CN203012135U - Frequency-modulated continuous wave radar system - Google Patents

Abstract

The utility model relates to a frequency-modulated continuous wave radar system, comprising a one-chip microcomputer, a modulation signal generation circuit, a voltage controlled oscillator, a directional coupler, a circulator, an antenna, a mixer, an intermediate frequency amplifier, and a signal processor, wherein the one-chip microcomputer, the modulation signal generation circuit, the voltage controlled oscillator, the directional coupler, the mixer, the intermediate frequency amplifier, and the signal processor are sequentially connected to form an annular loop; the directional coupler, the circulator, and the antenna are sequentially connected; and the circulator and the mixer are also connected. The frequency-modulated continuous wave radar system of the utility model has a simple structure and a strong anti-interference capability, and the false alarm rate of the system is greatly reduced.

Description

A kind of frequency modulated continuous wave radar system

[technical field]

The utility model relates to a kind of radar installations, is specifically related to a kind of frequency modulated continuous wave radar system, belongs to the radar equipment technical field.

[background technology]

The radar range finding technology is the study hotspot in present automobile collision preventing field.The main body of anti-collision system for automobile is a range radar that is arranged on automobile, and its major function is to measure in real time distance and the speed of opposite car, reports to the police or starts dead-man's device to the driver safely in the situation that jeopardize, and avoids the generation of collision accident.

The frequency of operation of frequency modulated continuous wave radar is usually in the millimere-wave band of 30-100GHz, compare with range-measurement infrared system with laser, be subjected to weather effect little, can normally move at rainy day, greasy weather and night, have simultaneously that emissive power is low, range resolution is high, an advantage such as large time-bandwidth product, high sensitivity and suitable close-in measurement.

Yet it is shorter that frequency modulated continuous wave radar is applied to the time of anti-collision system for automobile, adds the various clutters of this system works circumstance complication and noise stronger, the fixing ripe pattern of neither one also aspect its input processing.

Therefore, for solving the problems of the technologies described above, necessaryly provide a kind of structure improved frequency modulated continuous wave radar system of having, to overcome described defective of the prior art.

[utility model content]

For addressing the above problem, the purpose of this utility model is to provide a kind of antijamming capability strong, avoids the frequency modulated continuous wave radar system of false-alarm.

For achieving the above object, the technical scheme that the utility model is taked is: a kind of frequency modulated continuous wave radar system, and it comprises single-chip microcomputer, modulated signal producing circuit, voltage controlled oscillator, directional coupler, circulator, antenna, frequency mixer, intermediate frequency amplifier and signal processor; Wherein, described single-chip microcomputer, modulated signal producing circuit, voltage controlled oscillator, directional coupler, frequency mixer, intermediate frequency amplifier and signal processor connect successively and form a loop checking installation; Described directional coupler, circulator, antenna connect successively; Described circulator also is connected with described frequency mixer.

Frequency modulated continuous wave radar of the present utility model system further is set to: be provided with a warning circuit in described single-chip microcomputer.

Compared with prior art, the utlity model has following beneficial effect: frequency modulated continuous wave radar of the present utility model system simple in structure, antijamming capability is strong, and greatly reduces the false alarm rate of system.

[description of drawings]

Fig. 1 is the schematic diagram of frequency modulated continuous wave radar of the present utility model system.

[embodiment]

See also shown in Figure of description 1, the utility model is a kind of frequency modulated continuous wave radar system, and it is comprised of several parts such as single-chip microcomputer 1, modulated signal producing circuit 2, voltage controlled oscillator 3, directional coupler 4, circulator 5, antenna 6, frequency mixer 7, intermediate frequency amplifier 8 and signal processors 9.

Wherein, described single-chip microcomputer 1, modulated signal producing circuit 2, voltage controlled oscillator 3, directional coupler 4, frequency mixer 7, intermediate frequency amplifier 8 and signal processor 9 connect successively and form a loop checking installation.

Described directional coupler 4, circulator 5, antenna 6 connect successively.Described circulator 5 also is connected with described frequency mixer 7.

Further, be provided with a warning circuit 10 in described single-chip microcomputer 1, it is used for sending alarm signal.

the principle of work of frequency modulated continuous wave radar of the present utility model system is as follows: modulated signal producing circuit 2 forms low frequency triangular waves, this triangular wave is sent into voltage controlled oscillator 3 and is controlled its centre frequency f0, modulated microwave signal is by directional coupler 4, circulator 5, antenna 6 with the wave beam of certain width to the space radiation electromagnetic wave, run into reflected signal after target through antenna 6, circulator 5 is added to frequency mixer 7, the mixing that transmits with directional coupler 4, difference frequency signal is delivered to signal processor 9 after intermediate frequency amplifier 8 amplifies, single-chip microcomputer 1 coordinates relative distance and the speed of calculating with signal processor 9, and send corresponding alarm signal according to hazard level.

The theoretical foundation of frequency modulated continuous wave radar of the present utility model system is as follows: when radar is operated in the continuous wave state, transmit to be expressed as: s (t)=Acos (ω ₀T+ φ), in formula, ω ₀Be the angular frequency that transmits, φ is initial phase, and A is the radiofrequency signal amplitude.There is the echoed signal of target reflection to be: s _r(t)=Ks (t-t _r)=KAcos[ω ₀(t-t _r)+φ], t _rLag behind the time that transmits for echoed signal.

For fixed target, between radar and target, distance R is constant, and it is constant that echoed signal lags behind the time that transmits, and T represents with Δ, Δ T=2R/C, echoed signal and transmit between phase differential be ω ₀Δ T=2 π f ₀(2R/C)=4 π R/ λ, it is that the phase place that electromagnetic wave is travelled to and fro between between radar and target lags behind, and wherein C is propagation velocity of electromagnetic wave, and λ-wavelength transmits.

For moving target, the distance R temporal evolution is uniform motion between hypothetical target and radar, and at t constantly, the distance R between target and radar (t) is: R (t)=R ₀-Vt, R ₀Distance during for t=0, V be target relatively and the radial velocity between radar.Usually, between target and radar relative velocity V much smaller than velocity of electromagnetic wave C, therefore time delay t _rCan be similar to and be written as: t _r=2R (t)/c=2 (R ₀-Vt)/c.Echoed signal and transmit between the high frequency phase differential be: φ=-ω ₀t _r=-ω ₀2 (R ₀-Vt)/c=-4 π (R ₀-Vt)/λ.When speed is constant, to the φ differential, obtains echoed signal and with the difference on the frequency that transmits be: f _d=(1/2 π) (d φ./ dt)=2V/ λ is Doppler frequency.

When radar was operated in triangular wave linear frequency modulation state, for fixed target, the intermediate-freuqncy signal of frequency mixer output was f _I, f _I=4BR/TC.T is the modulated triangular wave cycle, and B is transmitted signal bandwidth.

For moving target, comprise Doppler frequency f in reflected signal _d, in the ascent stage of modulation signal,

$f_{I+}=\frac{4\mathrm{BR}}{\mathrm{TC}}-f_d---\left(1\right)$

In the descending branch of modulation signal,

$f_{I-}=\frac{4\mathrm{BR}}{\mathrm{TC}}-f_d---\left(2\right)$

With f _I+With f _I-Addition and subtracting each other obtains respectively:

$R=\frac{(f_{I+}+f_{I-})\mathrm{TC}}{8B}---\left(3\right)$

$V=\frac{C}{4f_0}(f_{I-}-f_{I+})---\left(4\right)$

f ₀Be the centre frequency that transmits.Can be found out by R, V formula, as long as calculate in real time f _I+, f _I-, can calculate easily distance and speed.

Frequency modulated continuous wave radar of the present utility model system transmits and is many slopes stepping Continuous Wave with frequency modulation, and the one-period of signal is triangle, and signal is carried out the time-frequency modulation, and the ascent stage is a sequence X sequence pairs, is modulated to the ascent stage; Be another sequence Y sequence pairs to the descending branch signal, be modulated to descending branch.As the place ahead, two objects are arranged, signal obtains two groups of four intermediate-freuqncy signals through reflection, demodulation

Respectively with four intermediate-freuqncy signals sequence X one to one ₁, X ₂, Y ₁, Y ₂(sequence X ₁, X ₂, Y ₁, Y ₂Be divided into the sequence that sequence X, Y are delayed time through reflection).By formula (3), (4),

To obtain corresponding four groups of R, V, wherein two is false-alarm, the example by

The R that obtains, V are false-alarm, this moment we by calculate with

Corresponding X ₂, Y ₁Autocorrelation function Because X ₂, Y ₁Be respectively the time-delay of X, Y, but delay time is different, has caused X ₂, Y ₁Autocorrelation function In τ be not 0, thereby make

Be 0, thus we can according to four intermediate-freuqncy signals

Sequence X one to one ₁, X ₂, Y ₁, Y ₂The value of autocorrelation function, distinguish the correct relation on the same group of intermediate-freuqncy signal, thereby obtain two groups of just genuine R, V, removed the false-alarm point, obtain real target information point, the generation of reduce false alarm greatly reaches the purpose of system.

Above embodiment is only the preferred embodiment of this creation, not in order to limiting this creation, all in this creation spirit and principle within make any modification, be equal to replacement, improvement etc., within all should being included in the protection domain of this creation.

Claims (2)

1. a frequency modulated continuous wave radar system, is characterized in that: comprise single-chip microcomputer, modulated signal producing circuit, voltage controlled oscillator, directional coupler, circulator, antenna, frequency mixer, intermediate frequency amplifier and signal processor; Wherein, described single-chip microcomputer, modulated signal producing circuit, voltage controlled oscillator, directional coupler, frequency mixer, intermediate frequency amplifier and signal processor connect successively and form a loop checking installation; Described directional coupler, circulator, antenna connect successively; Described circulator also is connected with described frequency mixer.

2. frequency modulated continuous wave radar as claimed in claim 1 system, is characterized in that: be provided with a warning circuit in described single-chip microcomputer.

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