JP2010216980A - Radar device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radar device for conducting measurement in a prescribed distance range in a short time. <P>SOLUTION: A receiver 120 includes a correlation pulse generation source 121 as a signal source and a clock generation source 128. A correlation pulse train generated in the generation source 121 continuously generates a plurality of (L) correlation pulses in a sampling cycle Ts in which sampling is performed in an A-D converter 130, and the correlation pulses have pulse widths equal to pulse widths of pulses generated in a pulse generation source 111. Furthermore, a clock signal train outputted from the generation source 128 is synchronized with the pulse train and continuously generates L clock signals in the same sampling cycle Ts as the pulse train. This structure can acquire L-pieces of different distance information every time one transmission signal is sent out. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a radar apparatus that detects distance information of an object ahead using a pulse signal.

  Conventionally, as a pulse radar using a correlator, one disclosed in Patent Document 1 is known. FIG. 15 shows a pulse radar described in Patent Document 1. In the pulse radar 900 shown in the figure, the pulse generated by the pulse source 901 passes through the transmission gate 902 and is input to the pulse modulation unit 903a. Further, the microwave or millimeter wave generated by the microwave source 904 is distributed by the power distributor 916a and input to the pulse modulator 903a as a carrier wave. In the pulse modulation unit 903a, the pulse input from the transmission gate 902 is up-converted by the carrier wave input from the microwave source 904, and is transmitted from the transmission antenna 905 to the space.

  The transmission pulse transmitted from the transmission antenna 905 is reflected by an object located at a position separated by a distance R, and is captured as a reception pulse by the reception antenna 906. The received pulse is divided into two signals (I signal and Q signal) whose phases are shifted by 90 degrees by the orthogonal power distributor 907 and inserted into the mixers 908 and 909, respectively.

  Apart from this, the above-mentioned pulse generated by the pulse source 901 is given a delay time τ corresponding to the time required for the radio wave to propagate the distance R in the delay time giving unit 910, and further passes through the reception gate 911. After that, the pulse modulation unit 903b performs up-conversion with the carrier wave input from the microwave source 904. A delay time τ is added, the pulse that has passed through the pulse modulator 903b and the power distributor 916b, and the I signal and the Q signal output from the orthogonal power distributor 907 are multiplied by the mixers 908 and 909, respectively, and down-converted. Each correlation is taken. The outputs of the mixers 908 and 909 are charged to the hold capacitor 912, amplified by the preamplifier 913, passed through the Doppler filter 914 that removes the Doppler component, and signal detection is performed by the detection unit 915.

  In Patent Document 1, since the power of the received wave is small, the amplitude voltages of a plurality of reflected waves are added coherently (synchronized). Since there is only one hold capacitor 912 for each of the I signal and the Q signal, one distance information corresponding to the delay time τ is detected by correlating with the pulse to which the delay time τ is added. According to Patent Document 1, the relative speed can also be detected, and the relative speed is calculated by monitoring how far the object has moved in a predetermined time. The delay time τ can be made variable by a program, whereby the range of the distance R to be detected can be made variable.

US6066704

  In the radar apparatus, in order to determine at which distance an object exists, a plurality of storage units for storing distance information called range bins are prepared, and the data obtained by the detection unit of the receiving system is sequentially stored. An example of storing distance information using a plurality of range bins is shown in FIG. In the figure, an example is shown in which a plurality of range bins 920 are provided so as to have a resolution of 1 ns (corresponding to a distance resolution of about 0.15 m). About 100 to 200 range bins 920 are normally used, and information such as amplitude values detected by the detection unit is stored. In the example shown in FIG. 16, information indicating the presence of an object is stored in the range bins 920a to 920d, and it is detected that there is an object at a distance corresponding to each range bin.

  In the configuration according to the above-described conventional technique, it is necessary to transmit several pulses to obtain information of one range bin and to synchronously add the received signals. Since it is necessary to acquire distance information by such a plurality of pulse transmissions, for example, for each of about 200 range bins, there is a problem that it takes a very long time to obtain a complete range of distance information. It was.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a radar apparatus that can process measurement in a predetermined distance range in a short time.

  In order to solve the above-described problem, a first aspect of a radar apparatus according to the present invention includes an oscillator that oscillates a carrier wave having a predetermined frequency, and a first power distribution that distributes the power of the carrier wave output from the oscillator to two outputs. A transmitter that inputs one carrier wave distributed by the first power distributor and generates a predetermined transmission signal, and a transmission that receives the transmission signal from the transmitter and transmits it to space by radio waves An antenna, a receiving antenna that receives a reflected radio wave reflected by an object, and the other carrier wave that receives a received signal from the receiving antenna and is distributed by the first power distributor And a digital signal processing unit for detecting an object based on a signal input from the receiving unit, wherein the transmitting unit is configured to perform predetermined signal processing. A pulse generation source that generates a pulse having a pulse width at a predetermined pulse repetition period; and a first pulse modulator that outputs the transmission signal by superimposing the one carrier wave on the pulse, and the reception unit includes: In synchronization with the pulse generation source, a single correlation pulse having the same pulse width as the predetermined pulse width is generated L times (L is an integer of 2 or more) at a predetermined time interval (Ts). A correlation pulse generation source to be output, a first delay element that outputs the correlation pulse output from the correlation pulse generation source by delaying the correlation pulse by a predetermined delay time (td), and output from the first delay element A second pulse modulator that superimposes the other carrier wave on a correlation pulse; a second power distributor that distributes a reception signal input from the reception antenna into two reception signals; A phase shifter that receives the output of the second pulse modulator and outputs a second output that is shifted by 90 degrees from the first output whose phase is unchanged, and the first output and the second output, respectively, Two mixers for multiplying the two received signals distributed by the power distributor, two power amplifiers for amplifying the output power of each of the two mixers, and a clock signal in synchronization with the correlation pulse generation source A clock generation source to be generated, a second delay element that delays the clock signal by the delay time td, and outputs of the two power amplifiers at the timing of the clock signal output from the second delay element, respectively. Two A / D converters, each time the A / D converter transmits the radio wave of the transmission signal from the transmission antenna to the clock signal. Thus, the sampling is performed L times.

  In the present invention configured as described above, it is possible to acquire distance information of L points (L ≧ 2) by sending a transmission signal once, and processing of a predetermined distance range can be processed in a short time. .

  In another aspect of the radar apparatus of the present invention, the delay time td is updated every time the radio wave of the transmission signal is transmitted M times (M is an integer of 2 or more) from the transmission antenna. . Thereby, S / N of distance information can be improved.

  In another aspect of the radar apparatus of the present invention, the first delay element and the second delay element update the delay time td by increasing the initial value by 0 and increasing the delay time td by a unit delay time t1. Is reset to 0 again when the time interval exceeds the predetermined time interval Ts. By sequentially updating the delay time td in the range of 0 to Ts, distance information within a predetermined range can be acquired.

  Another aspect of the radar apparatus of the present invention is characterized in that the unit delay time t1 is shorter than the predetermined pulse width. Thereby, it is possible to measure all within the predetermined distance range.

  In another aspect of the radar apparatus of the present invention, the digital signal processing unit inputs the outputs of the two A / D converters to calculate the distance and relative speed to the object, and the pulse generation source, Control is performed to achieve predetermined synchronization with respect to the correlation pulse generation source, the first delay element, the second delay element, and the clock generation source. Control that is synchronized by the control from the digital signal processing unit is facilitated.

  According to another aspect of the radar apparatus of the present invention, a first multiplier connected between the first pulse modulator and the transmitting antenna, and the first multiplier connected to the first multiplier. And a second multiplier connected between the second pulse modulator and the phase shifter, wherein the oscillator has 1 / N (1 N is an integer of 2 or more), and the frequency band of the first power divider, the first pulse modulator, and the second pulse modulator is 1 / N of the used frequency. The first multiplier and the second multiplier both multiply the frequency of the input signal by N times. Costs can be reduced by making it possible to use low-priced low-frequency equipment.

Another aspect of the radar apparatus of the present invention includes an oscillator that oscillates a carrier wave having a predetermined frequency, a first power distributor that distributes the power of the carrier wave output from the oscillator to two outputs, and the first power. A transmission unit that inputs one carrier wave distributed by a distributor to generate a predetermined transmission signal, a transmission antenna that inputs the transmission signal from the transmission unit and transmits the signal to space by radio waves, and a transmission from the transmission antenna A receiving antenna for receiving a reflected radio wave reflected by an object and a received signal from the receiving antenna and the other carrier wave distributed by the first power distributor for predetermined signal processing And a digital signal processing unit for detecting an object based on a signal input from the receiving unit, wherein the transmitting unit applies a pulse having a predetermined pulse width to a predetermined pulse width. And a first pulse modulator that outputs the transmission signal by superimposing the one carrier wave on the pulse, and the receiving unit is synchronized with the pulse generation source. A correlation pulse generating source that generates a correlation pulse having the same pulse width as the predetermined pulse width L times (L is an integer of 2 or more) at a predetermined time interval (Ts) for each of the pulses; A first delay element that outputs the correlation pulse output from the correlation pulse generation source after being delayed by a predetermined delay time (td) and a correlation pulse output from the first delay element are input from the receiving antenna. A second pulse modulator that superimposes the received signal, a second power distributor that distributes the output of the second pulse modulator to two outputs, and the other carrier wave And a phase shifter that outputs a second output that is 90 degrees out of phase with the first output whose phase is unchanged, and the first output and the second output are each distributed by the second power distributor. Two mixers for multiplying the two outputs, two power amplifiers for amplifying output power of the two mixers, a clock generation source for generating a clock signal in synchronization with the correlation pulse generation source, A second delay element that delays a clock signal by the delay time td, and two A / D converters that respectively sample the outputs of the two power amplifiers at the timing of the clock signal output from the second delay element; The A / D converter performs the sampling by the clock signal L times each time a radio wave of the transmission signal is transmitted from the transmission antenna. Features.
Even with the configuration as described above, measurement within a predetermined distance range can be processed in a short time.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the radar apparatus which can process the measurement of a predetermined distance range for a short time.

1 is a block diagram showing a configuration of a radar apparatus according to a first embodiment of the present invention. It is explanatory drawing which shows an example of the waveform of the signal produced | generated in the transmission part of 1st Embodiment. It is explanatory drawing which shows an example of the received signal (b) output to a receiving part from a transmission signal (a) and a receiving antenna. It is explanatory drawing which shows an example of the signal waveform produced | generated by the correlation pulse generation source and clock generation source of 1st Embodiment. It is explanatory drawing for demonstrating equivalent sampling. It is explanatory drawing for demonstrating the control by the digital signal processing part of 1st Embodiment. It is explanatory drawing explaining the signal processing for detecting an object in the receiving part of 1st Embodiment. It is explanatory drawing explaining the signal processing for detecting another object in the receiving part of 1st Embodiment. It is explanatory drawing which shows an example of I signal and Q signal input into the digital signal processing part of 1st Embodiment. It is a flowchart for demonstrating the process in the digital signal processing part of 1st Embodiment. It is a block diagram which shows the structure of the radar apparatus which concerns on the 2nd Embodiment of this invention. It is a block diagram which shows the structure of the radar apparatus which concerns on the 3rd Embodiment of this invention. It is explanatory drawing explaining the signal processing for detecting an object in the receiving part of 3rd Embodiment. It is explanatory drawing explaining the signal processing for detecting two objects which adjoin. It is a block diagram which shows the structure of the conventional pulse radar. It is explanatory drawing for demonstrating an example which stores distance information using a range bin.

  A radar apparatus according to a preferred embodiment of the present invention will be described in detail with reference to the drawings. Each component having the same function is denoted by the same reference numeral for simplification of illustration and description.

(First embodiment)
The configuration of the radar apparatus according to the first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram illustrating a configuration of a radar apparatus 100 according to the present embodiment. The radar apparatus 100 includes an oscillator 101 that oscillates a carrier wave having a predetermined frequency (referred to as fc), a first power distributor 102 that distributes the power of the carrier wave output from the oscillator 101 to two outputs, and a predetermined transmission. A transmission unit 110 that generates a signal, a transmission antenna 103 that transmits a transmission signal input from the transmission unit 110 to a space using radio waves, and a reception that receives the reflected radio waves after the radio waves transmitted from the transmission antenna 103 are reflected by an object. The antenna 104, the reception unit 120 that receives a reception signal from the reception antenna 104 and performs predetermined signal processing, detects an object based on the signal input from the reception unit 120, and transmits the transmission unit 110 and the reception unit 120. And a digital signal processing unit 140 that performs the above control.

  The transmission unit 110 includes a pulse generation source 111 that generates a pulse with a predetermined pulse width and a predetermined pulse repetition period, and one of the carrier waves distributed by the first power distributor 102 to pulses generated by the pulse generation source 111. And a first pulse modulator 112 that superimposes. The first pulse modulator 112 generates a high-frequency transmission pulse by cutting out the carrier wave input from the first power distributor 102 with the pulse input from the pulse generation source 111, and outputs this to the transmission antenna 103. The pulse generation source 111 generates a pulse in accordance with control from the digital signal processing unit 140.

  The receiving unit 120 generates a plurality of correlation pulses having a predetermined pulse width at a predetermined interval with respect to one pulse generated by the pulse generation source 111 in synchronization with pulse generation in the pulse generation source 111. 121, the first delay element 122 that outputs the correlation pulse output from the correlation pulse generation source 121 with a predetermined delay time, and the correlation pulse output from the first delay element 122 has a first power. A second pulse modulator 123 that superimposes the other of the carrier waves distributed by distributor 102, a second power distributor 124 that distributes the reception signal input from reception antenna 104 into two reception signals, and a second pulse. A phase shifter 125 that receives the output of the modulator 123 and generates two outputs that are 90 degrees out of phase and an output that does not change in phase; and the second power distributor 12 The two mixers 126 for multiplying each of the two received signal outputs and the two outputs of the phase shifter 125, two power amplifiers 127 for amplifying the output power of each of the mixers 126, and the correlation pulse generation source 121 The clock generation source 128 that generates a clock signal that is synchronized with the correlation pulse generated by the second delay element 129 that delays the clock signal output from the clock generation source 128 by the same delay time as the first delay element 122. And two A / D converters 130 for sampling the outputs of the two power amplifiers 127 at the timing of the clock signal output from the second delay element 129, respectively.

  The digital signal processing unit 140 simultaneously acquires the outputs of the two A / D converters 130 as an I signal and a Q signal, respectively, and performs signal processing in parallel on those obtained continuously, from this to the object Get distance information and relative speed information. The digital signal processing unit 140 controls the pulse generation source 111, the correlation pulse generation source 121, the first delay element 122, the second delay element 129, and the clock generation source 128 described above. The digital signal processing unit 140 is set so that the delay time delayed by the first delay element 122 and the second delay element 129 is shifted by a predetermined number of times by a predetermined unit delay time. Data is acquired by performing 120 processes.

  The process in the transmission part 110 is demonstrated below using an example of the signal waveform shown in FIG. FIG. 2 is an explanatory diagram illustrating an example of a waveform of a signal generated in the transmission unit 110. By timing control from the digital signal processing unit 140, the pulse generation source 111 generates a pulse train 10 as shown in FIG. 2A and outputs it to the first pulse modulator 112. Here, it is assumed that the pulse train 10 is composed of a plurality of pulses 10a having a pulse width τ generated at a period T. Further, in the oscillator 101, a carrier wave 11 having a frequency fc as shown in FIG. 2B is generated, and one of the two carrier waves distributed by the first power distributor 102 is input to the first pulse modulator 112. The One output input to the first pulse modulator 112 is the same as that shown in FIG.

  In the first pulse modulator 112, one of the carrier waves 11 distributed by the first power distributor 102 is superimposed on the pulse train 10 generated by the pulse generator 111 as a carrier wave. That is, in the first pulse modulator 112, the carrier wave 11 is cut out for each pulse width τ of each pulse 10a of the pulse train 10, and the transmission pulse train 12 having the period T shown in FIG. The pulse modulator 112 includes a mixer and a switch. The transmission pulse train 12 is output to the transmission antenna 103 and transmitted from the transmission antenna 103 as a radio wave (transmission wave).

  The transmission wave transmitted from the transmission antenna 103 is reflected by an object and received by the reception antenna 104, and the reception signal 20 is output from the reception antenna 104 to the reception unit 120. FIG. 3 is an explanatory diagram illustrating an example of a transmission signal (FIG. 3A) and a reception signal (FIG. 3B) output from the reception antenna 104 to the reception unit 120. FIGS. 3A and 3B show that the reception signal 20 corresponding to the transmission pulse 12a is received by the reception antenna 104 during a period in which the transmission pulse 12a is transmitted from the transmission antenna 103. FIG. FIG. 3B shows the reception signal 20a corresponding to one transmission pulse 12a with part of the time axis enlarged. Here, an example in which transmission waves are reflected by three objects is shown, and three reception pulses 20a1, 20a2, and 20a3 are received for one transmission pulse 12a. As described above, when there are a plurality of objects and reflection points, a plurality of reflected pulses are received by the receiving antenna 104 for one transmission pulse.

で算出される。ここで、ｃは光速を表し、ｔｄ１、ｔｄ２、ｔｄ３は、１つの送信パルス１２ａが送信アンテナ１０３から送出されてから受信アンテナ１０４で受信パルス２０ａ１、２０ａ２、２０ａ３が受信されるまでの遅延時間を表している。 If the distances to the three objects are d1, d2, and d3, respectively, the distances d1, d2, and d3 are expressed by the following equations.

Is calculated by Here, c represents the speed of light, and td1, td2, and td3 are delay times from when one transmission pulse 12a is transmitted from the transmission antenna 103 until reception pulses 20a1, 20a2, and 20a3 are received by the reception antenna 104. Represents.

  Next, processing in the receiving unit 120 will be described below with reference to FIGS. The receiving unit 120 includes a correlation pulse generation source 121 and a clock generation source 128 as signal sources. Signal waveforms generated by the correlation pulse generation source 121 and the clock generation source 128 are shown in FIGS. 4 (a) and 4 (b), respectively. As shown in FIG. 4A, the correlation pulse train 21 generated by the correlation pulse generation source 121 has a correlation pulse 21a having a pulse width τ equal to the pulse width of the pulse 10a generated by the pulse generation source 111 as A / A plurality (L (L ≧ 2)) of pulses 10a generated from the pulse generation source 111 are continuously generated at a sampling period Ts in which sampling is performed by the D converter 130. In the example shown in FIG. 4, five (L = 5) correlation pulses 21a are generated for one pulse 10a.

  As shown in FIG. 4B, the clock signal sequence 22 output from the clock generation source 128 has the same sampling as the correlation pulse sequence 21 because the clock signal 22a is synchronized with the correlation pulse 21a shown in FIG. L clock signals 22a are continuously generated at a period Ts. However, since there is actually a propagation delay from the mixer 126 to the A / D converter 130, the clock signal 22a is output after being delayed from the correlation pulse 21a by this propagation delay time.

  A first delay element 122 and a second delay element 129 are provided on the output side of the correlation pulse generation source 121 and the clock generation source 128, respectively, and the respective signals are delayed by a predetermined time and output. In the A / D converter 130, the delay time (referred to as td) set in the first delay element 122 and the second delay element 129 is changed by a minute unit delay time (referred to as t1). Equivalent sampling as illustrated in FIG. 5 can be performed. The delay time td is updated by control from the digital signal processing unit 140. By setting the unit delay time t1 to be equal to or less than the pulse width τ, a predetermined distance range can be continuously measured.

FIG. 5 shows that the second delay element 129 sequentially delays and outputs the clock signal sequence 22 output from the clock generation source 128 by the unit delay time t1. The clock signal sequence 22-1 to n shown in FIG. 5 is a delay time td = tdi (i = 1,..., N) expressed by the following equation for the clock signal sequence 22 generated by the clock generation source 128. It is a delayed one. Here, n is the number of divisions obtained by dividing the clock period (equal to the sampling period Ts) for each unit delay time t1.

By outputting the n clock signal trains 22-1 to 2-n sequentially delayed in this way, a predetermined distance range is measured. That is, each time one transmission pulse 12a is transmitted from the transmission antenna 103, a set of clock signal trains 22 including five (L) clock signals 22a is output. Thereby, five (L) points separated by a distance corresponding to the clock cycle Ts are measured by one transmission pulse 12a. Thereafter, the measurement is performed while updating the delay time td based on the formula (2), and when the transmission pulse 12a is transmitted n times, the measurement in the predetermined distance range is completed.
Although the clock signal train 22 has been described above, the correlation pulse train 21 also includes a correlation pulse train 21-i (i = 1, 1) including five (L) correlation pulses 21a in synchronization with the clock signal train 22. .., N) are sequentially delayed by unit delay time t1 and output n times.

In the A / D converter 130, sampling is performed for each clock signal 22a as shown in FIG. 5, and sampling is performed five times (L times) with one clock signal train 22-i. Such sampling is performed while being delayed by unit delay time t1. A unit of data sampled at each unit delay time t1 is called a range bin, and the range bin has a resolution for separating an object.
In the above description, for simplification of description, the delay time td is updated every time one transmission pulse 12a is transmitted. More generally, M (M is the same as the delay time td). It is also possible to update the delay time td after measuring M times (hereinafter referred to as “synchronous addition number”) with the transmission pulse 12a of a positive integer and adding the sampling result. By setting M to 2 or more, the same range bin is measured a plurality of times (M times), and the S / N can be improved.

  In FIG. 5, the equivalent sampling method when n = 10 will be described below. When the first pulse is transmitted from the transmission antenna 103, the clock signal sequence 22-1 is output to the A / D converter 130. Thereby, the data of the five (L) range bins of the 1st, 11th, 21st, 31st, and 41st are sampled at the timing of each clock signal 22a. Next, when the second pulse is transmitted, the clock signal sequence 22-2 delayed by the unit delay time t1 from the clock signal sequence 22-1 is output to the A / D converter 130. As a result, the data of the five range bins of the second, twelfth, twenty-second, thirty-second, and forty-second ranges are sampled at the timing of each clock signal 22a. In the same manner, sampling is performed while delaying the output of the clock signal train 22 by the unit delay time t1.

Then, when the tenth pulse is transmitted, a clock signal sequence 22-10 delayed by (n−1) × t 1 from the clock signal sequence 22-1 is output to the A / D converter 130. Thereby, the signals of the five range bins of the 10th, 20th, 30th, 40th and 50th are sampled at the timing of each clock signal 22a.
Thereby, it is possible to sample all the range bins from the first to the 50th. After the data of each range bin is output to the digital signal processing unit 140, each range bin is initialized and a new sampling is started. For subsequent pulse transmissions, the processing returns to sampling using the clock signal sequence 22-1 again.
When the synchronous addition number M is 2 or more, sampling is performed by using each clock signal sequence 22-i continuously M times and the sampling result is added, and then the next clock signal sequence 22- (i + 1). Proceed to sampling using.

  The digital signal processing unit 140 controls the pulse generation source 111, the correlation pulse generation source 121, the clock generation source 128, the first delay element 122, and the second delay element 129, and each signal is generated by this control. The timing is controlled as shown in FIG. 6A shows the generation timing of the pulse train 10 in the pulse generation source 111, and FIG. 6B shows the generation timing of the clock signal train 22 in the clock generation source 128. However, since the signal output timings of the correlation pulse generation source 121 and the clock generation source 128 are the same, the correlation pulse train 21 output from the correlation pulse generation source 121 is not shown in FIG. The digital signal processing unit 140 matches the timing at which the pulse generation source 111 generates a pulse with the timing at which the correlation pulse generation source 121 generates the correlation pulse train 21 and the timing at which the clock generation source 128 generates the clock signal sequence 22. Is controlling. Further, the first delay element 122 and the second delay element 129 are controlled so that the delay time td becomes zero for the first pulse generation in the pulse generation source 111. With respect to the generation of pulses after the first time, the clock signal train 22 is controlled to be output to the A / D converter 130 by sequentially delaying by unit delay time t1.

  On the other hand, in the second pulse modulator 123, the carrier wave of the frequency fc is cut out using the correlation pulse train 21 to which a predetermined delay time is added by the first delay element 122, and the waveform as shown in FIG. The pulse signal is output. This pulse signal is input to the phase shifter 125, the first signal whose phase is not changed and the second signal whose phase is shifted by 90 degrees are output and each is output to the two mixers 126. In the mixer 126, the first signal or the second signal input from the phase shifter 125 and the reception signal 20 (reproduced in FIG. 7B) input from the second power distributor 124 are mixed. As a result, an output having a pulse width τ is obtained at a location where the reception signal 20 and the correlation pulse train 21 have the same pulse position. Since the first signal and the second signal input from the phase shifter 125 have the delay time added by the first delay element 122, the output of the mixer 126 is information on the range bin corresponding to the delay time. It has become. An example of the output of the mixer 126 is shown in FIG. In FIG. 7C, in the received signal 20 shown in FIG. 7B, only the pulse corresponding to the reflected signal from the object 1 and the object 3 matches the pulse corresponding to the correlation pulse train 21 in FIG. Is illustrated.

  The outputs from the two mixers 126 are respectively input to separate A / D converters 130 where they are sampled according to a clock signal sequence 22-i synchronized with the correlation pulse sequence 21. As shown in FIG. 7D, the clock signal sequence 22-i input to the A / D converter 130 is delayed by the second delay element 129 (added by the first delay element 122). Therefore, the information of the range bin corresponding to the delay time tdi can be obtained by the above sampling in the A / D converter 130. When the output of the mixer 126 shown in FIG. 7 (c) is sampled by the clock signal train 22-i shown in FIG. 7 (d), the position information of the objects 1 and 3 is obtained. The sampling results obtained by the two A / D converters 130 are stored in an I signal range bin and a Q signal range bin, respectively.

  Similarly, when the pulse signal shown in FIG. 8A having a different delay time is used to correlate with the received signal 20 shown in FIG. 8B, it corresponds to the reflected signal from the object 2. The pulse is down-converted, and the output of the mixer 126 as shown in FIG. 8C is obtained. By sampling this in accordance with the clock signal sequence 22-j (j ≠ i) (shown in FIG. 8 (d)) synchronized with the pulse signal of FIG. 8 (a) in the A / D converter 130, the delay time. The position information of the object 2 is obtained in the range bin corresponding to tdj.

  When the equivalent sampling described with reference to FIG. 5 is performed for all delay times tdi (i = 1,..., N) as described above, the positions of the objects 1, 2, and 3 as shown in FIG. An I signal and Q signal having information are obtained and output to the digital signal processing unit 140. The I signal and Q signal as shown in FIG. 9 indicate that a large output is obtained in the range bin corresponding to the pulse position of the received signal 20. The I signal and the Q signal are information obtained by two orthogonal systems having the same time information but different amplitude information.

  In the digital signal processing unit 140, the intensity of the reflected wave from the object is obtained by calculating the sum of squares of the I signal and the Q signal, and the distance to each object is calculated from the information of the range bin having an intensity exceeding a predetermined threshold. To do. In addition, complex FFT (Fast Fourier Transform) is performed using the data of the I signal and Q signal in which each range bin information is stored every predetermined time, and the relative velocity is calculated from the Doppler component of each object. Can be calculated.

  Processing performed by the digital signal processing unit 140 in the radar apparatus 100 of the present embodiment will be described with reference to the flowchart shown in FIG. When the radar apparatus 100 according to the present embodiment is activated, the digital signal processing unit 140 performs predetermined initialization including initialization of the synchronous addition counter m, the delay time td, and the FFT counter F in step S1, and then performs steps. In S2, the pulse generation source 111 is controlled to transmit the transmission pulse 10a. At the same time, it instructs the correlation pulse generation source 121 and the clock generation source 128 to output the correlation pulse 21a and the clock signal 22a. The correlation pulse 21 a and the clock signal 22 a output from the correlation pulse generation source 121 and the clock generation source 128 are added with a delay time td by the first delay element 122 and the second delay element 129, and the A / D converter 130 The received signal is sampled.

  In step S3, 1 is added to the synchronous addition counter m, and in step S4, it is determined whether the number m has reached a preset synchronous addition number M. If it is determined that the synchronous addition counter m is less than the synchronous addition number M, the process returns to step S2 and the next sampling is performed with the same delay time td. If it is determined in step S4 that the synchronous addition counter m has reached the preset synchronous addition number M, the unit delay time t1 is added to the delay time td and updated in the next step S5. In the next step S6, it is determined whether the delay time td has reached the sampling period Ts. If it is determined that td is less than Ts, the process proceeds to step S7, where the synchronous addition counter m is initialized to 0. After that, the process returns to step S2 again to perform the next sampling.

  On the other hand, if it is determined in step S6 that the delay time td has reached the sampling period Ts, the process proceeds to the next step S8, and the results of all range bins are held in the memory in the digital signal processing unit 140. Thereafter, 1 is added to the FFT counter F in step S9, and it is determined in the next step S10 whether the FFT counter F has reached the number of times Fmax necessary for the FFT processing. Fmax can be set to 64 points, for example. If F is determined to be less than Fmax in step S10, the synchronous addition counter m and the delay time td are initialized in step S11, and then the process returns to step S2 to perform the next sampling. On the other hand, if it is determined in step S10 that F has reached Fmax, in step S12, FFT processing is performed using the data held in the memory in the digital signal processing unit 140. Calculate speed information.

  In the radar apparatus 100 according to the first embodiment having the above-described configuration, a correlation pulse is inserted on the local input side of the mixer 126 to obtain a correlation between the correlation pulse and the received signal. By performing equivalent sampling of reflected wave information from an object obtained by the receiving antenna 104 for one transmission pulse using a plurality of synchronized correlation pulses 21a and a plurality of clock signals 22a used in the A / D converter 130, Sampling can be performed at higher speed. In other words, in the above embodiment example, five (L) range bin information can be obtained for one transmission pulse. In the conventional technique, only one range bin information can be obtained for one transmission pulse. In the above embodiment, the number of synchronous additions M has been described as 1. However, normally, the S / N of the reflected wave is improved by performing multiple synchronous additions. Further, the A / D converter 130 can achieve higher reliability than charge addition by a conventional analog element by performing synchronous addition by digital signal processing using an A / D converted output.

(Second Embodiment)
A configuration of a radar apparatus according to the second embodiment of the present invention will be described with reference to FIG. FIG. 11 is a block diagram illustrating a configuration of the radar apparatus 200 according to the second embodiment. The radar apparatus 200 is configured by changing a part of the radar apparatus 100 of the first embodiment. In general, the higher the frequency, the more expensive the parts used. Therefore, in the present embodiment, 1 / N (N is an integer equal to or greater than 2) of the radio frequency band using the frequency band of the oscillator 201, the first power distributor 202, the first pulse modulator 212, and the second pulse modulator 223. ) And a first multiplier 213 and a second multiplier 231 having a multiplication ratio N are added.

In the transmission unit 210, by arranging the first multiplier 213 behind the first pulse modulator 212, the frequency of the output of the first pulse modulator 212 is multiplied by N, and a signal in a radio frequency band to be used is obtained. It has gained. As a result, the transmission pulse output to the transmission antenna is equivalent to the transmission pulse 12 of the first embodiment. Note that the first pulse generation source 211 and the second pulse generation source 214 are used as pulse generation sources, and the first pulse generation source 211 is equivalent to the pulse generation source 111 of the first embodiment. Things are used. The second pulse generation source 214 controls on / off of the first multiplier 213 and outputs a pulse having the same waveform as that of the first pulse generation source 211, but a voltage for driving the first multiplier 213. Since the value is different from the driving voltage value of the first pulse modulator 212, the voltage value of the output pulse is different between the two.
In the present embodiment, the first pulse modulator 212 and the first multiplier 213 cut out the carrier wave generated by the oscillator 201 in two stages, so that there is also an effect of reducing carrier leakage to the transmission signal. . Further, the multiplier is a non-linear device and can reduce carrier leakage more efficiently.

  Also in the receiving unit 220, a second multiplier 231 is arranged behind the second pulse modulator 223. Here, the frequency of the output of the second pulse modulator 223 is multiplied by N to obtain the second multiplier. The output of the device 231 is equivalent to the output of the second pulse modulator 123 in the first embodiment. In the receiving unit 220 of this embodiment, two receiving antennas 204 are arranged to receive a received signal, and the hybrid circuit 232 generates a combination (sum signal Σ) and a difference (difference signal Δ) of each received wave. The sum signal and the difference signal are switched by the antenna selector switch 233 to perform subsequent signal processing. In this embodiment, it is possible to detect the azimuth of an object by calculating the sum signal and difference signal data by the monopulse method.

(Third embodiment)
A configuration of a radar apparatus according to the second embodiment of the present invention will be described with reference to FIG. FIG. 12 is a block diagram illustrating a configuration of the radar apparatus 300 according to the third embodiment. The radar apparatus 300 is different from the radar apparatus 100 of the first embodiment in the position of the second pulse modulator (in this embodiment, the second pulse modulator is indicated by reference numeral 323). The process of generating the transmission signal in the transmission unit 110, the processing of the reception signal, the correlation pulse, the clock signal, and the equivalent sampling in the reception unit 320 are the same as in the first embodiment. Hereinafter, the processing of the receiving unit 320 of the present embodiment will be described focusing on differences from the radar apparatus 100 of the first embodiment.

  First, for the objects 1 and 3, the received signal 20 shown in FIG. 3B received by the receiving antenna 104 is extracted by the correlation pulse 21-i delayed by the delay time tdi in the second pulse modulator 323. . As a result, only the portion where the received signal 20 and the correlation pulse 21-i overlap is cut out, and a signal as shown in FIG. 13A is output. When this signal is mixed with the carrier wave from the oscillator 101 (continuous wave shown in FIG. 2B) in the mixer 126, it is shown in FIG. 7C equivalent to the output of the mixer 126 of the first embodiment. A signal with a waveform is obtained. The following processing is the same as in the first embodiment. In this way, position information of the objects 1 and 3 is obtained.

  Similarly, the object 2 is also extracted from the second pulse modulator 323 by the correlation pulse 21-j delayed by another delay time tdj (j ≠ i), and a signal as shown in FIG. 13B is output. The When this is mixed with the carrier wave from the oscillator 101 by the mixer 126, a signal having the waveform shown in FIG. 8C equivalent to the output of the mixer 126 of the first embodiment is obtained. Then, the position information of the object 2 is obtained by the same processing as in the first embodiment.

  In the present invention having the above configuration, a correlation pulse is inserted on the RF input side of the mixer 126 to obtain a correlation between the received wave and the correlation pulse. The processing after the mixer 126 is the same as in the first embodiment. Therefore, similarly to the first embodiment, a plurality of range bin information can be obtained simultaneously, and the update speed for collecting a series of radar information can be increased.

In the radar apparatus of the present invention, a correlator (correlation pulse generating means) is used, and the mixer, power amplifier, and A / D converter, which are devices constituting the receiver, have a wide frequency band (an impulse of about 1 ns). Can be obtained without a correlator.
However, a broadband device is expensive, and is required to be configured with a device that is as inexpensive as possible. On the other hand, an inexpensive device does not have a broadband frequency characteristic, and the high frequency component of the pulse is cut off, so that the pulse shape collapses. As a result, there arises a problem that the object detection resolution is lowered.

  As an example, a case where a received waveform in which the object 2 and the object 3 are close as illustrated in FIG. When an expensive device having a wideband frequency characteristic is used without using a correlator, the object 2 and the object 3 are detected separately from the received signal shown in FIG. 14A as shown in FIG. 14B. Is possible. However, when a radar device that does not use a correlator is configured by using an inexpensive device that does not have a wideband frequency characteristic, the pulse waveform is distorted as shown in FIG. Separation of the object 3 becomes difficult.

  On the other hand, in the radar apparatus of the present invention using a correlator, the object 2 and the object 3 are detected using different correlation pulses as shown in FIGS. 14D and 14E, for example. As a result, the object 2 and the object 3 can be completely separated and detected. Thus, by using a correlator, even when it is configured with an inexpensive device, it is possible to satisfy the same performance as when configured with an expensive device.

  The description in the present embodiment shows an example of the radar apparatus according to the present invention, and the present invention is not limited to this. The detailed configuration and detailed operation of the radar apparatus according to the present embodiment can be changed as appropriate without departing from the spirit of the present invention.

100, 200, 300 Radar apparatus 101, 201 Oscillator 102, 202, 302 First power distributor 103 Transmitting antenna 104, 204 Receiving antenna 110, 210 Transmitting unit 111, 211, 214 Pulse generation source 112, 212 First pulse Modulator 120, 220, 320 Receiver 121 Correlation pulse generation source 122 First delay element 123, 223, 323 Second pulse modulator 124 Second power distributor 125 Phaser 126 Mixer 127 Power amplifier 128 Clock generation source 129 First Two delay elements 130 A / D converter 140 Digital signal processing unit 213, 231 Multiplier 232 Hybrid circuit 233 Antenna selector switch

Claims (7)

An oscillator that oscillates a carrier wave of a predetermined frequency, a first power distributor that distributes the power of the carrier wave output from the oscillator to two outputs, and one carrier wave that is distributed by the first power distributor. A transmission unit that generates a predetermined transmission signal by input, a transmission antenna that receives the transmission signal from the transmission unit and transmits the transmission signal to space by a radio wave, and a reflection in which the radio wave transmitted from the transmission antenna is reflected by an object A receiving antenna that receives radio waves, a receiving unit that receives a received signal from the receiving antenna and inputs the other carrier wave distributed by the first power distributor, and performs predetermined signal processing; and A radar device comprising a digital signal processing unit for detecting an object based on an input signal,
The transmitter is
A pulse generation source for generating a pulse having a predetermined pulse width at a predetermined pulse repetition period;
A first pulse modulator that outputs the transmission signal by superimposing the one carrier wave on the pulse, and
The receiver is
In synchronization with the pulse generation source, a single correlation pulse having the same pulse width as the predetermined pulse width is generated L times (L is an integer of 2 or more) at a predetermined time interval (Ts). A correlation pulse generation source
A first delay element that outputs the correlation pulse output from the correlation pulse generation source by delaying the correlation pulse by a predetermined delay time (td);
A second pulse modulator that superimposes the other carrier on the correlation pulse output from the first delay element;
A second power distributor that distributes a reception signal input from the reception antenna into two reception signals;
A phase shifter that inputs the output of the second pulse modulator and outputs a second output that is shifted by 90 degrees from the first output whose phase is unchanged;
Two mixers for multiplying the first output and the second output by the two received signals respectively distributed by the second power divider;
Two power amplifiers for amplifying the output power of each of the two mixers;
A clock generation source for generating a clock signal in synchronization with the correlation pulse generation source;
A second delay element that delays the clock signal by the delay time td;
Two A / D converters that respectively sample outputs of the two power amplifiers at a timing of a clock signal output from the second delay element,
The radar apparatus according to claim 1, wherein the A / D converter performs sampling by the clock signal L times each time a radio wave of the transmission signal is transmitted from the transmission antenna. The radar apparatus according to claim 1, wherein the delay time td is updated every time a radio wave of the transmission signal is transmitted from the transmission antenna M times (M is an integer of 2 or more). The first delay element and the second delay element update the delay time td by incrementing the unit delay time t1 with an initial value of 0, and again when the delay time becomes equal to or greater than the predetermined time interval Ts. The radar apparatus according to claim 1, wherein the radar apparatus is initialized to zero. The radar apparatus according to claim 3, wherein the unit delay time t1 is shorter than the predetermined pulse width. The digital signal processing unit inputs the outputs of the two A / D converters to calculate the distance and relative speed to the object, and the pulse generation source, the correlation pulse generation source, and the first delay element 5. The radar apparatus according to claim 1, wherein the second delay element and the clock generation source are controlled to perform predetermined synchronization. 6. A first multiplier connected between the first pulse modulator and the transmitting antenna;
Another pulse generator connected to the first multiplier for controlling on / off of the first multiplier;
A second multiplier connected between the second pulse modulator and the phase shifter;
The oscillator oscillates a carrier wave having a frequency of 1 / N (N is an integer of 2 or more) of a use frequency, and the frequency band of the first power divider, the first pulse modulator, and the second pulse modulator. Is 1 / N of the used frequency, and both the first multiplier and the second multiplier both multiply the frequency of the input signal by N times. The radar device according to item. An oscillator that oscillates a carrier wave of a predetermined frequency, a first power distributor that distributes the power of the carrier wave output from the oscillator to two outputs, and one carrier wave that is distributed by the first power distributor. A transmission unit that inputs and generates a predetermined transmission signal; a transmission antenna that receives the transmission signal from the transmission unit and transmits the transmission signal to space; and a reflection in which the radio wave transmitted from the transmission antenna is reflected by an object A receiving antenna that receives radio waves, a receiving unit that inputs a received signal from the receiving antenna and inputs the other carrier wave distributed by the first power distributor, and performs predetermined signal processing; and A radar device comprising a digital signal processing unit for detecting an object based on an input signal,
The transmitter is
A pulse generation source for generating a pulse having a predetermined pulse width at a predetermined pulse repetition period;
A first pulse modulator that outputs the transmission signal by superimposing the one carrier wave on the pulse, and
The receiver is
In synchronization with the pulse generation source, a single correlation pulse having the same pulse width as the predetermined pulse width is generated L times (L is an integer of 2 or more) at a predetermined time interval (Ts). A correlation pulse generation source
A first delay element that outputs the correlation pulse output from the correlation pulse generation source by delaying the correlation pulse by a predetermined delay time (td);
A second pulse modulator for superimposing a reception signal input from the reception antenna on a correlation pulse output from the first delay element;
A second power distributor that distributes the output of the second pulse modulator to two outputs;
A phase shifter that inputs the other carrier wave and outputs a second output that is shifted by 90 degrees from the first output whose phase is unchanged;
Two mixers for multiplying the first output and the second output, respectively, with the two outputs distributed by the second power divider;
Two power amplifiers for amplifying the output power of each of the two mixers;
A clock generation source for generating a clock signal in synchronization with the correlation pulse generation source;
A second delay element that delays the clock signal by the delay time td;
Two A / D converters that respectively sample outputs of the two power amplifiers at a timing of a clock signal output from the second delay element,
The radar apparatus according to claim 1, wherein the A / D converter performs sampling by the clock signal L times each time a radio wave of the transmission signal is transmitted from the transmission antenna.

Images