JP2779279B2 - Radar equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radar apparatus using spread spectrum communication technology in which the frequency of a transmission signal changes with time.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram showing a conventional radar device. In the figure, 1 is a local oscillator for generating a sine wave signal, and 2 is an encoder for modulating the sine wave signal from the local oscillator 1 with an information signal. Reference numeral 3 denotes a PN code generator for generating a pseudo noise (hereinafter referred to as PN) code, and reference numeral 4 denotes a frequency synthesizer in which the frequency of a sine wave signal output by the PN code from the PN code generator 3 changes with time. .

[0005] Reference numeral 5 denotes an encoder 2 multiplied by a sine wave signal whose frequency changes with time from the frequency synthesizer 4.
Is a transmitting antenna as a radiating means for radiating the output of the antenna into the air. Reference numeral 6 denotes a target such as an airplane that reflects a signal radiated from the transmitting antenna 5, and reference numeral 7 denotes a receiving antenna as a receiving unit that receives a signal reflected by the target 6.

A mixer 8 multiplies a signal received by the receiving antenna 7 with a local signal whose frequency changes with time. Reference numeral 9 denotes a frequency synthesizer for generating a local signal to be supplied to the mixer 8, and reference numeral 10 denotes a PN for generating a pseudo-noise (hereinafter referred to as PN) code for temporally changing the frequency of the local signal generated by the frequency synthesizer 9. It is a code generator.

[0005] Reference numeral 11 denotes a demodulator for demodulating the signal from the mixer 8, and 12 denotes a decoder for decoding the signal demodulated by the demodulator 11. Reference numeral 13 denotes a synchronization system for synchronizing the PN code generated by the PN code generator 10 with the received signal.

Next, the operation will be described. Local oscillator 1
The sine wave signal generated in step (1) is modulated by the information signal in the encoder 2, multiplied by the sine wave from the frequency synthesizer 4 controlled by the PN code generator 3, and transmitted from the transmitting antenna 5 as a signal whose frequency changes with time. Radiation.

A signal radiated from the transmitting antenna 5 is reflected by a target 6 such as an airplane and received by a receiving antenna 7. The received signal is sent to a mixer 8, multiplied by a signal from a frequency synthesizer 9 controlled by a PN code generated by a PN code generator 10 synchronized by a synchronization system 13, and demodulated by a demodulator 11 and a decoder. An information signal is extracted by 12.

[0008] As a document describing the technology related to spread spectrum communication technology in such a conventional radar apparatus, for example, "Basic and Application of Spread Spectrum Communication Technology"(supervised; published by Masao Nakagawa; Trikeps Co., Ltd.)
1987).

[0009]

Since the conventional radar apparatus is configured as described above, it is necessary to acquire and maintain synchronization by the synchronization system 13. If synchronization is not achieved, demodulation of the received signal is performed. However, there is a problem that the synchronization cannot be performed and a complicated synchronization system 13 is required.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to obtain a radar apparatus which does not require a complicated synchronization system.

[0011]

According to a first aspect of the present invention, there is provided a radar apparatus, wherein one of a plurality of signals based on each sine wave signal generated by a plurality of first signal generating means is encoded. A signal whose frequency changes with time is radiated into the air from the radiating means by multiplying the signal by the signal generated by the generating means and multiplying the signal by the sine wave signal generated by the second signal generating means, and After multiplying the reflected signal by a sine wave signal generated by a predetermined one of the first signal generating means, it is detected and digitized for each frequency band,
Signal processing is performed in combination therewith.

According to a second aspect of the present invention, in the radar apparatus, a signal obtained by multiplying a reflected signal from a target by a sine wave signal generated by a predetermined one of the first signal generating means is obtained. Is separated, the remaining signal is further multiplied by a sine wave signal generated by the second signal generating means, and then detected for each frequency band.

[0013]

According to the first aspect of the present invention, the radar device comprises:
The predetermined signal in the first signal generating means is added to the reflected signal from the target.
After multiplying the generated sine wave signal, the signal is detected and digitized for each frequency band, and the signals are processed together to realize a radar device that does not require a complicated synchronous system.

The radar apparatus according to the second aspect of the present invention separates a part of a reflected signal from a target multiplied by a sine wave signal generated by a predetermined one of the first signal generating means. And multiplying the remaining signal by the sine wave signal generated by the second signal generating means, and then detecting and digitizing the signal for each frequency band, and performing signal processing together to obtain a complicated synchronous system. To realize a radar device that does not require a radar.

[0015]

【Example】

Embodiment 1 FIG. Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the first aspect of the present invention. In the figure, 5 is a transmitting antenna as a radiating means, 6 is a target, and 7 is a receiving antenna as a receiving means, which are equivalent to those of the prior art which are denoted by the same reference numerals in FIG.

Reference numerals 20a to 20c denote local oscillators as first signal generating means for generating sine wave signals having different frequencies f _S , f ₁ and f ₂ , respectively, and reference numerals 21a and 21b
Are multipliers for multiplying the sine wave signal of the frequency f _S generated by the local oscillator 20a with the sine wave signal of the frequency f ₁ or f ₂ generated by the local oscillators 20b and 20c.
22d is a frequency f _S output from the multipliers 21a and 21b.
+ F ₂ , f _S + f ₁ , f _S −f ₁ , and a band pass filter that separates signals of f _S −f ₂ .

Reference numeral 23 denotes each band-pass filter 22a to 22
d) and the local oscillator 20a
Is a switch as selection switching means for selecting one of the signals output by
This is a PN code generator as code generation means for generating a PN code which is a signal for controlling switching.

[0018] 25 is a local oscillator of the second signal generating means for generating a sine wave signal of frequency f ₀ different from the local oscillator 20 a to 20 c, 26 is selected signal by the switch 23 and the Multiplication means for multiplying the sine wave signal generated by the local oscillator 25. 27 is a first for limiting the band of the signal multiplied by the multiplication means 26
Is a bandpass filter as a band limiting means of
Reference numeral 8 denotes a power amplifier as amplifying means for power-amplifying the signal whose band is limited by the band-pass filter 27 and transmitting the signal to the transmitting antenna 5.

Reference numeral 30 denotes a low-noise amplifier as amplifying means for amplifying a signal received by the receiving antenna 7, and 31 denotes a signal amplified by the low-noise amplifier 30 and the local oscillator 20a. a multiplying means for multiplying the sinusoidal signal of a frequency f _S. 32a to 32e limit the band of the signal multiplied by the multiplication means 31, and
_{0 + f 2, f 0 +} f 1, f 0, f 0 -f 1, f 0 -f 2
Is a band-pass filter as a second band limiting unit that separates the frequency band into the respective frequency bands.

Reference numerals 33a to 33e denote phase detectors as phase detecting means for phase-detecting the signals separated by the band-pass filters 32a to 32e for each frequency band.
Reference numerals 34a to 34e denote low-pass filters as third band limiting means for removing high-frequency components of the signals detected by the phase detectors 33a to 33e.

Reference numerals 35a to 35e denote low-pass filters 3
A / D conversion means (hereinafter referred to as A / D conversion) means for digitizing each signal from which high-frequency components have been removed in 4a to 34e.
This is a signal processor as processing means for processing the digital signals converted at a to 35e together.

Next, the operation will be described. Local oscillator 2
Generated signal 0a~20c the frequency is f _S, the sine wave signal of f _1, f _2, respectively. Frequencies f _S and f
The sine wave signal of ₁ is multiplied by the multiplier 21a, and the sine wave signals of frequencies f _S and f ₂ are multiplied by the multiplier 21b. Therefore, the output of the multiplier 21a is a sine wave signal of the frequency f _S ± f ₁ , and the output of the multiplier 21b is a sine wave signal of the frequency f _S ± f ₂ .

These sine-wave signals are subjected to the frequencies f _S + f ₂ , f _S +
The signal is separated into four signals f ₁ , f _S −f ₁ , and f _S −f ₂ and sent to the switch 23. On the other hand, the sine wave signal of the frequency f _S generated by the
3 and one of these five signals is
The selection is switched at 3 and sent to the multiplication means 26.

Here, the switch 23 is connected to the PN code generator 2.
4 is operated in accordance with the signal generated, that is, the PN code. The multiplying means 26 multiplies the signal selected by the switch 23 by the sine wave signal of the frequency f ₀ generated by the local oscillator 25 to obtain a signal whose frequency changes with time. At this time, the frequency of the sine wave signal output from the multiplication means 26 is f _S + f ₂ ± f ₀ , f _S + f ₁ ± f ₀ , f _S
± f ₀ , f _S −f ₁ ± f ₀ , f _S −f ₂ ± f ₀ .

The output of the multiplying means 26 passes through a band-pass filter 27, so that the frequency f _S + f ₀ +
_{f 2, f S + f 0} + f 1, f S + f 0, f S + f 0 -f
₁ , five kinds of sine wave signals of f _s + f ₀ −f ₂ are amplified by the power amplifier 28 and radiated from the transmitting antenna 5 to the air.

The transmission signal radiated into the air from the transmission antenna 5 is reflected by the target 6 and received by the reception antenna 13 as a reflected signal. The received reflected signal is amplified by the low-noise amplifier 30 and is multiplied by the multiplication means 31 with the sine wave signal of the frequency f _S generated by the local oscillator 20a.

The frequency of the signal output from the multiplication means 31 at this _{time, f 0 + f 2 + 2v} / c (f S + f 0 + f 2), f 0 + f 1 + 2v / c (f S + f 0 + f 1), f _{0 + 2v / c (f S} + f 0), f 0 -f 1 + 2v / c (f S + f 0 -f 1), the _{f 0 -f 2 + 2v / c} (f S + f 0 -f 2). Here, v is a velocity component heading toward the transmitting antenna 5 and the receiving antenna 7 of the target 6, and c is the speed of light.

Next, the signal output from the multiplying means 31 is divided into 5 signals by frequency by the pan-pass filters 32a to 32e.
Phase detectors 33a to 33e for each frequency.
At 3e, the reference signal frequencies f ₀ + f ₂ , f ₀ + f ₁ , f ₀ ,
Phase detection is performed using f ₀ −f ₁ and f ₀ −f ₂ . The phase-detected signal has its harmonic components removed by low-pass filters 34a to 34e, and the A / D converter 3
After being converted into digital signals in 5a to 35e, they are input to the signal processor 36.

In the signal processor 36, a signal is inputted at regular time intervals, for example, as shown in FIG. FIG. 2 shows the frequency as the vertical and the time as the horizontal, and the display of “1” indicates that there is a reflected signal from the target 6. The signal processor 36 calculates a distance based on the input data, for example, based on the input data, and calculates a target moving speed by using data of the same transmission frequency for several cycles.

Embodiment 2 FIG. In the above embodiment, the reception signal is multiplied by the sine wave signal of the frequency f _S and then distributed to five. However, the reception signal is multiplied by the sine wave of the frequency f _S , and the transmission signal has a frequency f _0. Even if four signals other than + f _S are multiplied by a sine wave signal having a frequency f ₀ , and then distributed and processed, the same effect as in the first embodiment can be obtained.

FIG. 3 is a block diagram showing an embodiment of such an invention as set forth in claim 2. The same parts as those in FIG. 1 are denoted by the same reference numerals, and the description will not be repeated.

In the figure, reference numeral 37 denotes a band-pass filter as fourth band limiting means for limiting the band of the signal multiplied by the sine wave signal of the frequency f _S from the local oscillator 20a by the multiplying means 31. 9c is a part of the signal band-limited by the band-pass filter 37, that is, the frequency f _0.
This is a bandpass filter as fifth band limiting means for separating a signal related to + f _S and sending the separated signal to the phase detector 33c.

[0033] 3 8 sinusoidal said at bandpass filter 37 in the band-limited signal, the frequency f ₀ + f and a signal other than the relevant signals to the signal _S, the frequency f ₀ of the local oscillator 25 is generated Multiplication means for multiplying by a signal,
40a, 40b, 40d, 40e are separated by performing a band limitation multiplied signal by the multiplying means 3 8, they phase detector 33a, 33b, as a sixth band limiting means for sending to 33d or 33e This is a bandpass filter.

Next, the operation will be described. Here, the operation until the transmission signal is radiated into the air from the transmission antenna 5 and the signal received by the reception antenna 7 are multiplied by the multiplication means 31 with the sine wave signal of the frequency f _S from the local oscillator 20a. The operations up to this point are the same as those in the first embodiment, and the description thereof is omitted.

The signal multiplied by the multiplying means 31 is sent to a band-pass filter 37 and its band is limited, and the respective frequencies are f ₀ + f ₂ + 2v / c (f _S + f ₀ + f ₂ ), f _{0 + f 1 + 2v / c} (f S + f 0 + f 1), f 0 + 2v / c (f S + f 0), f 0 -f 1 + 2v / c (f S + f 0 -f 1), f 0 -f 2 _{+ 2v / c (f S +} f 0 -f 2) it becomes. Here, v is a velocity component heading toward the transmitting antenna 5 and the receiving antenna 7 of the target 6, and c is the speed of light.

Next, the signal output from the band-pass filter 37 is divided into two, one of which has a frequency f ₀ +2.
_{v / c (f S + f} 0) through a band-pass filter 3 9c
The other is sent to the multiplication means 38 and multiplied by the sine wave signal of the frequency f ₀ generated by the local oscillator 25.

The output of the multiplication means 38 is fed to 4 distributed in band-pass filter 40 a, 40 b, 40 d , 40 e, is the band each limit frequency _{f 2 + 2v / c (f} S + f 0 _{+ f 2), f 1 +} 2v / c (f S + f 0 + f 1), f 1 + 2v / c (f S + f 0 -f 1), the signal _{f 2 + 2v / c (f} S + f 0 -f 2) Separated. These signals are sent respectively with the output signal of the band-pass filter 3 9c previously described the phase detector 33a to 33e, the reference signal frequency f _2, f
Phase detection is performed at ₁ , f ₀ , f ₁ , and f ₂ .

Each of the phase-detected signals has its harmonic components removed by low-pass filters 34a to 34e.
After being converted into digital signals by the D converters 35a to 35e, the signals are sent to the signal processor 36, where the same processing as in the first embodiment is performed.

[0039]

As described above, according to the first aspect of the present invention, after multiplying a reflected signal from a target by a sine wave signal generated by a predetermined one of the first signal generating means, Since it is configured to detect and digitize it for each frequency band and to process them together, a radar device that does not require a complicated synchronization system at the time of reception and changes the frequency of the transmitted signal over time is available. There is an effect that can be obtained.

According to the second aspect of the present invention, a part of the reflected signal from the target multiplied by the sine wave signal generated by the predetermined one of the first signal generating means is separated. Since the remaining signal is multiplied by a sine wave signal generated by the second signal generating means, and then detected and digitized for each frequency band, and the signals are processed together, the reception signal is processed. Does not require complicated synchronization systems,
There is an effect that a radar apparatus in which the frequency of a transmission signal changes with time can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a time relationship of signals input to the signal processor.

FIG. 3 is a block diagram showing a second embodiment of the present invention.

FIG. 4 is a block diagram showing a conventional radar device.

[Explanation of symbols]

Reference Signs List 5 radiating means (transmitting antenna) 6 target 7 receiving means (receiving antenna) 20a to 20c first signal generating means (local oscillator) 23 selection switching means (switch) 24 code generating means (PN code generator) 25 second Signal generating means (local oscillator) 26 multiplying means 27 first band limiting means (band pass filter) 28 amplifying means (power amplifier) 30 amplifying means (low noise amplifier) 31 multiplying means 32a to 32e second band limiting means (Band pass filter) 33a to 33e Detecting means (phase detector) 34a to 34e Third band limiting means (low pass filter) 35a to 35e A / D converter 36 Processing means (signal processor) 37 Fourth band limiting means (bandpass filter) 38 multiplication means 39c fifth band limiting means (bandpass filter) 40a, 40b, 4 d, 40e sixth band limiting means (bandpass filter)

Claims (2)

(57) [Claims] 1. A plurality of first signal generators each generating a sine wave signal having a frequency different from each other, and one of a plurality of signals based on the sine wave signal generated by the first signal generator. Switching means for selecting a signal, a code generation means for generating a signal for controlling the selection switching means, and a second signal generation means for generating a sine wave signal having a different frequency from the first signal generation means Multiplying means for multiplying the signal selected by the selection switching means with a sine wave signal generated by the second signal generating means; and a first for limiting a band of the signal multiplied by the multiplying means. Band limiting means, amplifying means for power-amplifying the signal band-limited by the first band-limiting means, radiating means for radiating the signal power-amplified by the amplifying means to the air, and the radiating means The more radiated signal is the target Receiving means for receiving the reflected signal; amplifying means for amplifying the signal received by the receiving means; a signal amplified by the amplifying means;
Multiplying a sine wave signal generated by the predetermined one of the signal generating means, and performing band limitation on the signal multiplied by the multiplying means to separate the signal into a plurality of frequency band signals. A plurality of second band limiting means,
A plurality of detecting means for phase-detecting the signal separated by the band-limiting means for each frequency band, and a plurality of third band-limiting means for removing a high-frequency component of each signal phase-detected by the detecting means Analog-to-digital conversion means for converting each signal from which high-frequency components have been removed by the third band-limiting means into a digital signal; and signal processing by combining the digital signals converted by the analog-to-digital conversion means. Radar device comprising: 2. A plurality of first signal generating means each generating a sine wave signal having a frequency different from each other, and one of a plurality of signals based on the sine wave signal generated by the first signal generating means. Switching means for selecting a signal, a code generation means for generating a signal for controlling the selection switching means, and a second signal generation means for generating a sine wave signal having a different frequency from the first signal generation means Multiplying means for multiplying the signal selected by the selection switching means with a sine wave signal generated by the second signal generating means; and a first for limiting a band of the signal multiplied by the multiplying means. Band limiting means, amplifying means for power-amplifying the signal band-limited by the first band-limiting means, radiating means for radiating the signal power-amplified by the amplifying means to the air, and the radiating means The more radiated signal is the target Receiving means for receiving the reflected signal; amplifying means for amplifying the signal received by the receiving means; a signal amplified by the amplifying means;
Multiplying means for multiplying a sine wave signal generated by the predetermined one of the signal generating means, a fourth band limiting means for limiting a band of the signal multiplied by the multiplying means, Fifth band-limiting means for separating a part of the signal band-limited by the band-limiting means, remaining signals in the signal band-limited by the fourth band-limiting means, and generation of the second signal Multiplying means for multiplying the sine wave signal generated by the means, and a plurality of sixth band limiting means for performing band limiting of the signal multiplied by the multiplying means and separating the signals into a plurality of frequency bands. A plurality of detection means for phase-detecting the signals separated by the fifth and sixth band-limiting means for each frequency band; and removing high-frequency components of each signal phase-detected by the detection means. A plurality of third band limiting means, and the third band Analog-to-digital conversion means for converting each signal from which high-frequency components have been removed by the limiting means into a digital signal, and processing means for processing the combined digital signal by the analog-to-digital conversion means. Radar equipment.