JP5390780B2 - Pulse generation method, pulse generation apparatus, and radar apparatus - Google Patents

Description

  The present invention relates to a radio frequency signal (RF signal) generator, and more particularly, to an impulse-like pulse generation method and pulse generator used for a signal source such as a pulse radar, and a radar apparatus using the pulse generator.

  Conventionally, a method shown in FIG. 13 is known as a method for generating an impulse RF signal used in a pulse radar or the like. In the figure, as a conventional pulse generation method, (a) a method using a burst oscillator, (b) a method using a continuous wave oscillator and a switch, and (c) a method of up-converting a baseband impulse with a mixer. Show.

  In the method using the burst oscillator shown in FIG. 13A, a predetermined trigger signal 902 is input to the burst oscillator 901 to oscillate a pulse, which is transmitted from the transmission antenna 903. In this pulse generation method, the shape of the pulse is determined by the design of the burst oscillator 901. For example, the rise time of the pulse is determined by the performance of the components constituting the circuit of the burst oscillator 901. Therefore, it is difficult to adjust the pulse shape with the burst oscillator 901, and a design change, a hardware change, and the like are required.

  In the method using the continuous wave oscillator and the switch shown in FIG. 13B, a pulse signal is generated from the continuous wave output from the continuous wave oscillator 911 by opening and closing the switch 912 at a high speed. Transmitting from the transmission antenna 913. This method requires a switch 912 including a switch element 912a that opens and closes at high speed and an external circuit 912b that controls the switch element 912a. The pulse shape is determined by the characteristics of the switch 912. Therefore, it is not easy to change the pulse shape even with this method.

  Furthermore, in the method of upconverting the baseband impulse shown in FIG. 13C, the mixer 922 multiplies the carrier wave output from the continuous wave oscillator 923 by the baseband impulse 921, thereby oscillating an impulse RF signal. This is transmitted from the transmission antenna 924. In this method, the baseband impulse can be generated by digital processing, and the pulse generation control can be easily changed by software.

  Due to the above circumstances, when generating an impulse signal at a high frequency, a method of multiplying the carrier by the baseband impulse signal shown in FIG. In this method, it is ideal that only the baseband impulse signal multiplied by the carrier wave is output from the mixer 922, but actually, the carrier wave leaks from the mixer even when the baseband impulse is not supplied (carrier leak). Therefore, there is a problem that an unmodulated carrier wave is output.

  When the heterodyne system / superheterodyne system can be used as the method for up-converting the baseband impulse shown in FIG. 13C, the frequencies of the modulated signal (baseband impulse) and the carrier wave are separated. Therefore, unnecessary carrier waves can be removed by a band pass / reject filter or the like.

  However, the heterodyne system / superheterodyne system is expensive due to an increase in the number of parts. In addition, when generating a UWB pulse signal in which the frequency band to be used is an ultra-wide band, it is difficult to separate the baseband impulse and the carrier wave in terms of frequency. Therefore, when a UWB pulse signal is used, it is necessary to generate a pulse signal by the direct conversion method.

  In a radar apparatus, when a pulse signal is used as a radiation source, leakage of an unmodulated carrier wave is a major disadvantage in terms of performance such as deterioration of reception sensitivity. Further, it is not preferable in terms of utilization efficiency of the radio frequency. Therefore, in order to solve such a problem, Non-Patent Document 1 proposes a method of stopping a carrier wave using a switch or the like when a pulse signal is not generated.

In the method of stopping the carrier wave using a switch or the like, the carrier wave must also be supplied to the mixer at least during the period when the baseband impulse signal is supplied to the mixer. For this purpose, it is necessary to control the opening / closing timing of the switch in consideration of a signal transmission delay or the like in a circuit that controls the opening / closing of the switch. In Non-Patent Document 1, when a baseband impulse signal is not output by superimposing a high-speed pulse corresponding to the output period of the baseband impulse signal and a low-speed pulse corresponding to the carrier wave supply period on the switching control. The amount of carrier leakage is suppressed.
"Harmonic mixer type high-speed pulse modulation circuit using superposition pulse system", Kenji Kawakami et al., IEICE Technical Report, Electronic Devices, Vol.104, No.549, pp.7-11,

  However, in the switching control as described above, in addition to manufacturing variations, it is necessary to consider changes in performance due to environmental conditions such as temperature and humidity. For this reason, it is necessary to further extend the supply time of the carrier wave with a time margin before and after the period in which the baseband impulse signal is supplied. In addition, when the time during which the baseband impulse signal is supplied becomes extremely short (for example, several nanoseconds or less), the rate at which only the carrier wave is supplied is higher due to the limit of the operation speed of the switch that controls the carrier wave supply. Become. As a result, there arises a problem that the receiving sensitivity on the receiving side is deteriorated.

  When the pulse signal is used as a radar radiation source, the performance such as the maximum detection distance is dominantly determined by the peak value of the pulse signal. On the other hand, in order to adapt to the radio wave usage conditions in each country, it is necessary to keep the upper limit of the frequency spectrum within an allowable range. Even when the carrier wave is supplied intermittently, the spectrum peak increases due to the influence of the carrier leak. For this reason, it is necessary to reduce the peak value of the baseband impulse signal by an amount corresponding to an increase in the spectrum peak as compared with the case where there is no carrier leak, leading to a problem that the radar performance is deteriorated.

  Accordingly, the present invention has been made to solve the above-described problem, and an object thereof is to provide a pulse generation method, a pulse generation device, and a radar device that greatly reduce the increase in the peak value of the frequency spectrum due to carrier leak. To do.

According to a first aspect of the pulse generator of the present invention, a pulse signal generator that outputs a bipolar impulse, a high-frequency source that outputs a high-frequency carrier, the bipolar impulse and the carrier are input, and the carrier is A mixer that outputs a radio frequency signal modulated with the bipolar impulse, and a predetermined period (hereinafter referred to as a pulse output period) including a period during which the bipolar impulse is output from the pulse signal generator (hereinafter referred to as a pulse output period). A switch that inputs the carrier wave from the high-frequency source to the mixer and cuts off the carrier wave during other periods, and intermittently closes the switch so that the carrier wave is intermittently supplied to the mixer. Any one of the spectrum peaks generated in the frequency spectrum of the carrier wave by the output is the bipolar impedance. The switch closing period is controlled so that the spectrum peak with the highest level does not coincide with the frequency at which it exists .

  In another aspect of the pulse generator of the present invention, the switch closing period is a length obtained by multiplying the pulse output period by a multiple in a range of 1.3 to 1.5.

  In another aspect of the pulse generator of the present invention, the switch closing period is a length obtained by multiplying the pulse output period by a multiple in the range of 1.3 to 1.5 and further multiplying by a natural number. And

A first aspect of the pulse generation process of the invention, step a, the step of generating a carrier wave which is modulated by said bipolar impulse, pulse period (hereinafter said bipolar pulse is outputted to generate a bipolar impulse A pulse generation method comprising: outputting a carrier wave for a predetermined period (hereinafter referred to as a switch closing period ) including an output period; and outputting a radio frequency signal obtained by modulating the carrier wave with the bipolar impulse. Any one of the spectrum peaks generated in the frequency spectrum of the carrier by intermittently outputting the carrier during the switch closing period coincides with the frequency at which the highest spectrum peak of the bipolar impulse exists. The switch closing period is controlled so as not to occur.

  Another aspect of the pulse generation method of the present invention is characterized in that the switch is controlled so that the switch closing period has a length obtained by multiplying the pulse output period by a multiple of a range of 1.3 to 1.5. To do.

  In another aspect of the pulse generation method of the present invention, the switch is set so that the switch closing period has a length obtained by multiplying the pulse output period by a multiple of a range of 1.3 to 1.5 and further multiplying by a natural number. It is characterized by controlling.

  According to a first aspect of the radar apparatus of the present invention, there is provided a transmitter including the pulse generator according to any one of the above aspects, a transmission antenna that transmits a radio frequency signal generated by the pulse generator, and the radio A reception antenna that receives a reflected wave of a frequency signal and outputs a reception wave, and a reception unit that performs a predetermined process on the reception wave and outputs a reception signal are provided.

  In another aspect of the radar apparatus of the present invention, the receiving unit demodulates the received wave with a predetermined demodulation high frequency and outputs a demodulated signal, and detects the demodulated signal and outputs the received signal And a detection unit for performing the processing.

  According to another aspect of the radar apparatus of the present invention, the first multiplier for multiplying the frequency of the received wave by two times, the carrier wave from the pulse generator, the frequency is doubled, and the demodulation is performed. And a second multiplier for outputting as a high frequency.

According to another aspect of the radar apparatus of the present invention, a radio frequency signal is input from the pulse generator as the demodulation high frequency signal, and a sliding correlation process is performed on the demodulated signal to generate a unipolar detection signal to the detection unit. A sliding correlator for outputting is further provided.
It is characterized by that.

  According to the present invention, it is possible to provide a pulse generation method, a pulse generation apparatus, and a radar apparatus that can significantly suppress an increase in a peak value of a frequency spectrum due to carrier leak by using a bipolar impulse as a baseband impulse signal. .

  A pulse generation method, a pulse generation device, and a radar device 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, the influence of carrier leak on the frequency spectrum in a method of generating an impulse RF signal by up-converting a unipolar baseband impulse will be described with reference to FIGS. 3 and 4. FIG. In terms of the performance of the mixer, the level at which carrier leakage can be suppressed with respect to the RF signal is about 10 to 20 dB. 3 and 4, it is assumed that the carrier leak is suppressed to 20 dB. When means for further suppressing carrier leakage is not provided, as illustrated in FIG. 3A, a high peak (reference numeral 11) in the frequency position of the carrier wave in the frequency spectrum of the RF signal output from the mixer. Appears. In FIG. 3, the ideal frequency spectrum without carrier leak is also indicated by reference numeral 12 in FIG.

  As described above, when a means for further suppressing carrier leakage is not used, a high peak due to carrier leakage appears in the frequency spectrum, and the peak of the baseband impulse signal can be suppressed to keep it below a predetermined allowable range. The value itself must be reduced.

  On the other hand, when the period in which the carrier wave is supplied to the mixer is limited to an intermittent period including the period in which the baseband impulse signal is supplied using a switch or the like, as illustrated in FIG. A high peak seen at the frequency position of the carrier wave in the frequency spectrum is suppressed (reference numeral 13). Here, the period during which the carrier wave is supplied to the mixer is twice the period during which the baseband impulse signal is supplied. However, even in this case, the peak value of the frequency spectrum is increased by about 1.6 dB as compared with the ideal state indicated by reference numeral 14 in FIG.

  A pulse generation method and a pulse generation apparatus according to an embodiment of the present invention will be described below with reference to FIG. The pulse generator 100 of this embodiment includes a pulse signal generator 110 that outputs an impulse signal 101, a high-frequency source 120 that outputs a local signal 102 of a predetermined frequency, and a mixer that multiplies the impulse signal 101 and the local signal 102. 130, a switch 140 for cutting off the local signal 102 output from the high frequency source 120 to the mixer 130, and a switch control unit 150 for controlling the switch.

  The mixer 130 inputs a pulse signal input terminal 131 (hereinafter referred to as an IF terminal) for inputting the impulse signal 101 from the pulse signal generation unit 110 and a local signal carrier 102 output from the high-frequency source 120. Local signal input terminal 132 (hereinafter referred to as LO terminal) and a radio frequency output terminal 133 (hereinafter referred to as RF terminal) for outputting the output signal 103 multiplied by the mixer 130.

  In order to prevent only the carrier wave 102 from leaking out from the RF terminal 133 of the mixer 130 (carrier leak) during the period when the impulse signal 101 is not output from the impulse signal generator 110, the switch 140 is connected to the mixer 130 from the high frequency source 120. It is provided to block the carrier wave 102 output to. That is, the switch 140 is controlled to be in a closed state at least during a period in which the impulse signal 101 is output from the pulse signal generation unit 110, and to be in an open state as much as possible during a period in which the impulse signal 101 is not output. . The switch control unit 150 inputs timing information before and after the impulse signal 101 is output from the pulse signal generation unit 110, and performs opening / closing control of the switch 140 based on the timing information.

  In the pulse generator 100 and the pulse generation method of this embodiment, the pulse signal generator 110 generates a bipolar pulse as shown in FIG. 2A and outputs this as a baseband impulse signal 101. Further, the switch control unit 150 performs control as shown in FIG. 2B in order to control the switch 140 to be closed only for a predetermined period including the period in which the bipolar pulse 101 is output from the pulse signal generation unit 110. The signal 104 is output to the switch 140. In the present embodiment, the time width for closing the switch 140 (hereinafter referred to as switch closing time width) is a predetermined multiple of the time width (hereinafter referred to as pulse output time width) in which the bipolar pulse 101 is output (hereinafter referred to as pulse output time width). , Referred to as carrier wave supply time multiple). A value larger than 1 is set to the carrier supply time multiple. As the wave number of the bipolar pulse 101 output from the pulse signal generator 110 increases, the pulse output time width becomes longer and the switch closing time width becomes longer in proportion thereto.

  The bipolar pulse used in the pulse generation method of this embodiment is characterized in that the frequency component near the direct current is null. Then, by modulating the carrier wave 102 at the center frequency of the bipolar impulse 101, a spectrum peak does not appear at the frequency position of the carrier wave 102 in the frequency spectrum of the output signal 103.

  The carrier wave supply time multiple is determined so that the frequency spectrum degradation amount becomes as small as possible with respect to the high-frequency impulse that is the output signal 103. Here, the frequency spectrum degradation amount is the ratio (dB) of the frequency spectrum peak value of the output signal 103 when having a carrier leak to the frequency spectrum peak value of the high frequency impulse which is the output signal 103 when there is no carrier leak. It shall be indicated by

  In the present embodiment, since the switch 140 is intermittently closed to cause the carrier wave 102 to be intermittently output to the mixer 130, the frequency spectrum of the carrier wave 102 spreads and periodic spectrum peaks occur. ing. The carrier wave supply time multiple is preferably determined so that the frequency at which the spectrum peak of the bipolar impulse 101 exists does not match the frequency at which the frequency spectrum peak of the carrier wave 102 exists.

  As an example, FIG. 5 shows the frequency spectrum of the output signal 103 when the carrier supply time multiple is 2, that is, the switch closing time width is twice the pulse output time width. However, in the following, it is assumed that carrier leak from the mixer 130 is suppressed to 20 dB with respect to the output signal 103. In the figure, the frequency spectrum of the output signal 103 including carrier leak is denoted by reference numeral 21, and the frequency spectrum of the output signal 103 (high frequency impulse) when there is no carrier leak (ideal state) is denoted by reference numeral 22. . In this embodiment, at the peak of the frequency spectrum of the output signal 103 (near 26 GHz and 27 GHz of the spectrum shown in FIG. 5), the spectrum increase due to carrier leak is about 0.5 dB.

  FIG. 4 shows the frequency spectrum when the carrier leak of the mixer and the switch open / close control are the same as those in FIG. 5 and the unipolar impulse is used as the baseband impulse. When the polarity impulse is used, it is about 1.6 dB, whereas when the bipolar impulse of this embodiment is used, it is reduced to about 0.5 dB. Thus, it can be confirmed that the influence of the carrier leak on the spectrum peak can be greatly reduced by using the bipolar impulse.

  In the pulse generation method of the present embodiment, a method of determining the above-mentioned carrier supply time multiple so that the amount of frequency spectrum degradation of the high-frequency impulse that is the output signal 103 is reduced as much as possible will be described below. FIG. 6 shows changes in the frequency spectrum deterioration amount when the carrier wave supply time multiple is changed. As shown in the figure, the frequency spectrum degradation amount changes with a substantially constant period with respect to the carrier supply time multiple. It can be seen that when the carrier wave supply time multiple is set to about 1.35, the frequency spectrum degradation amount is minimized.

  Further, when the carrier wave supply time multiple is set to a natural number multiple of approximately 1.35, the frequency spectrum degradation amount is minimal. Therefore, it is desirable that the carrier supply time multiple is approximately 1.35, and when the supply time of the carrier 102 cannot be shortened because the pulse output time width is particularly short, the carrier supply time multiple is a natural number of approximately 1.35. It is better to double. Thereby, the frequency spectrum degradation amount can be suppressed as much as possible.

  The frequency spectrum degradation amount shown in FIG. 6 is minimized at a substantially constant cycle with respect to the multiple of the carrier wave supply time, and is maximized at substantially the same cycle. For example, when the carrier wave supply time multiple is 2.1 times, the frequency spectrum degradation amount is almost maximal. FIG. 7 shows the frequency spectrum of the output signal 103 when the carrier supply time multiple is 2.1. In the figure, the frequency spectrum of the output signal 103 when there is a carrier leak is indicated by reference numeral 31, and the frequency spectrum of the high-frequency impulse 103 when there is no carrier leak is indicated by reference numeral 32. In the figure, the frequency spectrum of the carrier wave 102 input to the LO end 132 of the mixer 130 is also shown (reference numeral 33).

  In the frequency spectrum 33 of the carrier wave 102 shown in the figure, the frequency spectrum of the carrier wave 102 is expanded and periodic spectrum peaks are generated by periodically closing the switch 140 for a time width corresponding to a multiple of the carrier supply time. It shows that As a result, since the spectrum peak of the output signal 103 and the spectrum peak of the carrier wave 102 substantially coincide with each other around 26.2 GHz, it can be confirmed that the amount of frequency spectrum degradation has increased.

  In the above description, the carrier leak from the mixer 130 has been described as being reduced to 20 dB with respect to the output signal 103 from the RF terminal 133, but the influence when the carrier leak reduction rate is different will be described with reference to FIG. explain. FIG. 8 shows the change of the frequency spectrum degradation amount when the carrier wave supply time multiple is changed as in FIG. 6, and the reduction rate of the carrier leak is 10 dB, 14 dB, 16 dB, 19 dB, 20 dB, 24 dB, 24 dB. , 30 dB, changes in the frequency spectrum degradation amount are indicated by reference numerals 41 to 47, respectively.

  In FIG. 8, when the carrier leak is the smallest 30 dB (reference numeral 37), the frequency spectrum degradation amount is the smallest, and the frequency spectrum degradation amount increases as the carrier leak increases. In addition, the carrier supply time multiple when the frequency spectrum degradation amount is minimum in each carrier leak is in a range of approximately 1.3 to 1.5, although a tendency to slightly increase as the carrier leak increases is observed. Its natural number is doubled. Thus, it is preferable to set the carrier supply time multiple within the range of about 1.3 to 1.5, or a natural number multiple thereof, regardless of the amount of carrier leak in the mixer 130.

  Next, a first embodiment of the radar apparatus of the present invention using the pulse generator of the present invention will be described with reference to FIG. The radar apparatus 200 according to this embodiment includes a transmission unit 210 and a reception unit 220. The transmission unit 210 includes a pulse generator 100, an amplifier 211 that amplifies the output signal 103 output from now, and a transmission antenna 212 that transmits the signal amplified by the amplifier 211 as a transmission wave.

  The receiving unit 220 includes a receiving antenna 221, a low noise amplifier (LNA) 222 that amplifies a signal received by the receiving antenna 221 to a predetermined level, and a baseband from the signal amplified by the low noise amplifier 222. A mixer 223 for demodulating the impulse and a receiving circuit 224 for processing a signal output from the mixer 223 are provided. The mixer 223 demodulates the received signal input from the low noise amplifier 222 to the RF terminal 223c with the local signal 102 input from the high frequency source 120 to the LO terminal 223b, and outputs the demodulated signal from the IF terminal 223a to the receiving circuit 224. . The receiving circuit 224 includes an A / D converter, converts the received signal into a digital signal, and outputs it to the next processing step.

  When the transmission wave transmitted from the transmission antenna 212 is reflected by the object and received by the reception antenna 221, the transmission wave is amplified to a level that secures a desired S / N by the low noise amplifier 222, and this is mixed with the mixer 223. Then, the signal is detected by a predetermined method. In general, a radar apparatus using a pulse employs a method of measuring a time difference between transmission and reception of a pulse as a signal source and calculating a distance to an object based on the time difference. . Since the conventional radar apparatus uses a unipolar pulse as a signal source, it is only necessary to detect the time when the received signal is maximum (peak) and calculate the difference between this time and the time when the transmission wave is transmitted. .

  On the other hand, in the radar apparatus 200 of the present embodiment using the bipolar pulse 101 as a signal source, the received signal also becomes a bipolar pulse, and it is necessary to perform appropriate processing in the receiving circuit 224. One example will be described below.

  A second embodiment of the radar apparatus of the present invention will be described with reference to FIG. In the radar apparatus according to the present embodiment, an envelope detector 231 is provided inside the receiving circuit 224. As shown in FIG. 10, the envelope detection unit 231 detects the magnitude (envelope) regardless of the carrier phase of the received signal, so that the output signal from the envelope detection unit 231 is a unipolar signal. Become. Thus, the reception circuit 224 may detect the peak of the signal input from the envelope detection unit 231 with the peak detection unit 232, as in the conventional unipolar pulse radar. Note that square detection means can be used in place of the envelope detector 231. In this case, a similar unipolar signal can be obtained.

  A third embodiment of the radar apparatus of the present invention will be described with reference to FIG. In the radar apparatus 300 of this embodiment, a multiplier 310 is added between the low noise amplifier 222 and the mixer 223. In the present embodiment, the bipolar pulse of the transmission signal is converted into a unipolar pulse by multiplying the frequency of the reception signal amplified by the low noise amplifier 222 by 2 with the multiplier 310.

  As the received signal is multiplied, the frequency of the local signal 102 for demodulating the received signal by the mixer 223 is doubled by the multiplier 320 before being input to the mixer 223. Both the reception signal and the local signal multiplied by two are input to the mixer 223, whereby a unipolar pulse signal is output from the IF end 223a of the mixer 223. Therefore, also in this embodiment, it is only necessary to detect the peak of the signal input from the IF terminal 223a of the mixer 223 by the receiving circuit 224.

  A fourth embodiment of the radar apparatus of the present invention will be described with reference to FIG. In the radar apparatus 400 of the present embodiment, a switch 410 is added in the transmitter 210 to switch the output destination of the output signal 103 from the pulse generator 100 to the amplifier 211 and the LO end 223b of the mixer 223. The switch 410 connects the pulse generator 100 and the amplifier 211, and switches the switch 410 from the time when the output signal 103 is input to the amplifier 211 to connect the pulse generator 100 and the LO end 223b of the mixer 223, thereby outputting the output signal. The interval until the time when 103 is input to the LO end 223b of the mixer 223 is sequentially changed.

  In the present embodiment, the sliding correlation process is performed by demodulating the reception signal amplified by the low noise amplifier 222 with the output signal 103 whose timing is sequentially changed. As for the correlation value output from the IF terminal 223a of the mixer 223, a unipolar signal is obtained only when the synchronization is detected. Therefore, also in this embodiment, it is only necessary to detect the peak of the signal input from the IF terminal 223a of the mixer by the receiving circuit 225. In the present embodiment, the number of sliding correlation processes and the processing time affect the processing time of the radar apparatus 400.

  As described above, according to the pulse generation method and the pulse generation apparatus of the present invention, an increase in the peak value of the frequency spectrum due to carrier leak can be significantly suppressed. Further, in the radar apparatus of the present invention, it is not necessary to reduce the peak value of the pulse signal by providing the pulse generator of the present invention as a radar radiation source, thereby improving the maximum detection distance and improving the performance of the radar apparatus. Can be increased.

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

1 is a block diagram of a pulse generator according to a first embodiment of the present invention. It is a figure which shows an example of a bipolar pulse and a switch control signal. It is a figure which shows the influence which a carrier leak has on the frequency spectrum of a unipolar pulse, (a) is the frequency spectrum of the state which received the influence of a carrier leak, (b) is the frequency spectrum of the ideal state without a carrier leak. It is. It is a figure which shows the influence which the carrier leak of the carrier wave supplied intermittently has on the frequency spectrum of a unipolar pulse. It is a figure which shows the frequency spectrum of an output signal when a carrier-wave supply time multiple is set to 2. It is a figure which shows the change of the frequency spectrum degradation amount when changing a carrier-wave supply time multiple. It is a figure which shows the frequency spectrum of an output signal when a carrier wave supply time multiple is set to 2.1. It is a figure which shows the change of the frequency spectrum degradation amount when changing a carrier-wave supply time multiple. 1 is a block diagram of a radar apparatus according to a first embodiment of the present invention. It is a figure explaining the signal processing in an envelope detection part. It is a block diagram of the radar apparatus which concerns on the 2nd Embodiment of this invention. It is a block diagram of the radar apparatus which concerns on the 3rd Embodiment of this invention. It is a block diagram explaining the conventional pulse generation method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Pulse generator 101 Bipolar pulse 102 Local signal 103 Output signal 110 Pulse signal generation part 120 High frequency source 130 Mixer 131 IF end 132 LO end 133 RF end 140 Switch 150 Switch control part 200, 300, 400 Radar apparatus 210 Transmission part 220 Reception unit 211 Amplifier 212 Transmission antenna 221 Reception antenna 222 Low noise amplifier 223 Mixer 224 Reception circuit 231 Envelope detection unit 232 Peak detection unit 310, 320 Multiplier

Claims (10)

A pulse signal generator for outputting a bipolar impulse;
A high frequency source that outputs a high frequency carrier;
A mixer for inputting the bipolar impulse and the carrier wave, and outputting a radio frequency signal obtained by modulating the carrier wave with the bipolar impulse;
The carrier wave is input from the high-frequency source to the mixer only during a predetermined period (hereinafter referred to as a switch closing period) including a period during which the bipolar impulse is output from the pulse signal generation unit (hereinafter referred to as a pulse output period). A switch that cuts off the carrier during a period other than
When the switch is intermittently closed and the carrier wave is intermittently output to the mixer, any one of the spectrum peaks generated in the frequency spectrum of the carrier wave has the highest spectrum peak of the bipolar impulse. The pulse generating device , wherein the switch closing period is controlled so as not to coincide with an existing frequency . The pulse generator according to claim 1, wherein the switch closing period is a length obtained by multiplying the pulse output period by a multiple of a range of 1.3 to 1.5 . 2. The pulse generator according to claim 1 , wherein the switch closing period has a length obtained by multiplying the pulse output period by a multiple of a range of 1.3 to 1.5 and further multiplying by a natural number . Generating a bipolar impulse; generating a carrier wave modulated by the bipolar impulse; and a period (hereinafter referred to as a pulse output period) during which the bipolar impulse is output (hereinafter referred to as a pulse output period). A method for generating a pulse comprising: outputting a carrier wave only during a closed period; and outputting a radio frequency signal obtained by modulating the carrier wave with the bipolar impulse,
  By intermittently outputting the carrier wave during the switch closing period, one of the spectrum peaks generated in the frequency spectrum of the carrier wave does not coincide with the frequency at which the highest spectrum peak of the bipolar impulse exists. Control the switch closing period
A pulse generation method characterized by the above. The pulse according to claim 4, wherein the switch is controlled so that the switch closing period has a length obtained by multiplying the pulse output period by a multiple of a range of 1.3 to 1.5. How it occurs. Claims between the switch closing time periods are the multiples of the range of the pulse output period 1.3 1.5 multiplied further characterized to control said switch <br/> be such that the length obtained by multiplying the natural number Item 5. The pulse generation method according to Item 4 . A transmission unit including the pulse generator according to any one of claims 1 to 3,
  A transmitting antenna for transmitting a radio frequency signal generated by the pulse generator;
  A receiving antenna that receives a reflected wave of the radio frequency signal and outputs a received wave;
  A receiving unit that performs predetermined processing on the received wave and outputs a received signal.
Radar apparatus characterized by the above. The receiving unit demodulates the received wave at a predetermined demodulation high frequency and outputs a demodulated signal; and
  And a detector that detects the demodulated signal and outputs a received signal.
The radar apparatus according to claim 7. A first multiplier that doubles the frequency of the received wave;
Claim 7 or claim 8, characterized in <br/> further comprising a second multiplier for outputting a frequency by entering a carrier from the pulse generator as the demodulation frequency by multiplying twice The radar device described in 1 . Input a radio frequency signal from the pulse generator as the demodulation high frequency,
The radar according to claim 7 or 8 , further comprising a sliding correlator that performs a sliding correlation process on the demodulated signal and outputs a unipolar detection signal to the detection unit. apparatus.

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