the generated signal is transmitted to the external power amplification unit; the power amplification unit is composed of a first power amplifier and a second power amplifier;
the transmitting signal synthesizing unit comprises a first transmitting channel and a second transmitting channel which are parallel, the first transmitting channel generates transmitting signals of a linear frequency modulation pulse system, and the second transmitting channel generates transmitting signals of a frequency modulation interrupt continuous wave system;
the signal generating circuit of the first transmitting channel transmits signal carrier frequency f according to a linear frequency modulation pulse system 0L Bandwidth B L Pulse period T of emission pulse L Pulse width T PL Setting parameters to generate a transmitting signal of a linear frequency modulation pulse system;
the signal generating circuit of the second transmitting channel transmits signal carrier frequency f according to frequency modulation interrupt continuous wave system 0H Bandwidth B H Gate control pulse period T H Gate control pulse width T pH Sweep period T s Sweep bandwidth B H Setting parameters to generate a transmitting signal of a frequency modulation interrupted continuous wave system;
the receiving and transmitting switches of the first transmitting path and the second transmitting path are subjected to the pulse period T output by the synchronous control unit L And a pulse width of T PL The on-off of the signal is realized by controlling the emission pulse, the switch is closed in the high level of the pulse, the signal is emitted, and the switch is opened in the low level, and the signal is not emitted;
the central frequency of the filter of the first transmission path is matched with the transmission signal carrier of a linear frequency modulation pulse systemWave frequency f 0L The consistency is achieved;
the central frequency of the filter of the second transmitting channel is matched with the transmitting signal f of the frequency modulation interrupted continuous wave system 0H And (5) the consistency is achieved.
3. The dual frequency composite waveform high frequency radar system of claim 2, wherein:
the first transmitting path and the second transmitting path respectively comprise a signal generating circuit, a filter circuit, a receiving and transmitting switch and an amplifying circuit which are connected in sequence; a transmission signal of a chirp system generated by the first transmission channel is accessed to a first transmission antenna through an external first power amplifier and is radiated; and the transmission signal of the frequency modulation interrupted continuous wave system generated by the second transmission channel is accessed to a second transmission antenna through an external second power amplifier to radiate.
4. The dual frequency composite waveform high frequency radar system of claim 2, wherein:
the receiving analog front end completes the amplification filtering and digital-to-analog conversion of the echo signal;
the receiving analog front end comprises a receiving and transmitting switch, a power divider, a first receiving path and a second receiving path; the receiving and transmitting switch is connected with the power divider in a wired mode; the power divider is respectively connected with the first receiving channel and the second receiving channel in parallel in sequence in a wired mode;
the pulse period of the receiving and transmitting switch output by the synchronous control unit is T L A pulse width of T BL The on-off of the signal is realized by the control of the received pulse, the switch is closed in the high level of the pulse, the signal is received, and the switch is opened in the low level and is not received;
the power divider divides the echo signal into two paths of signals with equal power and respectively transmits the two paths of signals to the first receiving path and the second receiving path;
the first receiving channel and the second receiving channel respectively comprise a filter, an amplifier and an analog-to-digital conversion circuit which are connected in sequence;
the filter of the first receive path is the same as the filter in the first transmit path; after the echo signal passes through the filter, the echo signal of the linear frequency modulation pulse system is reserved, and the echo signal of the frequency modulation interrupt continuous wave system is filtered;
the filter of the second receive path is the same as the filter in the second transmit path; after the echo signal passes through the filter, the frequency modulation interrupt continuous wave system echo signal is reserved, and the linear frequency modulation pulse system echo signal is filtered;
the first receiving channel outputs a chirp system echo digital signal;
and the second receiving channel outputs a frequency modulation interrupted continuous wave system echo digital signal.
5. The dual frequency composite waveform high frequency radar system of claim 2, wherein:
the echo signal demodulation unit comprises a first demodulation channel and a second demodulation channel;
the first demodulation channel demodulates the frequency modulation pulse system echo digital signal to obtain a linear frequency modulation pulse baseband signal; the second demodulation channel demodulates the frequency modulation interrupt continuous wave body echo digital signal to obtain a frequency modulation interrupt continuous wave baseband signal;
the first demodulation path adopts a matched filtering method for demodulation and comprises a quadrature frequency mixing module, an extraction filtering module and a matched filtering module which are connected in sequence; the matched filtering module comprises an FFT module, a complex multiplier module and an IFFT module which are connected in sequence;
the second demodulation path adopts a slope removal method for demodulation and comprises an orthogonal frequency mixing module and a decimation filtering module which are connected in sequence.
6. The dual frequency composite waveform high frequency radar system of claim 2, wherein:
the data transmission unit completes data transmission of the demodulated baseband signal and transmission of control parameters, and is connected with the upper computer;
the control parameters comprise: working frequency f of linear frequency-modulated pulse system 0L Sweep bandwidth B L Emission pulse period T L Emission pulse width T pL Receiving a pulse width T BL (ii) a Working frequency f of frequency-modulated interrupted continuous wave system 0M Sweep bandwidth B H Sweep period T s Gated pulse period T M Gated pulse width T pM Receiving a pulse width T BH ；
The data transmission unit can be controlled by an FPGA;
the synchronous control unit generates a transmitting pulse control signal and a receiving pulse control signal according to the control parameters transmitted by the data transmission unit, and is realized by an FPGA.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5376939A (en) * | 1993-06-21 | 1994-12-27 | Martin Marietta Corporation | Dual-frequency, complementary-sequence pulse radar |
| CN102291170A (en) * | 2010-06-21 | 2011-12-21 | 周运伟 | FM (Frequency Modulation)/Chirp modulation-based common-frequency simulcasting system |
| CN102538768A (en) * | 2012-01-10 | 2012-07-04 | 武汉大学 | Method for measuring water depth of shallow sea based on double-frequency high-frequency ground wave radar |
| CN206411265U (en) * | 2016-10-27 | 2017-08-15 | 中国人民解放军镇江船艇学院 | A kind of double mode radar |
| CN110837081A (en) * | 2019-11-08 | 2020-02-25 | 南京理工大学 | High-speed target detection method based on P/D band radar signal fusion processing |
-
2020
- 2020-06-03 CN CN202010495403.3A patent/CN111722218B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5376939A (en) * | 1993-06-21 | 1994-12-27 | Martin Marietta Corporation | Dual-frequency, complementary-sequence pulse radar |
| CN102291170A (en) * | 2010-06-21 | 2011-12-21 | 周运伟 | FM (Frequency Modulation)/Chirp modulation-based common-frequency simulcasting system |
| CN102538768A (en) * | 2012-01-10 | 2012-07-04 | 武汉大学 | Method for measuring water depth of shallow sea based on double-frequency high-frequency ground wave radar |
| CN206411265U (en) * | 2016-10-27 | 2017-08-15 | 中国人民解放军镇江船艇学院 | A kind of double mode radar |
| CN110837081A (en) * | 2019-11-08 | 2020-02-25 | 南京理工大学 | High-speed target detection method based on P/D band radar signal fusion processing |
Non-Patent Citations (2)
| Title |
|---|
| MIMO高频地波雷达典型正交波形性能评价;常广弘等;《中国海洋大学学报(自然科学版)》;20170215;第47卷(第02期);30-35 * |
| 海洋环境监测高频地波雷达波形参数设计;时玉彬等;《电讯技术》;20011228(第06期);1-3 * |
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