JP2013170827A - Pulse radar device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pulse radar device which can adjust a gain for a received signal with a simple structure, and which easily reduces its size and cost.SOLUTION: A pulse radar device 100 includes noise signal acquisition means 132a for acquiring a noise signal for monitoring (γ+δ) and gain change determination means 132b for detecting a gain change of a high frequency receiving section 120 by using the noise signal for monitoring (γ+δ) in a digital signal processing section 132. A change-over switch 136 is provided in a base band section 130 for suitably controlling a gain variable amplifier 135 when the gain change is detected by the gain change determination means 132b. A control section 133 outputs a control signal for switching the change-over switch 136 according to a control amount of the gain variable amplifier 135, which is inputted from the gain change determination means 132b.

Description

  The present invention relates to a radar apparatus, and in particular, an on-vehicle device that measures a distance to an object by measuring a round-trip time until a pulse signal is emitted from the apparatus, reflected by an object, and received again by the apparatus. The present invention relates to a pulse radar device.

  The pulse radar device includes a high-frequency transmission unit and a high-frequency reception unit (hereinafter, collectively referred to as an RF unit) that processes a high-frequency signal, and a baseband unit that processes a low-frequency signal. Among these, since it is necessary to use an expensive substrate that can handle high frequencies, the RF unit is placed on a substrate that can handle high frequencies, and the baseband unit is low-cost in order to reduce costs. Generally, it is arranged on the substrate. A multi-pin connector is used as means for connecting the RF unit and the baseband unit arranged on different substrates.

  When the baseband part and RF part formed on different substrates are connected using an inexpensive connector with many pins and reduced dimensions, the control signal leaks into the received signal as an interference noise signal. Problem arises. In a multi-pin connector, if an unnecessary wave such as a control signal that is generated side by side leaks into the received signal and becomes an interference noise signal, if sufficient reception intensity cannot be obtained, the interference noise signal A desired received signal is buried.

  Therefore, in order to reduce interference noise as much as possible, the spacing between multiple pins is increased to increase isolation, and the received signal is amplified by an amplifier and digitally processed so that even a signal with low received strength can be detected. Yes. In digital processing of a received signal, a baseband received signal output from a high frequency receiving unit is amplified by an amplifier in the baseband unit, converted into a digital signal by an A / D converter, and then a predetermined arithmetic processing unit And the distance to the object is calculated.

  In the pulse radar apparatus configured as described above, the gains of the high-frequency receiving unit and the amplifier may change due to changes in ambient temperature or the passage of time. If the gain with respect to the received signal changes, the signal amplified by the amplifier may deviate from the dynamic range of the A / D converter, and the target may not be detected. Therefore, it is necessary to control the amplifier so that the amplified signal does not deviate from the dynamic range of the A / D converter.

  As a conventional technique for controlling the gain of an amplifier, for example, one disclosed in Patent Document 1 is known. In Patent Document 1, a pilot signal is used to monitor the gain, and the pilot signal is superimposed on the received signal and amplified by an amplifier. Then, a pilot signal is extracted from the amplified signal and input to a level detection circuit to detect the signal level.

JP 2001-24601 A

  However, in the technique disclosed in Patent Document 1, a pilot signal oscillator, a circulator, a directional coupler, and the like for generating a pilot signal are necessary, and the receiving apparatus is increased in size and cost. There is. Therefore, it is not suitable for use as a vehicle-mounted radar device that requires small size and low cost.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a pulse radar device that can adjust the gain for a received signal with a simple configuration, can be easily miniaturized, and is low in cost.

  In order to solve the above-described problem, a first aspect of the pulse radar device of the present invention includes an oscillator that generates a carrier wave having a predetermined frequency, a first cutout unit that cuts out the carrier wave in a pulse shape, and the first cutout unit. A high-frequency transmission unit having a second cut-out unit that further cuts out the signal cut out in step 1 and outputs a pulse-like transmission signal; and transmission that radiates into the space as a radio wave by inputting the transmission signal from the high-frequency transmission unit An antenna, a receiving antenna that receives a reflected wave reflected by the object, a correlator that receives a received signal from the receiving antenna and correlates with the transmission signal, and an output signal of the correlator An IQ mixer unit that down-converts and outputs a baseband signal; a high-frequency receiving unit that includes: a gain variable amplifier that inputs and amplifies the baseband signal; and the gain An A / D converter for converting an output signal of the variable amplifier into a digital signal; a digital signal processor for detecting the information of the object by inputting the digital signal from the A / D converter; A baseband unit including a cutout unit, a second cutout unit, and a control unit that controls the correlator, and the digital signal processing unit includes the first cutout unit and the second cutout unit. Noise signal acquisition means for acquiring a signal input to the digital signal processing unit as a monitoring noise signal when only the correlator is operated without operating the correlator, and the monitoring noise signal from the noise signal acquisition means Gain change determining means for determining a control amount of the variable gain amplifier by determining a change in the monitoring noise signal by comparing with a predetermined reference data The has the control unit is characterized in that said control amount to said variable gain amplifier and inputs the control amount from the gain change determination means is controlled to be applied.

  In another aspect of the pulse radar apparatus of the present invention, when the noise signal acquisition unit acquires the monitoring noise signal, the gain of the variable gain amplifier is set to a predetermined constant value, and then the first signal is acquired. Only the correlator is operated without operating the cutout unit and the second cutout unit.

  In another aspect of the pulse radar apparatus of the present invention, the control amount of the variable gain amplifier is determined so that the output of the variable gain amplifier does not deviate from the dynamic range of the A / D converter. .

  Another aspect of the pulse radar apparatus of the present invention is characterized in that the reference data is the monitoring noise data acquired first at the time of activation.

  In another aspect of the pulse radar apparatus of the present invention, the baseband unit includes a storage unit that stores a table in which a control amount of the variable gain amplifier is set with respect to a change amount of the monitoring noise signal, and the gain change The determining unit reads the table from the storage unit and determines a control amount of the variable gain amplifier corresponding to a change amount of the monitoring noise signal from the reference data.

  In another aspect of the pulse radar apparatus of the present invention, the baseband unit includes changeover switch means for switching and selecting any one of two or more preset gains of the variable gain amplifier. The gain change determination means selects any one of the control amounts of the two or more gain variable amplifiers based on the change amount from the reference data of the monitoring noise signal, and outputs the selected control amount to the control unit, The control unit outputs a control signal instructing switching according to a control amount of the variable gain amplifier input from the gain change determination unit to the changeover switch unit.

  According to the present invention, it is possible to adjust a gain for a received signal with a simple configuration, and it is possible to provide a pulse radar device that can be easily miniaturized and reduced in cost.

It is a block diagram which shows the structure of the pulse radar apparatus which concerns on one Embodiment of this invention. It is a distance waveform figure of a noise signal when only a control signal to a correlator is outputted with a pulse radar device concerning one embodiment of the present invention. It is a figure which shows an example of the change with respect to ambient temperature of the gain in a high frequency receiver. It is the enlarged view which expanded and displayed the control line and signal line which pass a connector. It is a distance waveform figure of a noise signal when not outputting a control signal to the 1st gate part of a pulse radar device concerning one embodiment of the present invention. It is a distance waveform figure of a noise signal when not outputting a control signal to the 2nd gate part of a pulse radar device concerning one embodiment of the present invention. It is a distance waveform figure of a replica signal created by a pulse radar device concerning one embodiment of the present invention. It is a distance waveform figure of a digital signal containing a noise signal acquired from a received signal. It is a distance waveform figure of the received signal which does not contain a noise signal.

  A pulse 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 embodiment)
A pulse radar apparatus according to a first embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a block diagram illustrating a configuration of a pulse radar device 100 according to the present embodiment. In FIG. 1, a pulse radar apparatus 100 includes a high-frequency transmission unit (RF transmission unit) 110 and a high-frequency reception unit (RF reception unit) 120 that process high-frequency signals, a baseband unit 130 that processes low-frequency signals, and radio waves. A transmitting antenna 101 for radiating into space and a receiving antenna 102 for receiving a reflected wave reflected by an object are provided. Hereinafter, for ease of explanation, an object to be detected by the pulse radar device 100 is indicated by a symbol T.

  The high-frequency transmission unit 110 generates an oscillator 111 that generates a predetermined high-frequency signal (carrier wave) that is a generation source of an electromagnetic wave transmission signal, and a high-frequency signal generated by the oscillator 111 is a pulse signal (pulse signal) having a predetermined time width. ), A first gate portion (first cutout portion) 112 and a second gate portion (second cutout portion) 113 are provided. The first gate unit 112 and the second gate unit 113 are circuits that cut out a high-frequency signal input from the oscillator 111 into a pulse signal having a width of 1 [ns], for example, and a multiplier or a switch can be used. By using two signal extraction circuits of the first gate unit 112 and the second gate unit 113, a sharply shaped pulse signal can be generated. The pulse-shaped transmission signal output from the second gate unit 113 is transmitted to the transmission antenna 101 and radiated from the transmission antenna 101 into the air as a radio wave.

  The high-frequency receiving unit 120 receives a reception signal received by the reception antenna 102 and correlates the transmission signal with a time correlator 121. The signal input from the correlator 121 is down-converted by a carrier wave input from the oscillator 111. And an IQ mixer unit 122 for conversion. The IQ mixer unit 122 converts the first carrier 123 for down-converting into an I-phase baseband signal, the second mixer 124 for down-converting into a Q-phase baseband signal, and the carrier wave inputted from the oscillator 111 by 90 degrees. And a phase shifter 125 that outputs the phase difference to the first mixer 123 and the second mixer 124. The correlator 121 extracts a signal for each measurement distance from the received signal and outputs it to the first mixer 123 and the second mixer 124.

  The baseband unit 130 receives the I component and the Q component of the complex baseband signal down-converted by the first mixer 123 and the second mixer 124 and amplifies them in parallel up to a predetermined level. An A / D converter 131 that inputs the I component and Q component amplified by the amplifier 135 and converts them into a complex digital signal in parallel, and complex signal processing (complex Fourier transform) of the complex digital signal from the A / D converter 131 (FFT: Fast Fourier Transform)), a digital signal processing unit 132 that calculates information on the object T, a control unit 133 that controls the operation of the pulse radar device 100, and a storage unit 134. The control unit 133 performs on / off control of the power sources of the first gate unit 112, the second gate unit 113, and the correlator 121, which are high-frequency components. The control signal generated by the control unit 133 is a signal having a width of 1 [ns].

  In the pulse radar device 100 of the present embodiment configured as described above, each component constituting the high-frequency transmitter 110 and the high-frequency receiver 120 operates at a frequency of several tens of GHz band, whereas the baseband unit 130 is provided. Each component to be operated operates at a frequency of at most about 2 GHz. As described above, since the operating frequency of the high-frequency transmitting unit 110 and the high-frequency receiving unit 120 and the operating frequency of the baseband unit 130 are greatly different, it is preferable to form them on separate substrates designed for the respective frequency bands. . In the present embodiment, the high frequency transmitter 110 and the high frequency receiver 120 are formed on the high frequency substrate 103, and the baseband unit 130 is formed on the low frequency substrate 104. Further, the transmitting antenna 101 and the receiving antenna 102 that transmit and receive a high-frequency signal are also disposed on the high-frequency substrate 103.

  Since the substrate used for high frequency is more expensive than the substrate for low frequency, in this embodiment, the high frequency transmission unit 110, the high frequency reception unit 120, the transmission antenna 101, and the reception antenna 102 are provided on the expensive high frequency substrate 103. The baseband unit 130 that processes only low frequency signals and is disposed on the low-frequency low-frequency substrate 104. Thereby, the cost reduction of the pulse radar apparatus 100 can be aimed at.

  As described above, when each component of the pulse radar device 100 is divided into the high frequency substrate 103 and the low frequency substrate 104, the components on the high frequency substrate 103 and the components on the low frequency substrate 104 are electrically connected. A means to connect to is required. In the pulse radar device 100 of the present embodiment, a low-priced and small multi-pin connector 105 that has been conventionally used is used as means for electrically connecting two substrates. The complex baseband signal output from the high frequency receiving unit 120 on the high frequency substrate 103 is transmitted to the baseband unit 130 on the low frequency substrate 104 via the connector 105. The control signal output from the control unit 133 on the low frequency substrate 104 is transmitted to the high frequency transmission unit 110 and the high frequency reception unit 120 on the high frequency substrate 103 via the connector 105.

  A method for detecting object information using the pulse radar device 100 of the present embodiment will be described below with reference to FIG. In FIG. 1, the control signal (first control signal) output from the control unit 133 to the first gate unit 112 and the control line (first control line) that transmits the control signal are denoted by A and a, respectively. The control signal (second control signal) output to the two-gate unit 113 and the control line (second control line) that transmits the control signal are denoted by B and b, respectively. In addition, a control signal (third control signal) output from the control unit 133 to the correlator 121 and a control line (third control line) that transmits the control signal are denoted by C and c, respectively. The control signals A and B perform on / off control of the power of the first gate unit 112 and the second gate unit 113, respectively, and the control signal C performs on / off control of the power of the correlator 121.

  Further, the baseband signal (I component) output from the first mixer 123 of the IQ mixer section 122 to the variable gain amplifier 135 and the signal line for transmitting the baseband signal are D and d, respectively, and the variable gain amplifier 135 from the second mixer 124 is set. E and e are the baseband signals (Q components) output to, and the signal lines that transmit them. The control lines a, b, and c and the signal lines d and e all pass through different pins of the connector 105.

  In the pulse radar device 100, control signals A and B are output from the control unit 133 to the first gate unit 112 and the second gate unit 113 at appropriate timings via the control lines a and b. When the power sources of the first gate unit 112 and the second gate unit 113 are turned on for approximately 1 [ns] by the control signals A and B, the carrier wave generated by the oscillator 111 has a pulse width of 1 [ns]. Cut out. As a result, a 1 [ns] -width pulse transmission signal using a carrier wave having a predetermined frequency is generated, and is transmitted to the transmission antenna 101 to be radiated into the air as a radio wave. The radiated radio wave is reflected by the object T and received by the receiving antenna 102.

  The received signal received by the receiving antenna 102 is transmitted to the correlator 121 when the control signal C is output from the controller 133 via the control line c to the correlator 121 at a predetermined timing and the correlator 121 is turned on. Are correlated. The signal output from the correlator 121 is down-converted by the IQ mixer unit 122 into a complex baseband signal composed of an I component and a Q component. The I- and Q-component baseband signals D and E down-converted by the first mixer 123 and the second mixer 124 are input to the variable gain amplifier 135 of the baseband unit 130 through the signal lines d and e, Each signal is amplified in parallel to a predetermined level.

  The baseband signals of I component and Q component amplified by the variable gain amplifier 135 are input to the A / D conversion unit 131 and converted into a complex digital signal in parallel. The complex digital signal is input to the digital signal processing unit 132 and subjected to complex signal processing, and position information and relative velocity information relating to the object T are calculated.

  In the pulse radar device 100 that operates as described above, the gain of the high-frequency receiving unit 120 may change as the ambient temperature changes or the time elapses after activation. A signal output from the variable gain amplifier 135 may deviate from the dynamic range of the A / D converter 131 due to a gain change with respect to the received signal. If the output signal from the variable gain amplifier 135 deviates from the dynamic range of the A / D converter 131, the correct digital signal is not output from the A / D converter 131 to the digital signal processor 132, and the target cannot be detected. There is a fear.

  Therefore, in the pulse radar device 100 of the present embodiment, the above-described change in gain is compensated using self-mixing noise described below. The pulse radar device 100 is configured to output a carrier wave from the oscillator 111 to the IQ mixer unit 122 in order to down-convert the received signal into a baseband signal. Some of this carrier wave passes through the IQ mixer 122 and leaks to the correlator 121, is reflected by the correlator 121, returns to the IQ mixer 122 again, and is downconverted. This is self-mixing noise, which is mixed into the baseband signals D and E by the IQ mixer 122. In the following, the self-mixing noise is indicated by the symbol δ.

  The carrier wave leaking to the correlator 121 described above is output when the control signal C is output from the control unit 133 and the power of the correlator 121 is turned on so that the correlator 121 cuts out the received signal. 121 is transmitted to the IQ mixer 122 and becomes self-mixing noise δ. The self-mixing noise δ is transmitted to the baseband unit 130 via the signal lines d and e together with the baseband signals D and E, and is processed by the digital signal processing unit 132.

  The self-mixing noise δ changes in proportion to the change in the gain of the correlator 121. After being reflected by the correlator 121, it is amplified by the variable gain amplifier 135 in the same manner as the received signal, converted to a digital signal by the A / D converter 131 and transmitted to the digital signal processor 132. That is, the self-mixing noise δ is given a gain equivalent to that of the received signal by the high-frequency receiving unit 120, and is further amplified by the variable gain amplifier 135 equivalent to the received signal. Therefore, when the gain of the high-frequency receiving unit 120 changes with changes in ambient temperature, time, or the like, the self-mixing noise δ obtained by the digital signal processing unit 132 also changes. Therefore, by monitoring the self-mixing noise δ, it is possible to detect a change in the gain of the high-frequency receiving unit 120.

  The self-mixing noise δ is transmitted to the baseband unit 130 when the power of the correlator 121 is turned on. At this time, the control signal C is output from the control unit 133 to the correlator 121 via the connector 105. Since each pin (terminal) of the connector 105 is exposed, when the control signal C passes through the control line c in the connector 105, a part leaks into the signal lines d and e to become an interference noise signal γ. . Therefore, when the power of the correlator 121 is turned on, a noise signal (γ + δ) obtained by adding the self-mixing noise δ and the interference noise signal γ is transmitted to the baseband unit 130 via the signal lines d and e. Is done. Hereinafter, the noise signal (γ + δ) is referred to as a monitoring noise signal.

  An example of the monitoring noise signal (γ + δ) is shown in FIG. FIG. 2 is a graph showing an example of the waveform of the monitoring noise signal (γ + δ) processed by the digital signal processing unit 132. The horizontal axis represents the distance from the pulse radar device 100 (elapsed time since sending the pulse signal). Equivalent to time).

  In the pulse radar device 100 according to the present embodiment, the monitoring noise signal (γ + δ) is monitored in order to detect a change in the gain of the high-frequency receiving unit 120. When a change in the monitoring noise signal (γ + δ) is detected, the gain The variable amplifier 135 is controlled to compensate for a change in gain of the high-frequency receiving unit 120. In the following, a method for obtaining the monitoring noise signal (γ + δ) separately from the received signal will be described. In order to determine the control amount of the variable gain amplifier 135 from the change amount of the monitoring noise signal (γ + δ), a table is obtained by calculating in advance the relationship of the control amount of the gain variable amplifier 135 with respect to the change amount of the monitoring noise signal (γ + δ). It can be stored in the storage unit 134 in a format or the like and used.

  When a transmission radio wave is radiated from the transmission antenna 101 into the air, the transmission radio wave is reflected by some object and received by the reception antenna 102, and a signal obtained by adding a noise signal (γ + δ) to the reception signal is received by the digital signal processing unit. Will be processed. Therefore, it becomes impossible to extract only the monitoring noise signal (γ + δ). Therefore, when the monitoring noise signal (γ + δ) is acquired, the transmission radio wave is prevented from being radiated from the transmission antenna 101. The high-frequency transmission unit 110 is configured to output a pulse signal to the transmission antenna 101 when both the first gate unit 112 and the second gate unit 113 are turned on. Thus, by operating the pulse radar device 100 without outputting the control signals A and B from the control unit 133, it is possible to prevent the transmission radio wave from being radiated from the transmission antenna 101.

  Further, by not outputting the control signals A and B, it is possible to prevent the control signals A and B from leaking into the signal lines d and e at the connector 105. Therefore, when the monitoring noise signal (γ + δ) is acquired, the control signal 133 is not output from the control unit 133, but only the control signal C is output to operate the pulse radar apparatus 100. Thereby, the power of the correlator 121 is turned on, and the self-mixing noise δ is transmitted to the baseband unit 130 via the connector 105. At the same time, when the control signal C passes through the control line c in the connector 105, it leaks into the signal lines d and e. As a result, a noise signal (γ + δ) obtained by adding the self-mixing noise δ and the interference noise signal γ is transmitted to the baseband unit 130.

  The noise signal (γ + δ) transmitted to the baseband unit 130 is amplified by the variable gain amplifier 135, converted to a digital signal by the A / D conversion unit 131, and output to the digital signal processing unit 132. The digital signal processing unit 132 can detect the change from the digital value of the input monitoring noise signal (γ + δ). When a change in the monitoring noise signal (γ + δ) is detected, it is determined that the gain of the high-frequency receiving unit 120 has changed.

  When the monitoring noise signal (γ + δ) is acquired as described above, if the gain by the variable gain amplifier 135 changes each time, the monitoring noise signal (γ + δ) acquired by the digital signal processing unit 132 changes. Therefore, it cannot be distinguished whether it is due to a change in gain in the high-frequency receiving unit 120 or a change in gain of the variable gain amplifier 135. Therefore, when the monitoring noise signal (γ + δ) is acquired, the gain of the variable gain amplifier 135 is returned to a predetermined set value such as an initial value. Thereby, it is possible to determine that the gain change detected by the digital signal processing unit 132 is due to the gain change in the high-frequency receiving unit 120.

  The pulse radar device 100 according to this embodiment is configured to detect a gain change in the high-frequency receiving unit 120 using the monitoring noise signal (γ + δ) and control the variable gain amplifier 135 so as to compensate for the gain change. A detailed configuration will be described with reference to FIG. The pulse radar apparatus 100 includes a noise signal acquisition unit 132a and a gain change determination unit 132b in the digital signal processing unit 132 in order to acquire a monitoring noise signal (γ + δ) and detect a gain change. In addition, when the gain change is detected by the gain change determining means 132b, a changeover switch 136 is provided in the baseband unit 130 in order to suitably control the variable gain amplifier 135.

  Here, for ease of explanation, the changeover switch 136 is provided in the baseband unit 130. However, the present invention is not limited to this, and any switch having a switch function may be used. It can be replaced with another changeover switch means having As such a switch function, for example, PWM control is used, and the amplitude can be controlled by changing the output of the PWM signal.

  When the monitoring noise signal (γ + δ) is acquired, the control amount for the variable gain amplifier 135 is set to an initial value, and only the control signal C is output from the control unit 133 to operate the pulse radar apparatus 100. At this time, in the digital signal processing unit 132, the noise signal acquisition unit 132 a inputs the digital signal from the A / D conversion unit 131. When the noise signal acquisition unit 132a acquires a monitoring noise signal (γ + δ) having a waveform as illustrated in FIG. 2, the noise signal acquisition unit 132a outputs this to the gain change determination unit 132b. When the gain change determination unit 132b receives the monitoring noise signal (γ + δ) from the noise signal acquisition unit 132a, the gain change determination unit 132b compares it with predetermined reference data to determine whether the monitoring noise signal (γ + δ) has changed. .

  When the gain change determination unit 132b determines that the monitoring noise signal (γ + δ) has changed, the control amount of the variable gain amplifier 135 is determined according to the magnitude of the change in the monitoring noise signal (γ + δ), and the control unit 133 Is output. The control amount of the variable gain amplifier 135 can be determined, for example, by reading from the storage unit 134 a table in which the control amount of the gain variable amplifier 135 with respect to the change amount of the monitoring noise signal (γ + δ) is calculated and stored. The control unit 133 outputs a control signal for switching the changeover switch 136 according to the control amount of the variable gain amplifier 135 input from the gain change determination unit 132b.

  The reference data used to determine the change in the monitoring noise signal (γ + δ) by the gain change determination unit 132b is a monitoring noise signal (γ + δ) at a predetermined time, for example, when the pulse radar device 100 is activated. Can do. That is, at the time when the pulse radar device 100 is activated, the digital signal processing unit 132 acquires the monitoring noise signal (γ + δ) by the above method, and saves it in the storage unit 134 as reference data. Thereafter, when the monitoring noise signal (γ + δ) is appropriately acquired and the change in the monitoring noise signal (γ + δ) is determined by the gain change determination unit 132b, the reference data is read from the storage unit 134 and used.

  The control amount of the variable gain amplifier 135 determined by the gain change determining means 132b is to adjust the gain of the variable gain amplifier 135 so that the output of the variable gain amplifier 135 does not deviate from the dynamic range of the A / D converter 131. is there. Therefore, it is not always necessary to adjust the variable gain amplifier 135 in response to the change in the monitoring noise signal (γ + δ). For example, when the gain changes beyond a predetermined magnitude, the gain of the variable gain amplifier 135 is set to a predetermined value. Can be adjusted to the size of.

  An example of a change in gain in the high-frequency receiving unit 120 is shown in FIG. This figure shows an example of a change in gain in the high-frequency receiving unit 120 when the ambient temperature changes, and the horizontal axis is the temperature. The gain of the variable gain amplifier 135 is higher at low temperatures and decreases as the ambient temperature increases. Therefore, it is necessary to adjust the control amount of the variable gain amplifier 135 so that the output of the variable gain amplifier 135 does not deviate from the dynamic range of the A / D conversion unit 131 as the ambient temperature changes. In the following, the control amount of the variable gain amplifier 135 is a control voltage of the variable gain amplifier 135 as an example.

  In the present embodiment, the control amount of the variable gain amplifier 135 is selected stepwise in accordance with the magnitude of the gain change in the high frequency receiver 120 shown in FIG. As an example, the gain in the high-frequency receiving unit 120 is divided into levels 1, 2, and 3 as shown in FIG. 3, and the control voltage is set to the initial value V0 until the gain reaches level 2, and when the gain reaches level 2, the control voltage V1 is reached. When the level 3 is further reached, the control voltage V2 is selected.

  In the present embodiment, since the gain change in the high-frequency receiving unit 120 is monitored by the change in the monitoring noise signal (γ + δ), the monitoring noise signal (γ + δ) corresponding to each of the gains of levels 1, 2, and 3 is used. ) Change amount (change ratio with respect to the initial value) is determined in advance. Then, a table or the like in which the control voltages V0, V1, and V2 are set corresponding to the amount of change in the monitoring noise signal (γ + δ) is stored in the storage unit 134.

  When the gain change determination unit 132b determines the amount of change from the reference data of the monitoring noise signal (γ + δ), the table is read from the storage unit 134, and one of the control voltages V0, V1, and V2 is selected. Is output to the control unit 133. When any of the control voltages V0, V1, and V2 is input from the gain change determination unit 132b, the control unit 133 outputs a control signal F1 for switching to the control voltage to the changeover switch 136. Thus, the control voltage selected by switching the selector switch 136 is applied to the variable gain amplifier 135 as the control signal F2. When the pulse radar device 100 is operated to detect the monitoring noise signal (γ + δ), the changeover switch 136 is switched to the control voltage V0 in advance.

  The detection of the monitoring noise signal (γ + δ) is preferably performed immediately after the pulse radar apparatus 100 is activated in order to acquire the reference data, and can be appropriately performed thereafter. As an example, the pulse radar device 100 periodically processes a received signal by emitting a pulse signal in order to acquire object information. However, during the period from the emission of a pulse signal to the emission of the next pulse signal. Can detect the monitoring noise signal (γ + δ). Detection of the monitoring noise signal (γ + δ) may be performed periodically between the emission of the pulse signal and the next emission, or may be performed after a certain time has elapsed.

  In the above description, the control voltage of the variable gain amplifier 135 is configured to be switched using the changeover switch 136. However, the present invention is not limited to this. For example, the control voltage selected by the gain change determination unit 132b is converted to the D / A converter. It is also possible to configure so that the variable gain amplifier 135 is directly applied via

  In the pulse radar device 100 of this embodiment configured to detect the gain change of the high-frequency receiving unit 120 and control the control voltage of the variable gain amplifier 135, the connector 105 further removes interference noise mixed in the received signal. Is possible. A method for removing interference noise mixed in the connector 105 in the pulse radar device 100 of this embodiment will be described below. In this embodiment, an interference noise replica signal is created in advance, and unnecessary interference noise is removed by subtracting the interference noise replica signal from the received signal.

  FIG. 4 shows control lines and signal lines that pass through the connector 105. FIG. 4 is an enlarged view showing a control line and a signal line passing through the connector 105 in an enlarged manner. In the figure, in the connector 105, the signals that pass from the control lines a and b to the signal lines d and e are interference noise signals α and β, respectively. Further, the signals that circulate from the control line c described above to the signal lines d and e and the mixing noise are indicated by interference noise signals γ and δ, respectively.

  Control signals A, B, and C that flow through the control lines a, b, and c are signals for driving the RF components (the first gate unit 112, the second gate unit 113, and the correlator 121) on and off. On the other hand, the complex baseband signals D and E flowing through the signal lines d and e are signals obtained by down-converting a low-level signal reflected from the object T, and are very low-level signals. Therefore, the control signals A, B, and C are relatively high level signals compared to the baseband signals D and E, and the connector 105 changes the control lines a, b, and c to the signal lines d and e. The interference noises α, β, and γ of the control signals A, B, and C that leak into the baseband signals D and E are substantially the same level.

  When acquiring the interference noise replica signal mixed in the received signal, the pulse radar apparatus 100 is operated without outputting at least one of the control signals A and B, as in the case of acquiring the interference noise (γ + δ). Let As a result, transmission radio waves are not radiated from the transmission antenna 101, and only interference noise can be acquired.

  First, the control unit 133 outputs the control signals B and C to the second gate unit 113 and the correlator 121 via the control lines b and c, respectively, to operate the pulse radar device 100. At this time, since the control signal A is not output to the first gate unit 112, the pulse signal is not output to the transmission antenna 101, and the transmission radio wave is not radiated from the transmission antenna 101. As a result, the digital signal processing unit 132 has a noise signal (β + γ + δ) (first) obtained by synthesizing the interference noise signals β and γ mixed with the control signals B and C in the signal lines d and e and the self-mixing noise δ. 1 background signal) is input. An example of the distance waveform of the first background signal (β + γ + δ) is shown in FIG. The first background signal (β + γ + δ) is stored in the storage unit 134.

  Next, control signals A and C are output from the control unit 133 to the first gate unit 112 and the correlator 121 via the control lines a and c, respectively, and the pulse radar apparatus 100 is operated. At this time, since the control signal B is not output to the second gate unit 113, the pulse signal is not output to the transmission antenna 101, and the transmission radio wave is not radiated from the transmission antenna 101. As a result, the digital signal processing unit 132 has a noise signal (α + γ + δ) (first) obtained by combining the interference noise signals α and γ mixed with the control signals A and C into the signal lines d and e and the self-mixing noise δ. 2 background signals) is input. An example of the distance waveform of the second background signal (α + γ + δ) is shown in FIG. The second background signal (α + γ + δ) is added to the first background signal (β + γ + δ) stored in the storage unit 134 and stored.

  Furthermore, the control unit 133 outputs the control signal C to the correlator 121 via the control line c to operate the pulse radar device 100. However, when acquiring the interference noise replica signal mixed in the received signal, the same control voltage as that used when acquiring the object information is used as the control voltage applied to the variable gain amplifier 135. Accordingly, the digital signal processing unit 132 receives a noise signal (γ + δ) (third background signal) obtained by combining the interference noise signal γ in which the control signal C is mixed into the signal lines d and e and the self-mixing noise δ. Entered. The distance waveform of the third background signal (γ + δ) is the same as the waveform shown in FIG. The third background signal (γ + δ) is subtracted from the added value of the first background signal (β + γ + δ) and the second background signal (α + γ + δ) stored in the storage unit 134 and stored again.

Through the above processing, the interference signal replica signal (α + β + γ + δ) calculated by the following equation is stored in the storage unit 134.
(Β + γ + δ) + (α + γ + δ) − (γ + δ) = α + β + γ + δ
The distance waveform of the replica signal (α + β + γ + δ) is obtained by adding the distance waveform of FIG. 5 and the distance waveform of FIG. 6 and subtracting the distance waveform of FIG. FIG. 7 shows a distance waveform of the replica signal (α + β + γ + δ).

  In the operation of the pulse radar apparatus 100 for detecting the object information, the digital signal processing unit 132 subtracts the replica signal (α + β + γ + δ) from the digital signal acquired from the received signal. An example of the distance waveform of the digital signal including the noise signal acquired from the received signal is shown in FIG. By subtracting the distance waveform of the replica signal (α + β + γ + δ) shown in FIG. 7 from the distance waveform shown in FIG. 8, a distance waveform 10 not including a noise signal as shown in FIG. 9 is obtained. In the figure, it can be seen that the object is present at a distance where the amplitude is a peak.

  As described above, according to the pulse radar device 100 of the present embodiment, the gain change of the high-frequency receiving unit 120 is detected using self-mixing noise, and the variable gain amplifier 135 is based on the amount of change of the self-mixing noise. The control amount of can be determined. As a result, it is possible to adjust the gain for the received signal with a simple configuration, and it is possible to provide a pulse radar device that can be easily miniaturized and that is low in cost.

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

DESCRIPTION OF SYMBOLS 100 Pulse radar apparatus 101 Transmission antenna 102 Reception antenna 103 High frequency board 104 Low frequency board 105 Connector 110 High frequency transmission part 111 Oscillator 112 First gate part 113 Second gate part 120 High frequency reception part 121 Correlator 122 IQ mixer part 123 1 mixer 124 2nd mixer 125 phase shifter 130 baseband unit 131 A / D conversion unit 132 digital signal processing unit 132a noise signal acquisition unit 132b gain change determination unit 133 control unit 134 storage unit 135 variable gain amplifier 136 changeover switch

Claims (6)

An oscillator that generates a carrier wave having a predetermined frequency, a first cutout unit that cuts out the carrier wave in a pulse shape, and a second cutout signal that is cut out in the first cutout unit to output a pulsed transmission signal A high-frequency transmission unit having a cut-out unit;
A transmission antenna that inputs the transmission signal from the high-frequency transmission unit and radiates it into space as a radio wave;
A receiving antenna that receives a reflected wave in which the radio wave is reflected by an object;
A high-frequency receiving unit comprising: a correlator that inputs a reception signal from the reception antenna and correlates with the transmission signal; and an IQ mixer unit that down-converts the output signal of the correlator and outputs a baseband signal; ,
A variable gain amplifier that inputs and amplifies the baseband signal, an A / D converter that converts an output signal of the variable gain amplifier into a digital signal, and the digital signal that is input from the A / D converter A baseband unit including a digital signal processing unit for detecting information of an object, and a control unit for controlling the first clipping unit, the second clipping unit, and the correlator,
The digital signal processing unit converts a signal input to the digital signal processing unit into a monitoring noise signal when only the correlator is operated without operating the first cutout unit and the second cutout unit. When the monitoring noise signal is input from the noise signal acquisition unit, the change in the monitoring noise signal is determined by comparison with predetermined reference data, and the control amount of the variable gain amplifier is determined. And a gain change determining means for determining,
The pulse radar device, wherein the control unit performs control so that the control amount is applied to the variable gain amplifier when the control amount is input from the gain change determination unit. When the noise signal acquisition unit acquires the monitoring noise signal, the gain of the variable gain amplifier is set to a predetermined constant value, and then the first clipping unit and the second clipping unit are operated. The pulse radar apparatus according to claim 1, wherein only the correlator is operated without being operated. 3. The pulse radar device according to claim 1, wherein the control amount of the variable gain amplifier is determined so that an output of the variable gain amplifier does not deviate from a dynamic range of the A / D conversion unit. 4. The pulse radar device according to claim 1, wherein the reference data is the monitoring noise data acquired first at the time of startup. 5. The baseband unit includes a storage unit that stores a table in which a control amount of the variable gain amplifier is set with respect to a change amount of the monitoring noise signal.
2. The gain change determining unit reads the table from the storage unit and determines a control amount of the variable gain amplifier corresponding to a change amount of the monitoring noise signal from the reference data. The pulse radar device according to any one of 1 to 4. The baseband unit includes changeover switch means for switching and selecting any one of two or more preset gains of the variable gain amplifier.
The gain change determination means selects one of the control amounts of the two or more gain variable amplifiers based on the change amount from the reference data of the monitoring noise signal, and outputs the selected control amount to the control unit,
6. The control unit according to claim 1, wherein the control unit outputs a control signal instructing switching according to a control amount of the variable gain amplifier input from the gain change determination unit to the changeover switch unit. The pulse radar device according to item 1.

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