JPS6165179A - False signal generator - Google Patents

Abstract

PURPOSE:To obtain a false target signal having a required range and a range changing ratio by generating a Doppler offset signal corresponding to the range changing rate and range of a false target synchronously with timing for changing the transmitting frequency changing rate of a radar equipment. CONSTITUTION:A Doppler offset controller 9, timing signal 10, Doppler offset signal 11, false target signal 12, etc. are formed. The controller 9 inputs the range changing rate R' of the false target set up synchronously with the rise of the signal 10 supplied from a radar equipment and generates and holes a voltage for holding the frequency of the output signal (signal 11) of a voltage controlled oscillator 5 at a prescribed level. Then, the controller 9 inputs the range R and the range changing rate R' of the set-up false target and generates and holds a voltage for holding the frequency of the signal 11 at a prescribed level synchronously with the decay of the signal 10. A transmitted signal 1 is mixed with the signal 11 by a mixer 6 and the mixed signal is inputted to a filter 7, which removes an image signal due to mixing and outputs a signal 12.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an FM ranging type radar that performs frequency analysis of a target signal received during a plurality of periods in which the frequency change rate of the transmitted signal is different to measure the range of the target. The present invention relates to a pseudo signal generator that supplies a pseudo target signal to a device.

[Prior art]

A conventional pseudo signal generator will be explained with reference to FIGS. 1 and 2.

Figure 1 is a diagram showing the principle of FM ranging, and Figure 2 is a diagram showing the configuration of a conventional pseudo signal generator.
1) is a transmitted signal, (2) is a received signal, (3) is a phase detection signal, (4) is a control voltage generator, (5) is a voltage controlled oscillator, (6) is a mixer, (7) is a filter, (8) is a delay line.

First, the principle of FM ranging will be explained using FIG. In order to simplify the explanation, it is assumed that the transmission signal (1) periodically repeats an interval 1 in which the frequency change rate is zero and an interval 2 in which the frequency change rate is a constant value. Therefore, the transmission frequency in one section 1 is a constant value fQ. When such a transmission signal (1) is emitted to a target with a distance R2 and a distance change rate, the distance delay time T and the toggle frequency f1
The received signal (2) is received. Here, distance delay time T and Doppler frequency of 1 are given by equations (1) and (2), respectively.

R T=□ ・・・・・・・・・・・・・・・
(1) However, C: the speed of light.Next, when the received signal (2) is phase detected using the transmitted signal (1) as a reference signal, a phase detected signal (3) is obtained, and the frequency of this phase detected signal (3) is constant. When frequency analysis is performed in sections 3 and 4, it is possible to detect frequencies fl and fl. Here, since the two frequencies f2 are f2=fj - fT, the target distance R is obtained using a quadratic equation.

C(fl-fl) R=-11τ--- ・・・・・・・・・・・・・・・
(41f) Therefore, the configuration of a conventional pseudo signal generator used for testing such an FM ranging type radar device is as shown in FIG.

In FIG. 2, the control voltage generator (4) inputs the distance change rate hole of the set pseudo target and generates a voltage control oscillator (5).
) generates a control voltage VC whose oscillation frequency becomes 1 at the Doppler frequency given by equation (2). The mixer (6) mixes the transmission signal (1) supplied from the radar device and the output signal of the voltage controlled oscillator (5) and filters it (
7). After the image signal due to mixing is removed by the filter (7), it is input to the delay line (8) and a distance delay time T corresponding to the range of the pseudo target is given, resulting in a pseudo target signal that is the same as the received signal (2). S is obtained.

In this way, conventional pseudo signal generators use delay lines to provide distance delay time, so setting the distance of the pseudo target to an arbitrary and long distance requires an increase in the hardware required for the delay line. there were.

[Summary of the invention]

This invention generates a Doppler offset signal according to the distance change rate and distance of a pseudo target in synchronization with the timing when the transmission frequency change rate of the radar device is changed, and mixes it with the transmission signal supplied from the radar device. It is an object of the present invention to provide a pseudo signal generating device that can improve the above-mentioned drawbacks of the conventional art by generating a pseudo target signal.

[Embodiments of the invention]

This invention will be explained in detail using FIGS. 3 and 4.

FIG. 3 is a block diagram showing an embodiment of the present invention, and FIG. 4 is a diagram showing the principle of generation of a pseudo target signal in this invention. ~(7
) is the same as shown in FIG. 2 above, (9) is the Doppler offset controller, α[ is the timing signal, α
0 is a Doppler offset signal, (L3 is a pseudo target signal of this invention, and (+31 is a phase detection signal of this invention).

In FIGS. 3 and 4, the Doppler offset controller (9) is operated by a timing signal 0 supplied from the radar device.
The distance change rate hole of the pseudo target set in synchronization with the rising edge of Q is input, and the frequency of the output signal (hereinafter referred to as Doppler offset signal (Lυ)) of the voltage controlled oscillator (5) is (2). Generate and maintain a control voltage such that fl is given by the formula.Next, the Doppler offset controller (
9) inputs the distance range and distance change rate hole of the set pseudo target, and synchronizes with the falling edge of the timing signal a1 so that the frequency of the Doppler offset signal +111 becomes fl given by equation (3). Generates and maintains control voltage.

The mixer (6) mixes the transmission signal (1) supplied from the radar device and the Doppler offset signal αD, and inputs the mixed signal to the filter (7). The image signal due to mixing is removed by the filter (7), and the pseudo target signal α of the present invention is obtained.

Incidentally, when the pseudo target signal u2 of the present invention is input to the radar device and subjected to phase detection, a phase detection signal αJ of the present invention as shown in FIG. 4 is obtained. Although this signal waveform is different from the waveform of the phase detection signal (3) shown in FIG. 1, it is the same waveform in sections 3 and 4 in which the radar device performs frequency analysis.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to generate a pseudo target signal having a desired distance and distance change rate without using a large-scale hardware delay line.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the principle of FM ranging, and FIG. 2 is a diagram showing the configuration of a conventional pseudo signal generator. FIG. 3 is a block diagram showing an embodiment of the present invention, and FIG. 4 is a diagram showing the principle of generation of a pseudo target signal in the present invention. In FIG. 9, (1) is a transmission signal. (2) is the received signal, (3) is the phase detection signal, (4) is the control voltage generator, (5) is the voltage controlled oscillator, (6) is the mixer, (7) is the filter, and (8) is the delay line. , (9) is the Doppler offset controller, α1 is the timing signal, (l
υ is a Doppler offset signal, and α power is a pseudo target signal of this invention. Q,1 is a phase detection signal in this invention. In FIG. 2, the same or corresponding parts are designated by the same reference numerals. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] A pseudo signal generator configured to supply a pseudo target signal to an FM ranging radar device that performs frequency analysis of a target signal received during a plurality of periods in which the frequency change rate of the transmitted signal is different to measure the range of the target. , comprising means for generating a Doppler offset signal of a frequency corresponding to the distance of the pseudo target and the distance change rate in synchronization with the timing at which the transmission frequency change rate of the radar device is changed, What is claimed is: 1. A pseudo signal generating device characterized in that it is configured to be able to generate a pseudo target signal.