WO2019123613A1 - Phase difference detection circuit and radar device - Google Patents

Abstract

This phase difference detection circuit has a first transmission/reception circuit (40i), a second transmission/reception circuit (40j), measuring units (55i, 55j), and a phase difference calculation unit (54j). The first transmission/reception circuit (40i) and the second transmission/reception circuit (40j) respectively calculate, by operating in ranging mode, a first measurement value and a second measurement value, which indicate round-trip propagation time to a target (Tgt). Then, the first transmission/reception circuit (40i) operates in transmission mode, and transmits a frequency unmodulated signal. The second transmission/reception circuit (40j) operates in reception mode, receives, from the first transmission/reception circuit (40i), reflected waves arrived via the target Tgt, and generates a beat signal on the basis of a reception signal of the reflected waves. The second transmission/reception circuit (40j) calculates, on the basis of the first measurement value, the second measurement value, and the beat signal, a phase difference between transmission signals transmitted from a first antenna element (61i) and a second antenna element (61j).

Description

Phase difference detection circuit and radar device

The present invention relates to a technique for detecting a phase difference between transmission signals output from a plurality of antenna elements, and in particular, detects a phase difference between transmission signals output from a plurality of antenna elements constituting an array antenna of a radar device. Related to technology.

A frequency modulation method is widely adopted in a radar apparatus which detects target information such as a distance to a target (target) and a relative velocity of the target. As a frequency modulation method, for example, a frequency-modulated continuous-wave (FMCW) method is widely known. The FMCW scheme often uses a transmit signal called a chirp, which has a transmit frequency that varies linearly with time. A radar device operating in the FMCW system can measure a beat frequency which is a frequency difference between a transmission signal and a reception signal, and detect the distance to the target and the relative velocity of the target based on the beat frequency. It is.

For example, Patent Document 1 (Japanese Unexamined Patent Publication No. 2006-10404) discloses an FMCW radar device that detects a phase difference between N antennas (N is an integer of 2 or more). This radar apparatus selects a signal generator (voltage control oscillator) that generates a transmission signal, and any one of the N antennas, and outputs the transmission signal from the selected antenna 1 A pair N switch, a mixer for mixing a part of the output of the signal generator and the received signal, and a signal processing unit for measuring the voltage level of the output of the mixer. According to Patent Document 1, the 1-to-N switch sequentially selects N antennas while the frequency modulation of the transmission signal is stopped. Each of the selected antennas transmits a transmission signal without frequency modulation, and the mixer outputs a DC voltage level corresponding to the phase difference between the transmission signal and the reception signal. Then, the signal processing unit calculates phase values for the N antennas from the DC voltage levels measured for each of the N antennas, and detects a phase difference between the antennas based on these phase values.

JP-A-2006-10404 (For example, claim 1 and FIG. 1)

The phase difference detection technique described in Patent Document 1 described above is a technique based on the use of a common signal generator (voltage control oscillator) for N antennas. Therefore, in the case of a radar apparatus having a plurality of signal generators individually for a plurality of antennas, there is a problem that it is difficult to apply the phase difference detection technique described in Patent Document 1.

In view of the above, it is an object of the present invention to accurately detect the phase difference between transmission signals output from a plurality of antenna elements even when a plurality of signal generators are provided individually for a plurality of antenna elements. It is an object of the present invention to provide a phase difference detection circuit and a radar device that can be performed.

A phase difference detection circuit according to an aspect of the present invention is a phase difference detection circuit used in a state of being connected to a first antenna element and a second antenna element, and after operating in a first ranging mode. It is controlled to operate in the transmission mode, and in the first ranging mode, a frequency modulated first ranging signal is generated, and the first ranging signal is transmitted from the first antenna element. After that, a reflected wave is received from a target in the external space to generate a first reception signal, and in the transmission mode, a high frequency signal which is not frequency-modulated is generated, and the high frequency signal is transmitted from the first antenna element. The first transmission / reception circuit is controlled to operate in the reception mode after operating in the second distance measurement mode, and in the second distance measurement mode, the frequency-modulated second distance measurement signal is generated; The second measurement After transmitting a signal from the second antenna element, a reflected wave is received from the target to generate a second received signal, and in the reception mode, a reflected wave corresponding to the high frequency signal is received from the target Transmission / reception circuit that generates a third reception signal, and the round-trip propagation time of the first distance measurement signal between the first transmission / reception circuit and the target based on the first reception signal A second measurement signal indicating a first measurement value indicating a second measurement signal, and a second measurement signal indicating a round-trip propagation time of the second distance measurement signal between the second transmission / reception circuit and the target based on the second reception signal; And a phase difference calculation unit calculating a phase difference between the first distance measurement signal and the second distance measurement signal, wherein the second transmission / reception circuit Third received signal and second ranging signal Generating a beat signal indicating a frequency difference between them, and calculating the phase difference based on the first measurement value, the second measurement value, and the beat signal. Do.

According to the present invention, it is possible to detect the phase difference between ranging signals transmitted from a plurality of antenna elements with high accuracy.

FIG. 1 is a view showing a schematic configuration of a radar device 1 according to a first embodiment of the present invention. FIG. 2 is a block diagram showing an example of a signal generator in Embodiment 1. FIG. 7 schematically shows an operating state of the array antenna of the first embodiment. It is a graph which shows roughly the relationship between transmitting frequency Ft and receiving frequency Fr. 5 is a flowchart schematically illustrating an example of a procedure of an operation control process according to the first embodiment. 6A and 6B are graphs showing examples of signal waveforms of beat signals used for phase difference detection. It is a figure which shows schematic structure of the radar apparatus of Embodiment 2 which concerns on this invention. FIG. 13 is a flowchart schematically showing an example of the procedure of control processing according to Embodiment 2. FIG. 7 is a graph schematically showing an example of a power waveform of a beat signal according to Embodiment 2. FIG.

Hereinafter, various embodiments according to the present invention will be described in detail with reference to the drawings. Note that components given the same reference numerals throughout the drawings have the same configuration and the same function.

Embodiment 1
FIG. 1 is a view showing a schematic configuration of a radar device 1 according to a first embodiment of the present invention. As shown in FIG. 1, the radar device 1, one-dimensional or planar N pieces arranged in a (planar shape or a curved surface) of the antenna elements 61 1 _~ 61 N _(N is an integer of 2 or more) Array antenna 60, N slave modules 30 ₁ to 30 _N respectively connected to the _N antenna elements 61 ₁ to 61 _N , and a master for individually controlling the operations of these slave modules 30 ₁ to 30 _N And a module 20. Each of the slave modules 30 ₁ to 30 _N is a radar circuit that can function as a radar module.

The radar apparatus 1 of the present embodiment incorporates a phase difference detection circuit having a function of detecting a phase difference between transmission signals output from a pair of antenna elements 61 _i and 61 _j (i ≠ j). There is. Phase difference detecting circuit of this embodiment, for example, can be configured by the slave module 30 1 _~ 30 _N and the master module 20.

The master module 20 generates a reference signal RS having a preset reference frequency and supplies the reference signal RS to the slave modules 30 ₁ to 30 _N, and a reference signal generator 22 for the slave modules 30 ₁ to 30 _N. having an operation control circuit 23 for individually controlling the operation, and a data storage unit 28 for storing the measurement data obtained by the slave modules 30 1 _~ 30 _N. The reference signal generator 22 may be configured, for example, using an oscillator such as a crystal oscillator.

N signal transmission paths C ₁ to C _N are provided between the reference signal generator 22 and the slave modules 30 ₁ to 30 _N. One end of the signal transmission path C ₁ to C _N is connected to the signal output end of the reference signal generator 22, and the other end of the signal transmission path C ₁ to C _N is a slave module 30 ₁ to Each is connected to a 30 _N signal input terminal. The reference signal generator 22 is a signal source for supplying a reference signal RS to the slave modules 30 ₁ to 30 _N through the signal transmission paths C ₁ to C _N. The signal transmission paths C ₁ to C _N can be configured by transmission cables such as coaxial cables, for example.

The wiring length of the signal transmission lines C _{1 ~} C _N is not necessarily equal length, not necessarily the electrical length of the signal transmission line C _{1 ~} C _N is also equal in length.

The operation control circuit 23 has a function of determining the operation sequence of the slave modules ₃₀ 1 ~ 30 _N, and a function of specifying each operating mode of the slave modules ₃₀ 1 ~ _{30 N.} The hardware configuration of the operation control circuit 23 may be realized by, for example, a processor having a semiconductor integrated circuit such as a digital signal processor (DSP), an application specific integrated circuit (ASIC), or a field-programmable gate array (FPGA). Alternatively, the hardware configuration of the operation control circuit 23 is realized by a processor including an arithmetic device such as a central processing unit (CPU) or a graphics processing unit (GPU) that executes the program code of software or firmware read from the memory. It may be done. The hardware configuration of the operation control circuit 23 can also be realized by a processor having a combination of the semiconductor integrated circuit and the arithmetic device. Furthermore, the hardware configuration of the operation control circuit 23 may be realized by a plurality of processors operating in cooperation with one another.

Between the master module 20 and the slave modules 30 1 _~ 30 _N, the signal line group for transmitting (not shown) is provided to control and data signals. The operation control circuit 23 is capable of supplying an operation command to each of the slave modules 30 1 _~ 30 _N via the signal line group. The operation control circuit 23, the slave measurement data from any of the modules 30 1 _~ 30 _N can be obtained through the signal line group, also the signals already stored measurement data to the data storage unit 28 It is also possible to supply the slave modules 30 ₁ to 30 _N through the line group.

The data storage unit 28 has a first storage area 28 ₁ to an N-th storage area 28 _N for storing measurement values of measurement data. The operation control circuit 23 can store the measurement values obtained from the slave modules 30 ₁ to 30 _{N in} the first storage area 28 ₁ to the Nth storage area 28 _N , respectively. The data storage unit 28 may be configured of one or more storage devices.

Next, the configuration of the slave modules ₃₀ 1 ~ _{30 N.} The slave modules 30 ₁ to 30 _N of the present embodiment have the same circuit configuration. The n-th slave module 30 _n includes a transmission / reception circuit 40 _n and a signal processing circuit 50 _n . The transmission / reception circuit 40 _n and the signal processing circuit 50 _n operate in the operation mode specified by the operation control circuit 23. As shown in FIG. 1, the transmitting and receiving circuit 40 _n includes a signal generator 42 _n , a switch circuit 43 _n , a circulator 44 _n , a mixer 45 _n and an A / D converter (ADC) 46 _n. There is.

The signal generator 42 _n receives the reference signal RS supplied from the reference signal generator 22 via the signal transmission line C _n and, according to the modulation control signal MC _n supplied from the signal processing circuit 50 _n , a frequency modulation signal A transmission signal of either a ranging signal or an RF signal (hereinafter referred to as a "frequency non-modulated signal") which is a CW (continuous wave) signal which is not frequency-modulated can be generated. For example, the signal generator 42 _n determines a ranging signal of a chirp signal having a transmission frequency which repeats to change linearly at a fixed modulation bandwidth according to a frequency-modulated continuous-wave (FMCW) system. Can be generated as The signal generator 42 _n supplies the generated transmission signal (ranging signal or frequency unmodulated signal) to both one end of the switch circuit 43 _n and the input end of the mixer 45 _n . Further, the signal generator 42 _n has a phase adjustment function of shifting the output phase of the signal generator 42 _n by a designated phase shift amount according to the phase control signal PC _n supplied from the signal processing circuit 50 _n. doing.

Such a signal generator 42 _n may be configured by, for example, an integrated circuit (IC) including a PLL (Phase-Locked Loop) circuit. Specifically, it is possible to use a discrete IC which incorporates a fractional PLL circuit.

FIG. 2 is a block diagram showing an example of a signal generator 42 _n incorporating a fractional frequency division type PLL circuit. The signal generator 42 _n shown in FIG. 2 has a fractional frequency division type PLL circuit 420 and a ΔΣ (delta-sigma) modulator 428 functioning as a frequency division ratio control circuit. The PLL circuit 420 includes a phase comparator 421, a charge pump circuit 422, a loop filter 423, a voltage-controlled oscillator (VCO) 424, a directional coupler 425, a variable phase shifter 426 and a variable divider 427. It is comprised including.

The phase comparator 421 compares the phase of the input reference signal RS and the phase of the feedback signal output from the variable divider 427 with each other to obtain the difference between the phase of the reference signal RS and the phase of the feedback signal. Output as the amount of phase difference. The charge pump circuit 422 outputs a voltage or current proportional to the phase difference amount. The loop filter 423 is a circuit for smoothing the voltage signal or current signal output from the charge pump circuit 422 to stabilize the PLL operation. The VCO 424 outputs an RF signal having a transmission frequency according to the output of the loop filter 423 to the outside through the directional coupler 425. Here, the directional coupler 425 branches a part of the output from the output of the VCO 424.

The variable phase shifter 426 functions as a phase adjustment circuit that variably adjusts the output phase of the signal generator 42 _n . The variable phase shifter 426 can shift the phase of the input signal from the directional coupler 425 according to the phase control signal PC _n . The phase control unit 56 _n shown in FIG. 1 can control the output phase of the signal generator 42 _n by supplying the phase control signal PC _n to the signal generator 42 _n .

The variable divider 427 divides the output signal of the variable phase shifter 426 by the division number designated by the output of the ΔΣ modulator 428 to generate a divided signal, and the divided signal is used as a feedback signal. The phase comparator 421 is supplied as ΔΣ modulator 428, subjected to ΔΣ modulation to generate a division control signal to the input modulated control signal MC _n, and outputs the division control signal to the variable frequency divider 427. Here, by adopting the ΔΣ modulation, it becomes possible to form a division ratio pattern which can reduce the quantization phase noise generated by the variable frequency divider 427.

The frequency band of the transmission signal to be generated by the signal generator 42 _n may be appropriately determined according to the application of the radar device 1. For example, when the radar device 1 is designed as an FMCW radar for mounting on a car, the signal generator 42 _n may be configured to generate a transmission signal in the millimeter wave band or the quasi-millimeter wave band. In this case, as the array antenna 60, a planar antenna in which a conductor pattern is formed on a ceramic substrate can be used.

Referring to FIG. 1, the switch circuit 43 _n performs a switching operation according to the switching control signal supplied from the signal processing circuit 50 _n . That is, switch circuit 43 _n forms an on signal path between signal generator 42 _n and circulator 44 _n according to the switching control signal, or a signal path between signal generator 42 _n and circulator 44 _n Do one of the off actions to disconnect the As the switch circuit 43 _n , a switching element such as a power FET (Field-Effect T transistor) can be used.

The circulator 44 _n, to the transmission signal input to the forward direction from the output terminal of the switch circuit 43 _n, while the switch circuit 43 _n is coupled to the antenna element 61 _n, mixer 45 _n inputs of a switching circuit 43 _n Do not bond with the end. Therefore, most of the transmission signal is propagated to the antenna element 61 _n and radiated to the external space. On the other hand, with respect to the received signal input to the reverse direction from the antenna element 61 _n, the circulator 44 _n is the antenna element 61 _n to coupled to the input of the mixer 45 _n, the antenna element 61 _n switch circuits 43 _n Do not combine with Therefore, most of the received signal is propagated to the mixer 45 _n . As such a circulator 44 _n , for example, a drop-in type circulator (Drop-in Circulator) can be used.

The mixer 45 _n mixes the transmission signal input from the signal generator 42 _n with the reception signal input from the circulator 44 _n to generate an analog beat signal indicating the frequency difference between the transmission signal and the reception signal. It is a circuit to generate. The mixer 45 _n outputs the generated analog beat signal to the ADC 46 _n . For such a mixer 45 _n , for example, discrete components may be used. The ADC 46 _n converts the analog beat signal into a digital beat signal by sampling the input analog beat signal at a predetermined frequency, and the digital beat signal (hereinafter simply referred to as a “beat signal”) is converted to a signal processing circuit 50 _n. Output to

The signal processing circuit 50 _n shown in FIG. 1, a modulation control unit 52 _n for controlling the signal generator 42 _n modulation operation according to the operation command inputted from the operation control circuit 23, in accordance with the operation instruction switch A transmission control unit 53 _n that controls the switching operation of the circuit 43 _n , a phase control unit 56 _n that shifts the output phase of the signal generator 42 _n according to the operation command, and a pair of antenna elements 61 _i and 61 _n (i ≠ n) and the phase difference calculating section 54 _n for calculating a phase difference between the transmit signal outputted from, and a distance measuring unit 55 _n to measure the measurement data for the target Tgt in the external space. The measuring unit of the present embodiment can be configured by distance measuring units 55 ₁ to 55 _N.

The target Tgt may be a known reflective object prepared before shipment of the radar device 1 or may be selected at an appropriate timing (for example, periodically) after shipment of the radar device 1 in an operating environment. It may be any reflective object present. For example, a flat metal wall installed in front of the radar device 1 can be used as a target Tgt. When the radar device 1 is operated as a vehicle-mounted radar device, a stationary vehicle separated by an arbitrary distance may be used as the target Tgt.

The operation control circuit 23 individually controls the operations of the modulation control units 52 ₁ to 52 _N , the transmission control units 53 ₁ to 53 _N and the phase control units 56 ₁ to 56 _{N in} the slave modules 30 ₁ to 30 _N. The array antenna 60 can function as a phased array antenna. In this case, the transmission control units 53 ₁ to 53 _N turn on all the switch circuits 43 ₁ to 43 _N. At the same time, the modulation control units 52 ₁ to 52 _N and the phase control units 56 ₁ to 56 _N are radiated from the array antenna 60 by causing the signal generators 42 ₁ to 42 _N to output the phase-adjusted transmission signals. The propagation direction of the beam can be controlled.

FIG. 3 schematically shows an operating state of array antenna 60 functioning as a phased array antenna. As shown in FIG. 3, the array antenna 60 can form a beam propagating in a direction perpendicular to the equal phase plane of the transmission signal (transmission wave). Here, as described above, the wiring length of the signal transmission lines C _{1 ~} C _N is not necessarily equal length, not necessarily the electrical length of the signal transmission line C _{1 ~} C _N is also equal in length. For example, when the electrical length of the i-th signal transmission path C _{i and} the electrical length of the j-th signal transmission path C _j are not equal, two of the two input to the slave modules 30 _i and 30 _j , respectively. Between the reference signal RC, a phase shift occurs due to the difference in electrical length. The phase shift is multiplied by the PLL circuit in the signal generators 42 _i and 42 _j , and may cause a phase difference between the transmission signals output from the antenna elements 61 _i and 61 _j to deteriorate the beam shape. .

The radar device 1 of this embodiment generates a signal based on the phase difference detection function of detecting the phase difference between the transmission signals output from the pair of antenna elements 61 _i and 61 _j and the detected phase difference. And a phase error correction function of correcting the error of the output phase of the units 42 _i and 42 _j . As an operation mode for phase difference detection, "ranging mode", "transmission mode" and "reception mode" are incorporated.

When an operation command for specifying a distance measurement mode is input to the signal processing circuit 50 _n , the transmission control unit 53 _n outputs a switching control signal for turning on the switch circuit 43 _n . At the same time, the modulation control unit 52 _n supplies to the signal generator 42 _n a modulation control signal MC _n that generates a frequency modulated ranging signal. Further, the phase difference calculation unit 54 _n is controlled not to operate. At this time, the antenna element 61 _n radiates the transmission wave of the distance measurement signal input from the signal generator 42 _n via the switch circuit 43 _n and the circulator 44 _n toward the target Tgt.

Thereafter, the transmitting and receiving circuit 40 _n receives a reflected wave corresponding to the distance measuring signal from the target Tgt. The reflected wave is transmitted to the mixer 45 _n through the circulator 44 _n . The mixer 45 _n mixes the received signal indicating the reflected wave with the local signal (a part of the distance measuring signal) output from the signal generator 42 _n to generate an analog beat signal. The ADC 46 _n converts the analog beat signal into a digital beat signal, and supplies the beat signal to the signal processing circuit 50 _n . The distance measuring unit 55 _n performs frequency analysis such as fast Fourier transform (FFT) on the beat signal to detect the frequency of the beat signal, that is, the beat frequency f _b . Further, based on the beat frequency f _b , the distance measuring unit 55 _n can calculate the round-trip propagation time τ of the distance measurement signal between the slave module 30 _n and the target Tgt as a measurement value.

FIG. 4 is a graph schematically showing the relationship between the transmission frequency Ft of the transmission signal (FMCW signal) and the frequency Fr of the reception signal. In the example of FIG. 4, the transmission frequency Ft which repeats rising linearly with the modulation period T in the modulation bandwidth BW is shown. The received signal is observed after being delayed by a delay time τ which is a round-trip propagation time. In the case of the example of FIG. 4, the delay time τ can be calculated according to the following equation (1).

The distance measuring unit 55 _n transfers measurement data indicating the measurement value to the master module 20. The operation control circuit 23 stores the measurement data transferred from the distance measuring unit 55 _n in the n-th storage area 28 _n of the data storage unit 28.

On the other hand, when an operation command specifying a transmission mode is input to the signal processing circuit 50 _n , the transmission control unit 53 _n outputs a switching control signal to turn on the switch circuit 43 _n . At the same time, the modulation control unit 52 _n supplies a modulation control signal MC _n for generating a frequency non-modulated signal to the signal generator 42 _n . The phase difference calculating unit 54 _n and the distance measuring unit 55 _n are controlled not to operate. At this time, the antenna element 61 _n radiates the transmission wave of the frequency non-modulated signal input from the signal generator 42 _n through the switch circuit 43 _n and the circulator 44 _n toward the target Tgt.

On the other hand, when an operation command specifying the reception mode is input to the signal processing circuit 50 _n , the modulation control unit 52 _n sends the modulation control signal MC _n for generating a non-modulated local signal to the signal generator 42 _n . Supply. At the same time, the transmission control unit 53 _n disconnects the signal path between the signal generator 42 _n and the antenna element 61 _n by outputting a switching control signal to turn off the switch circuit 43 _n . Further, the distance measuring unit 55 _n is controlled not to operate.

At this time, since the other slave modules 30 _i constituting the slave modules 30 _n and pair operating in the receive mode is operating in transmit mode, corresponding to the frequency unmodulated signal transmitted from the other slave modules 30 _i reflected A wave propagates from the target Tgt to the slave module 30 _n . In the transmitting / receiving circuit 40 _n , the mixer 45 _n receives the received signal transmitted through the antenna element 61 _n and the circulator 44 _n as input, and mixes this received signal with the local signal output from the signal generator 42 _n. Generate an analog beat signal. The ADC 46 _n converts the analog beat signal into a beat signal in digital form, and supplies the beat signal to the phase difference calculating unit 54 _n .

The phase difference calculation unit 54 _n determines the position between the distance measurement signals output from the pair of antenna elements 61 _i and 61 _n based on the measurement data obtained from the data storage unit 28 and the beat signal output from the ADC 46 _n. The phase difference can be calculated. The phase control unit 56 _n controls the phase adjustment circuit (variable phase shifter) in the signal generator 42 _n to correct the error of the output phase of the signal generator 42 _n based on the calculated phase difference. Can.

The hardware configuration of the signal processing circuit 50 _n described above may be realized by, for example, a processor having a semiconductor integrated circuit such as a DSP, an ASIC, or an FPGA. Alternatively, the hardware configuration of the signal processing circuit 50 _n may be realized by a processor including an arithmetic device such as a CPU or a GPU that executes program code of software or firmware read from a memory. It is also possible to realize the hardware configuration of the signal processing circuit 50 _n by a processor having a combination of the semiconductor integrated circuit and the arithmetic device. Furthermore, the hardware configuration of the signal processing circuit 50 _n may be realized by a plurality of processors.

The details of phase difference detection and phase error correction in the radar device 1 will be described below with reference to FIG. FIG. 5 is a flowchart schematically showing an example of the procedure of the operation control process according to the first embodiment. The operation control process shown in FIG. 5 is executed by the operation control circuit 23.

First, the operation control circuit 23 selects one set of slave modules 30 _i and 30 _j from the combinations of slave modules 30 ₁ to 30 _N (step ST 10). Hereinafter, one of the slave modules 30 _i is referred to as a first slave module 30 _i, and that the other slave module 30 _j is referred to as a second slave module 30 _j.

Next, the operation control circuit 23, by supplying an operation command that specifies the distance measurement mode in the first slave module 30 _i, the first slave module 30 _i ranging mode (first distance measurement mode) To operate (step ST11). At this time, the first slave module 30 _i, the distance measuring unit 55 _i is a delay time corresponding to the distance between the target Tgt (RTT) and tau ₁ is calculated as the measurement value, the measurement data indicating the measured value Are transferred to the master module 20. The operation control circuit 23 stores the measurement data transferred from the distance measuring unit 55i in the _i- th storage area _i (step ST12).

Next, the operation control circuit 23 supplies an operation command for designating the distance measurement mode to the second slave module 30 _j , whereby the distance measurement mode (second distance measurement mode) of the second slave module 30 _j is obtained. To operate (step ST13). At this time, in the second slave module 30 _j , the distance measuring unit 55 _j calculates a delay time (round-trip propagation time) τ ₂ corresponding to the distance from the target Tgt as a measurement value, and measurement data indicating the measurement value Are transferred to the master module 20. The operation control circuit 23 stores the measurement data transferred from the distance measuring unit 55 _j to the j memory area 28 _j (step ST14).

Thereafter, the operation control circuit 23, by supplying an operation command that specifies the transmission mode is supplied to the first slave module 30 _i, and an operation command that specifies the receive mode to the second slave module 30 _j, the 1 of the slave module 30 _i is operating in transmission mode and to operate the second slave module 30 _j in the receive mode (step ST15).

　ここで、Ａ_０は信号振幅、ｔは時間、φ_１は位相状態値である。 At this time, the first slave module 30 _i which operate in transmission mode, operates as a transmission circuit corresponding to the second slave module 30 _j. First slave module 30 _i transmits the transmission signal _{S TX1} frequency unmodulated having transmitting frequencies _{f cw1} be transmitted to the target Tgt. The transmission signal S _TX1 propagates to the second slave module 30 _j after being reflected at the target Tgt. Transmission signal S _TX1 is represented, for example, by the following equation (2).

Where A ₀ is the signal amplitude, t is time, and φ ₁ is the phase state value.

　ここで、Ｂ_０は信号振幅、φ_２は位相状態値である。 On the other hand, the second slave module 30 _j operating in the reception mode operates as a reception circuit corresponding to the first slave module 30 _i . In the transmission / reception circuit 40 _j , the mixer 45 _j receives the reception signal S _RX2 transmitted via the antenna element 61 _j and the circulator 44 _j , and the reception signal S _RX2 and the frequency output from the signal generator 42 _j The unmodulated local signal S _LO (frequency: f _cw2 ) is mixed to generate an analog beat signal. The ADC 46 _j converts the analog beat signal into a beat signal S _{bcw 2} in digital form, and supplies the beat signal S _{bcw 2} to the phase difference calculation unit 54 _j . Local signal S _LO is expressed, for example, by the following equation (3).

Here, B ₀ is a signal amplitude, and φ ₂ is a phase state value.

　ここで、Ａ_１は信号振幅である。 Further, the reception signal S _RX2 is represented by, for example, the following equation (4).

Here, A ₁ is a signal amplitude.

Beat signal S _bcw2 is represented by following Formula (5), for example.

Further, the phase difference calculation unit 54 _j obtains step ST11, ST13 measurements tau ₁ calculated in the tau ₂ from the data storage unit 28, the measurement value tau _1, based on the tau ₂ and the beat signal _{S Bcw2,} The phase difference Δφ (= φ ₂ −φ ₁ ) between the distance measurement signals output from the antenna elements 61 _i and 61 _j is calculated.

Here, the above equation (5) can be transformed into the following equation (6).

When the frequency _{f cw2} transmission frequency _{f cw1} and the local signal _{S LO} do not match, the beat signal _{S Bcw2} shows AC voltage waveform as illustrated in Figure 6A. For example, phase difference calculation unit 54 _j detects the maximum value and the minimum value of the voltage waveform of beat signal S _{bcw 2} , and the difference between the maximum value and the minimum value (peak-to-peak voltage) _determines the signal amplitude A of beat signal S _{bcw 2. 1} B ₀ can be calculated. Also, the phase difference calculation unit 54 _j can detect the DC component D _bcw2 of the beat signal S _bcw2 . The direct current component D _bcw2 shows a direct current voltage waveform as illustrated in FIG. 6B.

　ここで、α＝Ａ_１×Ｂ_０である。 The equation representing the DC component D _bcw2 can be derived by _setting f _cw1 = f _cw2 in the above equation (5). Therefore, phase difference Δφ with respect to direct-current component D _bcw2 is represented by, for example, the following equation (7).

Here, α = A ₁ × B ₀ .

The phase difference calculating unit 54 _j can calculate the phase difference Δφ based on the equation (7).

After execution of step ST15, the operation control circuit 23 controls the phase controller 56 _j, and the output phase of the first slave module 30 _i signal generator 42 _i in the second slave module 30 _j The error between the signal generator 42 _{j and} the output phase of the signal generator 42 _j is corrected (step ST16). Specifically, the phase control unit 56 _j controls the phase adjustment circuit (variable phase shifter) in the signal generator 42 _j based on the calculated phase difference Δφ to obtain the signal generator 42 _i . An error in the output phase of the signal generator 42 _j with respect to the output phase can be corrected.

Thereafter, the operation control circuit 23 determines whether all pairs among the slave modules ₃₀ 1 ~ 30 _N is selected (step ST17). If all sets have not been selected (NO in step ST17), the operation control circuit 23 selects a new set (step ST10), and executes steps ST11 to ST16 for the new set. On the other hand, if all sets have been selected (YES in step ST17), the operation control circuit 23 ends the operation control process.

As a method of selecting a set of slave modules in step ST10, for example, a second slave module 30 ₂ which makes a pair with the _first slave module 301 with reference to the first slave module 30 ₁ (i = 1). , ..., 30 _N may be selected in order. When a set of slave modules is represented by (30 _i , 30 _j ), select the set in the order of (30 ₁ , 30 ₂ ), (30 ₁ , 30 ₃ ), ..., (30 ₁ , 30 _N ) Is possible.

As described above, according to the first embodiment, the first and second slave modules 30 _i and 30 _j operate in the ranging mode to obtain the first and second measured values τ ₁ and τ Measure ₂ respectively. Then, at the same time when the first slave module 30 _i is operating in transmission mode, the second slave module 30 _j generates a beat signal S _Bcw2 operating in receive mode. Then, the phase difference calculation unit 54 _j in the second slave module 30 _j determines between the distance measurement signals output from the antenna elements 61 _i and 61 _j based on the measurement values τ ₁ and τ ₂ and the beat signal S _{bcw 2.} Phase difference .DELTA..phi. Therefore, although the radar apparatus 1 according to the present embodiment includes the plurality of signal generators 42 ₁ to 42 _N for the plurality of antenna elements 61 ₁ to 61 _N , these antenna elements 61 ₁ to 61 _N It is possible to calculate the phase difference between the distance measurement signals output from the high accuracy. Even if the slave modules 30 ₁ to 30 _N are arranged in a distributed manner, it is possible to calculate the phase difference between ranging signals with high accuracy. Therefore, the phase difference detection circuit according to the present embodiment can synchronize the output phases of the signal generators 42 ₁ to 42 _{N in} the slave modules 30 ₁ to 30 _N with high accuracy.

The above-described phase difference detection and phase error correction may be performed before shipment of the radar device 1, or may be performed periodically according to a preset schedule or at a designated timing. Good.

Second Embodiment
Next, Embodiment 2 according to the present invention will be described. As described above, according to the first embodiment, two slave modules 30 _i and 30 _j detect the phase difference between the ranging signals output from the antenna elements 61 _i and 61 _j . On the other hand, in the second embodiment, three slave modules cooperate to detect a phase difference.

FIG. 7 is a view showing a schematic configuration of a radar device 2 according to a second embodiment of the present invention. As shown in FIG. 7, the radar device 2 includes an array antenna 60 including _N antenna elements 61 ₁ to 61 _N (N is an integer of 3 or more), and the N antenna elements 61 ₁ to 61 _N. is configured by including a N number of slave modules ₃₁ 1 ~ 31 _N connected respectively, a master module 21 for individually controlling the operation of the slave modules ₃₁ 1 ~ 31 _N to. Each of the slave modules 31 ₁ to 31 _N is a radar circuit that can function as a radar module.

The radar apparatus 2 according to the present embodiment detects a phase difference between transmission signals output from a pair of antenna elements 61 _i and 61 _j (i and j are integers in the range of 1 to N−1). Phase difference detection circuit having the function of The phase difference detection circuit of the present embodiment can be configured by, for example, slave modules 31 ₁ to 31 _N and master module 21.

The master module 21 individually operates the reference signal generator 22 for supplying the reference signal RS to the slave modules 31 ₁ to 31 _N through the signal transmission paths C ₁ to C _N , and the slave modules 31 ₁ to 31 _N. It has the control circuit 24 to control, and the data storage part 28 which stores the measurement data obtained by the slave modules 31 ₁ to 31 _N.

The control circuit 24 is configured to include an operation control unit 25, a phase difference calculation unit 26, and a phase control unit 27. The hardware configuration of the control circuit 24 may be realized by, for example, a processor having a semiconductor integrated circuit such as a DSP, an ASIC, or an FPGA. Alternatively, the hardware configuration of the control circuit 24 may be realized by a processor including an arithmetic device such as a CPU or a GPU that executes program code of software or firmware read from a memory. It is also possible to realize the hardware configuration of the control circuit 24 with a processor having a combination of the semiconductor integrated circuit and the arithmetic device. Furthermore, the hardware configuration of the control circuit 24 may be realized by a plurality of processors operating in cooperation with one another.

Between the master module 21 and slave module 31 1 _~ 31 _N, the signal line group for transmitting (not shown) is provided to control and data signals. The control circuit 24 can supply an operation command to each of the slave modules 31 ₁ to 31 _N through the signal line group.

The operation control unit 25 can obtain measurement data from any of the slave modules 31 ₁ to 31 _N via the signal line group, and can store the measurement data in the data storage unit 28. Further, the operation control unit 25 has a function of determining the operation order of the slave modules 31 ₁ to 31 _N-1 and a function of designating an operation mode of each of the slave modules 31 ₁ to 31 _N.

The phase difference calculating unit 26 sets one of the antenna elements 61 _i and 61 _j (i, j is based on the phase shift amount supplied from the _Nth slave module 31 _N and the measurement data obtained from the data storage unit 28). , And an integer in the range of 1 to N−1) to calculate the phase difference between the transmission signals output. The method of detecting the amount of phase shift will be described later. The phase control unit 27 controls the signal generators 42 _i and 42 _j in the slave modules 31 _i and 31 _j based on the phase difference calculated by the phase difference calculation unit 26 to control these signal generators 42 _i and 42 _j. It is possible to correct the error of the output phase of

Next, the configuration of the slave modules 31 ₁ to 31 _N will be described. In the present embodiment, the slave modules 31 ₁ to 31 _N-1 have the same circuit configuration. On the other hand, the Nth slave module 31 _N has a circuit configuration different from that of the slave modules 31 ₁ to 31 _N−1 .

The m-th (m is an integer in the range of 1 to N-1 other than N) slave modules 31 _m other than the N-th slave module 31 _N include a transmission / reception circuit 41 _m and a signal processing circuit 51 _m . These receiving circuit 41 _m and the signal processing circuit 51 _m operates in the operation mode designated by the operation control unit 25 ( "distance measurement mode", "normal transmission mode" or "phase sweep transmission mode").

As shown in FIG. 7, the transmitting and receiving circuit 41 _m is configured to include a signal generator 42 _m , a circulator 44 _m , a mixer 45 _m and an ADC 46 _m . The configurations of the signal generator 42 _m , circulator 44 _m , mixer 45 _m and ADC 46 _m are the same as the configurations of the signal generator 42 _n , circulator 44 _n , mixer 45 _n and ADC 46 _{n in} the first embodiment (FIG. 1). is there. Further, the signal processing circuit 51 _m includes a modulation control unit 52 _m and a distance measuring unit 55 _m . Configuration of modulation control unit 52 _m and the distance measuring unit 55 _m is the same as that of the modulation control unit 52 _n and the distance measuring unit 55 _n (Fig. 1) in the first embodiment. The measurement unit of the present embodiment can be configured by distance measurement units 55 ₁ to 55 _N−1 .

On the other hand, N-th slave module 31 _N includes a transceiver circuit 41 _N and the signal processing circuit 51 _N. These receiving circuit 41 _N and the signal processing circuit 51 _N operates in the operation mode designated by the operation control unit 25 ( "distance measurement mode" or "receive mode"). The transmission / reception circuit 41 _N of FIG. 7 has the same configuration as the transmission / reception circuit 40 _N (FIG. 1) of the first embodiment. The configuration of the signal processing circuit 51 _N in FIG. 7, except that it has a phase shift amount detector 58 _N in place of the phase difference calculation section 54 _N of Figure 1, the signal processing circuit of the first embodiment 50 _N It is the same as

The hardware configuration of the signal processing circuit 51 _n (where n is an integer in the range of 1 to N) may be realized by a processor having a semiconductor integrated circuit such as a DSP, an ASIC or an FPGA. Alternatively, the hardware configuration of the signal processing circuit 51 _n may be realized by a processor including an arithmetic device such as a CPU or a GPU that executes a program code of software or firmware read from a memory. It is also possible to realize the hardware configuration of the signal processing circuit 51 _n by a processor having a combination of the semiconductor integrated circuit and the arithmetic device. Furthermore, the hardware configuration of the signal processing circuit 51 _n may be realized by a plurality of processors.

Operation control unit 25 and phase control unit 27 individually control the operations of modulation control units 52 ₁ to 52 _N-1 and signal generators 42 ₁ to 42 _N-1 in slave modules 31 ₁ to 31 _N−1 . Thus, the array antenna 60 can function as a phased array antenna. As with the first embodiment, the wiring length of the signal transmission lines C _{1 ~} C _N-1 is not necessarily the same length, the electrical length of the signal transmission lines C _{1 ~} C _N-1 in isometry It does not have to be. For example, when the electrical length of the i-th signal transmission path C _{i and} the electrical length of the j-th signal transmission path C _j are not equal, two of the two input to the slave modules 31 _i and 31 _j , respectively. Between the reference signal RC, a phase shift occurs due to the difference in electrical length. The phase shift is multiplied by the PLL circuit in the signal generators 42 _i and 42 _j , and may cause a phase difference between the transmission signals output from the antenna elements 61 _i and 61 _j to deteriorate the beam shape. .

The radar device 2 of this embodiment generates a signal based on a phase difference detection function of detecting a phase difference between transmission signals output from a pair of antenna elements 61 _i and 61 _j , and the detected phase difference. And a phase error correction function of correcting the error of the output phase of the units 42 _i and 42 _j . As an operation mode for phase difference detection, a “ranging mode”, a “normal transmission mode”, a “phase sweep transmission mode” and a “reception mode” are incorporated.

When an operation command for specifying a distance measurement mode is input to the signal processing circuit 51 _n (n is an integer in the range of 1 to N) for any of the slave modules 31 ₁ to 31 _N , the modulation control unit 52 _n A modulation control signal MC _n for generating a frequency modulated ranging signal is supplied to a signal generator 42 _n . Here, the N-th slave module 31 _N, the transmission controller 53 _N, and outputs a switching control signal to turn on the operation switch circuit 43 _N. The antenna element 61 _N radiates the transmission wave of the ranging signal input from the signal generator 42 _N via the circulator 44 _N toward the target Tgt.

Thereafter, the transmission / reception circuit 41 _n receives a reflected wave corresponding to the distance measurement signal from the target Tgt. The reflected wave is transmitted to the mixer 45 _n through the circulator 44 _n . The mixer 45 _n mixes the received signal indicating the reflected wave with the local signal output from the signal generator 42 _n to generate an analog beat signal. The ADC 46 _n converts the analog beat signal into a beat signal in digital format, and supplies the beat signal to the distance measuring unit 55 _n of the signal processing circuit 51 _n .

The distance measuring unit 55 _n performs frequency analysis such as fast Fourier transform (FFT) on the beat signal to detect the frequency of the beat signal, that is, the beat frequency f _b . Further, based on the beat frequency f _b , the distance measuring unit 55 _n can calculate the round-trip propagation time τ of the distance measurement signal between the slave module 31 _n and the target Tgt as a measurement value. Then, the distance measuring unit 55 _n transfers measurement data indicating the measurement value to the master module 21. The operation control unit 25 stores the measurement data transferred from the distance measuring unit 55 _n in the n-th storage area 28 _n of the data storage unit 28.

On the other hand, for any of the slave modules 31 ₁ to 31 _N−1 , an operation command specifying the phase sweep transmission mode which is the first transmission mode is the signal processing circuit 51 _m (m is in the range of 1 to N−1. Modulation control section 52 _m sweeps the phase of the frequency unmodulated signal within a predetermined range (for example, within the range of 0 ° to 360 °) while generating the frequency unmodulated signal. The modulation control signal MC _m to be generated (ie, changed with time) is supplied to the signal generator 42 _m . The distance measuring unit 55 _m is controlled not to operate. At this time, the antenna element 61 _m radiates the transmission wave of the frequency unmodulated signal input from the signal generator 42 _m via the circulator 44 _n toward the target Tgt.

On the other hand, for any of the slave modules 31 ₁ to 31 _N−1 , an operation instruction for designating the normal transmission mode which is the second transmission mode is the signal processing circuit 51 _m (m is in the range of 1 to N−1. when entered in an integer), the modulation controller 52 _m supplies a modulated control signal MC _m to produce a frequency unmodulated signal to the signal generator 42 _m. The distance measuring unit 55 _m is controlled not to operate. At this time, the antenna element 61 _m radiates the transmission wave of the frequency unmodulated signal input from the signal generator 42 _m via the circulator 44 _n toward the target Tgt.

When an operation command specifying the reception mode is input to the signal processing circuit 51 _N for the _Nth slave module 31 _N , the modulation control unit 52 _N generates a modulation control signal MC _N that generates a non-modulated local signal. and supplies the signal generator 42 _N. At the same time, the transmission control unit 53 _N by outputting a switching control signal to turn off the operation switch circuit 43 _N, to disconnect the signal path between the signal generator 42 _N and the antenna element 61 _N. The distance measuring unit 55 _N is controlled not to operate.

At this time, the slave module 31 _N and the corresponding two slave modules 31 _i, 31 _j operating in the receive mode is respectively operating in phase sweep transmit mode and the normal transmission mode. Therefore, from one of the slave modules 31 _i, the reflected wave having a phase corresponding to the swept frequency unmodulated signal (hereinafter referred to as "phase sweep signal".) Propagates from the target Tgt the slave module 31 _N, at the same time, from the other slave module 31 _j, the reflected wave corresponding to the frequency unmodulated signal whose phase is not swept propagates from the target Tgt the slave module 31 _N. Therefore, the reflected waves of two waves that arrive from the two slave modules 31 _i , 31 _j via the target Tgt are superimposed on each other by the antenna element 61 _N. The mixer 45 _N of the transmitting and receiving circuit 41 _N inputs the received signal transmitted via the antenna elements 61 _N and the circulator 44 _N, by mixing the local signal output from the reception signal and the signal generator 42 _N and Generate an analog beat signal. Then, the ADC 46 _N converts the analog beat signal into a beat signal in digital format, and outputs the beat signal to the phase shift amount detection unit 58 _N.

Phase shift amount detector 58 _N can detect a phase shift amount phi _cnt0 phase sweep signal to maximize the signal amplitude of the input beat signal. The slave module 31 _i which operate in phase sweep transmit mode, the signal generator 42 _i, since changing the phase of the transmission signal at a predetermined sweep rate, the target Tgt from two slave modules 31 _i, 31 _j through to interfere interference condition reflected wave together two waves arriving to the slave module 31 _N varies according to the time variation in the amount of phase shift in the signal generator 42 _i. Thereby, the signal amplitude of the beat signal also changes with time. For example, the phase shift amount detector 58 _N may be a power of the input beat signal measures the time t ₀ to maximize, to obtain the phase shift amount phi _cnt0 corresponding to the measurement time t _0. Phase shift amount detector 58 _N transfers the data indicative of the detected phase shift amount phi _cnt0 the master module 20.

The phase difference calculation unit 26 measures the output from the antenna elements 61 _i and 61 _j based on the phase shift amount φ _cnt0 transferred from the phase shift amount detection unit 58 _N and the measurement data obtained from the data storage unit 28. The phase difference between distance signals can be calculated. The phase control unit 27 controls at least one of the signal generators 42 _i and 42 _{j in} the slave modules 31 _i and 31 _j based on the calculated phase difference to output the outputs of these signal generators 42 _i and 42 _j . Errors between the phases can be corrected.

Hereinafter, the details of phase difference detection and phase error correction in the radar device 2 will be described with reference to FIG. FIG. 8 is a flowchart schematically showing an example of the procedure of control processing according to the second embodiment. The control process shown in FIG. 8 is performed by the control circuit 24.

First, the operation control unit 25 selects one set of slave modules 31 _i and 31 _j from the combinations of slave modules 31 ₁ to 31 _N-1 (step ST20). Hereinafter, one of the slave modules 31 _i is referred to as a first slave module 31 _i, the other slave module 31 _j is called the second slave module 31 _j, referred to as slave modules 31 _N and the third slave module 31 _N To be.

Next, the operation control unit 25 supplies an operation command specifying the distance measurement mode to the first slave module _31i , thereby setting the first slave module _31i in the distance measurement mode (first distance measurement mode). To operate (step ST21). At this time, the first slave module 31 _i, the distance measuring unit 55 _i is a delay time corresponding to the distance between the target Tgt (RTT) and tau ₁ is calculated as the measurement value, the measurement data indicating the measured value Are transferred to the master module 21. The operation control unit 25 stores the measurement data transferred from the distance measuring unit 55i in the _i- th storage area _i (step ST22).

Next, the operation control unit 25 supplies an operation command for specifying a distance measurement mode to the second slave module 31 _j , whereby the distance measurement mode (second distance measurement mode) of the second slave module 31 _j is performed. To operate (step ST23). At this time, in the second slave module 31 _j , the distance measuring unit 55 _j calculates a delay time (round-trip propagation time) τ ₂ corresponding to the distance to the target Tgt as a measurement value, and measurement data indicating the measurement value Are transferred to the master module 21. The operation control unit 25 stores the measurement data transferred from the distance measuring unit 55 _j in the j-th storage area 28 _j (step ST 24).

Thereafter, the operation control unit 25 supplies an operation instruction specifying the phase sweep transmission mode to the first slave module _31i , supplies an operation instruction specifying the normal transmission mode to the second slave module _31j , and , by supplying an operation command that specifies the receive mode to the third slave module 31 _N, the first slave module 31 _i is operated in the phase sweep transmit mode, the second slave module 31 _j in the normal transmission mode The third slave module 31 _N is operated in the reception mode (step ST 25).

　ここで、Ａ_０は信号振幅、ｔは時間、φ_１は位相状態値の初期値、φ_ｃｎｔは所定の掃引速度で変化させられる移相量である。 At this time, the first slave module 31 _i which operate in phase sweep transmit mode, operates as a transmission circuit corresponding to the third slave module 31 _N. First slave module 31 _i has a phase sweep signal _{S TX1} frequency unmodulated having a predetermined transmission frequency _{f cw} transmitted toward the target Tgt. The phase sweep signal S _TX1 propagates to the third slave module 31 _N after being reflected by the target Tgt. Phase sweep signal S _TX1 is represented, for example, by the following equation (8).

Here, A ₀ is a signal amplitude, t is time, φ ₁ is an initial value of the phase state value, and φ _cnt is a phase shift amount to be changed at a predetermined sweep speed.

　ここで、Ｂ_０は信号振幅、φ_２は位相状態値である。 Second slave module 31 _j which operates in the normal transmission mode, operates as a transmission circuit corresponding to the third slave module 31 _N. The second slave module 31 _j transmits the frequency non-modulated transmission signal S _TX2 having the predetermined transmission frequency f _cw toward the target Tgt. The transmission signal S _TX2 propagates to the third slave module 31 _N after being reflected by the target Tgt. Transmission signal S _TX2 is expressed, for example, by the following equation (9).

Here, B ₀ is a signal amplitude, and φ ₂ is a phase state value.

　ここで、Ｃ_０は信号振幅である。 On the other hand, the third slave module 31 _N operating in the receive mode, operates as a receiving circuit corresponding to the first and second slave module ₃₁ i, 31 _j. In the transmission / reception circuit 41 _N , the mixer 45 _N receives the reception signal S _RX3 transmitted through the antenna element 61 _N and the circulator 44 _N , and the reception signal S _RX3 and the frequency output from the signal generator 42 _N The unmodulated local signal S _LO (frequency: f _LO ) is mixed to generate an analog beat signal. The ADC 46 _N converts the analog beat signal into a beat signal S _{bcw 3} in digital form, and supplies the beat signal S _{bcw 3} to the phase shift amount detection unit 58 _N. Local signal S _LO is expressed, for example, by the following equation (10).

Here, C ₀ is the signal amplitude.

　ここで、Ａ_１，Ｂ_１は信号振幅である。 Further, received signal S _RX3 is expressed, for example, by the following equation (11).

Here, A ₁ and B ₁ are signal amplitudes.

Beat signal S _bcw3 is represented, for example, by the following equation (12).

Furthermore, the phase shift amount detector 58 _N detects the phase shift amount φ _cnt = φ _cnt0 phase sweep signal _{S TX1} to maximize signal amplitude of the beat signal _{S Bcw3} input. As described above, the two reflected waves arriving from the first and second slave modules 31 _i and 31 _j via the target Tgt to the third slave module 31 _N interfere with each other, and the interference state is a signal It changes according to the time change of the phase shift amount φ _cnt in the generator 42 _i . Phase shift amount detector 58 _N monitors the power waveform of the beat signal S _Bcw3 input may be detected amount of phase shift phi _cnt0 corresponding to the maximum value of the power waveform. FIG. 9 is a graph schematically showing an example (cosine curve) of the power waveform of the beat signal S _bcw3 .

Referring to the above equation (12), the condition for maximizing the signal amplitude of the beat signal S _bcw3 is the phase condition of the first term on the right side of equation (12) and the phase condition of the second term on the right side of equation (12) Are in agreement with each other. Therefore, the condition for maximizing the signal amplitude of the beat signal S _bcw3 is expressed by the following equation (13).

If equation (13) is modified, the following equation (14) is derived.

After execution of step ST25, the phase difference calculating section 26, the step ST21, ST23 measurements tau ₁ calculated in acquires tau ₂ from the data storage unit 28, the measurement value tau _1, tau ₂ and phase shift amount φ Based on _cnt0 , the phase difference Δφ (= φ ₁ −φ ₂ ) between the distance measurement signals output from the antenna elements 61 _i and 61 _j is calculated (step ST 26). The phase difference calculating unit 26 can calculate the phase difference Δφ based on the equation (14).

After execution of step ST26, the phase control unit 27 controls at least one of the signal generators 42 _i and 42 _j in the first and second slave modules 31 _i and 31 _j based on the calculated phase difference Δφ. Then, the error between the output phases of the signal generators 42 _i and 42 _j is corrected (step ST27). Specifically, the phase control unit 27 corrects the error by controlling the phase adjustment circuit (variable phase shifter) in the signal generators 42 _i and 42 _j based on the calculated phase difference Δφ. Can.

After that, the operation control unit 25 determines whether or not all pairs are selected from the slave modules 31 ₁ to 31 _N-1 (step ST 28). If all sets have not been selected (NO in step ST28), operation control unit 25 selects a new set (step ST20), and executes steps ST21 to ST27 for this new set. On the other hand, if all sets have been selected (YES in step ST28), the operation control unit 25 ends the control process.

As a method of selecting a set of slave modules in step ST20, for example, a second slave module 30 ₂ paired with the _first slave module 301 with reference to the first slave module 30 ₁ (i = 1). ,..., 30 _N-1 may be selected in order. When a set of slave modules is represented by (30 _i , 30 _j ), select the set in the order of (30 ₁ , 30 ₂ ), (30 ₁ , 30 ₃ ), ..., (30 ₁ , 30 _N-1 ) It is possible. In this case, the phase controller 27 controls the second slave module 31 signal generator 42 _j in _j, for the output phase of the signal generator 42 _i, the error of the output phase of the signal generator 42 _j correction (Step ST27).

As described above, according to the second embodiment, the first and second slave modules 31 _i , 31 _j operate in the distance measurement mode to obtain the first and second measured values τ ₁ , τ Measure ₂ respectively. Then, the first slave module 31 _i is at the same time operate at a phase sweep transmit mode, the second slave module 31 _j operates in the normal transmission mode. Third slave module 31 _N is operating in the receive mode, to detect a phase shift amount phi _cnt0 to maximize signal amplitude of the beat signal _{S bcw3.} Then, the phase difference calculation unit 26 calculates the phase difference Δφ between the ranging signals output from the antenna elements 61 _i and 61 _j based on the measured values τ ₁ and τ ₂ and the phase shift amount φ _cnt0. it can. Therefore, although the radar apparatus 2 according to the present embodiment includes the plurality of signal generators 42 ₁ to 42 _N-1 for the plurality of antenna elements 61 ₁ to 61 _N-1 , these antenna elements 61 The phase difference between the ranging signals output from ₁ to 61 _N-1 can be calculated with high accuracy. Even if the slave modules 31 ₁ to 31 _N-1 are distributed, high-precision calculation of the phase difference is possible. Therefore, the phase difference detection circuit of the present embodiment can synchronize the output phases of the signal generators 42 ₁ to 42 _{N-1 in} the slave modules 31 ₁ to 31 _N-1 with high accuracy.

As mentioned above, although various embodiments according to the present invention have been described with reference to the drawings, these embodiments are merely examples of the present invention, and various embodiments other than these embodiments can be adopted. For example, although the phase difference detection circuit of the first and second embodiments is applied to radar technology, it is not limited to this. The phase difference detection circuit of Embodiments 1 and 2 may be applied to a wireless communication system.

Within the scope of the present invention, free combinations of Embodiments 1 and 2 described above, deformation of any component of each embodiment, or omission of any component of each embodiment are possible.

The phase difference detection circuit according to the present invention can be applied to, for example, a radar system or a wireless communication system mounted on a mobile object such as a vehicle (for example, a car or a railway vehicle).

Tgt target, 1 and 2 radar devices, 20 master modules, 21 master modules, 22 reference signal generators, 23 operation control circuits, 24 control circuits, 25 operation control units, 26 phase difference calculation units, 27 phase control units, 28 data Memory unit, 30 ₁ to 30 _N , 31 ₁ to 31 _N slave module, 40 ₁ to 40 _N , 41 ₁ to 41 _N transceiver circuit, 42 ₁ to 42 _N signal generator, 420 PLL circuit, 421 phase comparator, 422 Charge pump circuit 423 loop filter 424 voltage controlled oscillator (VCO) 425 directional coupler 426 variable phase shifter 427 variable frequency divider 428 Δ 変 調 modulator 43 ₁ to 43 _N switch circuit 44 ₁ to 44 _{N circulator,} 45 1 ~ 45 _{N mixers, 46 1 ~ 46 N A /} D converter (ADC), 50 ₁ 50 _{N, 51} 1 ~ _{51 N} signal processing _circuits, 52 1 ~ 52 _N modulation control _unit, 53 1 ~ 53 _N transmission control _unit, 54 1 ~ 54 _N phase difference calculating _section, 55 1 ~ 55 _N distance measuring unit, 56 ₁ to 56 _N phase control unit, 58 _N phase shift amount detection unit, 60 array antennas, 61 ₁ to 61 _N antenna elements.

Claims (16)

A phase difference detection circuit used in connection with a first antenna element and a second antenna element, comprising:
After operating in the first ranging mode, it is controlled to operate in the transmission mode, and in the first ranging mode, a frequency-modulated first ranging signal is generated, and the first ranging signal is generated. Is transmitted from the first antenna element to receive a reflected wave from a target in the external space to generate a first reception signal, and in the transmission mode, generate a high frequency signal which is not frequency-modulated, and the high frequency signal A first transmission / reception circuit for transmitting the signal from the first antenna element;
After being operated in the second ranging mode, it is controlled to operate in the receiving mode, and in the second ranging mode, a frequency-modulated second ranging signal is generated, and the second ranging signal is generated. Is transmitted from the second antenna element to receive a reflected wave from the target to generate a second reception signal, and in the reception mode, a reflected wave corresponding to the high frequency signal is received from the target A second transmission / reception circuit that generates a third reception signal;
A first measurement value indicating a round-trip propagation time of the first distance measurement signal between the first transmission / reception circuit and the target is calculated based on the first received signal, and the second measured value is calculated. A measurement unit that calculates a second measurement value indicating a round-trip propagation time of the second distance measurement signal between the second transmission / reception circuit and the target based on the reception signal;
A phase difference calculation unit that calculates a phase difference between the first distance measurement signal and the second distance measurement signal;
The second transmission / reception circuit generates a beat signal indicating a frequency difference between the third reception signal and the second ranging signal.
The phase difference detection circuit, wherein the phase difference calculation unit calculates the phase difference based on the first measurement value, the second measurement value, and the beat signal. The phase difference detection circuit according to claim 1, wherein
It further comprises a phase control unit,
The first transmission / reception circuit includes a first signal generator that outputs the first ranging signal.
The second transmission / reception circuit includes a second signal generator that outputs the second ranging signal, and a phase adjustment circuit that variably adjusts the output phase of the second signal generator.
The phase control unit controls the phase adjustment circuit based on the phase difference calculated by the phase difference calculation unit to correct an error in the output phase of the second signal generator. Detection circuit. The phase difference detection circuit according to claim 2, wherein the phase adjustment circuit comprises a variable phase shifter. The phase difference detection circuit according to claim 1, wherein
The first transmission / reception circuit includes a first signal generator connected to a reference signal generator via a first signal transmission line.
The second transmission / reception circuit includes a second signal generator connected to the reference signal generator via a second signal transmission line.
The first signal generator and the second signal generator respectively generate the first ranging signal and the second ranging signal based on the reference signal supplied from the reference signal generator. A phase difference detection circuit characterized by The phase difference detection circuit according to claim 1 or 2, wherein the phase difference calculation unit detects a direct current component of the beat signal and an amplitude of the beat signal, and detects the detected direct current component. A phase difference detection circuit that calculates the phase difference based on the amplitude, the first measurement value, and the second measurement value. The phase difference detection circuit according to claim 5, wherein the direct current component of the beat signal is D _bcw2 , the amplitude of the beat signal is α, the first measurement value is τ ₁ , and the second measurement value is τ _2. When the frequency of the high frequency signal is represented by f _cw1 and the phase difference is represented by Δφ, the phase difference is
Δφ = Arccos (2 × D _bcw2 / α) -2πf _cw1 (τ ₁ + τ ₂ ) / 2,
The phase difference detection circuit, which is calculated based on the following equation. The phase difference detection circuit according to claim 1, wherein
The second transmission / reception circuit is
A second signal generator for outputting the second ranging signal;
And a switch circuit provided between the signal output terminal of the second signal generator and the second antenna element,
The switch circuit connects between the signal output end of the second signal generator and the second antenna element when the second transmission / reception circuit operates in the second ranging mode, When the second transmission / reception circuit operates in the reception mode, the signal path between the signal output terminal of the second signal generator and the second antenna element is disconnected. Detection circuit. The phase difference detection circuit according to claim 1 or 2, wherein
The measurement unit calculates a first measurement circuit that calculates the first measurement value based on the first reception signal, and calculates a second measurement value based on the second reception signal. Including the measurement circuit of
The first transmission / reception circuit and the first measurement circuit constitute a first radar circuit,
A phase difference detection circuit characterized in that the second transmission / reception circuit and the second measurement circuit constitute a second radar circuit. A phase difference detection circuit according to claim 2 or 3;
A radar apparatus comprising: an array antenna including the first antenna element and the second antenna element. A phase difference detection circuit used in a state of being connected to a first antenna element, a second antenna element, and a third antenna element, comprising:
After operating in a first ranging mode, it is controlled to operate in a first transmission mode, and in the first ranging mode, a frequency modulated first ranging signal is generated, and the first ranging mode is performed. After the ranging signal is transmitted from the first antenna element, the reflected wave is received from the target in the external space to generate a first reception signal, and in the first transmission mode, the first reception signal is not modulated. A first transmission / reception circuit that generates a high frequency signal and causes the first high frequency signal to be transmitted from the first antenna element and simultaneously changes the phase of the first high frequency signal with time;
After operating in the second ranging mode, it is controlled to operate in the second transmission mode, and in the second ranging mode, a frequency modulated second ranging signal is generated, and the second ranging mode is performed. After the ranging signal is transmitted from the second antenna element, the reflected wave is received from the target to generate a second reception signal, and in the second transmission mode, the second high frequency signal which is not frequency modulated is A second transmission / reception circuit that generates and transmits the second high frequency signal from the second antenna element;
A reflected wave corresponding to both the first high frequency signal and the second high frequency signal is received from the target to generate a third reception signal, and the third reception signal has a predetermined frequency. A receiving circuit for generating a beat signal indicating a frequency difference between the local signal and
A first measurement value indicating a round-trip propagation time of the first distance measurement signal between the first transmission / reception circuit and the target is calculated based on the first received signal, and the second measured value is calculated. A measurement unit that calculates a second measurement value indicating a round-trip propagation time of the second distance measurement signal between the second transmission / reception circuit and the target based on the reception signal;
A phase shift amount detection unit that detects the phase shift amount of the first high frequency signal that maximizes the amplitude of the beat signal;
A phase difference for calculating a phase difference between the first distance measurement signal and the second distance measurement signal based on the detected phase shift amount, the first measurement value, and the second measurement value. A phase difference detection circuit comprising: a calculation unit. 11. The phase difference detection circuit according to claim 10, wherein
It further comprises a phase control unit,
The first transmission / reception circuit includes a first signal generator that outputs the first ranging signal.
The second transmission / reception circuit includes a second signal generator that outputs the second ranging signal.
The signal generator of at least one of the first signal generator and the second signal generator includes a phase adjustment circuit that variably adjusts the output phase of the at least one signal generator,
The phase control unit controls the phase adjustment circuit based on the phase difference calculated by the phase difference calculation unit to control the output phase of the first signal generator and the output phase of the second signal generator. A phase difference detection circuit characterized by correcting at least one of the errors. The phase difference detection circuit according to claim 11, wherein the phase adjustment circuit comprises a variable phase shifter. 11. The phase difference detection circuit according to claim 10, wherein
The first transmission / reception circuit includes a first signal generator connected to a reference signal generator via a first signal transmission line.
The second transmission / reception circuit includes a second signal generator connected to the reference signal generator via a second signal transmission line.
The first signal generator and the second signal generator respectively generate the first ranging signal and the second ranging signal based on the reference signal supplied from the reference signal generator. A phase difference detection circuit characterized by 12. The phase difference detection circuit according to claim 10, wherein the first measurement value is τ ₁ , the second measurement value is τ ₂ , and the phase shift amount is φ _cnt0 , the first and the first. When the common frequency of the high frequency signals of _No. 2 is represented by f _cw and the phase difference is represented by Δφ, the phase difference is
Δφ = φ _cnt0 + 2πf _cw × (τ ₁ −τ ₂ ) / 2,
The phase difference detection circuit, which is calculated based on the following equation. 12. The phase difference detection circuit according to claim 10, wherein
The measurement unit calculates a first measurement circuit that calculates the first measurement value based on the first reception signal, and calculates a second measurement value based on the second reception signal. Including the measurement circuit of
The first transmission / reception circuit and the first measurement circuit constitute a first radar circuit,
A phase difference detection circuit characterized in that the second transmission / reception circuit and the second measurement circuit constitute a second radar circuit. A phase difference detection circuit according to claim 11 or 12;
A radar apparatus comprising: an array antenna including the first antenna element, the second antenna element, and the third antenna element.

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