CN106772288A - A kind of Stepped Frequency analogue echoes method - Google Patents

Abstract

The invention discloses a kind of Stepped Frequency analogue echoes method, comprise the following steps, receive Stepped frequency radar transmission signal s_tr(t)；The Properties of Range Profile h of a frame in guinea pig target is obtained, and h is updated according to frame synchronizing signal；For each pulse of a frame in, it is modulated using target Properties of Range Profile h, carries out convolutional calculation；Calculate radar simulation target output signal s_rT (), output result is the target echo signal of each pulse of present frame.The present invention not only solves conventional method for being tested the problem of the demand of radar Step Frequency rule, also solves the conventional method problem high for signal to noise ratio requirement, with extensive adaptability, possesses good application prospect.

Description

A kind of Stepped Frequency analogue echoes method

Technical field

The invention belongs to radar target analogy method technical field, more particularly to a kind of Stepped Frequency echo Analogy method.

Background technology

Stepped frequency signal synthesizes high-resolution signal form as one kind, with the spy that instant bandwidth is low, synthetic bandwidth is high Point, can reduce the requirement to digital signal processor instant bandwidth while Distance function is obtained, it is easy to accomplish, closely It is widely used over year.In order to effectively be detected to Stepped frequency radar and be tested, before equipment does field trial Sufficiently tested, checked the function of equipment each several part, the simulation of target echo is significantly.

In the prior art, for the simulation of conventional radar target echo, each pulse to radar emission is carried out respectively The modulation of target range, speed and target signature is so as to obtain target echo；For the simulation of Stepped frequency radar echo, simply exist On the basis of the simulation of conventional radar target echo, it is contemplated that the phase relation of multiple pulses in a frame.Sent out for Stepped frequency radar Each pulse penetrated carries out the modulation of target range, speed and target signature so as to obtain target echo respectively, and a frame signal In each pulse be required for knowing its centre frequency and the initial time of each pulse, its obtain approach often have：(1) quilt Examination radar is provided；(2) using digital detection and the method for digital Frequency Measuring；For (1), if the stepping rule of tested radar is line Property, the method has certain applicability, if the stepping rule of tested radar is nonlinear, the method is unavailable, right In (2), detection and frequency measurement are carried out in numeric field, the requirement for signal to noise ratio is higher, when signal to noise ratio is low, detection occurs burr, Frequency-measurement accuracy can be very poor.

The above method in view of Step Frequency Radar particularity, i.e., using multiple pulse combination broadband signals come Realize high-resolution, but processed only for each pulse, therefore, in actual use, otherwise need in advance know by The relevant parameter of radar is tried, otherwise needs are used on the premise of signal to noise ratio is very high.

The content of the invention

Goal of the invention：The present invention is directed in many military uses, and the parameter of tested radar is the situation of secrecy, it is proposed that A kind of analogy method of Stepped Frequency, the stepping rule without knowing tested Stepped frequency radar in advance is examined without numeral Ripple and frequency measurement, to solve the problems, such as to need radar prior information in the prior art and require compared with high s/n ratio.

Technical scheme：To achieve the above object, the technical solution adopted by the present invention is：

A kind of analogy method of Stepped Frequency, comprises the following steps：

Step one, receives Stepped frequency radar transmission signal s_tr(t)；

Step 2, obtains the Properties of Range Profile h of a frame in radar simulation target, and h is entered according to frame synchronizing signal Row updates；

Step 3, each pulse for a frame in is modulated using target Properties of Range Profile h, carries out convolution meter Calculate；

Step 4, calculates radar simulation target output signal s_r(t)；

Radar simulation target output signal s_rT () is the echo of Stepped frequency radar transmission signal.

Further, the Stepped frequency radar transmission signal s of step one input_trShown in the expression formula of (t) such as formula (1)：

Wherein,Represent the rectangle subpulse envelope of stepped frequency signal；T_rIt is stepped frequency signal Pulse repetition period；τ is transmission signal subpulse width；T is the time；One frame includes N number of pulse, and the carrier frequency of n-th pulse is f_n=f₀+ nVf, n=0,1 ..., N-1；E is natural constant 2.718282；

Further, the expression formula such as formula (2) of the Properties of Range Profile h of the radar simulation target of step one input It is shown：

Wherein, M is the quantity of scattering point on the one-dimensional range profile of radar simulation target；Represent the one-dimensional range profile I the scattering properties i=1,2 ... M, A of scattering point_iExpression amplitude,Represent phase；

The Properties of Range Profile h of the radar simulation target that the step 2 is obtained, is carried out according to frame synchronizing signal Update.

Further, shown in the expression formula of the convolutional calculation of the step 3 such as formula (3)：

Wherein, it is modulated using Properties of Range Profile h；s_r-nT () is the echo of n-th pulse after modulation；* represent Convolution algorithm.

Further, the simulated target output signal s of the step 4_rShown in the expression formula of (t) such as formula (4)：

Wherein, s_rT () is the target echo signal of the N number of pulse of frame in of Stepped frequency radar one of this method simulation.

Beneficial effect：Compared with prior art, the present invention has advantages below：

For in many military uses, the parameter of tested radar is the situation of secrecy, and target simulation is carried out using by frame Method, it is not necessary to know the relevant parameter of tested radar in advance；

Method using target simulation is carried out by frame, it is not necessary to carry out frequency measurement, detection treatment, therefore do not need noise high Than applied widely；

Meanwhile, the characteristics of for Stepped frequency radar：It is that big bandwidth is realized in the pulse of multiple different frequencies by a frame in Treatment, the frequency Changing Pattern of its multiple pulse can be linear, or nonlinear, be mentioned in background of the present invention It is prior provide linear rule by tested radar, in this case traditional target echo analogy method can be applicable, but for The traditional method of non-linear stepping rule is not applied to then, and the tested radar in reality is linear, also there is nonlinear, also Be linearity and non-linearity combination, conventional method cannot be applicable, and this is the defect of conventional method；The method of the present invention is not required to important affair First know radar stepping rule, be all suitable for for all of Stepped frequency radar.

Brief description of the drawings

Fig. 1 is structured flowchart of the invention.

Specific embodiment

A kind of analogy method of Stepped Frequency, comprises the following steps：

Step one, receives Stepped frequency radar transmission signal s_tr(t)；

Step 2, obtains the Properties of Range Profile h of a frame in radar simulation target, and h is entered according to frame synchronizing signal Row updates；

Step 3, each pulse for a frame in is modulated using target Properties of Range Profile h, carries out convolution Calculate；

Step 4, calculates radar simulation target output signal s_r(t)；

Radar simulation target output signal s_rT () is the echo of Stepped frequency radar transmission signal.

The Stepped frequency radar transmission signal s of the input of abovementioned steps one_trShown in the expression formula of (t) such as formula (1)：

Wherein,Represent the rectangle subpulse envelope of stepped frequency signal；T_rIt is stepped frequency signal Pulse repetition period；τ is transmission signal subpulse width；T is the time；One frame includes N number of pulse, and the carrier frequency of n-th pulse is f_n=f₀+ nVf, n=0,1 ..., N-1；E is natural constant 2.718282；

Shown in the expression formula such as formula (2) of the Properties of Range Profile h of the radar simulation target of the input of abovementioned steps two：

Wherein, M is the quantity of scattering point on the one-dimensional range profile of radar simulation target；Represent the one-dimensional range profile I the scattering properties i=1,2 ... M, A of scattering point_iExpression amplitude,Represent phase；

Shown in the expression formula of the convolutional calculation of abovementioned steps three such as formula (3)：

Wherein, it is modulated using Properties of Range Profile h；s_r-nT () is the echo of n-th pulse after modulation；* represent Convolution algorithm.

The simulated target output signal s of abovementioned steps four_rShown in the expression formula of (t) such as formula (4)：

Wherein, s_rT () is the target echo signal of the N number of pulse of frame in of Stepped frequency radar one of this method simulation.

The operating procedure of aforementioned analog is realized in FPGA by programming in logic.

The present invention is further described with reference to embodiment.

A kind of Stepped Frequency analogy method, comprises the following steps：

1st, the Stepped frequency radar transmission signal s of input is received_trT (), its expression formula is：

Wherein,Represent the rectangle subpulse envelope of stepped frequency signal, T_rIt is stepped frequency signal Pulse repetition period, τ is transmission signal subpulse width, and t represents the time, and a frame includes N number of pulse, the carrier frequency of n-th pulse It is f_n=f₀+ nVf, n=0,1 ..., N-1, e are natural constants 2.718282；

Have a M scattering point on the one-dimensional range profile that the 2nd, radar simulation target is set, acquisition radar simulation target it is one-dimensional away from From as characteristic h, its expression is shown as：

Wherein,Represent the scattering properties of i-th scattering point of the one-dimensional range profile, A_iExpression amplitude,Represent phase；I=1,2 ... M；

3rd, convolutional calculation, for the echo of each pulse of a frame in, is adjusted using target Properties of Range Profile h System, the echo s of n-th pulse after modulation_r-nT () is：

Wherein, * represents convolution algorithm；

4th, radar simulation echo signal output, target one-dimensional range profile modulated after each pulse s_r-nT () is used as current Exomonental echo, then whole Step Frequency transmission signal echo be：

Embodiment one

As shown in figure 1, by taking certain Stepped frequency radar simulation system as an example, the frame of Stepped frequency radar one includes 64 pulses, frequency Stepping is 8MHz, and synthetic bandwidth is 512MHz, it is necessary to the typical target of simulation is a ship, and setting on its one-dimensional range profile has 16 Individual scattering point, target Properties of Range Profile h can be expressed asWherein,Represent this one Tie up the scattering properties of i-th scattering point of Range Profile, i=1,2 ..., 16；At present, the core for realizing target property modulation is numeral The PLD in domain, the V5SX95T fpga chips of mainly a piece of Xilinx companies.

Its concrete operation step is as follows：

(1) framework as shown in Figure 1 is realized by programming in logic in FPGA；

(2) for 64 pulses of a frame in, Convolution Modulation is carried out using identical one-dimensional range profile h, accordingly N-th pulse echo be：

(3) 64 pulses of a frame in are overlapped in chronological order, you can obtain the Stepped Frequency of a frame in Echo：According to above-mentioned

The above is only the preferred embodiment of the present invention, it should be pointed out that：For the ordinary skill people of the art For member, under the premise without departing from the principles of the invention, some improvements and modifications can also be made, these improvements and modifications also should It is considered as protection scope of the present invention.

Claims (5)

1. a kind of analogy method of Stepped Frequency, it is characterised in that comprise the following steps：

Step one, receives Stepped frequency radar transmission signal s_tr(t)；

Step 2, obtains the Properties of Range Profile h of a frame in guinea pig target, and h is carried out more according to frame synchronizing signal Newly；

Step 3, for each pulse of a frame in, is modulated using target Properties of Range Profile h, carries out convolutional calculation；

Step 4, calculates radar simulation target output signal s_r(t)；

The output signal s_rT () is the echo of Stepped frequency radar transmission signal.

2. the analogy method of Stepped Frequency according to claim 1, it is characterised in that：Step one input Stepped frequency radar transmission signal s_trShown in the expression formula of (t) such as formula (1)：

$s_{tr}\left(t\right)=\underset{n=0}{\overset{N-1}{\Σ}}rect\left(\frac{t-{\mathrm{nT}}_r}{\mathrm{\τ}}\right)e^{j2{\mathrm{\πf}}_{n}t}---\left(1\right)$

Wherein,Represent the rectangle subpulse envelope of stepped frequency signal；T_rIt is the pulse of stepped frequency signal Repetition period；τ is transmission signal subpulse width；T is the time；One frame includes N number of pulse, and the carrier frequency of n-th pulse is f_n=f₀ + nVf, n=0,1 ..., N-1；E is natural constant 2.718282；

3. the analogy method of Stepped Frequency according to claim 2, it is characterised in that：What the step 2 was obtained Shown in the expression formula such as formula (2) of the Properties of Range Profile h of radar simulation target：

Wherein, M is the quantity of scattering point on the one-dimensional range profile of radar simulation target；Represent the one-dimensional range profile i-th The scattering properties i=1,2 ... M, A of scattering point_iExpression amplitude,Represent phase；

The Properties of Range Profile h of the radar simulation target that the step 2 is obtained, is updated according to frame synchronizing signal 's.

4. the analogy method of Stepped Frequency according to claim 3, it is characterised in that：The convolution of the step 3 Shown in the expression formula of calculating such as formula (3)：

$s_{r-n}\left(t\right)=rect\left(\frac{t-{\mathrm{nT}}_r}{\mathrm{\τ}}\right)e^{j2{\mathrm{\πf}}_{n}t}*h---\left(3\right)$

Wherein, it is modulated using Properties of Range Profile h；s_r-nT () is the echo of n-th pulse after modulation；* convolution is represented Computing.

5. the analogy method of Stepped Frequency according to claim 4, it is characterised in that：The simulation of the step 4 Target output signal s_rShown in the expression formula of (t) such as formula (4)：

$s_r\left(t\right)=\underset{n=0}{\overset{N-1}{\Σ}}{s}_{r-n}\left(t\right)=\underset{n=0}{\overset{N-1}{\Σ}}rect\left(\frac{t-{\mathrm{nT}}_r}{\mathrm{\τ}}\right)e^{j2{\mathrm{\πf}}_{n}t}*h---\left(4\right)$

Wherein, s_rT () is the target echo signal of the N number of pulse of frame in of Stepped frequency radar one of this method simulation.