JPH1039010A - Radar device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To disperse the energy of noise and enable the improvement of the sensitivity of reception by providing a digital filter processing part which removes undesired signals and a frequency analysis processing part which analyzes frequencies. SOLUTION: The oscillation output signals of an oscillator 5 are inputted to a PLL(phase lock loop) synthesizer 4 and step recovery diode 9 to become the signals of transmitted waves via the synthesizer 4, and which are transmitted from an antenna 1 via a switch part 3. Reflected radio waves are received by the antenna 1 and inputted to an amplifier 6 via a transmitting/receiving device 2. Then the signals are inputted to a double balance mixer 7. The output signals of the diode 9 are inputted to this mixer 7 to be mixed with the signals of the received waves, the signals of a Doppler frequency are outputted, and inputted to an A/D converter 8 to be converted to digital signals. The converted signals, from which undesired signal components are removed at a digital filter processing part 11, are inputted to a frequency analysis processing part to be converted to the signals of relative speed from the signals of a Doppler frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radar device for detecting a relative speed with respect to a target by using a Doppler frequency. A radar device that detects a relative speed with respect to a target is known by a Doppler frequency of a difference between a frequency of a transmission wave and a frequency of a reception wave received by the transmission wave reflected from the target. There is a demand for improving the sensitivity by reducing the influence of noise included in the received wave.

[0002]

2. Description of the Related Art FIG. 8 is an explanatory view of a main part of a conventional radar apparatus, wherein 51 is an antenna, 52 is a duplexer such as a circulator, 53 is a high-frequency amplifier circuit, 54 is a synthesizer, 55 is an oscillator, and 56 is an oscillator. The first local oscillator, 57
Mixer, 58 is a first intermediate frequency circuit, 59 is a second mixer,
60 is a second local oscillator, 61 is a second intermediate frequency circuit, 62
Is a demodulation circuit.

An oscillator 55 generates a fundamental frequency of a synthesizer.
4, the signal becomes a transmission wave signal having a frequency of several GHz to several tens GHz, and is transmitted from the duplexer 52 to the antenna 51.
Is transmitted in the direction of the target. When the reflected wave from the target is received by the antenna 51 as a received wave,
The signal is input to the high-frequency amplifier circuit 53 via the duplexer 52, amplified, input to the first mixer 57, mixed with the oscillation output signal of the first local oscillator 56, and converted into a first intermediate frequency signal.

The first intermediate frequency signal is input to a first intermediate frequency circuit 58, amplified, input to a second mixer 59, mixed with an oscillation output signal of a second local oscillator 60, and Converted to a signal. This second intermediate frequency signal is input to the second intermediate frequency circuit 61 and amplified,
A signal indicating the relative speed is input to the demodulation circuit 62 to output a signal, and the relative speed is displayed on a display unit or the like (not shown).

Assuming that the oscillation frequency of the oscillator 55 is f,
Oscillation frequency f is several GHz to several tens GHz as described above.
And the oscillation frequency of the first local oscillator 56
Wave number f₁Is, for example, f + 500 MHz or f-500
MHz. In this case, the first intermediate frequency signal is
500 MHz. The oscillation frequency of the second local oscillator 60
Number f_TwoIs selected to be, for example, 500 MHz. This place
The Doppler frequency corresponding to the relative speed with respect to the target is f_d
Then, the first intermediate frequency is 500 MHz ± f _dBecomes
Therefore, the output signal of the second mixer 59 is ± f_dBecomes Follow
And the Doppler frequency f_dIs obtained, this Doppler frequency
The relative speed of the target can be determined based on the number.

[0006]

In the above-mentioned radar device, the transmission wave from the antenna 51 is formed based on the oscillation output signal of the oscillator 55.
The oscillation output signal includes noise over a relatively wide frequency range centered on the oscillation frequency f. In addition, the level of the received wave reflected from the target and received by the antenna 51 is low, and the oscillation output signal of the local oscillator also contains many noise components, so that it is not easy to extract the received signal containing the Doppler frequency component. was there. That is, there is a problem that the receiving sensitivity is low. An object of the present invention is to increase reception sensitivity by dispersing noise energy.

[0007]

According to the radar apparatus of the present invention, (1) the output signal of the oscillator 5 is converted into a transmission wave via the synthesizer 4, and this transmission wave is transmitted from the antenna 1 via the duplexer 2. In a radar apparatus which receives a reflected wave from a target object by the antenna 1 and demodulates the signal in a demodulation unit via a duplexer 2, a switch unit 3 which intermittently transmits a transmission wave from a synthesizer 4 at a predetermined cycle. And oscillator 5
A step recovery diode 9 which makes the spectrum of the output signal energy dispersed, a double balance mixer 7 which adds the output signal of the step recovery diode 9 and the signal of the received wave via the duplexer 2, and a double balance mixer 7 An A / D converter 8 for converting an output signal of the mixer 7 into a digital signal; and a switch unit 3 and an A / D converter so that the operation of the A / D converter 8 is stopped when the switch unit 3 is turned on. 8, a pulse oscillator 10 for adding a pulse signal, a digital filter processing unit 11 for adding an output digital signal of the A / D converter 8 to remove unnecessary signals, and a frequency of an output signal of the digital filter processing unit 11 is analyzed. And a frequency analysis processing unit 12. Therefore, the noise component included in the output signal of the oscillator is dispersed, and the noise component included in the output signal of the oscillator is also dispersed in the mixing in the processing of the received wave.
In addition, by controlling the operation period of the A / D converter 8, it is possible to remove the influence of the noise component in which the transmission wave leaks to the receiving side.

(2) The output signal of the oscillator 5 is converted into a transmission wave via the synthesizer 4, and the transmission wave is transmitted from the antenna 1 via the duplexer 2, and the reflected wave from the target is transmitted by the antenna 1. In a radar device for receiving and demodulating by a demodulation unit via a duplexer 2, a switch unit for intermittently transmitting a transmission wave from a synthesizer at a predetermined cycle, and a spectrum in which energy of an output signal of an oscillator is dispersed. And a signal having a phase difference of 90 degrees from the output signal of the step recovery diode and the signal of the received wave via the duplexer, respectively.
/ Q mixer, an A / D converter for converting the output signals of the quadrature components from the I / Q mixer into digital signals, and an operation of the A / D converter when the switch unit is turned on. A pulse oscillator for applying a pulse signal to a switch unit and an A / D converter, a digital filter processing unit for adding an output digital signal of the A / D converter to remove unnecessary signals, and a digital filter processing unit A frequency analysis processing unit for analyzing a frequency.

(3) The output signal of the oscillator 5 is converted into a transmission wave via the synthesizer 4, and the transmission wave is transmitted from the antenna 1 via the duplexer 2, and the reflected wave from the target is transmitted by the antenna 1. In a radar device that receives and demodulates data in a demodulation unit via a duplexer 2, a switch unit that intermittently transmits a transmission wave from a synthesizer at a predetermined cycle, and a signal of a received wave through a duplexer and an oscillator. And a sampling mixer for outputting a signal of a mixed output waveform of a dispersed spectrum, and an A / D for converting an output signal of the sampling mixer into a digital signal.
A converter, a pulse oscillator for applying a pulse signal to the switch unit and the A / D converter so as to stop the operation of the A / D converter when the switch unit is turned on, and an output digital signal of the A / D converter And a frequency analysis processor for analyzing the frequency of the output signal of the digital filter processor.

(4) In each of the above-mentioned radar apparatuses, a pulse control processing section for controlling a pulse oscillator so that the switch section is continuously turned off to stop transmission can be provided.

[0011]

FIG. 1 is an explanatory view of a first embodiment of the present invention, wherein 1 is an antenna, 2 is a duplexer such as a circulator, 3 is a switch section, and 4 is a PLL (phase locked loop). ) Synthesizer, 5 is an oscillator (OSC), 6 is an amplifier, 7 is a double balance mixer, 8 is an A / D converter, 9 is a step recovery diode (SRD), 1
0 is a pulse oscillator, 11 is a digital filter processing unit,
12 is a frequency analysis processing unit, 13 is a display unit such as a cathode ray tube or a liquid crystal panel, 14 is a pulse control processing unit, and 15 is a PL.
The L synthesizer control processing unit 16 is a system controller.

The oscillation output signal of the oscillator 5 is input to the PLL synthesizer 4 and the step recovery diode 9, becomes a transmission wave signal via the PLL synthesizer 4, and is input to the duplexer 2 via the switch unit 3. It is transmitted from the antenna 1 via the duplexer 2. The radio wave reflected from the target is received by the antenna 1 and input to the amplifier 6 via the duplexer 2, and the amplified output signal is input to the double balance mixer 7.

Various known configurations can be applied to the double balance mixer 7. The output signal of the step recovery diode 9 is input, mixed with the signal of the received wave, and the signal of the Doppler frequency is output. The signal is input to the A / D converter 8 and converted into a digital signal. The converted digital signal is input to a frequency analysis processing unit 12 after removing unnecessary signal components by a digital filter processing unit 11, is converted from a Doppler frequency signal to a relative speed signal, is input to a display unit 13, The relative speed of the object is displayed.

The system controller 16 is constituted by a processor or the like and controls each unit. The pulse control processing unit 14 controls the pulse oscillator 10 in accordance with a command from the system controller 16 and switches the pulse oscillator 10 A control pulse signal for turning on / off the section 3 and a control pulse signal for controlling the operation and non-operation of the A / D converter 8 are generated. In this case, when the switch unit 3 is turned on, the A / D converter 8 is controlled to a non-operating state,
When the switch unit 3 is turned off, the A / D converter 8 is controlled to an operating state. System controller 1
The control pulse signal applied from the pulse oscillator 10 to the switch unit 3 according to the control command from 6 can be controlled so that the switch unit 3 is continuously turned off and transmission is stopped. Also, the PLL synthesizer control processing unit 15
It controls the synthesizer 4 to switch the frequency of the transmission wave.

The spectrum of the output signal of the oscillator 5 is, for example, as shown in FIG. In other words, ideally, it is desirable that the line spectrum has the oscillation frequency f. However, in actuality, as shown in the figure, the oscillation frequency f
, And a frequency component whose level gradually decreases around the center, and noise components other than the oscillation frequency f become noise components. Further, when the switching is performed at a predetermined cycle by the switch unit 3, the spectrum shown in FIG. That is, noise components are also dispersed on the frequency axis. Note that the dotted waveform shows an envelope due to folding.

The step recovery diode 9 has p
It has a profile in which the impurity concentration in the p and n regions increases sharply from the n junction surface, respectively, and is used for higher-order frequency multiplication in the UHF and SHF bands. FIG. 3 is an explanatory diagram of a spectrum waveform by the step recovery diode.
Assuming that (a) is the spectrum of the oscillation output signal of the oscillator 5, the spectrum of the output signal of the step recovery diode 9 is arranged at regular intervals on the frequency axis as shown in (b). The frequency range is relatively narrow. For example, by extracting a signal of a desired frequency using a resonance circuit or the like, a frequency multiplication circuit can be easily configured.

[0017] The received signal of a frequency f _r, the oscillation output signal of the oscillator 5 becomes the relationship shown in FIG. 3 (a), and the relationship shown in FIG. 3 (b) is the output signal of the step recovery diode 9 Becomes Therefore, when mixing the output signal of the step recovery diode 9 and the reception signal shown in FIG. 3B with respect to the case where the oscillation output signal of the oscillator 5 is mixed with the reception signal, the noise component is dispersed. As a result, the influence of the noise component can be significantly reduced.

FIG. 4 is an explanatory diagram of the transmission / reception processing.
Shows a control pulse signal applied from the pulse oscillator 9 to the switch unit 3, and (b) shows a control pulse signal applied from the pulse oscillator 9 to the A / D converter 8. In other words, the operation of the A / D converter 8 is stopped (OFF) during the transmission period when the switch unit 3 is turned on, and the operation of the A / D converter 8 is performed during the transmission stop period when the switch unit 3 is turned off. Then, the output signal of the double balance mixer 7 is converted into a digital signal during the transmission stop period.

FIG. 2C shows a transmission signal input from the switch unit 3 to the duplexer 2. The duplexer 2 formed by a circulator or the like ideally does not cause a wraparound of the transmitted signal. Actually, a small amount of wraparound occurs, which becomes a noise component in the reception processing. (D)
Indicates a received signal input to the A / D converter 8. The noise in (c) and (d) indicates a component caused by the wraparound of the transmission signal via the duplexer 2.

Therefore, during the transmission period when the switch unit 3 is on, the noise component sneaking through the duplexer 2 is input to the A / D converter 8, but the A / D converter 8 is not turned on. Since the operation is in progress, this noise component is not converted into a digital signal. During the reception period in which the switch unit 3 is off, the noise component circulating through the duplexer 2 is zero. Therefore, only the received signal is input to the A / D converter 8 and converted into a digital signal.

FIG. 5 is an explanatory diagram of the received signal processing.
(A) shows a spectrum waveform of an output signal of the double balance mixer 7, which becomes a reception wave having a waveform according to the transmission wave of the waveform shown in (b) of FIG. 2 and a step recovery shown in (b) of FIG. Since the output signal of the diode 9 is mixed with the frequency-divided output signal, the output signal is discontinuously arranged on the frequency axis, and the received signal is located between them.
Except for the received signal, it becomes an unnecessary wave.

Therefore, the digital filter processing unit 11
By ideally performing a filtering process with characteristics as indicated by a chain line DF, it is possible to extract a received signal that is not affected by noise as illustrated in FIG. The frequency analysis processing unit 12 performs a frequency analysis of the received signal to calculate a relative speed of the target, and displays the relative speed on the display unit 13 according to various methods already known.

FIG. 6 is an explanatory view of the second embodiment of the present invention. In FIG. 6, the same reference numerals as those in FIG.
Q mixers, 18 and 19 are A / D converters, and 20 is a digital filter processing unit.

The I / Q mixer 17 splits the output signal of the amplifier 6 into two and inputs it, splits the output signal of the step recovery diode 9 into two, and gives a phase difference of 90 degrees to the other. These are mixed and output orthogonal components. Therefore, the A / D converters 18 and 19 are provided for the orthogonal components, and the digital filter processing unit 2
Even at 0, filter processing is performed for each orthogonal component, and only the received signal component is synthesized and output.

The frequency analysis processing section 12 analyzes the frequency based on the output signal of the digital filter processing section 20 from which only the received signal is extracted, obtains the relative speed with respect to the target, and displays it on the display section 13. Therefore, the noise component is also distributed to the quadrature component by the mixing of the quadrature component by the I / Q mixer 17, so that it is possible to contribute to the improvement of the reception sensitivity.

FIG. 7 is an explanatory view of the third embodiment of the present invention. The same reference numerals as in FIG. 1 denote the same parts, and 27 denotes a sampling mixer. This sampling mixer 27
Can apply various known configurations. By mixing the output signal of the amplifier 6 and the output signal of the oscillator 5, a plurality of higher-order signals can be obtained in the same manner as when the step recovery diode 9 is used. An output signal obtained by mixing the harmonic and the output signal of the amplifier 6 can be obtained. That is, the sampling mixer 27 includes a function similar to that of the step recovery diode 9, thereby dispersing a noise component included in the oscillation output signal of the oscillator 5. Can be.

In each of the above embodiments, the switch unit 3 is turned on and off by a control pulse signal from the pulse oscillator 10. However, it may be necessary to stop the emission of radio waves. At that time, by instructing the pulse control processing unit 14 to stop transmission from the system controller 16, the pulse control processing unit 14 controls the pulse oscillator 10 and applies a control signal to turn off the switch unit 3 continuously. become. Such a pulse oscillator 10
The function of the pulse control processing unit 14 for controlling the processing can be realized by the processing function of a processor constituting the system controller 16.

[0028]

As described above, according to the present invention, the output signal of the oscillator 5 is used as a transmission wave via the synthesizer 4, and this transmission wave is transmitted from the antenna 1 via the duplexer 2, and the antenna 1 In a radar device that receives a reflected wave from a target object and demodulates the signal via a duplexer 2 and a demodulation unit including a mixer and a frequency analysis processing unit, a transmission wave from a synthesizer 4 is switched by a switch unit 3. The signal is transmitted intermittently at a predetermined cycle, and the output signal of the oscillator 5 is input to the mixer via the step recovery diode 9 to be mixed with the received signal, and the output signal of the mixer is transmitted during the transmission period when the switch unit 3 is on. Is inactive, and is operated during the transmission suspension period when the switch unit 3 is off. The digital signal is converted by the A / D converter 8 and the unnecessary signal is converted by the digital filter processing unit 11. In this case, the noise component included in the output signal of the oscillator 5 is dispersed, and the noise component in which the transmission wave has passed to the receiving side can be removed by setting the A / D converter 8 inactive. Therefore, there is an advantage that the receiving sensitivity can be improved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a spectrum waveform of a transmission wave.

FIG. 3 is an explanatory diagram of a spectrum waveform by a step recovery diode.

FIG. 4 is an explanatory diagram of transmission / reception processing.

FIG. 5 is an explanatory diagram of received signal processing.

FIG. 6 is an explanatory diagram of a second embodiment of the present invention.

FIG. 7 is an explanatory diagram of a third embodiment of the present invention.

FIG. 8 is an explanatory view of a main part of a conventional radar device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Antenna 2 Duplexer 3 Switch part 4 PLL synthesizer 5 Oscillator (OSC) 6 Amplifier 7 Double balance mixer 8 A / D converter 9 Step recovery diode (SRD) 10 Pulse oscillator 11 Digital filter processing part 12 Frequency analysis processing part 13 Display unit 14 Pulse control processing unit 15 PLL synthesizer control processing unit 16 System controller

Claims (4)

[Claims] An output signal of an oscillator is converted into a transmission wave via a synthesizer, the transmission wave is transmitted from an antenna via a duplexer, and a reflected wave from a target is received by the antenna. In a radar device that performs demodulation processing in a demodulation unit via a switch unit that intermittently transmits a transmission wave from the synthesizer at a predetermined period, and a step recovery diode that has a spectrum in which energy of an output signal of the oscillator is dispersed. A double balance mixer for adding an output signal of the step recovery diode and a signal of a reception wave via the duplexer; an A / D converter for converting an output signal of the double balance mixer into a digital signal; The switch unit and the A / D converter so as to stop the operation of the A / D converter when the unit is turned on.
A pulse oscillator for applying a pulse signal to the converter;
A radar apparatus comprising: a digital filter processing unit that removes an unnecessary signal by adding an output digital signal of a D converter; and a frequency analysis processing unit that analyzes a frequency of an output signal of the digital filter processing unit. 2. An output signal of an oscillator is converted into a transmission wave via a synthesizer, the transmission wave is transmitted from an antenna via a duplexer, and a reflected wave from a target is received by the antenna. In a radar device that performs demodulation processing in a demodulation unit via a switch unit that intermittently transmits a transmission wave from the synthesizer at a predetermined period, and a step recovery diode that has a spectrum in which energy of an output signal of the oscillator is dispersed. An I / Q mixer for adding a signal of a received wave via the duplexer and a signal having a phase difference of 90 degrees from the output signal of the step recovery diode, and output of a quadrature component from the I / Q mixer An A / D converter for converting each signal into a digital signal; and stopping the operation of the A / D converter when the switch unit is turned on. As such, the switch unit and the A / D
A pulse oscillator for applying a pulse signal to the converter, a digital filter processing section for adding an output digital signal of the A / D converter to remove unnecessary signals, and a frequency analysis for analyzing a frequency of an output signal of the digital filter processing section A radar device comprising a processing unit. 3. An output signal of an oscillator is converted into a transmission wave via a synthesizer, the transmission wave is transmitted from an antenna via a duplexer, and a reflected wave from a target is received by the antenna. In a radar device that performs demodulation processing by a demodulation unit via a switch unit that intermittently transmits a transmission wave from the synthesizer at a predetermined cycle, a signal of a reception wave via the duplexer, and a signal from the oscillator. And a sampling mixer for outputting a signal of a mixed output waveform of a dispersed spectrum; an A / D converter for converting an output signal of the sampling mixer into a digital signal; The switch unit and the A / D converter are configured to stop the operation of the A / D converter.
A pulse oscillator for applying a pulse signal to the converter, a digital filter processing section for adding an output digital signal of the A / D converter to remove unnecessary signals, and a frequency analysis for analyzing a frequency of an output signal of the digital filter processing section A radar device comprising a processing unit. 4. The pulse control processing unit according to claim 1, further comprising a pulse control processing unit that controls the pulse oscillator so that the switch unit is continuously turned off to stop transmission. Radar equipment.