JP7069644B2 - Signal processing systems, signal processing equipment, signal processing methods and signal processing programs - Google Patents

Description

The present invention relates to a signal processing system, a signal processing apparatus, a signal processing method and a signal processing program.

In the above technical field, in Non-Patent Document 1, a certain time in a band permitted to be transmitted is divided into a plurality of time-frequency tiles on the time axis and the frequency axis, and in each time-frequency tile, 3 Send the waveform with the type selected. The three types of selection are that when the signal is not generated in the time-frequency tile, the frequency called Up-sweep LFM (Linear Frequency Modulation) rises, and when the FM wave is generated, the frequency called Down sweep LFM falls. There are three cases where FM waves are generated. Taking advantage of the fact that the patterns of the time-frequency tiles are different as a whole, it is possible to distinguish and process a large number of waveforms transmitted at the same time.

Wen-Qin Wang, H.C. So, Longting Huang, Yuan Chen, “LOWPEAK-TO-AVERAGE RATIO OFDM CHIRP WAVEFORM DIVERSITY DESIGN,” 2014 IEEE International Conference on Acoustic, Speech and Signal Processing. Lecture materials Yasunari Yokota Signal processing Part 3 Unsteady signal analysis / cepstrum analysis (http://www.ykt.info.gifu-u.ac.jp/sp3.pdf)

However, in the techniques described above, the choice of waveforms within each time-frequency tile is limited, and the number of transmitted waveforms that can be processed separately at the same time is limited. For example, even with the 8 × 8 64 tiles of Non-Patent Document 1, the maximum type of transmission waveform is 3 × 64 = 192, and considering whether or not the waveforms of each tile are adjacent waveforms, the transmission waveform Types are reduced. As a result, the waveforms that can be identified and used at the same time are limited, and many objects and directions cannot be detected. In addition, it is necessary to make changes such as reducing the bandwidth used in order to increase the radar that can be used at the same time, and reducing the bandwidth used reduces the accuracy.

An object of the present invention is to provide a technique for solving the above-mentioned problems.

In order to achieve the above object, the signal processing device according to the present invention is
A modulated wave having a waveform in which the modulation speed of the modulation waveform is changed, or a waveform in which the bandwidth of the modulation waveform corresponding to the maximum frequency of the frequency to be added to the center frequency is changed, and the frequency changes non-repetitively. In order to generate the modulated wave, a transmission waveform generating means for generating a transmission waveform obtained by changing the modulation speed and performing frequency modulation, or a transmission waveform obtained by changing the bandwidth and performing frequency modulation.
A transmission waveform changing means that changes the frequency modulation by the transmission waveform generation means so that the cross-correlation of the spectrograms of the transmission waveform is equal to or less than the threshold value.
A transmission waveform arrangement means for arranging transmission waveforms whose spectrogram cross-correlation is equal to or less than a threshold value on a plurality of tiles divided by a time axis and a frequency axis.
To prepare for.

In order to achieve the above object, the signal processing method according to the present invention
A modulated wave having a waveform in which the modulation speed of the modulation waveform is changed, or a waveform in which the bandwidth of the modulation waveform corresponding to the maximum frequency of the frequency to be added to the center frequency is changed, and the frequency changes non-repetitively. In order to generate the modulated wave, a transmission waveform generation step for generating a transmission waveform obtained by changing the modulation speed and performing frequency modulation, or a transmission waveform obtained by changing the bandwidth and performing frequency modulation, and a transmission waveform generation step.
A transmission waveform change step that changes the frequency modulation in the transmission waveform generation step so that the cross-correlation of the spectrograms of the transmission waveform is equal to or less than the threshold value.
A transmission waveform placement step that places transmission waveforms whose spectrogram cross-correlation is below the threshold on multiple tiles divided by the time axis and frequency axis.
including.

In order to achieve the above object, the signal processing program according to the present invention is
A modulated wave having a waveform in which the modulation speed of the modulation waveform is changed, or a waveform in which the bandwidth of the modulation waveform corresponding to the maximum frequency of the frequency to be added to the center frequency is changed, and the frequency changes non-repetitively. In order to generate the modulated wave, a transmission waveform generation step for generating a transmission waveform obtained by changing the modulation speed and performing frequency modulation, or a transmission waveform obtained by changing the bandwidth and performing frequency modulation, and a transmission waveform generation step.
A transmission waveform change step that changes the frequency modulation in the transmission waveform generation step so that the cross-correlation of the spectrograms of the transmission waveform is equal to or less than the threshold value.
A transmission waveform placement step that places transmission waveforms whose spectrogram cross-correlation is below the threshold on multiple tiles divided by the time axis and frequency axis.
Let the computer run.

In order to achieve the above object, the signal processing system according to the present invention is
Equipped with transmitter and receiver,
The transmitter is
A modulated wave having a waveform in which the modulation speed of the modulation waveform is changed, or a waveform in which the bandwidth of the modulation waveform corresponding to the maximum frequency of the frequency to be added to the center frequency is changed, and the frequency changes non-repetitively. In order to generate the modulated wave, a transmission waveform generating means for generating a transmission waveform obtained by changing the modulation speed and performing frequency modulation, or a transmission waveform obtained by changing the bandwidth and performing frequency modulation.
A transmission waveform changing means that changes the frequency modulation by the transmission waveform generation means so that the cross-correlation of the spectrograms of the transmission waveform is equal to or less than the threshold value.
A transmission waveform arrangement means for arranging transmission waveforms whose spectrogram cross-correlation is equal to or less than a threshold value on a plurality of tiles divided by a time axis and a frequency axis.
A transmission means for transmitting the signal of the transmission waveform and
Have,
The receiver is
A receiving means for receiving the reflected signal in which the signal of the transmitted waveform is reflected by the target object,
Correlation calculation means for calculating the correlation function between the transmission waveform and the waveform of the reflection signal, and
An object detection means for detecting the target object based on the correlation function,
Have.

According to the present invention, many objects and directions can be detected by increasing the transmission waveforms that can be identified and used at the same time.

It is a block diagram which shows the structure of the signal processing apparatus which concerns on 1st Embodiment of this invention. It is a figure which shows the outline of the signal processing by the signal processing apparatus which concerns on 2nd Embodiment of this invention. It is a figure which shows the outline of the signal processing by the signal processing apparatus which concerns on a prerequisite technique. It is a block diagram which shows the functional structure of the signal processing apparatus which concerns on 2nd Embodiment of this invention. It is a block diagram which shows the functional structure of the frequency changing part and the modulated wave setting part of the signal processing apparatus which concerns on 2nd Embodiment of this invention. It is a block diagram which shows the structure of the signal processing system which includes the signal processing apparatus which concerns on 2nd Embodiment of this invention. It is a block diagram which shows the hardware composition of the signal processing apparatus which concerns on 2nd Embodiment of this invention. It is a figure which shows the structure of the time-frequency tile table which concerns on 2nd Embodiment of this invention. It is a figure which shows the structure of the transmission waveform generation table which concerns on 2nd Embodiment of this invention. It is a flowchart which shows the processing procedure of the signal processing apparatus which concerns on 2nd Embodiment of this invention. It is a block diagram which shows the functional structure at the time of the 1st operation of the signal processing apparatus which concerns on 2nd Embodiment of this invention. It is a block diagram which shows the functional structure of the modulation wave setting part at the time of the 1st operation of the signal processing apparatus which concerns on 2nd Embodiment of this invention. It is a figure which shows the spectrogram of the transmission waveform at the time of the 1st operation which concerns on 2nd Embodiment of this invention. It is a figure which shows the self-ambiguity function of the transmission waveform at the time of the 1st operation which concerns on 2nd Embodiment of this invention. It is a block diagram which shows the functional structure of the modulation wave setting part at the time of the 2nd operation of the signal processing apparatus which concerns on 2nd Embodiment of this invention. It is a figure which shows an example of the spectrogram of the transmission waveform at the time of the 2nd operation which concerns on 2nd Embodiment of this invention. It is a figure which shows the self-ambiguity function of the transmission waveform at the time of the 2nd operation which concerns on 2nd Embodiment of this invention. It is a figure which shows the other example of the spectrogram of the transmission waveform at the time of the 2nd operation which concerns on 2nd Embodiment of this invention. It is a figure which shows the further example of the spectrogram of the transmission waveform at the time of the 2nd operation which concerns on 2nd Embodiment of this invention. It is a figure which shows the further example of the spectrogram of the transmission waveform at the time of the 2nd operation which concerns on 2nd Embodiment of this invention. It is a block diagram which shows the functional structure of the modulation wave setting part at the time of the 3rd operation of the signal processing apparatus which concerns on 2nd Embodiment of this invention. It is a figure which shows an example of the spectrogram of the transmission waveform at the time of the 3rd operation which concerns on 2nd Embodiment of this invention. It is a figure which shows the other example of the spectrogram of the transmission waveform at the time of the 3rd operation which concerns on 2nd Embodiment of this invention. It is a block diagram which shows the functional structure of the modulation wave setting part at the time of the 4th operation of the signal processing apparatus which concerns on 2nd Embodiment of this invention. It is a figure which shows an example of the spectrogram of the transmission waveform at the time of the 4th operation which concerns on 2nd Embodiment of this invention. It is a figure which shows the other example of the spectrogram of the transmission waveform at the time of the 4th operation which concerns on 2nd Embodiment of this invention. It is a block diagram which shows the functional structure of the modulation wave setting part at the time of the 5th operation of the signal processing apparatus which concerns on 2nd Embodiment of this invention. It is a figure which shows the outline of the signal processing by the signal processing apparatus which concerns on 3rd Embodiment of this invention. It is a figure explaining the signal processing by the signal processing apparatus which concerns on 3rd Embodiment of this invention. It is a block diagram which shows the functional structure of the signal processing apparatus which concerns on 3rd Embodiment of this invention. It is a figure which shows the structure of the time-frequency tile table which concerns on 3rd Embodiment of this invention. It is a flowchart which shows the processing procedure of the signal processing apparatus which concerns on 3rd Embodiment of this invention. It is a figure which shows the outline of the signal processing by the signal processing apparatus which concerns on 4th Embodiment of this invention. It is a block diagram which shows the functional structure of the signal processing apparatus which concerns on 4th Embodiment of this invention. It is a figure which shows the structure of the time-frequency tile table which concerns on 4th Embodiment of this invention. It is a flowchart which shows the processing procedure of the signal processing apparatus which concerns on 4th Embodiment of this invention. It is a figure which shows the other field which can use this invention.

Hereinafter, embodiments of the present invention will be described in detail exemplary with reference to the drawings. However, the components described in the following embodiments are merely examples, and the technical scope of the present invention is not intended to be limited thereto.

[First Embodiment]
The signal processing device 100 as the first embodiment of the present invention will be described with reference to FIG. The signal processing device 100 is a device that generates a transmission waveform for detecting an object.

As shown in FIG. 1, the signal processing device 100 includes a transmission waveform generation unit 101, a transmission waveform change unit 102, and a transmission waveform arrangement unit 103. The transmission waveform generation unit 101 generates a frequency-modulated transmission waveform in order to generate a modulated wave whose frequency changes non-repetitively. The transmission waveform changing unit 102 changes the frequency modulation by the transmission waveform generation unit 101 so that the cross-correlation of the spectrogram 110 of the transmission waveform is equal to or less than the threshold Th. The transmission waveform arrangement unit 103 arranges the transmission waveform whose cross-correlation of the spectrogram 110 is equal to or less than the threshold value Th on a plurality of tiles 111 divided by the time axis and the frequency axis.

According to the present embodiment, by generating a transmission waveform in which the cross-correlation of the spectrograms of the transmission waveform is equal to or less than the threshold value, it is possible to detect many objects and directions by increasing the transmission waveforms that can be identified and used at the same time. In addition, it is possible to increase the number of radars that can be used at the same time while maintaining accuracy.

[Second Embodiment]
Next, the signal processing apparatus according to the second embodiment of the present invention will be described. The signal processing apparatus according to the present embodiment relaxes the limitation of generating a transmission waveform having a cross-correlation equal to or less than a threshold by generating a modulated waveform in which the frequency changes iteratively and a modulated waveform in which the frequency changes non-repetitively. do. Here, the modulated waveform whose frequency changes non-repetitively includes a waveform in which the modulation speed of the modulated waveform is changed and a waveform in which the bandwidth of the modulated waveform corresponding to the maximum frequency of the frequency to be added to the center frequency is changed. And so on. Such a modulated waveform whose frequency changes non-repetitively is below the threshold value even in autocorrelation. In addition, each generated transmit waveform is placed on multiple time-frequency tiles that divide a certain amount of time in the band allowed to be transmitted on the time axis and frequency axis, and the number of transmit waveforms is not limited, so accuracy. It is possible to detect various objects while maintaining the frequency.

<< Explanation of prerequisite technology >>
Before explaining the signal processing apparatus of this embodiment, the outline of the prerequisite technique and its problems will be described in order to clarify its characteristics.

FIG. 3 is a diagram showing an outline 300 of signal processing by a signal processing device according to a prerequisite technique. FIG. 3 is similar to FIG. 2 (Fig. 2) of Non-Patent Document 1, and a plurality of time-frequency tiles in which a transmission waveform divides a certain time in a band allowed to be transmitted by a time axis and a frequency axis. Is located in. Note that FIG. 2 of Non-Patent Document 1 shows an 8 × 8 time-frequency tile, while FIG. 3 shows a 6 × 6 time-frequency tile.

As shown in FIG. 3, in Non-Patent Document 1, waveforms with three types of selections are transmitted in each time-frequency tile. The three types of selection are that when the signal is not generated in the time-frequency tile, the frequency called Up-sweep LFM (Linear Frequency Modulation) rises, and when the FM wave is generated, the frequency called Down sweep LFM falls. There are three cases where FM waves are generated. Therefore, in the case of 64 tiles of 8 × 8, the maximum number of transmission waveform types is 3 × 64 = 192, and the number of transmission waveforms is further reduced when considering whether or not the waveforms can be adjacent to each other. There is a limit to the number of transmitted waveforms.

By the signal processing of this embodiment, the number of transmission waveforms that can be identified and used at the same time is increased, and many detection targets can be detected.

<< Explanation of the present embodiment >>
Hereinafter, the configuration and operation of the present embodiment for solving the problems of the above-mentioned prerequisite technique will be described.

<< Overview of signal processing >>
FIG. 2 is a diagram showing an outline 200 of signal processing by the signal processing device according to the present embodiment. FIG. 2 shows a spectrogram of the transmitted waveform in a 6x6 time-frequency tile.

In FIG. 2, in the same 6 × 6 time-frequency tile as in FIG. 3, in addition to Up-sweep LFM201 and Down sweep LFM202, SFM (Sinusoidal Frequency Modulation) transmission waveform 203 and transmission waveform with different modulation speeds in SFM are shown. 204, a transmission waveform 205 with a different bandwidth in SFM, is arranged. The number and arrangement of such transmitted waveforms are not limited to FIG. In reality, innumerable types of transmission waveforms can be placed on each tile, and if the cross-correlation is below the threshold value, even if multiple transmission waveforms are placed on the same tile, adjacent tiles can be placed. Can also be placed in.

That is, in the 6 × 6 time-frequency tile, it is possible to transmit different waveforms, which are preferably selected based on the detection target, in the number of 6 × 6 × (type of transmission waveform).

<< Functional configuration of signal processing equipment >>
FIG. 4A is a block diagram showing a functional configuration of the signal processing device 400 according to the present embodiment.

The signal processing device 400 includes a signal waveform generation unit 401. The signal waveform generation unit 401 includes a frequency modulation waveform generation unit 411, an initial phase designation unit 412, and a frequency designation unit 403. The transmission waveform is generated by the frequency modulation waveform generation unit 411. The frequency modulation waveform generation unit 411 receives the initial phase designation from the initial phase designation unit 412, and generates a transmission waveform based on the frequency information from the frequency designation unit 403.

The frequency designation unit 403 includes an addition unit 431, a frequency change unit 432, a modulation wave setting unit 433, and a time-frequency tile table 434. The addition unit 431 adds the modulation frequency information of the center frequency (fc (ti)) to the frequency (alfa (ti)) from the frequency change unit 432 and the modulation wave (beta (ti)) from the modulation wave setting unit 433. Is sent to the frequency modulation waveform generation unit 411. The frequency changing unit 432 provides a frequency (alfa (ti)) added by the adding unit 431 to the center frequency (fc (ti)) in order to linearly modulate the transmission waveform. When the modulated wave setting unit 433 modulates the transmitted waveform with a smooth waveform (particularly a sine wave), the modulated wave (beta (ti)) having a bandwidth added to the center frequency (fc (ti)) by the adder unit 431. )I will provide a. Here, the frequency (alfa (ti)) is a component that linearly modulates the transmission waveform, and the modulated wave (beta (ti)) is a component of a smooth waveform that modulates the transmission waveform. Note that the frequency (alfa (ti)) and the modulated wave (beta (ti)) are modulation of the transmission waveform by a non-zero component when either of them is zero. The time-frequency tile table 434 is used in association with each time-frequency tile when a certain time in the band allowed to be transmitted is divided into a plurality of time-frequency tiles on the time axis and the frequency axis. Memorize the waveform.

(Frequency change section and modulated wave setting section)
FIG. 4B is a block diagram showing a functional configuration of a frequency changing unit 432 and a modulated wave setting unit 433 of the signal processing device 400 according to the present embodiment.

The frequency changing unit 432 of the signal processing device 400 includes an adding unit 451 and a multiplying unit 452. The addition unit 451 adds the initial frequency f0 of each time-frequency tile and the linear modulation frequency (slope alfa0 * time ti) and sends it to the addition unit 431 of FIG. 4A. The multiplication unit 452 multiplies the slope alfa0 by the time ti. With such modulation frequency information, the transmission waveforms of the Up-sweep LFM201 and Down sweep LFM202 of FIG. 2 can be generated.

The modulation wave setting unit 433 of the signal processing device 400 includes a multiplication unit 453, a modulation wave generation unit 454, and a modulation wave generation unit 455. The modulated wave generation unit 454 generates a sine wave that controls the modulation of the SFM with an amplitude of “1” and sends it to the multiplication unit 453 of the modulation wave setting unit. The multiplication unit 453 multiplies the sine wave received from the modulation wave generation unit 454 by the bandwidth beta1 (ti) from the modulation wave generation unit 455 and sends the sine wave to the addition unit 431 in FIG. 4A. When the bandwidth beta1 (ti) is a constant value beta_n (n = 0 ... N), the modulation bandwidth due to the modulated wave is constant.

<< Method of generating a transmission waveform of this embodiment >>
The generation of the transmission waveform in the present embodiment in the configurations of FIGS. 4A and 4B is the generation of the linearly modulated transmission waveform shown in Non-Patent Document 1, the generation of the SFM transmission waveform, and the generation of the SFM transmission waveform. It is an appropriate combination of the generation of the transmission waveform with the change of the modulation speed and the change of the bandwidth of the SFM.

なお、式（１）において、alfa(ti)がゼロであり、beta1(ti)が一定値beta0の場合が、ＳＦＭである。ＳＦＭは、正弦波で正弦波を周波数変調した波形である。送信素子の共振周波数をキャリア周波数とし、キャリア周波数と比較して低い周波数の正弦波で周波数変調する。このキャリア周波数と比較して低い周波数の波形を、変調波と呼ぶ。ＳＦＭでは変調波は正弦波である。周波数変調の範囲は、送信素子の共振周波数を大きく外れないように設定する。このＳＦＭで発生される波形は、キャリア送信素子への負担が少なく、信号の電力を大きくすることができる。 In the present embodiment, the equation for generating the frequency f1 (ti) used for modulation is shown in equation (1), and an example of a pseudo program for generating a waveform by the equation is shown in equation (2). Here, * is multiplication, ti is the sample number (that is, time), f1 is the frequency of the modulated sine wave (transmission signal), fc (ti) is the center frequency, and alfa (ti) is the modulation frequency Up / Down, beta. (Ti) represents the bandwidth, pi represents the circumference ratio, M represents the number of modulations and sinusoidal modulations repeated during the length of the waveform, and len represents the length of the signal. sig (ti) is a transmission waveform, phi is a phase, fs is a sampling frequency, 1i is an imaginary unit, and exp is a complex exponential function. The same applies to other mathematical formulas and pseudo-programs for symbols and variables that are not specified.

In the equation (1), when alfa (ti) is zero and beta1 (ti) is a constant value beta0, it is SFM. SFM is a waveform obtained by frequency-modulating a sine wave with a sine wave. The resonance frequency of the transmitting element is set as the carrier frequency, and the frequency is modulated by a sine wave having a frequency lower than the carrier frequency. A waveform having a frequency lower than this carrier frequency is called a modulated wave. In SFM, the modulated wave is a sine wave. The range of frequency modulation is set so as not to deviate significantly from the resonance frequency of the transmitting element. The waveform generated by this SFM has less burden on the carrier transmission element, and can increase the power of the signal.

<< Signal processing system >>
FIG. 5 is a block diagram showing a configuration of a signal processing system 500 including a signal processing device 400 according to the present embodiment.

As shown in FIG. 5, the signal processing system 500 receives a signal processing device 400 as a transmitter for transmitting the transmission signal 531 and a reflection signal 532 obtained by reflecting the transmission signal 531 on the target object 530. It is equipped with a receiver 550. The receiver 550 detects the existence of the target object 530 and the distance to the target object 530 or the moving speed of the target object 530 based on the correlation between the transmission signal 531 and the reflection signal 532.

The signal processing device 400 as a transmitter includes a transmission waveform generation unit 401, a wireless transmission unit 501, and a transmission antenna 502. The receiver 550 includes a receiving antenna 552, a wireless receiving unit 555, a correlation calculation unit 554, an absolute value generation unit 555, and an output unit 556.

The transmission waveform generation unit 401 generates a transmission waveform and sends it to the wireless transmission unit 501, and also sends the transmission waveform to the correlation calculation unit 554. The wireless transmission unit 501 performs frequency conversion or the like on the transmission waveform, converts it into a wireless signal, and transmits it from the transmission antenna 502. The radio receiving unit 553 receives the reflected signal 532 obtained by reflecting the transmission signal 531 on the target object 530 via the receiving antenna 552, performs frequency conversion of the received radio signal, and performs a desired frequency. It is sent to the correlation calculation unit 554 as a received waveform of the band. The correlation calculation unit 554 calculates a cross-correlation function between the transmission waveform and the reception waveform, and sends it to the absolute value generation unit 555. The existence of the target object 530, the distance to the target object 530, and the moving speed of the target object 530 are detected based on the cross-correlation function output from the output unit 556 by the absolute value generation unit 555.

In the present embodiment, the transmitter is used as a signal processing device, but a device in which a transmitter and a receiver are integrated or a device composed of some constituent groups thereof is used as a signal processing device. May be good.

<< Hardware configuration of signal processing device >>
FIG. 6 is a block diagram showing a hardware configuration of the signal processing device 400 according to the present embodiment.

In FIG. 6, the CPU (Central Processing Unit) 610 is a processor for arithmetic control, and realizes the functional components of FIGS. 4A and 4B by executing a program. There may be a plurality of CPU 610s corresponding to each function. The ROM (Read Only Memory) 620 stores fixed data and programs such as initial data and programs. The network interface 630 controls communication with other devices via the network.

The RAM (Random Access Memory) 640 is a random access memory used by the CPU 610 as a temporary storage work area. The RAM 640 secures an area for storing data necessary for realizing the present embodiment. The transmission waveform generation table 641 is a table used to generate the transmission waveform of the present embodiment. The transmission waveform generation table 641 includes a transmission waveform generation parameter 642 used to generate a transmission waveform, a modulation frequency 643 generated using the transmission waveform generation parameter 642, and a transmission waveform generation parameter 642 and a modulation frequency 643. The generated transmission waveform 644 and the transmission waveform 644 are stored. The transmit selection tile 645 stores the time-frequency tiles used based on the time-frequency tile table 434. The transmission radio data 646 is data for transmission radio generated corresponding to the transmission waveform 644. The input / output data 647 is data that is input / output to / from the input / output device including the wireless transmission unit 501 via the input / output interface 660. The transmission / reception data 648 is data for transmission / reception to / from another device via the network interface 630.

The storage 650 stores a database, various parameters, and the following data or programs necessary for realizing the present embodiment. The time-frequency tile table 434 stores the transmission waveform of each time-frequency tile. The transmission waveform generation algorithm 651 is an algorithm that generates a transmission waveform from the transmission waveform generation parameter 642.

The following programs are stored in the storage 650. The signal processing device control program 652 is a program that controls the entire processing of the signal processing device 400 of the present embodiment. The tile control module 653 is a module that controls the assignment of the transmission waveform to the time-frequency tile. The transmission waveform generation module 654 is a module that generates a transmission waveform from the transmission waveform generation parameter 642 according to the transmission waveform generation algorithm 651. The wireless transmission module 655 is a module that controls transmission of a transmission waveform signal from the wireless transmission unit 501.

The input / output interface 660 provides an interface for controlling data input / output with an input / output device. In the present embodiment, the input / output interface 660 is connected to a wireless transmission unit 501 that transmits a signal to the transmission antenna 502. If the signal processing device 400 also has a function of detecting an object by receiving a reflected signal, a wireless receiving unit 553 that receives the reflected signal by the receiving antenna 552 may be connected. The input / output interface 660 may be further connected to a display unit 661 and an operation unit 662 in order to monitor and operate the operation of the signal processing device 400.

The RAM 640 and the storage 650 of FIG. 6 do not show programs or data related to general-purpose functions and other feasible functions of the signal processing device 400.

(Time-Frequency tile table)
FIG. 7A is a diagram showing the configuration of the time-frequency tile table 434 according to the present embodiment. The time-frequency tile table 434 is used to assign transmission waveforms to each time-frequency tile.

The time-frequency tile table 434 stores the tile time zone 702, the frequency band 703, and the assigned transmission waveform 704 in association with the tile ID 701.

(Transmission waveform generation table)
FIG. 7B is a diagram showing the configuration of the transmission waveform generation table 641 according to the present embodiment. The transmission waveform generation table 641 is used to generate the transmission waveform of the present embodiment. In FIG. 7B, the same reference numbers are assigned to the same components as those in FIG.

The transmission waveform generation table 641 stores the transmission waveform generation parameter 642, the modulation frequency 643, and the transmission waveform 644. The transmission waveform generation parameter 642 includes the center waveform fc (ti), the modulation gradient (alfa (ti)), the initial frequency (f0), the bandwidth beta1 (ti), the number of repetitions Mu (ti), and the signal length. Includes len and initial phase (phi). It also includes the maximum bandwidth beta0, which is the parameter 745 for generating the bandwidth beta1 (ti), and the bandwidth change parameters c1 and C2.

<< Processing procedure of signal processing device >>
FIG. 8 is a flowchart showing a processing procedure of the signal processing device 400 according to the present embodiment. This flowchart is executed by the CPU 610 of FIG. 6 using the RAM 640 to realize the functional components of FIGS. 4A and 4B.

In step S801, the signal processing apparatus 400 selects a tile to be used to generate a transmission waveform from a plurality of time-frequency tiles divided by a time axis and a frequency axis. The signal processing device 400 specifies the transmission waveform in each selected tile to be used in step S803.

The signal processing device 400 selects one tile from the plurality of selected tiles in step S805. Then, it is determined whether the transmission waveform of the tile is designated as linear modulation or modulation by the modulated wave. When designated as linear modulation, the signal processing apparatus 400 performs modulation with fc (ti) + alfa (ti) as the modulation frequency in step S809.

On the other hand, when it is designated as modulation by a modulated wave, the signal processing apparatus 400 determines in step S811 whether or not to change the bandwidth in the spectrogram of the transmission waveform. When changing the bandwidth, the signal processing apparatus 400 modulates in step S813 with beta (ti) due to the changing bandwidth of beta1 (ti) as the modulation frequency. Further, when the bandwidth is not changed, the signal processing apparatus 400 modulates in step S815 with beta (ti) having the unchanged bandwidth of beta0 as the modulation frequency (this corresponds to the SFM transmission waveform).

In step S817, the signal processing device 400 determines whether or not the generation of the transmission waveform for the designated tile is completed. If the generation of the transmission waveform has not been completed, the signal processing apparatus 400 generates the transmission waveform for the next tile from step S805. When the generation of the transmission waveform for the designated tile is completed, the signal processing device 400 executes the wireless transmission process based on the transmission waveform generated in each tile in step S819.

<< Example of generation of each transmission waveform >>
Hereinafter, with reference to FIGS. 9A to 17, some of the transmission waveforms in the various tiles generated in the present embodiment are shown.

(0th operation)
In the signal processing device 400 of FIG. 4A, when the output beta (ti) from the modulation wave setting unit 433 is set to zero, only the linear frequency alfa (ti) from the frequency change unit 432 is the frequency modulation waveform generation unit as the modulation frequency. Provided at 411. In this case, when the slope alfa0 of FIG. 4B is positive, the Up-sweep LFM201 of FIG. 2 is generated, and when the slope alfa0 is negative, the Down-sweep LFM202 of FIG. 2 is generated.

(First operation)
In the signal processing device 400 of FIG. 4A, when the output alfa (ti) from the frequency changing unit 432 is set to zero, only the modulated wave beta (ti) from the modulation wave setting unit 433 is used as the modulation frequency in the frequency modulation waveform generation unit 411. Provided to. In the first operation, the case of the so-called transmission waveform 203 of the SFM of FIG. 2 in which the bandwidth does not change in the spectrogram of the transmission waveform is shown.

The modulation frequency f1 (ti) in the first operation is generated according to the equation (3).

FIG. 9A is a block diagram showing a functional configuration of the signal processing device 400 according to the present embodiment during the first operation. In FIG. 9A, the same reference numbers are assigned to the functional components similar to those in FIG. 4A, and duplicate description will be omitted. At the time of the first operation, only the modulated wave beta (ti) from the modulated wave setting unit 933 is provided as the modulation frequency by the frequency designation unit 903 to the frequency modulation waveform generation unit 411.

FIG. 9B is a block diagram showing a functional configuration of the modulated wave setting unit 933 at the time of the first operation of the signal processing device 400 according to the present embodiment. In FIG. 9B, the same reference numbers are assigned to the functional components similar to those in FIG. 4B, and duplicate description will be omitted. A constant value bandwidth beta0 is input to the multiplication unit 453 of the modulation wave setting unit 933.

FIG. 10A is a diagram showing a spectrogram 1010 of a transmission waveform during the first operation according to the present embodiment. Here, exemplary, the center frequency fc is 1 GHz, the modulation bandwidth beta0 is plus or minus 5 MHz, the waveform length is 100 μSec, and the number of repetitions M is 16.5. The sampling frequency fs was set to 3 GHz. The waveform length len is 300,000 samples. The horizontal axis is time and the vertical axis is frequency. You can see on the spectrogram that the frequency draws a sine wave. That is, the spectrogram represents a change in the frequency of the transmitted signal.

ここでA(τ,v)は曖昧度関数、τは時間差、vは周波数偏移量（ドップラー効果）、U(t)は波形を時刻tについて表現したものである。*は複素共役、eは対数の底、iは虚数単位、πは円周率をそれぞれ表す。 Since SFM has a sharp peak in the correlation function, the position detection accuracy is high. Also, the Doppler detection capability is not low. Therefore, it is used in radar and the like. However, since there is a correlation in the section where the frequency modulation waveforms are similar, a peak called a side lobe or a grating lobe may occur in the correlation function in addition to the peak of the true correlation. This sidelobes and grating lobes are confirmed by a display called the auto ambiguity function. The self-ambiguity function is defined by the equation (4), for example, as described in [Non-Patent Document 2].

Here, A (τ, v) is the ambiguity function, τ is the time difference, v is the frequency shift amount (Doppler effect), and U (t) is the waveform expressed for time t. * Is the complex conjugate, e is the base of the logarithm, i is the imaginary unit, and π is the pi.

FIG. 10B is a diagram showing a self-ambiguity function 1020 of the transmission waveform at the time of the first operation according to the present embodiment. In FIG. 10B, the vertical axis represents frequency deviation (corresponding to moving speed), the horizontal axis represents time difference (corresponding to distance), and brightness is the value of the correlation function. Tracing on the horizontal axis passing through the origin, the density becomes a correlation function when the moving speed of the target object is “0”. Ideally, there should be a bright (high) part only in the center and a low part otherwise. It can be seen that FIG. 10B is close to the ideal when looking only at the region near the central portion. However, some peaks other than the origin on the vertical axis are sidelobes. Not expensive enough to be a problem here.

(Second operation)
In the second operation, the case of the transmission waveform 205 of the SFM of FIG. 2 in which the bandwidth changes in the spectrogram of the transmission waveform is shown. That is, in this second operation, the method of changing the frequency of the modulated sine wave of SFM is further modulated. As a method of changing the frequency of the modulated sine wave, it is desirable to make a smooth change. Smooth changes include gradually narrowing and then widening the modulation bandwidth, gradually widening and then narrowing, gradually narrowing, gradually widening, and gradually increasing the overall bandwidth. There are methods such as gradually lowering the entire bandwidth, gradually changing both wide and narrow bandwidth and high and low bandwidth. In this second operation, the modulation bandwidth is gradually narrowed and then widened.

The modulation frequency f1 (ti) in the first operation is generated according to the equation (5). In equation (5), compared to equation (3), the bandwidth beta0 of frequency f1 was a constant, whereas {(c1 + c2 * cos (2 * pi * ti / (len))) / (c1 + c2)} changes over time. The maximum bandwidth of the entire waveform remains beta0. Mu (ti) in the equation (1) is a constant M.

FIG. 11 is a block diagram showing a functional configuration of the modulated wave setting unit 1133 at the time of the second operation of the signal processing device 400 according to the present embodiment. Since FIG. 11 is the same as the modulation wave setting unit 433 of FIG. 4B, overlapping description will be omitted.

FIG. 12A is a diagram showing an example of the spectrogram 1210 of the transmission waveform during the second operation according to the present embodiment. The spectrogram 1210 is a spectrogram of the transmission waveform generated according to the equation (6). Here, c1 = 2 and c2 = 1. In FIG. 12A, it can be seen that the spectrogram (frequency change) has a sinusoidal modulation similar to SFM, but the bandwidth of the frequency change gradually narrows and then widens.

FIG. 12B is a diagram showing a self-ambiguity function 1220 of the transmission waveform during the second operation according to the present embodiment. FIG. 12B is a self-ambiguity function of the waveform of the spectrogram of FIG. 12A, and the effect of the present embodiment is analyzed from the ambiguity function. It can be seen that the ambiguity function at the time of the second operation is high near the origin and the correlation coefficient is small in other parts. Looking at the correlation function along the horizontal axis passing through the origin, we can see that there are almost no sidelobes or grating lobes. Even if you look at the correlation function along the vertical axis passing through the origin, there are few points where the correlation function other than the origin is high. This ambiguity function means that false positives can be reduced.

That is, by modulating the bandwidth, the waveform correlation changes. As a result, it is possible to have a single peak in the self-ambiguity function, that is, to improve the accuracy of the velocity and position of the object to be detected. Further, in the self-ambiguity function, the effect that the self-ambiguity function can be obtained by lowering the grating lobe and increasing the detection accuracy of the position and the speed can be obtained. In addition, by changing the arbitrary function, it is possible to obtain a waveform having a small cross ambiguity function, that is, a waveform having little cross-correlation, and it is possible to increase the choice of waveforms in the time-frequency tile.

According to the transmission waveform of FIG. 12A, the frequency of the modulated sine wave (f1 (ti)) is changed with time to change the bandwidth of the frequency modulation to suppress the height of the correlation function, thereby generating a grating lobe. Can be suppressed and the object can be detected accurately.

That is, as shown in Eq. (5), by changing the amplitude beta1 (ti) of the modulated sine wave with time, the modulation bandwidth appearing in the spectrogram of FIG. 4A is continuously changed. , This complex change changes the ambiguity function in the desired direction.

The waveform of the second operation can be easily distinguished from other waveforms by slightly changing the parameters, and has the effect of increasing the choice of waveforms within the time-frequency frame.

ここで、U1(t)とU2(t)とは相互相関をとる波形である。U1(t)とU2(t)とが同一である場合が自己曖昧度関数である。曖昧度関数は、時間の軸（time）と周波数偏移量（doppler）の軸を有する。 In order to show this, whether or not the waveform of FIG. 12A is easily distinguishable from other waveforms is evaluated by a function called the mutual ambiguity function expressed by the following equation (6), and it is sufficiently easy to distinguish. confirmed.

Here, U1 (t) and U2 (t) are cross-correlated waveforms. The self-ambiguity function is when U1 (t) and U2 (t) are the same. The ambiguity function has an axis of time and an axis of frequency offset (doppler).

The difference between equation (4) and equation (6) is that different functions U1 and U2 are used as U. Equivalent to calculating the reciprocal similarity between another function U1 and U2. If this value is small overall, it means that U1 and U2 are dissimilar, that is, distinguishable, even if they are staggered or have a Doppler effect.

Since the shape of the spectrogram of the waveform differs greatly between the waveform of FIG. 12A and LFM or CW (continuous wave), the mutual ambiguity function is less than "0.1" in all cases. This means that it is easy to distinguish waveforms. It is possible to use the waveform of FIG. 12A as one of the options in the time frequency frame, and the increase in the options means that even when many waveforms are received at the same time, it is possible to process them separately. It means that the effect can be obtained. Further, when the waveform of FIG. 12A is used, it is easy to distinguish by the cross-correlation function even when there is only one frame of time frequency.

ここで、繰り返しの速さＭは“11.5”とした。 FIG. 12C is a diagram showing another example 1230 of the spectrogram of the transmission waveform during the second operation according to the present embodiment. In the example of FIG. 12C, similarly to FIG. 12A, the bandwidth of the modulated sine wave is gradually narrowed and then widened, but the timing of narrowing is different. The equation for changing the timing is shown in equation (7). In beta (ti) that determines the modulation width, the timing is off due to the term (pi / 4). The amount that determines the timing of shifting does not have to be limited to (pi / 4).

Here, the repetition speed M is set to "11.5".

According to the transmission waveform of FIG. 12C, even if the timing of gradually narrowing the bandwidth of the modulated sine wave is changed, the height of the correlation function is suppressed to suppress the generation of the grating lobe and detect the object with high accuracy. be able to.

ここでは、一例としてＭ=11.5、c1=2、c2=1とした。 FIG. 12D is a diagram showing still another example 1240 of the spectrogram of the transmission waveform during the second operation according to the present embodiment. This example is characterized in that the bandwidth of the modulated sine wave is gradually widened and then narrowed. The equation that generates the waveform is shown in Equation (8). Compared with the equation (5), the positive and negative signs of c2 are different.

Here, as an example, M = 11.5, c1 = 2, and c2 = 1.

According to the transmission waveform of FIG. 12D, even if the bandwidth of the modulated sine wave is gradually widened and then narrowed, the height of the correlation function is suppressed to suppress the generation of grating lobes and accurately detect the object. be able to.

この式（９）と式（５）とを比較すると、式（５）では、波形長の間の帯域幅の増減の回数が１回であったのに対して、式（９）では、波形長の間に帯域幅がＲ回増減する。ここでは、Ｍを“16.5”、Ｒを“3”にしており、図１２Ｅのスペクトルグラムを見るとわかるように、変調正弦波の変調幅の増減回数が３回である。また、波形全体の帯域幅の最大値はプラスマイナス５MHzに保たれていることが分かる。 The transmission waveform of FIG. 12E is a diagram showing still another example 1250 of the spectrogram of the transmission waveform at the time of the second operation according to the present embodiment. This example is characterized in that the speed of the modulated sine wave is further increased. The equation for generating the transmission waveform of this embodiment is shown in Equation (9).

Comparing the equation (9) and the equation (5), in the equation (5), the number of times of increase / decrease of the bandwidth during the waveform length was once, whereas in the equation (9), the waveform. Bandwidth increases or decreases R times during the length. Here, M is set to "16.5" and R is set to "3", and as can be seen from the spectrum gram of FIG. 12E, the number of times the modulation width of the modulated sine wave is increased or decreased is three times. Further, it can be seen that the maximum value of the bandwidth of the entire waveform is maintained at plus or minus 5 MHz.

According to FIG. 12E, since it is asymmetric even if similar waveforms are repeated, it is possible to suppress the generation of grating lobes and accurately detect an object by suppressing the height of the correlation function.

(Third operation)
FIG. 13 is a block diagram showing a functional configuration of the modulated wave setting units 1333 and 1334 during the third operation of the signal processing device 400 according to the present embodiment. In FIG. 13, the same reference number is assigned to the same functional component as in FIG. 4B or FIG. 9B, and duplicate description will be omitted.

The modulation wave setting units 1333 and 1334 of the signal processing device 400 further include a modulation speed generation unit 1356. In the third operation, the modulation speed in the modulation wave generation unit 454 is further modulated by the modulation speed Mu (ti) generated by the modulation speed generation unit 1356. The third operation of the present embodiment is characterized in that not only the bandwidth of the modulated sine wave is changed, but also the modulation speed of the modulated sine wave is changed.

In the configuration of the modulation wave setting unit 1333, the bandwidth is constant and the modulation speed changes. On the other hand, in the configuration of the modulation wave setting unit 1334, the bandwidth also changes and the modulation speed also changes. The spectrogram of the transmission waveform generated by the configuration of the modulated wave setting unit 1334 is shown below.

FIG. 14A is a diagram showing an example 1410 of a spectrogram of a transmission waveform during a third operation according to the present embodiment. It can be seen that the modulation bandwidth of the spectrogram gradually decreases and then increases, but the frequency of the sine wave, which represents the frequency change of the spectrogram, gradually increases.

The equation that generates the transmission waveform of this example is shown in equation (10). In equation (10), the constant M in equation (5) is changed to the time-varying function Mu (ti) in order to change the velocity of the modulated sine wave. Here, Mu (ti) is a cubic polynomial of ti, but higher-order polynomials, exponential functions, logarithmic functions, trigonometric functions, and other arbitrary functions can be used. The effect of the velocity change of the modulated sine wave has the effect of reducing the mutual ambiguity function, further increasing the variation.

As a method of changing the frequency of the modulated sine wave in the present embodiment, it is desirable to make a smooth change. Smooth changes include gradual speeding up, gradual slowing down, gradual speeding up and then slowing down, gradual slowing down and then speeding up, etc. The case will be described as an example. As an example, M0 = 7, M1 = 2.5, M2 = 2, and M3 = 0.

FIG. 14B is a diagram showing another 1420 example of the spectrogram of the transmission waveform at the time of the third operation according to the present embodiment. It can be seen that the modulation bandwidth of the spectrogram gradually increases and then decreases, but the frequency of the sine wave, which represents the frequency change of the spectrogram, gradually increases.

本例においても、徐々に速くしていく場合を例に説明する。その一例として、Ｍ0=7、Ｍ1=2.5、M2=2、Ｍ3=0とした。 The equation that generates the transmission waveform of this example is shown in Equation (11). In the equation (11), the constant M in the equation (8) of the fifth embodiment is changed to the time-varying function Mu (ti) in order to change the velocity of the modulated sine wave. Here, Mu (ti) is a cubic polynomial of ti, but higher-order polynomials, exponential functions, logarithmic functions, trigonometric functions, and other arbitrary functions can be used. The effect of the velocity change of the modulated sine wave has the effect of reducing the mutual ambiguity function, further increasing the variation.

Also in this example, the case of gradually increasing the speed will be described as an example. As an example, M0 = 7, M1 = 2.5, M2 = 2, and M3 = 0.

In this example, the modulation speed is gradually increased, but it can also be used in methods such as gradually slowing down, gradually increasing the speed and then slowing down, and gradually slowing down and then speeding up. It has the same effect.

According to the third operation, the height of the correlation function is further suppressed by changing the modulation speed in addition to the change in the modulation width, so that the generation of the grating lobe can be suppressed and the object can be detected accurately.

That is, as shown in the equations (10) and (11), the angular frequency representing the frequency modulation f1 of the sine wave is changed by a higher-order function with respect to the time ti / len. By continuously and unidirectionally changing the frequency of the modulation appearing in the spectrogram (here, the direction in which the frequency increases), the ambiguity function is changed in the desired direction.

(4th operation)
FIG. 15 is a block diagram showing a functional configuration of the modulated wave setting units 1533 and 1534 during the fourth operation of the signal processing device 400 according to the present embodiment. In FIG. 15, the same reference numbers are assigned to the functional components similar to those in FIG. 4B, and duplicate description will be omitted.

The difference from FIGS. 4A and 4B of FIG. 15 is that in the modulation wave setting units 1533 and 1534, the addition unit 431 of FIG. 4A is replaced with the addition unit of 4 inputs, and the modulation generated by the modulation wave generation unit 1554 there. A modulated wave obtained by multiplying the wave by the bandwidth beta2 by the multiplying unit 1553 is newly input. As a result, new modulation is added.

FIG. 16A is a diagram showing an example 1610 of a spectrogram of a transmission waveform during the fourth operation according to the present embodiment. Here, beta1 = 10/3 [MHz], beta2 = 5/3 [MHz], and M2 = 1/2. It can be seen that the maximum value of the bandwidth of the entire waveform is maintained at plus or minus 5 MHz. Similar to SFM, the spectrogram (frequency change) has a sinusoidal modulation, but it can be seen that the entire bandwidth of the sinusoidal wave representing the frequency change is gradually reduced. Since the modulated sine wave is further modulated, there are few parts where the curves of the modulated sine wave match. This reduces the cross-correlation.

この式（１２）は、式（１）と比較して、変調の帯域幅をbeta0からbeta1に変更し、さらに“beta2*cos(2*pi*M2*ti/(len))”による新たな変調を加えた形である。Ｍ2は新たに加えた変調の回数である。beta1+beta2 = beta0とすることで、波形全体での帯域幅の最大値はbeta0に保つことができる。 The signal generation method according to this example is characterized in that the center of the modulation band of SFM moves. Equation (12) shows an equation expressing the frequency for generating the transmission waveform of this example. Others are the same as the previous equations, so detailed explanations of the same symbols and variables will be omitted.

This equation (12) changes the modulation bandwidth from beta0 to beta1 as compared with equation (1), and is newly added by "beta2 * cos (2 * pi * M2 * ti / (len))". It is a modulated form. M2 is the number of newly added modulations. By setting beta1 + beta2 = beta0, the maximum bandwidth of the entire waveform can be kept at beta0.

According to the transmission waveform of FIG. 16A, the height of the correlation function can be suppressed by moving the center of the modulation width without changing the modulation width, the generation of grating lobes can be suppressed, and the object can be detected accurately. can do.

FIG. 16B is a diagram showing another example 1620 of the spectrogram of the transmission waveform at the time of the fourth operation according to the present embodiment. As can be seen from the spectral gram of FIG. 16B, both the modulation width and the center of the modulated sine wave are further modulated. It can also be seen that the maximum value of the bandwidth of the entire waveform is maintained at plus or minus 5 MHz.

In this example, both the modulation width and the center of the modulated sine wave are further modulated. The equation that generates the waveform of this example is shown in equation (13).

(Fifth operation)
FIG. 17 is a block diagram showing a functional configuration of the modulated wave setting unit 1733 at the time of the fifth operation of the signal processing device 400 according to the present embodiment. In FIG. 17, the same reference numbers are assigned to the functional components similar to those in FIG. 4B or FIG. 13, and duplicate explanations will be omitted.

The difference between FIG. 17 and FIGS. 4A and 4B is that the addition unit 431 is replaced with the addition unit of a plurality of inputs so that a large number of inputs can be added. Further, it has a plurality of modulation blocks including a modulation wave generation unit 454, a modulation wave generation unit 455, a modulation speed generation unit 1356, and a multiplication unit 453, and sends modulation information to the addition unit. This difference allows complex modulations to be applied, resulting in a self-ambiguity function producing more desirable waveforms or a larger number of candidate waveforms with smaller mutual ambiguity functions. ..

That is, it is also possible to increase the number of terms to complicate the modulation as in Eq. (14).

When the frequency modulation is fast, the spectrum is widened and there are many frequency components that exceed the modulation bandwidth. It should be noted that the spread of the spectrum may be a burden on the transmitting element, or frequency components exceeding the allowable band may be generated and interfere with other devices. In order to suppress the spread of the spectrum, in order to suppress the spread of the spectrum at the start and end of the waveform or at the sudden change part of the modulated waveform, not only windowing (taper processing, also called Raised Cosine processing) but also through a band limiting filter May be good.

According to the configuration of FIG. 17, even by changing the modulation width by combining various modulation waveforms, the generation of the grating lobe can be suppressed and the object can be detected accurately by suppressing the height of the correlation function. ..

According to the present embodiment, a large number of objects and directions can be detected by increasing the transmission waveforms that can be identified and used at the same time by generating the transmission waveforms in which the modulation speed is changed and the transmission waveforms in which the bandwidth is changed. Can be done. In addition, it is possible to increase the number of radars that can be used at the same time while maintaining accuracy.

[Third Embodiment]
Next, the signal processing apparatus according to the third embodiment of the present invention will be described. The signal processing apparatus according to the present embodiment is different from the second embodiment in that the transmission waveform is frequency-modulated so that the spectral grams between adjacent time-frequency tiles are smoothly connected. Since other configurations and operations are the same as those in the second embodiment, the same configurations and operations are designated by the same reference numerals and detailed description thereof will be omitted.

<< Overview of signal processing >>
FIG. 18A is a diagram showing an outline 1800 of signal processing by the signal processing apparatus according to the present embodiment. FIG. 18A shows a spectrogram of the transmitted waveform in a 6x6 time-frequency tile.

In FIG. 18A, in addition to the Up-sweep LFM201 and Down sweep LFM202, the transmission waveform 203 of SFM (Sinusoidal Frequency Modulation) and the modulation speed in SFM are changed in the same 6 × 6 time-frequency tile as in FIGS. 2 and 3. The transmission waveform 204 and the transmission waveform 205 with different bandwidths in the SFM are arranged. In addition, for example, Up-sweep LFM1801, Down sweep LFM1802, and other transmitted waveforms 1803-1805 are smoothly connected using taper processing between adjacent time-frequency tiles. The transmitted waveform that is smoothly connected between adjacent time-frequency tiles using taper processing is not limited to FIG. 18A. In reality, innumerable types of transmission waveforms can be placed on each tile, and if the cross-correlation is below the threshold value, even if multiple transmission waveforms are placed on the same tile, adjacent tiles can be placed. Can also be placed in.

That is, in the 6 × 6 time-frequency tile, it is possible to transmit different waveforms of 6 × 6 × (type of transmission waveform) × (type of spectrogram connection between adjacent tiles), which are suitably selected based on the detection target. Is.

FIG. 18B is a diagram illustrating signal processing by the signal processing apparatus according to the present embodiment. In FIG. 18B, the left 1810 shows the normal taber treatment, and the right 1820 shows the overlapping taber treatment of the present embodiment.

The taper processing is performed by gradually increasing the amplitude at the beginning of the waveform and gradually decreasing the amplitude at the end of the waveform, as shown in the left 1810 of FIG. 18B, so that the beginning and end of the waveform, that is, time-frequency. This is a process for reducing the wide-band component generated at the connection portion of the tile. Since the amplitude is small at the beginning and end of the waveform in the taper processing, the time-frequency tiles can be packed in the time direction by overlapping these time intervals as shown in 1820 on the right side of FIG. 18B. As a result, it is possible to further increase the distinguishable transmission waveforms by providing more time-frequency tiles within the same time.

<< Functional configuration of signal processing equipment >>
FIG. 19 is a block diagram showing a functional configuration of the signal processing device 1900 according to the present embodiment. In FIG. 19, the same reference numbers are assigned to the functional components similar to those in FIG. 4A, and duplicate description will be omitted.

The time-frequency tile table 1934 stores the processing for each tile of the adjacent time-frequency tiles in this embodiment. The inter-tile connection 1935 smoothly connects spectrograms between specified adjacent time-frequency tiles by taber processing.

(Time-Frequency tile table)
FIG. 20 is a diagram showing the configuration of the time-frequency tile table 1934 according to the present embodiment. The time-frequency tile table 1934 is used to assign transmission waveforms to each time-frequency tile and to connect spectrograms of adjacent time-frequency tiles. In FIG. 20, the same components as those in FIG. 7A are designated by the same reference numbers, and duplicate description will be omitted.

The time-frequency tile table 1934 associates with tile ID 701 and stores a flag 2005 as to whether or not to connect the spectrogram of the transmit waveform in the tile with the spectrogram of the transmit waveform in the adjacent tile.

<< Processing procedure of signal processing device >>
FIG. 21 is a flowchart showing a processing procedure of the signal processing apparatus 1900 according to the present embodiment. In FIG. 21, the same steps as in FIG. 8 are assigned the same step numbers, and duplicate description is omitted.

In step S2105, the signal processing apparatus 1900 determines whether or not the transmission waveform is arranged in the adjacent time-frequency tile. If the transmit waveforms are located on adjacent time-frequency tiles, the signal processor 1900 instructs in step S2106 to connect the spectrograms by taper processing.

According to the present embodiment, the time-frequency tiles can be packed in the time direction by overlapping the time intervals. As a result, it is possible to further increase the distinguishable transmission waveforms by providing more time-frequency tiles within the same time.

[Fourth Embodiment]
Next, the signal processing apparatus according to the fourth embodiment of the present invention will be described. Compared with the second embodiment and the third embodiment, the signal processing apparatus according to the present embodiment has a plurality of times-time adjacent to each other by selecting frequency tiles-in order to make the spectrum gram a single stroke that smoothly connects the spectrum grams. It differs in that it frequency-modulates the transmitted waveform so that the spectral grams are smoothly connected between frequency tiles. Since other configurations and operations are the same as those of the second embodiment or the third embodiment, the same configurations and operations are designated by the same reference numerals and detailed description thereof will be omitted.

<< Overview of signal processing >>
FIG. 22 is a diagram showing an outline 2200 of signal processing by the signal processing apparatus according to the present embodiment.

In the present embodiment, the time-frequency tiles are adjacent, and in the waveform in the time-frequency tile, the last frequency in the time in the tile becomes the same as the first frequency in the next time-frequency tile. There is a feature. In the spectrum gram 2201 of FIG. 22, since the frequencies are smoothly connected and there is no sudden change in amplitude, a wide band component is unlikely to occur at the connection portion of the time-frequency tile. The waveform in the time-frequency tile does not have to be tapered. Although the combination of time-frequency tiles is limited, it is not necessary to apply a taper, so a large amount of power can be transmitted.

The transmission waveform of the time-frequency tile in the present embodiment is designed with a constraint that the frequency can be smoothly connected to the adjacent time-frequency tile. If time-frequency tiles can overlap, it can be easily designed by simply connecting them.

<< Functional configuration of signal processing equipment >>
FIG. 23 is a block diagram showing a functional configuration of the signal processing device 2300 according to the present embodiment. In FIG. 23, the same reference numbers are assigned to the functional components similar to those in FIGS. 4A and 19, and duplicate description will be omitted.

The signal processing device 2300 further includes a tile designation unit 2336. The tile designation unit 2336 selects a time-frequency tile for making the spectral gram a single stroke that connects smoothly, and notifies the tile-to-tile connection unit 1935.

(Time-Frequency tile table)
FIG. 24 is a diagram showing the configuration of the time-frequency tile table 2334 according to the present embodiment. The time-frequency tile table 2334 assigns transmission waveforms to each time-frequency tile, selects the time-frequency tile to make the spectrum gram a smooth connection, and connects the spectrograms of the adjacent time-frequency tiles. Used to do. In FIG. 24, the same reference numbers as those in FIG. 7A are assigned the same reference numbers, and duplicate description will be omitted.

The time-frequency tile table 2334 is associated with the tile ID 701 and is a connection destination for connecting the time-frequency tile selection order 2405 and the spectrogram of the transmission waveform in the tile to make the spectrum gram into a single stroke that connects smoothly. Tile ID 2406 and is stored.

<< Processing procedure of signal processing device >>
FIG. 25 is a flowchart showing a processing procedure of the signal processing device 2300 according to the present embodiment. In FIG. 25, the same steps as those in FIGS. 8 and 21 are assigned the same step numbers, and duplicate description is omitted.

In step S2500, the signal processing device 2300 determines whether or not the spectrograms are continuously connected as shown in FIG. If the spectrograms are connected in succession, the signal processor 2300 selects the time-frequency tile in step S2501 so that the spectrogram is a single stroke.

According to this embodiment, since there is no sudden change in amplitude, a wide band component is unlikely to occur at the connection portion of the time-frequency tile, and the waveform in the time-frequency tile does not have to be tapered, so that it is large. Can transmit power.

[Other embodiments]
By generating the transmission waveform of the present embodiment, it is possible to superimpose the transmission waveform so far. Since each transmitted waveform is a waveform that can be easily distinguished, it is easy to separate them even if they are superimposed. It is also possible to properly design the ease of distinction by combining superpositions. In particular, when a waveform with the modulation direction reversed is superimposed, in addition to the effect of the present invention, the ambiguity function becomes symmetric in the velocity direction with respect to the axis of velocity 0 (zero), and the correlation function is synthesized. This has the effect of facilitating processing such as lowering the sensitivity to a specific speed. Further, in the above embodiment, the SFM waveform is used as the transmission waveform that changes the bandwidth, but the present invention is not limited to these waveforms. Other phase-modulated signals may be used.

Further, FIG. 26 is a diagram showing other fields in which the present invention can be used. As shown in FIG. 26, the object detection methods described above include a technique 2610 for robots to pass each other without colliding with each other, a vehicle collision avoidance technique 2620, an artificial satellite collision avoidance technique, and an observation technique on the earth 2630. Can be used for. However, the present invention is not limited to these, and can be used for monitoring intruders in offices and the like, and for detecting human movements in gymnasiums. The present invention can be used for both an object detection method using radio waves in the air and an object detection method using sound waves in the air or water, but is more suitable for object detection using sound waves because of the frequency of the transmitted wave. The present invention can be applied to the principle of a distance detection method using a sound wave called Active Sonar in underwater monitoring such as a harbor. Therefore, if the center frequency (carrier frequency), waveform time length, modulated wave frequency, frequency correction amount, etc. suitable for the sound wave are appropriately set, the effect of the present invention can be obtained in the same manner. As described above, by using the present invention in the distance detection, it is possible to detect a moving object with a small error in the distance measurement.

Further, although the invention of the present application has been described with reference to the embodiments, the invention of the present application is not limited to the above-described embodiment. Various changes that can be understood by those skilled in the art can be made within the scope of the present invention in terms of the configuration and details of the present invention. Also included in the scope of the present invention are systems or devices in which the different features contained in each embodiment are combined in any way. That is, the same effect can be obtained by arbitrarily combining the changes in the bandwidth of each of the above embodiments.

Further, the present invention may be applied to a system composed of a plurality of devices, or may be applied to a single device. Furthermore, the present invention is also applicable when the signal processing program that realizes the functions of the embodiment is supplied directly or remotely to the system or device. Therefore, in order to realize the functions of the present invention on a computer, a program installed on the computer, a medium containing the program, and a WWW (World Wide Web) server for downloading the program are also included in the scope of the present invention. .. In particular, at least a non-transitory computer readable medium containing a program for causing a computer to execute the processing steps included in the above-described embodiment is included in the scope of the present invention.

[Other expressions of the embodiment]
Some or all of the above embodiments may also be described, but not limited to:
(Appendix 1)
In order to generate a modulated wave whose frequency changes non-repetitively, a transmission waveform generation means for generating a frequency-modulated transmission waveform and a transmission waveform generation means.
A transmission waveform changing means that changes the frequency modulation by the transmission waveform generation means so that the cross-correlation of the spectrograms of the transmission waveform is equal to or less than the threshold value.
A transmission waveform arrangement means for arranging transmission waveforms whose spectrogram cross-correlation is equal to or less than a threshold value on a plurality of tiles divided by a time axis and a frequency axis.
A signal processing device.
(Appendix 2)
The signal processing device according to Appendix 1, wherein the transmission waveform changing means changes the frequency modulation by the transmission waveform generation means so that the autocorrelation of the spectrogram of the transmission waveform is equal to or less than a threshold value.
(Appendix 3)
The signal processing device according to Appendix 1 or 2, wherein the transmission waveform arranging means arranges an appropriate spectrogram transmission waveform at positions on the time axis and the frequency axis of each tile.
(Appendix 4)
The signal processing device according to any one of Supplementary note 1 to 3, wherein the transmission waveform changing means performs taper processing for smoothly connecting spectrograms between adjacent tiles.
(Appendix 5)
The signal processing device according to any one of Supplementary note 1 to 4, wherein the transmission waveform arranging means sequentially selects adjacent tiles so that the spectrogram is written in one stroke.
(Appendix 6)
The signal processing device according to any one of Supplementary note 1 to 5, wherein the transmission waveform changing means changes the bandwidth of the frequency modulation in the transmission waveform generating means.
(Appendix 7)
The signal processing apparatus according to Appendix 6, wherein when the transmission waveform generation means generates an SFM (Sinusoidal Frequency Modulation) waveform that has been frequency-modulated with a sine wave, the SFM waveform is further modulated by the transmission waveform changing means.
(Appendix 8)
The signal processing apparatus according to Appendix 6 or 7, wherein the frequency modulation bandwidth is modulated and changed by a smoothly changing waveform, and a sine wave is included as the smoothly changing waveform.
(Appendix 9)
The signal processing apparatus according to any one of Supplementary note 6 to 8, wherein the frequency modulation bandwidth is narrowed and then modulated to be widened, or the frequency modulation bandwidth is widened and then modulated to be narrowed. ..
(Appendix 10)
The signal processing apparatus according to any one of Supplementary note 6 to 9, wherein the center of the bandwidth of the frequency modulation is modulated so as to move.
(Appendix 11)
The signal processing apparatus according to any one of Supplementary note 6 to 10, which moves the timing at which the bandwidth of the frequency modulation changes.
(Appendix 12)
The signal processing device according to any one of Supplementary note 1 to 11, wherein the transmission waveform changing means changes the modulation speed of the frequency modulation in the transmission waveform generating means.
(Appendix 13)
In order to generate a modulated wave whose frequency changes non-repetitively, a transmission waveform generation step that generates a frequency-modulated transmission waveform, and a transmission waveform generation step.
A transmission waveform change step that changes the frequency modulation in the transmission waveform generation step so that the cross-correlation of the spectrograms of the transmission waveform is equal to or less than the threshold value.
A transmission waveform placement step that places transmission waveforms whose spectrogram cross-correlation is below the threshold on multiple tiles divided by the time axis and frequency axis.
Signal processing methods including.
(Appendix 14)
In order to generate a modulated wave whose frequency changes non-repetitively, a transmission waveform generation step that generates a frequency-modulated transmission waveform, and a transmission waveform generation step.
A transmission waveform change step that changes the frequency modulation in the transmission waveform generation step so that the cross-correlation of the spectrograms of the transmission waveform is equal to or less than the threshold value.
A transmission waveform placement step that places transmission waveforms whose spectrogram cross-correlation is below the threshold on multiple tiles divided by the time axis and frequency axis.
A signal processing program that causes a computer to execute.
(Appendix 15)
Equipped with transmitter and receiver,
The transmitter is
In order to generate a modulated wave whose frequency changes non-repetitively, a transmission waveform generation means for generating a frequency-modulated transmission waveform and a transmission waveform generation means.
A transmission waveform changing means that changes the frequency modulation by the transmission waveform generation means so that the cross-correlation of the spectrograms of the transmission waveform is equal to or less than the threshold value.
A transmission waveform arrangement means for arranging transmission waveforms whose spectrogram cross-correlation is equal to or less than a threshold value on a plurality of tiles divided by a time axis and a frequency axis.
A transmission means for transmitting the signal of the transmission waveform and
Have,
The receiver is
A receiving means for receiving the reflected signal in which the signal of the transmitted waveform is reflected by the target object,
Correlation calculation means for calculating the correlation function between the transmission waveform and the waveform of the reflection signal, and
An object detection means for detecting the target object based on the correlation function,
Signal processing system with.

Claims (10)

A modulated wave having a waveform in which the modulation speed of the modulation waveform is changed, or a waveform in which the bandwidth of the modulation waveform corresponding to the maximum frequency of the frequency to be added to the center frequency is changed, and the frequency changes non-repetitively. In order to generate the modulated wave, a transmission waveform generating means for generating a transmission waveform obtained by changing the modulation speed and performing frequency modulation, or a transmission waveform obtained by changing the bandwidth and performing frequency modulation.
A transmission waveform changing means that changes the frequency modulation by the transmission waveform generation means so that the cross-correlation of the spectrograms of the transmission waveform is equal to or less than the threshold value.
A transmission waveform arrangement means for arranging transmission waveforms whose spectrogram cross-correlation is equal to or less than a threshold value on a plurality of tiles divided by a time axis and a frequency axis.
A signal processing device. The signal processing device according to claim 1, wherein the transmission waveform changing means further changes the frequency modulation by the transmission waveform generation means so that the autocorrelation of the spectrogram of the transmission waveform is equal to or less than a threshold value. The signal processing device according to claim 1 or 2, wherein the transmission waveform arranging means arranges an appropriate spectrogram transmission waveform at positions on the time axis and the frequency axis of each tile. The signal processing device according to any one of claims 1 to 3, wherein the transmission waveform changing means performs a taper process for smoothly connecting spectrograms between adjacent tiles. The signal processing device according to any one of claims 1 to 4, wherein the transmission waveform arranging means sequentially selects adjacent tiles so that the spectrogram is written in one stroke. The signal processing device according to any one of claims 1 to 5, wherein the transmission waveform changing means changes the bandwidth of the frequency modulation in the transmission waveform generating means. The signal processing device according to any one of claims 1 to 6, wherein the transmission waveform changing means changes the modulation speed of the frequency modulation in the transmission waveform generating means. A modulated wave having a waveform in which the modulation speed of the modulation waveform is changed, or a waveform in which the bandwidth of the modulation waveform corresponding to the maximum frequency of the frequency to be added to the center frequency is changed, and the frequency changes non-repetitively. In order to generate the modulated wave, a transmission waveform generation step for generating a transmission waveform obtained by changing the modulation speed and performing frequency modulation, or a transmission waveform obtained by changing the bandwidth and performing frequency modulation, and a transmission waveform generation step.
A transmission waveform change step that changes the frequency modulation in the transmission waveform generation step so that the cross-correlation of the spectrograms of the transmission waveform is equal to or less than the threshold value.
A transmission waveform placement step that places transmission waveforms whose spectrogram cross-correlation is below the threshold on multiple tiles divided by the time axis and frequency axis.
Signal processing methods including. A modulated wave having a waveform in which the modulation speed of the modulation waveform is changed, or a waveform in which the bandwidth of the modulation waveform corresponding to the maximum frequency of the frequency to be added to the center frequency is changed, and the frequency changes non-repetitively. In order to generate the modulated wave, a transmission waveform generation step for generating a transmission waveform obtained by changing the modulation speed and performing frequency modulation, or a transmission waveform obtained by changing the bandwidth and performing frequency modulation, and a transmission waveform generation step.
A transmission waveform change step that changes the frequency modulation in the transmission waveform generation step so that the cross-correlation of the spectrograms of the transmission waveform is equal to or less than the threshold value.
A transmission waveform placement step that places transmission waveforms whose spectrogram cross-correlation is below the threshold on multiple tiles divided by the time axis and frequency axis.
A signal processing program that causes a computer to execute. Equipped with transmitter and receiver,
The transmitter is
A modulated wave having a waveform in which the modulation speed of the modulation waveform is changed, or a waveform in which the bandwidth of the modulation waveform corresponding to the maximum frequency of the frequency to be added to the center frequency is changed, and the frequency changes non-repetitively. In order to generate the modulated wave, a transmission waveform generating means for generating a transmission waveform obtained by changing the modulation speed and performing frequency modulation, or a transmission waveform obtained by changing the bandwidth and performing frequency modulation.
A transmission waveform changing means that changes the frequency modulation by the transmission waveform generation means so that the cross-correlation of the spectrograms of the transmission waveform is equal to or less than the threshold value.
A transmission waveform arrangement means for arranging transmission waveforms whose spectrogram cross-correlation is equal to or less than a threshold value on a plurality of tiles divided by a time axis and a frequency axis.
A transmission means for transmitting the signal of the transmission waveform and
Have,
The receiver is
A receiving means for receiving the reflected signal in which the signal of the transmitted waveform is reflected by the target object,
Correlation calculation means for calculating the correlation function between the transmission waveform and the waveform of the reflection signal, and
An object detection means for detecting the target object based on the correlation function,
Signal processing system with.

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