JPH0540167A - Distance-measuring device - Google Patents

Abstract

PURPOSE:To obtain a distance-measuring device which enables ambiguity of distance to be reduced since a useless reflection signal from a remote area such as a multi-dimensional echo to be identified in a radar distance-measuring device. CONSTITUTION:Signals of a sinusoidal signal generator 9 and a code generator 10 are code-modulated by a code modulator 8, are amplified by a power amplifier 7, and then are transmitted by an antenna 1 for transmission/reception via a transmission/reception switcher 2. At a reception side, each code is demodulated by a plurality of matched filters 4a-4n and is converted to digital signal by a plurality of A/D converters 5a-5n and a distance to a target is calculated by a distance calculator 6 based on this digital signal, thus enabling a distance to be processed to be N times longer than that by a radar with only one PRT and a useless signal from a remote area to be identified by setting N to be fully large.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distance measuring device, and more particularly to a distance measuring device using code-modulated or transmission frequency-modulated pulse signals.

[0002]

2. Description of the Related Art FIG. 7 is a block circuit diagram showing a block configuration of a conventional pulse radar, in which 1 is a transmitting / receiving antenna for transmitting and receiving a transmission signal and a reception signal,
Reference numeral 2 is a transmission / reception switch that switches transmission signals and reception signals according to transmission and reception, 3 is a low noise amplifier that suppresses and amplifies noise of reception signals, and 11 is a bandpass filter that demodulates the amplified reception signals. , 12 are bandpass filters 1
1 is a detector for detecting the received signal demodulated by 1, 5 is an A / D converter for converting the analog signal detected by the detector 12 into a digital signal, and 15 is 2 based on the A / D converter.
It is a signal processor that performs signal processing such as PRF (pulse repeat frequency) ranging and speed measurement.

Reference numeral 9 is a local oscillator for oscillating a frequency for pulse-modulating a transmission signal, 14 is a pulse modulator for pulse-modulating the oscillation frequency of the local oscillator 9, and 7 is a pulse-modulated transmission signal for the pulse modulator 4. Is a power amplifier that amplifies power.

Further, FIGS. 8 (a) to 8 (c) are waveform diagrams showing a transmission signal and a reception signal in a conventional pulse radar range finder, in which 25 is a PRT (pulse repeat timing). Of the transmitted / received signals of PRT2
Of the transmission / reception signal of,
28 is a received signal in PRT1, 29 is a transmitted pulse in PRT2, 30 is a received signal in PRT2, 31 is PRT1
Of transmission / reception signals obtained by the communication between PRT2 and PRT2, 32
Is the intersection of the received signals of PRT1 and PRT2, and 33 is P
It is the intersection of the transmission pulses of RT1 and PRT2.

FIGS. 9 (a), 9 (b) and 10 (a)-(c) are waveform charts showing the waveforms of the transmission signal and the reception signal of the pulse radar.

Next, the operation will be described. In the pulse radar, the sine wave generated by the local oscillator 9 is pulse-modulated by the pulse modulator 14 and the pulse 27 is transmitted among the transmission / reception signals 25 shown in FIG. 8 (a) using PRT1 (cycle 4 μs), and the reception signal 28 is transmitted. obtain. Then PRT2 (cycle 5μ
The pulse 29 is transmitted and the reception signal 30 is obtained from the transmission / reception signal 26 shown in FIG. Here, PRT1 and PRT2 are disjoint.

For example, if the transmission pulse shown in FIG. 9 (a) is transmitted and the reception signal shown in FIG. 9 (b) is obtained, it cannot be determined which pulse of the transmitted pulses corresponds to which reception signal. Also, as shown in Fig. 10 (a), Goal 1
-When the first pulse shown in Fig. 10 (b) is transmitted to the target 3, three received signals are obtained as shown in Fig. 10 (c). The received signal of target 1 can be processed as the received signal from target 1, but the received signals of target 2 and target 3 are processed as if they were returned from the 2nd and 3rd transmitted pulses, so they should actually be far away. The reflected waves from the target 2 and the target 3 of FIG. 3 are processed as if the target is close, and the accurate position of the target cannot be obtained.

Since the received signals shown in FIGS. 8 (a) and 8 (b) thus obtained are signals with ambiguity in distance, as shown in FIG. 8 (c), PRT1 and PRT2 are separated from each other. A target signal can be considered as a reception signal in which the transmission / reception signal 25 and the transmission / reception signal 26 match in the section of the least common multiple (4 × 5 = 20) of the cycle. Is.

[0009]

Since the conventional distance measuring device is constructed as described above, the PRT is increased in order to remove the ambiguity of the distance, that is, the setting of PRT1 and PRT2 becomes complicated. There was a problem that it became.

The present invention has been made in order to solve the above-mentioned problems, and it is possible to eliminate the ambiguity of the distance without changing the PRT and the like, and to measure the unnecessary reflection signal from a distance. The purpose is to obtain the device.

[0011]

A distance measuring apparatus according to the present invention generates a sine wave signal by a sine wave signal generator, and generates a code for code-modulating the sine wave signal by a code generator. The sine wave signal is code-modulated by a code modulator and transmitted as a pulse signal. This pulse signal is reflected by the target and is demodulated as a reception signal for each code by a plurality of matched filters. The demodulated signal is converted into a digital signal by a plurality of A / D converters. The distance is calculated by the distance calculator.

In the distance measuring apparatus according to the present invention, the sine wave signal generator generates a sine wave signal, the pulse modulator modulates the sine wave signal into a pulse signal, and the pulse output from the pulse modulation means. A signal for changing the carrier frequency of the signal is oscillated by a plurality of local oscillators, the plurality of local oscillators is switched by a frequency switch, and the signal of the local oscillator switched by the frequency switch and the pulse signal are multiplied. Are multiplied by and transmitted as a pulse signal.
This pulse signal is reflected by the target and is divided into frequencies by a plurality of frequency classifiers as a reception signal. The signals classified by the frequency classifiers are respectively detected by a plurality of wave detectors, and the signals detected by the wave detectors. Are converted into digital signals by a plurality of A / D converters, and the distance to the target is calculated by the distance calculator based on the digital signals.

[0013]

In the present invention, since each pulse is differentiated by code modulation or modulation of the transmission frequency of the pulse, the PRT is several times the code or frequency used, which makes the range ambiguous. In addition, the unnecessary reflection signal from a distance can be identified by increasing the number of codes or the frequency used.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block circuit diagram showing a block configuration of a distance measuring apparatus according to an embodiment of the present invention, in which 1 is a transmitting / receiving antenna for transmitting and receiving a transmission signal and a reception signal, and 2 is a transmission signal and a reception signal. A transmission / reception switcher that performs switching according to transmission and reception, 3 is a low noise amplifier that suppresses and amplifies noise of a reception signal to be low, 4a to 4n are matched filters that demodulate the reception signal, and 5a to 5n are the matched filters 4a to A / D converter for converting an analog signal demodulated by 4n into a digital signal, 6 is the A / D converter 5
It is a distance calculator that calculates the distance to the target based on the outputs of a to 5n.

Further, 9 is a local oscillator for oscillating a sine wave signal for code modulation, 10 is a code generator for generating a code for code modulating the sine wave signal of the local oscillator 9, and 8 is a code generator 10. A code modulator for code-modulating a transmission pulse by a code and the transmission frequency of the local oscillator 9, and a power amplifier 7 for power-amplifying the code-modulated transmission pulse of the code modulator 8.

2 (a) to 2 (d) are diagrams showing the waveform of the transmission signal in the distance measuring apparatus according to the embodiment of the present invention, in which 17 is the transmission signal and 18 is the code 1 of the transmission signal. In the figure, reference numeral 19 is a signal showing only the pulse modulated by (4), 19 is a signal showing only the pulse modulated by code 2 in the transmission signal, and 20 is a signal showing only the pulse modulated by code N in the transmission signal.

FIGS. 3 (a), 3 (b) and 4 (a), 4 (b) are waveform diagrams showing a transmission signal and a reception signal of the distance measuring device according to the embodiment of the present invention.

Next, the operation will be described. Local oscillator 9
The sine wave signal generated in 1 is modulated in the code modulator 8 by the code generated in the code generator 10. The code-modulated signal becomes, for example, the transmission signal 17 shown in FIG. The transmission pulse is code1 shown in Fig. 2 (b) for each pulse.
Is a signal intra-pulse modulated with N codes of code N shown in FIG. 2 (d). The modulated pulse signal is power-amplified by the power amplifier 7, passes through the transmission / reception switch 2, and is radiated into the air from the transmitting / receiving antenna 1.

The reflected signal reflected by the target is received by the transmitting / receiving antenna 1, passes through the transmission / reception switch 2, and is amplified by the low noise amplifier 3. The amplified signal is matched filter 4a-
4n, and the signals demodulated by the filters having the same sign are output. The output signal is converted into a digital signal for each matched filter output by the A / D converters 5a to 5n, and the distance calculator 6 calculates the distance to the target based on the digital signal from the A / D converters 5a to 5n. Done. For example, as shown in Fig. 3 (a), code1
If transmission signals of codeN to codeN are transmitted, reception signals corresponding to the transmission signals of code1 to codeN are obtained as shown in FIG. 3 (b). Also, as shown in Fig. 4 (a), PR
If N of T is made sufficiently large, the unnecessary reflection signal becomes weaker as the line-of-sight distance increases, so that the received signal such as case 2 shown by the broken line in FIG. There is no return from 1.

In the above embodiment, the case where the transmission pulse is modulated by different codes has been described as an example, but the same effect can be obtained even if the transmission frequencies of the transmission pulses are modulated separately and transmitted at the frequencies. ..

FIG. 5 is a block circuit diagram showing a block configuration of a range finder according to another embodiment as described above. In the figure, 1 is a transmission / reception antenna for transmitting and receiving a transmission signal and a reception signal, and 2 is a transmission signal. And a transmission / reception switch for switching the reception signal according to transmission and reception, 3 is a low noise amplifier for suppressing and amplifying noise of the reception signal, 11a to 11n are bandpass filters for demodulating the reception signal, and 12a to 12
n is a detector for detecting the reception signals demodulated by the bandpass filters 11a to 11n, 5a to 5n are A / D converters for converting the analog signals detected by the detectors 12a to 12n into digital signals, 6 Is a distance calculator that calculates the distance to the target based on the outputs of the A / D converters 5a to 5n.

Reference numeral 9 is a local oscillator for oscillating a sine wave signal for pulse modulation, 14 is a pulse modulator for pulse modulating the sine wave signal of the local oscillator 9, and 16a to 16n.
Is a local oscillator for changing the transmission frequency for transmitting the pulse signal, 15 is a frequency switch for switching the local oscillators 16a to 16n, 13 is a signal pulse-modulated by the pulse modulator 14, and the frequency switch 15 Multipliers 13 and 7 for multiplying the transmission frequency switched by are power amplifiers for power-amplifying the output of the multiplier 13.

6 (a) to 6 (d) are diagrams showing the waveforms of transmission signals in the distance measuring device according to another embodiment. In FIG. 6, 21 is a transmission signal and 22 is a transmission signal. A signal showing only the pulse of f ₁ ; 23 is a signal showing only the pulse of the transmission frequency of f ₂ among the transmission signals; 24
Is a signal showing only pulses of the transmission frequency having a transmission frequency f _N.

Next, the operation will be described. Local oscillator 9
The sine wave signal generated in 1 becomes a pulse signal in the pulse modulator 14. The local oscillators 16a to 1 are arranged in accordance with the pulse signal and the order preset by the frequency switcher 15.
The signal selected from 6n is multiplied by the multiplier 13 to determine the transmission frequency.

Here, the frequency switch 15 switches the transmission frequency for each pulse. The output signal of the multiplier 13 is, for example, the transmission signal 21 shown in FIG. 6 (a).
The transmission pulse is f ₁ to FIG. 6 shown in FIG. 6 (b) for each pulse.
The signal is divided into N transmission frequencies of f _N shown in (d). The output signal of the multiplier 13 is power-amplified by the power amplifier 7, passes through the transmission / reception switch 2, and is radiated into the air from the transmitting / receiving antenna 1.

The reflected signal reflected by the target is received by the transmitting / receiving antenna 1, passes through the transmission / reception switch 2, and is amplified by the low noise amplifier 3. The amplified signal is a bandpass filter 11
a to 11n, and the signals are output from the filters whose frequencies match. The output signal is the detector 12a
After being detected by .about.12n, the signals are converted into digital signals by A / D converters 5a to 5n for each band pass filter output. The distance calculator 6 calculates the distance to the target based on the digital signals from the A / D converters 5a to 5n.

As described above, in the above two embodiments, the transmission pulse signal is configured to be differentiated by code modulation or modulation of the transmission frequency for transmitting the transmission pulse. By separately processing, the code-modulated signals 18 to 20 shown in FIGS. 2 (b) to (d), or the transmission frequency modulated signal to transmit the transmission pulse shown in FIGS. 6 (b) to (d). 22 to 24 can practically multiply the PRT by N times, and by making N sufficiently large, it becomes possible to measure distances to a considerable distance without ambiguity in distance, and to distinguish unnecessary reflected waves. can do.

[0028]

As described above, according to the distance measuring apparatus of the present invention, the transmission pulse signal is code-modulated or the transmission frequency for transmitting the transmission pulse is modulated to distinguish the transmission pulse signal. By processing each pulse separately in the distance calculator, the code-modulated signals 18 to 20 shown in FIGS. 2 (b) to (d) or the transmission pulse shown in FIGS. 6 (b) to (d) are transmitted. As in the signals 22 to 24 obtained by modulating the transmission frequency, the effective PRT can be multiplied N times. Further, if N is set to be sufficiently large, it is possible to measure a distance to a considerable distance without ambiguity of the distance, and it is possible to distinguish an unnecessary reflected wave.

[Brief description of drawings]

FIG. 1 is a block circuit diagram showing a block configuration of a distance measuring device for a pulse radar according to an embodiment of the present invention.

FIG. 2 is a waveform diagram showing a waveform of a transmission signal in the distance measuring device of the pulse radar according to the embodiment of the present invention.

FIG. 3 is a waveform diagram showing waveforms of a transmission signal and a reception signal in the pulse radar range finder according to the embodiment of the present invention.

FIG. 4 is a waveform diagram showing waveforms of a transmission signal and a reception signal of the pulse radar range finder according to the embodiment of the present invention.

FIG. 5 is a block circuit diagram showing a block configuration of a pulse radar range finder according to another embodiment of the present invention.

FIG. 6 is a waveform diagram showing a waveform of a transmission signal in a distance measuring device for a pulse radar according to another embodiment of the present invention.

FIG. 7 is a block circuit diagram showing a block configuration of a conventional pulse radar range finder.

FIG. 8 is a waveform diagram showing waveforms of a transmission signal and a reception signal in a conventional pulse radar range finder.

FIG. 9 is a waveform diagram showing waveforms of a transmission signal and a reception signal in a conventional pulse radar range finder.

FIG. 10 is a waveform diagram showing waveforms of a transmission signal and a reception signal in a conventional pulse radar range finder.

[Explanation of symbols]

1 Transmitting / receiving antenna 2 Transmission / reception switcher 3 Low noise amplifier 4a-4n Matched filter 5a-5n A / D converter 6 Distance calculator 7 Power amplifier 8 Code modulator 9 Local oscillator 10 Code generator 11a-11n Bandpass filter 12a ~ 12n Detector 13 Multiplier 14 Pulse modulator 15 Frequency switcher 16a ~ 16n Local oscillator 17,21 Transmission signal 18 Signal showing the waveform modulated by code1 of the transmission signal 19 Waveform modulated by code2 of the transmission signal Signals shown 20 Signals showing waveforms modulated by codeN of transmission signals 22 Signals showing waveforms of frequency f ₁ among transmission signals 23 Signals showing waveforms of frequency f ₂ of transmission signals 24 Transmission signals Of the signals whose frequency is f _N

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[Procedure amendment]

[Submission date] January 14, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0002

[Correction method] Change

[Correction content]

[0002]

2. Description of the Related Art FIG. 7 is a block circuit diagram showing a block configuration of a conventional pulse radar, in which 1 is a transmitting / receiving antenna for transmitting and receiving a transmission signal and a reception signal,
Reference numeral 2 is a transmission / reception switch that switches transmission signals and reception signals according to transmission and reception, 3 is a low noise amplifier that suppresses and amplifies noise of reception signals, and 11 does not require amplified reception signals
Bandpass filter for band limiting to remove waves , 1
Reference numeral 2 is a detector for detecting a reception signal band-limited by the bandpass filter 11, 5 is an A / D converter for converting an analog signal detected by the detector 12 into a digital signal, 1
A signal processor 5 performs signal processing such as 2PRF (pulse repeat frequency) ranging and speed measurement based on the A / D converter.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0019

[Correction method] Change

[Correction content]

The reflected signal reflected by the target is received by the transmitting / receiving antenna 1, passes through the transmission / reception switch 2, and is amplified by the low noise amplifier 3. The amplified signal is matched filter 4a-
Is input to 4n, respectively signal demodulated by the matched filter code is output. The output signal is converted into digital signals by the matched filter outputs by the A / D converters 5a to 5n, and the distance calculator 6 calculates the distance to the target based on the digital signals from the A / D converters 5a to 5n. Done. For example, as shown in Fig. 3 (a), code
If transmission signals 1 to codeN are transmitted, reception signals corresponding to the respective transmission signals code1 to codeN are obtained as shown in FIG. 3 (b). In addition, as shown in FIG.
By making N of RT sufficiently large, the unwanted reflection signal becomes weaker as the line-of-sight distance becomes larger, and therefore the received signal such as case 2 shown by the broken line in Fig. 4 (b) is pulsed in the signal starting at the next cycle. There is no return from 1.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Correction content]

In the above embodiment, the case where the transmission pulse is modulated by different codes has been described as an example, but the transmission frequency of the transmission pulse is different at each frequency.
The same effect can be obtained by modulating and transmitting.

Claims (2)

[Claims] 1. A distance measuring device having a transmitting / receiving antenna, transmitting a pulse, and measuring the distance to the target by the pulse reflected by the target, a signal generating means for generating a sine wave signal, and the sine Code generating means for generating a code for code-modulating the wave signal;
The sine wave signal is code-modulated by the code generating means, and a transmitting means having a code modulating means for making a pulse signal, a plurality of matched filters for demodulating the code-modulated received signal for each code, and the matched filter A receiving means having a plurality of digital converting means for converting the demodulated signal into a digital signal, and a distance calculating means for calculating a distance to a target based on the digital signal from the digital converting means. Ranging device. 2. A distance measuring device having a transmitting / receiving antenna, transmitting a pulse, and measuring the distance to the target by the pulse reflected by the target, the signal generating means for generating a sine wave signal, and the sine Pulse modulating means for converting a wave signal into a pulse signal, a plurality of local oscillating means for obtaining a signal for changing the carrier frequency of the pulse signal output from the pulse modulating means, and frequency switching for switching the carrier frequency of the local oscillating means Means, transmitting means having a multiplying means for multiplying the local oscillation signal obtained by the frequency switching means by the pulse signal outputted from the pulse modulating means, and a plurality of frequency separating means for separating the received signals by frequency. , A plurality of detecting means for detecting the signals separated by the frequency separating means, and digital signals for detecting the signals detected by the detecting means. A plurality of the digital converting means, the distance measuring apparatus characterized by comprising a receiving means and a distance calculation means for calculating the distance to the target based on the digital signal from said digital conversion means for converting the items.