WO2006085360A1

WO2006085360A1 - Arrival direction estimating apparatus

Info

Publication number: WO2006085360A1
Application number: PCT/JP2005/001908
Authority: WO
Inventors: Kazuo Shirakawa
Original assignee: Fujitsu Limited
Priority date: 2005-02-09
Filing date: 2005-02-09
Publication date: 2006-08-17

Abstract

An arrival direction estimating apparatus using a plurality of sensors and capable of quickly performing an arrival direction estimation of an arriving wave with high precision. The arrival direction estimating apparatus comprises a code generating part for generating orthogonal codes corresponding to the respective ones of the plurality of sensors; a modulating part for modulating the arrival signals, which are received by the plurality of sensors, by use of the orthogonal codes corresponding to the respective sensors that receive those arrival signals; a multiplexing part for multiplexing the modulated arrival signals; a frequency converting part for converting the multiplexed signal to a baseband signal; a demodulating part for distributing the baseband signal in accordance with the number of the plurality of sensors and then demodulating the distributed baseband signals by use of the orthogonal codes corresponding to the respective sensors; and an estimating part for estimating the arrival direction of the arrival signal by use of the demodulated baseband signal.

Description

Specification

Direction of arrival estimation device

Technical field

The present invention relates to an arrival direction estimation device that detects an arrival angle of a signal using a plurality of sensors.

Background art

In recent years, direction-of-arrival estimation of incoming radio waves has been used as elemental technology in various fields such as propagation environment analysis, mobile communication, and radar, and an inexpensive and highly accurate arrival direction estimation device is strongly desired. ing. Here, the functional configuration of the conventional direction-of-arrival estimation apparatus will be described with reference to FIG. 5, taking an FMCW (Frequency Modulated Continuous Wave) radar apparatus as an example. Fig. 5 is a diagram showing the functional configuration of a conventional FMCW radar system.

[0003] A conventional FMCW radar apparatus has N sensor elements A—A receiving sensor.

1 N

One array 10, Sensor element A force Transmitting sensor 11, Switch box 15

T, RF (

Radio Frequency) It is composed of transceiver Z receiver unit 20. The RF unit 20 includes a transceiver unit, a transceiver baseband unit, a receiver unit, and a receiver baseband unit that are not shown.

[0004] The transceiver unit is a high-power amplifier (hereinafter referred to as HPA (High Power Amplifier)) 25, a distributor (hereinafter referred to as HYB (Hybrid)) 26, and an RF voltage controlled oscillator (hereinafter referred to as RF). — VCO (RF-Voltage Controlled Oscillator) 27) etc. The receiver unit is also configured with a low noise amplifier (hereinafter referred to as LNA (Low Noise Amplifier)) 14 and a mixer (hereinafter referred to as MIX (Mixer)) 22 isotropic force. The transceiver baseband part is a BB (Base Band) voltage controlled oscillator (BB-VCO (BB-Voltage Controlled Oscillator)) 60 etc., and the receiver baseband part is a low-pass filter (hereinafter LPF). 30), an analog Z-digital (hereinafter referred to as AZD) converter 40, a CPU (Central Processing Unit) 50, and the like.

[0005] The FMCW radar apparatus having such a configuration is received by the receiving sensor array 10. By mixing the reflected wave from the measured object (target) with a part of the transmission wave (sent from the transmission sensor 11) (22 shown in Fig. 5), a signal containing distance and velocity components The direction of arrival is estimated using the signal. The mixing of the transmission wave and the reception wave is performed by the MIX 22 of the RF unit 20. The receiver unit of the RF unit 20 generates a baseband signal including the mixed received wave force including distance and velocity components. Then, the L PF 30 performs band limitation on the baseband signal and extracts a desired band signal component. The AZD converter 40 converts this baseband signal into a digital baseband signal. Then, the CPU 50 performs the direction of arrival estimation using the digitalized signal.

In such an FMCW radar apparatus, a configuration as shown in FIG. 5 is usually adopted in order to reduce the number of RF units 20 that are expensive and have large variations in component characteristics in the manufacturing process. In the FMCW radar apparatus shown in FIG. 5, the signal from each sensor element of the receiving sensor array 10 is switched by each switch in the switch box 15 and input to the receiver unit of the RF unit 20. . In other words, the FMCW radar apparatus in FIG. 5 has a configuration in which one RF unit 20 is shared for N sensor elements.

[0007] Accurate! In order to perform direction-of-arrival estimation, all signals received by each sensor element are required. Therefore, when the configuration as described above is adopted, the receiver unit of the RF unit 20 is installed. A time sharing method is adopted. For example, there is a method of sharing the receiver unit of the RF unit 20 by switching the signal output from each sensor element at the timing shown in FIG. Figure 6 shows the time transition for receiving the signals necessary for direction-of-arrival estimation at each sensor element. Note that T in Fig. 6 is the modulation signal (BB—OCS60

F

Output signal), and is generally about several milliseconds.

[0008] In the FMCW radar apparatus according to the example of Fig. 6, when estimating the direction of arrival, data is collected for one period of the modulation signal for each sensor element. BB-OSC shown in FIG. 6 indicates a modulation signal (for example, a triangular wave) emitted from the oscillation circuit 60 in each cycle. A is the presence of the received signal output from sensor element A due to the operation of switch box 15.

1 1

Indicates nothing. A—OUT is the demodulated signal output from sensor element A

1 1

The waveform is shown. Similarly, A, A -OUT, A, A one OUT are shown for each sensor element. ing.

[0009] According to FIG. 6, in this configuration, the number of elements (N) X modulation signal period (T) time is the direction of arrival

F

You can see that it is required for estimation. However, since this time only takes into account the minimum time required for sampling, in actuality, this time of about 100 times is required to increase the signal-to-noise ratio (hereinafter referred to as the SZN ratio). Will be. In this case, when the angle measurement target (target) is moving, the angle measurement target moves greatly depending on the time required to collect data for direction-of-arrival estimation. If a certain direction of arrival estimation fails, the result will be a tumbling fall (for example, if the target is moving at a speed of about 60 kmZh, the number of elements is N = ll, and the period is T = 3 milliseconds. data

F

And the target moves 0.5-55 to 55 meters while hitting).

[0010] Sarako, comparing waveforms for A-OUT, A-OUT, A-OUT demodulated signals in Figure 6

1 2 N

Then, so that the force is divided, if the number of each sensor element based on A is k (k = l N),

1

The demodulated signal of the signal from element A is compared with that of sensor element A.

K 1

In addition to the phase {2 π (k-l) d / l} sin (0) derived from, the uncertain phase Φ other than the direction of arrival is superimposed. This is mainly because the signal from each sensor element is

Because the pulling time is different, the demodulated signal has phase fluctuations that are not related to the direction of arrival. In order to suppress this, it is necessary to collect more data and perform operations such as averaging, but this further increases the time required for data collection, and direction-of-arrival estimation fails. In the above equation, Θ is the angle to be measured, d is the distance between sensor elements in the sensor array (with a uniform spacing), and λ is the wavelength of the RF carrier. To simplify the explanation, the number of angle measurement objects is assumed to be one.

[0011] Each switch 16-19 in the switch box 15 has a loss (insertion loss) of about 5 dB when SP3T is used, for example. Therefore, if a switch with a large loss is placed immediately after the sensor element, the SZN ratio decreases, so it is necessary to provide an LNA 14 with a gain of about 10 dB for each input port of each switch. However, this complicates the circuit configuration of the apparatus and increases the cost.

[0012] These become more prominent problems when it is necessary to increase the number of angle measuring objects that can be identified. Usually, the number of angle measurement objects that can be identified is about 1Z2 of the number of sensors. If it is necessary to increase the number of angle measurement objects that can be identified, it is necessary to increase the number of sensors. Such a configuration increases the number of sensors, which not only saves more time for data collection but also increases the number of switches. As a result, as described above, high-precision direction-of-arrival estimation cannot be realized, and the circuit configuration becomes more complicated.

[0013] In addition, in the configuration using a switch as described above, in order to achieve isolation between ports, it is usually necessary to simultaneously open and close the LNA and the like as the switch is opened and closed. FIG. 7 is a diagram illustrating a circuit configuration example of the SP3T switch. The above operation will be described with reference to FIG. In the SP3T switch 16 shown in Fig. 7, the receiving sensor element A is connected to the tip of the LNA701 (lower part of the figure), and the receiving sensor element A is connected to the tip of the LNA702 (lower part of the figure).

1 2

Receiving sensor element A is connected to the tip of NA703 (bottom of the figure), and to the tip of 700 (top of the figure)

Three

The receiver unit of the RF unit 20 is connected via the LNA 14 and SP3T19. In the configuration shown in Figure 7, when the signal received by sensor element A is output from 700,

1

Switch 704 is closed (ON) and switches 705 and 706 are open (OFF). At the same time, LNA 701 is closed (ON) and LNA 702 and 703 are open (OFF). SP3T17 and 18 and LNAs arranged in these signal paths are also opened (OFF).

[0014] However, such an operation is normally uniform as a circuit and involves impedance fluctuations, and therefore adversely affects the receiver unit of the RF unit 20 connected to the switch. For this reason, in the configuration using the switch, it is necessary to design the entire circuit including the receiver unit of the RF unit 20 and the like, which makes it difficult to design the receiver.

[0015] As regards the point of multiplexing the signals from the antenna, it is possible to multiplex the antenna output using Walsh codes in the diversity device and reduce the cable connecting the antenna and the radio base station. Proposed! (See Patent Document 1).

Patent Document 1: Japanese Patent Publication No. 10-509848

Disclosure of the invention

Problems to be solved by the invention

[0016] An object of the present invention is to estimate the arrival direction of an incoming wave using a plurality of sensors with high accuracy. Another object of the present invention is to provide a direction-of-arrival estimation apparatus that can be performed at high speed.

Means for solving the problem

The present invention employs the following configuration in order to solve the above-described problems. That is, the present invention provides a plurality of sensors that receive incoming signals of angle measurement target force, a code generation unit that generates orthogonal codes corresponding to each of the plurality of sensors, and the arrival received by the plurality of sensors. Each of the signals is modulated using the above orthogonal code corresponding to the sensor that received the incoming signal, a multiplexing unit that multiplexes each modulated incoming signal, and the multiplexed signal. A frequency conversion unit for converting into a baseband signal, the baseband signal is distributed according to the number of the plurality of sensors, and each distributed baseband signal is assigned to each of the orthogonal codes corresponding to the plurality of sensors. An arrival direction estimation apparatus comprising: a demodulation unit that demodulates; and an estimation unit that estimates an arrival direction of the arrival signal using a demodulated baseband signal. It is.

In the present invention, the modulation unit modulates each received signal having a plurality of sensor forces using an orthogonal code, and multiplexes the modulated signals. The frequency change generates a baseband signal with the multiplexed signal power and the orthogonal code added. The demodulator obtains the baseband signal corresponding to each sensor simultaneously by demodulating the baseband signal with the orthogonal code assigned to each sensor.

Accordingly, the present invention can perform direction-of-arrival estimation using signals simultaneously received by the sensors. Therefore, according to the present invention, it is possible to prevent an extra signal component from being added to the signal received by each sensor, and it is possible to perform arrival direction estimation with high accuracy.

[0020] Also, the estimation unit uses a vector processor, a GPU (Graphic Processing Unit), or the like for each baseband signal demodulated according to the number of the plurality of sensors when estimating the direction of arrival. May be processed in parallel.

Accordingly, the present invention can perform high-speed arrival direction estimation processing.

[0022] Further, the code generation unit may switch the orthogonal code at a predetermined cycle. Moreover, you may make it change based on the positional information on an own apparatus.

[0023] Thereby, it is possible to prevent interference with signals from other devices and to accurately estimate the direction of arrival. Can do.

[0024] Further, the code generation unit may change the orthogonal code according to the phase noise of the signal source of the frequency conversion unit!

[0025] Thereby, the signal-to-noise ratio (SZN ratio) of the signal processed in the present invention can be improved, and thus the arrival direction can be estimated with high accuracy.

Note that the present invention may be a method for causing a computer to realize any one of the functions described above. Further, the present invention may be a program for realizing any of the functions described above. In the present invention, such a program may be recorded in a computer-readable storage medium.

The invention's effect

[0027] According to the present invention, it is possible to realize an arrival direction estimation device that can perform arrival direction estimation of an incoming wave using a plurality of sensors with high accuracy and high speed.

Brief Description of Drawings

FIG. 1 is a functional configuration diagram of an FMCW radar apparatus receiver unit according to an embodiment.

FIG. 2 is a diagram showing a circuit example of a BPSK module.

FIG. 3 is a diagram showing a relationship between a time waveform of a PN code and a demodulated waveform.

FIG. 4 is a timing chart of signal demodulation in the embodiment.

FIG. 5 is a functional configuration diagram of the FMCW radar apparatus in the prior art.

FIG. 6 is a diagram showing a signal output timing chart in the prior art.

FIG. 7 is a diagram showing a circuit example of switch 3PST.

Explanation of symbols

[0029] 10, 100 sensor array

11 Transmitter sensor

15 Switch box

16, 17, 18, 19 switch (SP3T)

110 Amplifier box

20 RF transceiver / receiver unit

140 RF downconverter 22 Mixer

25 High power amplifier (HPA)

26 Distributor (HYB)

27 Oscillator (RF-VCO)

60 Oscillator (BB-VCO)

150 Pseudo-noise code generator (PN code generator)

151 External input

160 PN code demodulation module

30, 170— 1— 170— N Low pass finoleta (LPF)

40, 180 Analog Z digital converter (AZD converter)

50, 190 CPU (Central Processing Unit)

14, 120-1— 120-N Low noise amplification module (LNA module)

130 Hybrid synthesizer

121— 1— 121-N Low Noise Amplifier (LNA)

122— 1— 122— N BPSK module

123— 1— 123— N Buffer

191 Other functions

200 input terminals

201 Output terminal

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an arrival direction estimation apparatus according to the best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described with reference to the drawings. The configuration of the embodiment is an exemplification, and the present invention is not limited to the configuration of the embodiment.

[First embodiment]

An FMCW radar apparatus as a first embodiment in the arrival direction estimation apparatus of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a functional configuration of the FMCW radar apparatus in the first embodiment. is there. The functional configuration of the FMCW radar apparatus according to the first embodiment will be described below with reference to FIG. FIG. 1 mainly shows functions for processing received signals, and functions related to signal transmission processing are the same as those of the conventional apparatus shown in FIG.

[0032] The FMCW radar apparatus according to the first embodiment includes a reception sensor array 100, a transmission sensor (not shown), an amplifier box 110, an RF down converter 140 (corresponding to the frequency conversion unit of the present invention), and pseudo noise. Code (hereinafter referred to as PN code) generator 150 (corresponding to the code generator of the present invention), PN code demodulator module 160 (corresponding to the demodulator of the present invention), N corresponding to the number of receiving sensor elements Low-pass filters (hereinafter referred to as LPF) 170-1—170-N, analog Z-digital (hereinafter referred to as AZD) converter 180, and CPU (Central Processing Unit) 190 (in accordance with the present invention) Equivalent to an estimation unit).

[0033] The amplifier box 110 includes N low-noise amplification modules (hereinafter referred to as LNA modules) 120-1—120-N (corresponding to the modulation unit of the present invention), and a hybrid synthesizer 130 (the present invention). Equivalent to a multiplexing unit). Each LNA module is composed of a low noise amplifier (hereinafter referred to as LNA) 121-1, a B PSK module 122-1, and a buffer 123-1, taking the LNA module 120-1 as an example. . The other LNA modules 120-2-2-1-N have the same configuration. The PN code demodulator module 160 is also configured with N PN code demodulators 161-1 to 161-N corresponding to each sensor element for reception.

Hereinafter, functions in each configuration will be described.

[0035] <Receiving sensor array 100>

The receiving sensor array 100 is also configured with N sensor elements A—A force. Each Sen

1 N

The cir elements are arranged, for example, in a line of lines, and receive incoming signals (arrival waves). The received incoming wave is output to the LNA module in the amplifier box 110.

<0036> <PN code generator 150>>

The PN code generator 150 generates different PN codes that are orthogonal to each other for each receiving sensor element, for the number of all the receiving sensor elements (N). The PN code generator 150 sends each generated PN code to an LNA connected to the sensor element corresponding to the PN code. Output to each module. Further, the PN code generator 150 outputs each generated PN code to a PN code demodulator corresponding to the sensor element corresponding to the PN code. For example, the PN code generated for sensor element A corresponds to sensor element A.

1 1 Output to the corresponding LNA module 120-1 and PN code demodulator 161-1.

[0037] In the present embodiment, a PN (Pseudo Noise) code that is a rectangular wave is used as the orthogonal code. For example, another orthogonal code such as an orthogonal wavelet wave or a sine wave may be used.

[0038] <LNA module>

An LNA module is provided for each sensor element for reception, and is connected to each sensor element. In other words, LNA module 120-1 is connected to sensor element A,

1

LNA module 120-2 (not shown) is connected to sensor element A, and sensor element

2

LNA module 120-N is connected to A. In the following description, N LNA modules

N

Since all the modules have the same configuration, the LNA module 120-1 will be described as a representative.

The LNA module 120-1 modulates the incoming signal input from the receiving sensor element and outputs the modulated signal to the hybrid synthesizer 130. In modulating the incoming signal, LNA121-1 amplifies the incoming signal with low noise, and the BPSK (Binary Phase Shift Keying) module 12

Output to 2-1. The BPSK module 122-1 spreads the input signal using the PN code from the PN code generator 150. Then, the signal is output to the buffer 123-1. The notifier 123-1 suppresses extra signal components such as impedance fluctuations of other circuit powers for the input signal, and outputs it to the hybrid synthesizer 130.

[0040] Each of the BPSK modules 122-1 to 122-N includes, for example, a circuit as shown in FIG. FIG. 2 is a diagram showing a circuit example of the BPSK module. The B PSK module according to this example uses a diode as a switch element and includes switches 202 and 203. When a PN code is input, the diode is controlled by the PN code, and a signal input from the input terminal 200 is modulated. The modulated signal is output from the output terminal 201. For example, when FIG. 2 shows the BPSK module 122-1, the LNA 121-1 is connected to the input terminal 200, and the buffer 12 is connected to the output terminal 201.

3—It must be connected by one force. [0041] <KU Hybrid Synthesizer 130>

The hybrid synthesizer 130 synthesizes the signals from all the LNA modules 120-1—120—N and outputs the synthesized signal to the RF down converter 140.

[0042] <KU RF down converter 140>

The RF down-converter 140 mixes the synthesized signal from the hybrid synthesizer 130 with a part of the transmission wave that also transmits the FMCW radar device power, and generates a baseband signal. The baseband signal generated here is a signal with a PN code applied. This baseband signal is output to the PN code demodulation module 160.

[0043] <PN code demodulation module 160 >>

The PN code demodulating module 160 is composed of N PN code demodulators 161-1 to 161-N corresponding to each sensor element for reception. When receiving the signal from the RF down converter 140, the PN code demodulation module 160 distributes the signal to all the PN code demodulators. Each PN code demodulator receives the corresponding sensor PN code from the PN code generator 150, and despreads the distributed signal using the PN code. As a result, each PN code demodulator can extract a signal component corresponding to each sensor element for reception from the synthesized signal. The despread signal is output to the LPF corresponding to each sensor element for reception.

<0044> <Low-pass filter (LPF)>

There are as many LPFs as the number of receiving sensor elements (N). Each LPF takes out only the baseband signal component of the input signal power desired band. The extracted signal is output to the AZD converter 180.

[0045] <KU AZD Transform 180 >>

The AZD converter 180 converts each LPF force input signal into a digital baseband signal and outputs it to the CPU 190.

[0046] <KU CPU 190 >>

The CPU 190 estimates the direction of arrival using a digital baseband signal corresponding to each receiving sensor element. In this embodiment, a higher-speed processing is possible by using a vector processor (Vector Processing Unit) that excels in power parallel processing as CPU190. It becomes ability.

Next, an operation example of the FMCW radar apparatus in the first embodiment will be described with reference to FIGS. FIG. 3 shows the relationship between the time waveform of the PN code and the demodulated waveform. FIG. 4 is a timing chart showing a time transition in which the signal received by each sensor element is modulated by the PN code and output as a signal to the noise synthesizer 130 and the RF down converter 140 in this embodiment. . In the explanation of the operation example of this system, it will be explained in association with the functional configuration shown in FIG.

[0048] First, the operation of each functional unit of the FMCW radar apparatus in the first embodiment will be described using a signal received by the reception sensor element A as an example. In addition, other

1

Even in the case of sensor element A A, the functional part that operates (LNA module 120-2

2 N

1) 120-N, PN code demodulator 161-2-161-N, and LPF 170-2-170-N) are different, and the operation of each functional unit is the same.

[0049] The sensor element A of the receiving sensor array 100 receives an incoming signal having a target force for angle measurement.

1

Then, the received incoming signal is output to the LNA module 120-1 in the amplifier box 110. The incoming signal input to the LNA module 120-1 is amplified by the LNA 121-1, and input to the BPSK module 122-1. In the BPSK module 122-1, the input signal is multiplied with the PN code for the sensor element A to spread and output

1

Is done. The signal modulated by the PN code is output to the hybrid synthesizer 130 and is synthesized by the hybrid synthesizer 130 with the modulation signal from the other sensor elements A—A.

2 N

The The synthesized signal is mixed with the transmission signal by the RF down converter 140 to become a baseband signal.

[0050] When a signal obtained by combining baseband components corresponding to each sensor element power is input to the PN code demodulation module 160, it is distributed to each PN code demodulator. The PN code demodulator 161-1 despreads this baseband signal. At this time, the PN code demodulator 1 61-1 has a code corresponding to the sensor element A output from the PN code generator 150.

1

Because it is used, LPF170-1 only has a baseband component corresponding to sensor element A.

1

Appears. After that, the baseband signal corresponding to sensor element A is LPF170-1. Bandwidth is limited and output to AZD translation 180. The AZD conversion 180 converts the input signal into a digital baseband signal and outputs it to the CPU 190. When the CPU 190 receives a digital baseband signal corresponding to each sensor element A—A,

1 N

The direction-of-arrival estimation used is performed.

[0051] <Reception signal multiplexing principle>

Here, the principle of multiplexing of received signals using the PN code (processing by the LNA module and the hybrid synthesizer) and demodulation (processing by the PN code demodulating module) will be described with reference to FIG. explain.

FIG. 3 (A) shows the time waveform of the PN code corresponding to each sensor element output from the PN code generator 150. The PN code in which the waveform indicated by A is output for sensor element A

1 1

It is a waveform. Similarly, the PN code waveforms output for sensor elements A and A are shown.

2 N

Has been. Fig. 3 (B) shows the PN code for sensor element A for each PN code shown in Fig. 3 (A).

1

The signal waveform obtained by multiplying and integrating is shown.

[0053] From the result in Fig. 3 (B), the PN code for A is multiplied by the PN code for A and integrated.

1 1

It can be seen that a waveform is output only when This is the force with which each PN code is an orthogonal code, and this is the principle of multiplexing received signals by the FMCW radar apparatus according to the present invention. That is, the PN code for the sensor element is multiplied by each LNA module, and the signal synthesized by the hybrid synthesizer 130 is despread again by each PN code demodulator by the PN code, and corresponds to each sensor element. A signal can be obtained. Thus, one RF down converter 140 can be shared for a plurality of receiving sensor elements, and baseband signals corresponding to the desired sensor elements can be acquired in a batch.

[0054] <Base signal conversion of received signal>

Next, the incoming signal from the object to be measured is received by each sensor element, and the RF signal power modulated by the PN code assigned to each sensor is converted into a baseband signal by the RF down converter 140. The timing will be described with reference to Fig. 4. FIG. 4 is a timing chart showing the transition of the signal received by each sensor element by the RF down converter 140 for each sensor. Na FIG. 4 corresponds to the timing chart in the prior art of FIG. 6 described above, where T shown in FIG. 4 indicates the period of the modulation signal and shows the same time as T in FIG.

F F

[0055] BB-OSC shown in FIG. 4 shows a time waveform of a modulation signal (for example, a triangular wave) emitted from an oscillation circuit (not shown), and shows that it is a chart for one period (T). . LNA

FM

ZBUFFER shows the ON / OFF status of the LNA and buffers in the LNA module. In Fig. 4, the LNA and buffers of all LNA modules are in the ON status. PN-A is a sensor element output by the PN code generator 150.

1

The time waveform of the PN code for child A is shown. In other words, PN-A is an LNA module

1 1

The BPSK module 122-1 of 120-1 shows the waveform of the PN code used for signal modulation (spreading). A—IN is input to sensor element A force LNA module 120-1

1 1

The waveform of the incoming signal is shown. A—OUT is output from LNA module 120-1

1

The signal waveform is shown. Below are graphs showing the PN code of each LNA module, the signal input to the LNA module, and the waveform of the signal output from the LNA module.

[0056] The PN code input to each LNA module is an orthogonal code as described above. In addition, the number of each sensor element with reference to sensor element A is k (k = l

1 1 N), the incoming signal (A—IN) input to each LNA module is 2 π (k−l) d / l sin 0

k

The phase is shifted. The signals output from each LNA module (A—OU

k

T) is the result of multiplying each input signal (A -IN) by each PN code.

k

. Where Θ is the angle to be measured, d is the distance between the sensor elements that make up the sensor array (uniform spacing), and λ is the RF carrier wavelength. To simplify the explanation, the number of angle measurement objects is assumed to be one.

Here, when the FMCW radar apparatus in the prior art shown in FIG. 6 and the FMCW radar apparatus in the present invention shown in FIG. 4 are compared, the time required to acquire the signal necessary for estimating the direction of arrival is In conventional devices, at least (number of receiving sensor elements) X (Τ

F

Whereas it takes time, the device according to the present invention requires only one period (Τ).

F

I understand. In addition, as shown in the timing chart of FIG. 4, in the FMCW radar apparatus according to the present embodiment, both the LNA and the BUFFER are always in the ON state, so that the impedance in each LNA module is stable and includes the frequency converter. This makes it easier to design a receiver.

In the FMCW radar apparatus in the first embodiment, the LNA module spreads the received signal from each sensor element constituting the receiving sensor array 100 using the PN code, and the hybrid synthesizer 130 spreads the spread signal. Combine (multiplex). In the FMCW radar device, the RF down converter 140 collectively demodulates the multiplexed signal to generate a baseband signal. The FMCW radar apparatus simultaneously obtains a baseband signal corresponding to each sensor element by demodulating the baseband signal with the PN code assigned to each sensor element for reception by the PN code demodulation module 160.

Accordingly, in the first embodiment, it is possible to perform the direction of arrival estimation using signals received simultaneously by the sensors. Therefore, it is possible to prevent an extra signal component from being added to the signal received by each sensor, and to create a situation close to the theoretical assumption of direction of arrival estimation. As a result, it is possible to perform direction of arrival estimation with high accuracy.

[0061] In addition, since the time required for estimating the arrival direction of the device can be shortened, the throughput of the device can be improved to at least 1ZN (the number of sensor elements).

[0062] As a result, it is possible to accurately detect the arrival direction for a target whose direction is difficult to be detected, such as when the angle measurement target is moving, at high speed. In particular, it can be expected to be highly effective in a device that requires real-time performance, such as the radar device of the first embodiment. appear.

[0063] Further, in the FMCW radar apparatus in the embodiment, one RF down converter is shared by synthesizing reception signals received from a plurality of reception sensors.

As a result, the conventional apparatus configuration shown in FIG. 5 requires more LNAs than the number of sensor elements to compensate for the insertion loss of the switch, whereas the FMCW radar apparatus in the present embodiment The number of LNAs can be reduced and BPSK as shown in Figure 2 Since the module is simpler in circuit, it is also effective in circuit design. As a result, it not only reduces circuit design man-hours, improves circuit quality, and reduces costs, but also enables one-chip radar.

[0065] Variations>

In the FMCW radar apparatus in this embodiment, the PN code generator 150 generates a PN code corresponding to each sensor element, but the PN code assigned to each sensor element is generated in a form that changes periodically. It may be.

[0066] In addition, the PN code generator 150 acquires the position information of its own device using another device such as a navigation system, GPS, magnetic nails, or a traffic light, and switches the PN code based on the position information. It may be. In this case, the PN code generator 150 may receive the position information of its own device as the external input 151 shown in FIG. 1, and switch the PN code using this.

[0067] Thereby, the FMCW radar apparatus according to the present embodiment can prevent signal interference with other radio apparatuses that use the same PN code as a transmission wave, and is therefore affected by the other apparatuses. It becomes possible to perform precise direction-of-arrival estimation.

[0068] Further, the PN code generator 150 may change the frequency of the PN code in accordance with the phase noise in the signal source in the RF down converter 140. In this case, the PN code generator 150 may receive the phase noise information as the external input 151 shown in FIG. 1, and use it to switch the PN code.

[0069] Thereby, the FMCW radar apparatus according to the present embodiment can perform the direction of arrival estimation based on the signal with improved signal-to-noise ratio (SZN ratio).

In the FMCW radar apparatus according to the present embodiment, baseband signals corresponding to all sensor elements are obtained by the PN code demodulation module 160, and the arrival direction is estimated using all these signals. However, first, the baseband signal force corresponding to one of the sensor elements is roughly estimated for the position or velocity of the angle measurement target, and based on the estimation result, the precision using the baseband signals corresponding to all sensor elements is used. It may be determined whether or not to perform the arrival direction estimation. In this case, the rough estimation is performed by the predetermined function unit 191 in the CPU unit 190, and then the subsequent accurate estimation is performed. Or not, and the determination result may be returned to the CPU unit 190.

[0071] With this, it is possible to omit extra processing, such as when it is determined by rough estimation that the angle measurement target is not the estimation target, and it is possible to perform accurate arrival direction estimation with an appropriate load. It becomes possible.

[0072] Also, in this embodiment, the arrival signals received by a plurality of sensors are multiplexed by diffusing Z despreading with a PN code to perform arrival direction estimation, but using a frequency hopping method, Modulation Z demodulation may be performed according to a hopping frequency pattern corresponding to each sensor. In that case, the PN code generator 150 generates a hopping frequency pattern corresponding to one element of each sensor, and each LNA module and each PN code demodulator receives the hopping frequency pattern and applies to each sensor element. Process each corresponding signal! ヽ.

Claims

The scope of the claims

[1] Multiple sensors that receive incoming signals from the object to be measured,

A code generation unit that generates orthogonal codes corresponding to each of the plurality of sensors, and each of the incoming signals received by the plurality of sensors, using the orthogonal code corresponding to the sensor that has received the incoming signals. A modulating unit for modulating;

A multiplexing unit for multiplexing each modulated incoming signal;

A frequency converter that converts the multiplexed signal into a baseband signal with the orthogonal code added thereto;

A demodulator that distributes the baseband signal according to the number of the plurality of sensors, and demodulates the distributed baseband signals by the orthogonal codes corresponding to the plurality of sensors;

An estimation unit that estimates an arrival direction of the incoming signal using a demodulated baseband signal;

An arrival direction estimation apparatus comprising:

2. The direction of arrival according to claim 1, wherein the estimation unit estimates the direction of arrival by performing parallel processing on each baseband signal demodulated according to the number of the plurality of sensors using a vector processor. Estimating device.

[3] The direction-of-arrival estimation apparatus according to claim 1, wherein the code generation unit changes the frequency of the orthogonal code in accordance with phase noise of a signal source of the frequency conversion unit.

4. The arrival direction estimation apparatus according to claim 1, wherein the code generation unit uses a pseudo noise code, a sine wave, or a wavelet code as the orthogonal code.

[5] The apparatus further comprises a position estimation unit that estimates the position or velocity of the angle measurement target using at least one of the baseband signals demodulated by the demodulation unit,

The estimation unit determines a priority of direction of arrival estimation based on the estimated position or velocity of the angle measurement target, and switches between precise estimation and rough estimation according to the priority. Direction of arrival estimation device.

6. The arrival direction estimation apparatus according to claim 1, wherein the code generation unit switches the orthogonal code at a predetermined period.

[7] It further comprises an acquisition unit for acquiring the position information of the own device,

The arrival direction estimation device according to claim 1, wherein the code generation unit generates the orthogonal code corresponding to the position information.

[8] The code generation unit generates a hopping frequency pattern corresponding to each of the plurality of sensors,

The modulator modulates each of the incoming signals received by the plurality of sensors using the hopping frequency pattern corresponding to the sensor that has received the incoming signals,

The demodulator demodulates each distributed baseband signal with the hopping frequency pattern corresponding to a sensor assigned to each baseband signal.

The arrival direction estimation apparatus according to claim 1.

[9] An arrival direction estimation method for receiving an arrival signal from an object to be measured by a plurality of sensors and estimating an arrival direction of the arrival signal,

Generating an orthogonal code corresponding to each of the plurality of sensors, and modulating each of the incoming signals received by the plurality of sensors using the orthogonal code corresponding to the sensor that received the incoming signals. And multiplexing each modulated incoming signal;

Converting the multiplexed signal into a baseband signal with the orthogonal code added thereto;

Distributing the baseband signal according to the number of the plurality of sensors, and demodulating each distributed baseband signal by the respective orthogonal codes corresponding to the plurality of sensors;

Using the demodulated baseband signal to estimate the direction of arrival of the incoming signal;

A direction of arrival estimation method comprising: