JP2014160059A - Radio wave sensor, radio wave sensing method and radio wave sensing program - Google Patents

Abstract

[PROBLEMS] To avoid interference with other wireless systems and to detect objects with high accuracy even when the degree of overlap with the band used by other wireless systems is high and only a band with low continuity can be secured. The distance detection accuracy is realized.
A transmitting unit emits a radio wave W1 while discretely changing a frequency, and a receiving unit 20 receives a reflected wave W2 of the radio wave W1. The transmission frequency of the transmission unit 10 and the reception frequency of the reception unit 20 are controlled by the control unit 30 as follows. That is, the frequencies of the radio waves W1 emitted by the transmission unit 10 are discrete from each other, and include at least the maximum frequency fmax and the minimum frequency fmin in the frequency range R corresponding to the distance resolution necessary for detecting the target T. Be controlled. And the target object detection part 40 performs the arithmetic processing for detecting the target object T based on the reflected wave W2.
[Selection] Figure 2

Description

  The present invention relates to a radio wave sensor, a radio wave sensing method, and a radio wave sensing program for detecting an object using radio waves.

  In recent years, with the spread of high-speed wireless communication and high-range resolution radio sensors (radars) and the widening of wireless communication systems such as smartphones, it has become difficult to secure frequency bands for radio sensors that sense distance and human movement. ing. For this reason, development of a technique for securing a necessary frequency band while avoiding interference with existing radio wave use services is awaited.

  Here, in Patent Document 1, in a broadband wireless transmission or broadband radio wave sensor using a multicarrier or stepped FM (Frequency Modulation) method, a frequency band used by another wireless system is a spectrum hole (unused band). And a technique for improving the detection accuracy of the target and the detection accuracy of the distance to the target while interfering with other radio systems by interpolating the spectrum hole by the signal processing in the subsequent stage is disclosed. .

JP2012-108109A

  However, the technique of Patent Document 1 described above is based on the premise that the short-range radio wave sensor can use a continuous band to some extent, and the continuity is high as in the case where the degree of overlap with the used band of other wireless systems is high. It was not a technology based on the premise that only a low bandwidth could be secured.

  The present invention has been made in view of the above problems, and avoids interference with other wireless systems even when only a band with a low degree of continuity can be secured with a high degree of overlap with the bands used by other wireless systems. On the other hand, an object of the present invention is to provide a radio wave sensor, a radio wave sensing method, and a radio wave sensing program that have high object detection accuracy and high distance detection accuracy.

  One aspect of the present invention is a transmitter that emits a detection wave while discretely changing the frequency, a receiver that receives a reflected wave of the detection wave, and an object that is detected based on the reflected wave. A radio wave sensor comprising a maximum frequency and a minimum frequency in a predetermined frequency range corresponding to a distance resolution necessary for detecting the target object.

  Such a radio wave sensor includes various modes such as being implemented in a state of being incorporated in another device or being implemented together with another method. The present invention also relates to a radio wave sensing system including the radio wave sensor, a radio wave sensing method having a process corresponding to the configuration of the above-described device, a program for causing a computer to realize a function corresponding to the configuration of the above-described device, and the program recorded therein. It can also be realized as a computer-readable recording medium.

  According to the present invention, even when the overlapping band with the band used by another wireless system is high and only a band with low continuity can be secured, it is possible to detect an object or target while avoiding interference with the other wireless system. The distance from the object can be detected with high accuracy.

It is a block diagram which shows the structure of the electromagnetic wave sensor which concerns on this embodiment. It is a figure explaining the frequency range of the electromagnetic wave which a transmission part emits. It is a figure explaining the relationship between the some frequency memorize | stored in memory in this embodiment. It is a figure explaining the frequency set to a guard band and the said guard band. It is a figure explaining the determination method of the bandwidth of the electromagnetic wave W1 for every frequency. It is an example of the several frequency set using the already occupied frequency band transversely. It is an example of the several frequency set using the already occupied frequency band transversely. It is a flowchart which shows the flow of the process which concerns on target object detection. It is a figure explaining reconstruction of a reflected wave. It is a flowchart which shows the flow of DAA processing. It is a figure explaining the range gate process which concerns on this embodiment.

Hereinafter, the present invention will be described in the following order.
(1) First embodiment:
(2) Second embodiment:
(3) Third embodiment:
(4) Summary:

(1) First embodiment:
FIG. 1 is a block diagram showing the configuration of the radio wave sensor according to the present embodiment. The radio wave sensor 100 shown in the figure schematically includes a transmission unit 10, a reception unit 20, a control unit 30, and an object detection unit 40. Data relating to the distance from the object T detected by the object detection unit 40 is output to the display device 200 as necessary and displayed on the display unit of the display device.

  The transmission unit 10 emits a radio wave W1 as a detection wave through the antenna At1 under the control of the control unit 30. The receiving unit 20 receives a radio wave W1 reflected by the object T (hereinafter referred to as a reflected wave W2) via the antenna At2. The antenna At1 of the transmission unit 10 and the antenna At2 of the reception unit 20 may be shared using a circulator or the like. The control unit 30 controls the transmission frequency and output duration of the transmission unit 10, the reception frequency and reception duration of the reception unit 20, and the timing at which the reception unit 20 receives the reflected wave W2. The object detection unit 40 detects the distance from the object T based on the reflected wave W2 received by the reception unit 20. If the antennas At1 and At2 that can switch directivity are used, the direction of the target T can also be detected, and the target detection unit 40 can detect the position of the target T.

  Hereinafter, each part of the radio wave sensor 100 will be described more specifically along the flow of signal processing.

  The transmission unit 10 can be realized by using, for example, a local oscillator 11 that generates a baseband signal having a frequency corresponding to a control signal. At this time, the control unit 30 controls the frequency of the radio wave W1 emitted from the transmission unit 10 by inputting a control signal to the local oscillator 11, and the transmission unit 10 detects the radio wave W1 having a frequency corresponding to the baseband signal. Output as.

  The transmitter 10 transmits a radio wave W1 having the same frequency as the baseband signal in the case of the direct conversion method, and separately generates a predetermined coherent frequency signal and mixes it with the baseband signal in the case of the superheterodyne method. The radio wave W1 having the frequency as described above is transmitted.

  The control unit 30 includes a memory 31 that stores control data D indicating the change order of the frequency of the radio wave W1. The control data D is composed of, for example, a plurality of frequency control data D1 to Dm (m is an integer of 2 or more, not shown) combined in an appropriate order. The frequency control data D1 to Dm are configured to include data representing the center frequency and the output duration, respectively.

  The control unit 30 sequentially changes the frequency of the radio wave W1 emitted by the transmission unit 10 by sequentially controlling the transmission unit 10 based on the frequency control data D1 to Dm. When the transmitter 10 is realized using the local oscillator 11, each of the frequency control data D <b> 1 to Dm corresponds to one control signal to the local oscillator 11.

  The frequency control data D1 to Dm correspond to any of a plurality of candidate frequencies f1 to fk that are discrete from each other (k is an integer equal to or greater than m, not shown). That is, the radio wave W1 is transmitted at any one of the candidate frequencies f1 to fk. Although not all of the frequency control data D1 to Dm are associated with the same value in the candidate frequencies f1 to fk, two or more of the frequency control data D1 to Dm are the same in the candidate frequencies f1 to fk. It may be associated with the value of.

  Next, with reference to FIG. 2, the distribution range of frequencies f1 to fn (n is an integer of 2 or more) actually associated with the frequency control data D1 to Dm in the control data D stored in the memory 31. Will be described.

  FIG. 2 is a diagram for explaining the distribution range of discrete frequencies f1 to fn. As shown in the figure, the frequencies f1 to fn are discretely distributed in the frequency range R, and the frequencies f1 to fn are set so as to cover the entire range of the frequency range R. That is, the frequencies f1 to fn are set such that the frequency width Δf as the difference between the minimum value fmin and the maximum value fmax of the frequencies f1 to fn is substantially coincident with the frequency range R, so that a desired distance resolution can be obtained. It has been decided. This distance resolution will be described later. The frequency range R constitutes the first frequency range in the present embodiment.

  Note that a plurality of discrete frequencies are not only the center frequency is discontinuous, but also the radio waves of adjacent frequencies including the base of the spread in the frequency direction having a certain level of output intensity on both sides of the center frequency. It means that the ranges in which W1 has a certain output level or higher do not overlap each other in the frequency space.

  FIG. 3 is a diagram illustrating a relationship between a plurality of frequencies stored in the memory 31 in the present embodiment. In the figure, two radio wave sensors (hereinafter referred to as radio wave sensors 100a and 100b) in separate bodies have the frequency of the radio wave W1 sequentially transmitted based on the control data D stored in the memory 31 of each radio wave sensor. An example is shown. The numbers with circles indicate the change order of the frequency of the radio wave W1.

  As shown in the figure, the radio wave sensor 100a emits by changing the frequency of the radio wave W1 in the order of f2, f5, f1, f3, fn-1, fn-2, fn,. , Changes the frequency of the radio wave W1 in the order of f3, fn-2, fn-1, f5, f3, f1, f4,.

  In other words, in the present embodiment, the frequency control data D1 to Dm constituting the control data D are associated with any of the frequencies f1 to fn in an order irrelevant to the magnitude relationship of the frequencies. Therefore, the frequency of the radio wave W1 output from the transmission unit 10 sequentially changes to the frequencies associated with the frequency control data D1 to Dm. As a result, the frequency of the radio wave W1 output from the transmission unit 10 changes in an order that is unrelated to the magnitude relationship of the frequencies. Of course, the frequencies f1 to fn respectively associated with the frequency control data D1 to Dm may be set in a regular order (ascending order, descending order, etc.) determined based on the frequency value. In this case, the transmitting unit 10 The frequency of the radio wave W1 output by the signal changes in a regular order (ascending order, descending order, etc.) determined based on the frequency value. Hereinafter, the change order of the frequency of the radio wave W1 output from the radio wave sensor 100a will be described as a first frequency series, and the change order of the frequency of the radio wave W1 output from the radio wave sensor 100b will be described as a second frequency series.

  The first frequency series is specific to the radio wave sensor 100a, and the second frequency series is specific to the radio wave sensor 100b. That is, the frequency series set for each aircraft is in an order unique to each aircraft.

  For this reason, even when the output start timing of the radio wave W1 from each radio wave sensor is matched, the frequency of the radio wave W1 output by each aircraft does not overlap, and the output start timing of the radio wave W1 is shifted by a predetermined amount. The probability that the frequency of the radio wave W1 output from each aircraft overlaps is extremely low.

  Thus, since the frequency series is different for each body of the radio wave sensor 100, even when a plurality of radio wave sensors 100 are arranged at a short distance where the radio waves reach each other, the radio wave W1 emitted by each radio wave sensor is The probability of mutual interference is extremely low, and a reduction in detection accuracy is prevented as much as possible.

  In FIG. 3, in the radio wave W1 output from the radio wave sensor 100b, the first and fifth frequencies overlap at f3. That is, the same frequency among the candidate frequencies f1 to fk may be used redundantly in the frequencies f1 to fn.

  Further, the frequencies f1 to fn do not need to be set at regular intervals when they are arranged in ascending or descending order, and are set at unequal intervals in the present embodiment. The same applies to the candidate frequencies f1 to fk that are the selection sources of the frequencies f1 to fn. Since the frequencies f1 to fn can be set at unequal intervals in this manner, the radio wave sensor 100 according to the present embodiment can detect an object with high accuracy as long as there are a plurality of irregularly remaining narrow bands. I can do it.

  For example, the frequencies f1 to fn can be set using the unused narrow band remaining in the gap between the used bands used by the existing devices. As a result, even if a wide frequency band dedicated to the radio wave sensor 100 is not secured, the late-set radio wave sensor 100 can achieve high distance resolution while avoiding interference with other existing devices.

  Specific examples of such unused bands include guard bands GB1, GB2, GB3,... As shown in FIG. FIG. 4 is a diagram for explaining a guard band and frequencies set in the guard band. A guard band is an unused narrow band set between channels to prevent radio interference between adjacent channels. White space is a license for a specific frequency band for the purpose of a specific radio service. Is a frequency region that is not actively used to prevent harmful interference between channels. For example, in the frequency band of television broadcasting, generally, it is set in units of regions in order to prevent interference between adjacent regions.

  That is, even in the already occupied frequency band that has already been allocated to other devices and services, it includes a use band that is actually actively used and a non-use band that is not actually used. Such a non-use band is reserved for a passive use purpose, and is not occupied by the other device, although it is occupied by the other device or service. As long as the interference with the radio wave sensor 100 can be avoided, the radio wave sensor 100 other than the other device may be used.

  The guard band set in the TV broadcast frequency band shown in FIG. 4 has a bandwidth of 428 kHz. For this reason, when the radio wave W1 is transmitted within the guard band, the frequency used by the radio wave W1 within the band of the guard band is an abbreviation of the guard band in consideration of spurious radiation to the adjacent channel (band used). It is desirable to set it at the center.

  In addition, the bandwidth of the frequency used by the radio wave W1 within the guard band is desirably about 10% or less of the guard band bandwidth. For example, if the bandwidth of the radio wave W1 emitted using a frequency in the guard band is 10 kHz, it is about 2.3% of the guard band bandwidth, and the spurious radiation to the adjacent channel is 0.05%. The following can be suppressed. Therefore, assuming that the transmission power of the radio wave sensor 100 is 1 mW, the spurious radiation to the adjacent channel is 0.5 μW, which is 25 μW or less, which is an allowable value in the radio equipment.

  FIG. 5 is a diagram illustrating a method for determining the bandwidth of the radio wave W1 for each frequency. In the figure, the frequency spread is shown for a certain frequency when the output duration is t1 and when t2 (<t1). The frequency spread Δ1 (indicated by the half width in the figure) when the output duration is t1 is narrower than the frequency spread Δ2 when the output duration is t2. This is based on the general relationship between the frequency spread (Δf (Δ1, Δ2, etc.)) and the output duration (T (t1, t2, etc.)) (Δf = 1 / T).

  That is, by controlling the output duration of the radio wave W1 at each frequency, the frequency spread of the radio wave W1 can be controlled. For example, according to the bandwidth of the band including the frequency of the radio wave W1, the radio wave W1 at that frequency can be controlled. By appropriately determining the output duration, it is possible to prevent interference with the use band adjacent to such a band.

  More specifically, if the bandwidth of the band including the frequency of the radio wave W1 is narrowed, the output duration of the radio wave W1 at that frequency is lengthened to suppress the frequency spread, thereby preventing interference with adjacent use bands. If the bandwidth of the band including the frequency of the radio wave W1 is widened, the time required for detecting the object can be shortened by shortening the output duration of the radio wave W1 at the frequency.

  As a more specific example, the bandwidth (fw) of the band including the frequency of the radio wave W1 and the output duration (tc) of the radio wave W1 at the frequency are inversely proportional such that fw = 1 / tc. The output duration of the radio wave W1 is determined so as to be related.

  Further, as shown in FIG. 6, a plurality of frequencies f1 to fn (in FIG. 6, f1, f2,..., Fp, fp + 1,...) Can be set beyond the assigned frequency band. . For example, the frequencies f1 to fn can be set using the already occupied frequency band R1 in which the guard band is set at the interval d1 and the already occupied frequency band R2 in which the guard band is set at the interval d2.

  Also, as shown in FIG. 7, a plurality of frequencies f1 to fn can be set using both the guard band and the white space. At this time, for example, in the occupied frequency band R3 in which the guard band is set, any one of the frequencies f1 to fn is set in each guard band, and in the already occupied frequency band R4 in which the white space is set. It is possible to set a plurality of frequencies among the frequencies f1 to fn by narrowing the setting interval as compared to the case of the guard band or by setting the setting intervals to be equal intervals.

  That is, the setting interval of the frequencies f1 to fn set in the already occupied frequency band R3 is set according to the interval of the guard band, and the setting interval of the frequencies f1 to fn set in the white space of the already occupied frequency band R4 is set. It can be set freely.

  In this way, it is possible to use a wide range of frequencies by using the unused band of the already occupied frequency band or by using the already occupied frequency band of multiple types of devices. Even if it can only be used, the detection accuracy in the detection of an object to be described later can be dramatically increased.

  Further, if a white space with no restriction on the setting interval of the frequencies f1 to fn is used, it is not necessary to perform data interpolation described later in the frequency range using this white space. Of course, other non-occupied frequency bands, guard bands, and white spaces may be used in appropriate combinations.

  The control data D described above may be generated in advance and stored in the memory 31. However, the control data D may be generated based on the unique information given to each body of the radio wave sensor 100 by the arithmetic processing of the control unit 30. It can be generated by various methods such as generation using random numbers. Further, as in a second embodiment described later, the control unit 30 may generate the control data D based on the result of the DAA process and store it in the memory 31.

<Receiver>
Next, the receiving unit 20 is realized using, for example, a local oscillator 21 and a phase detector 22. The local oscillator 21 generates, from the reflected wave W2 received via the antenna At2, an I phase signal SI in phase with the radio wave W1 emitted by the transmission unit 10 and a Q phase signal SQ whose phase is different by π / 2 by phase detection. Detect. These I phase signal SI and Q phase signal SQ are output to the object detection unit 40.

  Note that the local oscillator 21 of the receiving unit 20 is generally shared with the local oscillator 11 of the transmitting unit 10. Further, the reception duration of the receiving unit 20 is determined in accordance with the output duration of the transmitting unit 10. That is, when the output duration of the transmission unit 10 is increased to suppress the frequency spread, the reception duration of the reception unit 20 is also increased accordingly.

<Object detection unit>
The object detection unit 40 reflects the radio wave W1 based on the phase signal (I phase signal SI, Q phase signal SQ, or each of the I phase signal and the Q phase signal) of the reflected wave W2 input from the reception unit 20. The distance to the target T is determined. In addition, since the transmission part 10 changes and outputs the frequency of the electromagnetic wave W1 based on the control data D, the frequency of the reflected wave W2 which the receiving part 20 receives also changes according to the frequency of the electromagnetic wave W1. That is, the frequency of the radio wave W1 output from the transmitter 10 and the frequency of the reflected wave W2 received by the receiver 20 are in the same order as the frequencies f1 to fn corresponding to the frequency control data D1 to Dm constituting the control data D. Change. As a result, the frequency of the radio wave W1 and the frequency of the reflected wave W2 received by the receiving unit 20 also change. Therefore, based on the control data D of the control unit 30, the object detection unit 40 arranges the phase signal of the reflected wave W2 input from the reception unit 20 in order of frequency and stores it in a memory or the like.

  Thereafter, the object detection unit 40 performs a calculation process for specifying the distance from the object T based on the I phase signal SI and the Q phase signal SQ. At this time, the reflected wave W2 is generated by the reflected wave W2. The problem is that it is obtained for each discrete step frequency.

  Therefore, in the present embodiment, a method of interpolating a missing portion of the reflected wave W2 using a periodogram statistic as a likelihood function is employed. As a result, it is possible to generate pseudo reflected wave data corresponding to the power spectrum of the reflected wave received at the continuous frequency using the reflected wave W2 received at the discrete frequency.

  FIG. 8 is a flowchart showing a flow of processing related to object detection, and FIG. 9 is a diagram for explaining generation of pseudo reflected wave data. In the processing relating to the generation of the pseudo reflected wave data shown in FIGS. 8 and 9, the Lomb-Scale periodogram method which is a kind of interpolation calculation using the power spectrum is performed on the phase signal of the reflected wave W2 obtained discretely. By applying, a spectrum substantially equivalent to the reflected wave W2 obtained when the radio wave W1 is emitted in a continuous wave or at equal intervals is calculated. Of course, the interpolation calculation using the likelihood function is not limited to the Lomb-Scale periodogram method, and spline interpolation or polynomial interpolation can be used.

  In the process shown in FIG. 8, first, as shown in FIG. 9A, the phase signal of the reflected wave W2 obtained discretely is obtained by detection (S10). The phase signal of the reflected wave W2 obtained here becomes an unequally spaced signal when the radio wave W1 is transmitted using a plurality of narrow bands remaining irregularly as in the present embodiment.

Next, as shown in FIG. 9B, the power spectrum of the reflected wave W2 is calculated by using the Lomb-Scalgle periodogram method for calculating the power spectrum from the phase signal of the reflected wave W2 with uneven spacing (S20). ). Equation (1) shown below is an equation of Lomb normalized periodogram as an example of the Lomb-Scalgle periodogram method. In this embodiment, the phase signal of the reflected wave W2 is substituted for y _i in the following formula (1). According to the following equation (1), a power spectrum P _N (ω) obtained by integrating (aggregate average) phase signals received (sampled) in time series for each angular frequency is calculated.

In the above equation (1), P _N (ω) is the power spectrum, ω is the angular frequency, n is the number of samples of y _i (i = 1, 2,..., N), and a is the following equation (2) ), And b is a parameter represented by the following formula (3). In the following formulas (2) and (3), t _i (i = 1, 2,..., N) represents the sampling timing of each y _i , and t _ave is ((t ₁₊ t _n ) / 2), and τ is defined by the following equation (4).

Next, a dominant frequency component (main spectrum component) is extracted from the power spectrum P _N (ω) (S30). The main spectrum component is extracted by, for example, extracting a frequency component having a certain intensity or higher by threshold determination. By estimating the following phase signal using only the extracted main spectrum components in this way, unnecessary signal components and noise components included in the power spectrum P _N (ω) can be cut.

Next, as shown in FIG. 9C, the phase signal of the reflected wave W2 is estimated from the main spectrum component of the power spectrum P _N (ω). This estimation is performed using the following equation (5). In the following formula (5), y _f (t _i ) is a phase signal (hereinafter, estimated signal) estimated from the main spectral components of the power spectrum P _N (ω), and A (ω) is the following formula (6). It is represented by

The estimated signals y _f (t _i ) obtained by the above equation (5) are obtained at equal intervals without missing portions in the frequency. Therefore, interpolation is performed to embed the estimated signal y _f (t _i ) shown in FIG. 9C in the unequal interval portion or missing portion of y _i as the original phase signal shown in FIG. 9A (FIG. 9). (See (d)). As a result, the equally-spaced phase signal y _i ′ obtained by interpolating the missing or unequal-interval portions of y _i as the original phase signal shown in FIG. 9A is obtained (S35).

Thereafter, by transforming the equally-spaced phase signal y _i ′ from frequency space to time space by inverse Fourier transform, as shown in FIG. 9E, when the transmission frequency is a continuous wave or at regular intervals, The pseudo reflected wave data P _N (ω) ′ corresponding to the power spectrum of the received reflected wave is calculated (S40).

Next, the object detection unit 40 estimates the distance from the object T. Specifically, since a sharp peak indicating the received wave reflected by the object T appears in the spectrum of the pseudo reflected wave data P _N (ω) ′ described above, first, the phase φpeak of this peak is subjected to peak detection processing. Specify by etc. Then, the distance d is estimated by the following equation (7) using this φpeak and the frequency width Δf that is the difference between the minimum value fmin and the maximum value fmax of the frequencies f1 to fn. In the example shown in FIG. 9 (e), since the spectrum of the pseudo reflected wave data P _N (ω) ′ has a plurality of peaks, the radio wave W1 is reflected by the object T at a plurality of different distances. I understand that.

  From the above equation (7), the distance resolution ΔR of the radio wave sensor 100 is expressed by the following equation (8). c represents the speed of light. From the following equation (8), it can be seen that the distance resolution ΔR increases (decreases) as Δf increases. That is, if a certain frequency width Δf is secured, a distance resolution ΔR greater than a certain value is realized, and thus it is understood that the distance to the object T can be detected with a certain accuracy.

(2) Second embodiment:
Next, the radio wave sensor according to the second embodiment will be described. The radio wave sensor according to the second embodiment confirms the presence / absence of interference waves in the frequencies f1 to fn before emitting the radio wave W1 from the transmission unit 10, and detects an interference wave detection / avoidance process (hereinafter, referred to as “avoidance band”). This is different from the radio wave sensor 100 according to the first embodiment in that it is described as DAA (Detect And Avoid) processing.

  FIG. 10 is a diagram for explaining DAA processing. Note that the configuration of the radio wave sensor according to the present embodiment is the same as that of the radio wave sensor 100 according to the first embodiment described above, and thus the description thereof will be omitted. Hereinafter, the same reference numerals as those in the first embodiment will be used. I do.

  In the DAA process, first, the control unit 30 serving as the interference wave detection unit stops the output of the radio wave W1 by the transmission unit 10 and performs predetermined processing over the entire frequency range R as shown in FIG. The receiving unit 20 is caused to perform a receiving operation while changing the frequency discretely and sequentially at the frequency interval d1. Hereinafter, this reception operation is referred to as a first interference wave detection operation. By performing this first interference wave detection operation, it is possible to roughly check the presence or absence of interference waves over the entire frequency range R. In the example shown in FIG. 10B, an interference wave having a peak in the range of d1 centering on the frequency f13 is detected.

  In the DAA process, an interference wave may be detected at the minimum frequency fmin or the maximum frequency fmax in the frequency range R. At this time, if the control of the transmission frequency of the transmission unit 10 and the control of the reception frequency of the reception unit 20 are performed while avoiding the minimum frequency fmin and the maximum frequency fmax where the interference wave is detected as will be described later, a desired distance resolution or more is achieved. There is a possibility that the distance resolution ΔR cannot be secured. Therefore, when an interference wave is detected at the minimum frequency fmin, the range is expanded to a lower frequency side than the minimum frequency fmin and DAA processing is performed to obtain a frequency fmin ′ at which no interference wave is detected on the lower frequency side than the minimum frequency fmin. The control data D is corrected or generated such that the frequencies f1 to fn identified and associated with the frequency control data D1 to Dm include the frequency fmin ′. When an interference wave is detected at the maximum frequency fmax, the range is expanded to a higher frequency side than the maximum frequency fmax and DAA processing is performed to identify a frequency fmax ′ at which no interference wave is detected on the higher frequency side than the maximum frequency fmax. Then, the control data D is corrected or generated so that the frequencies f1 to fn associated with the frequency control data D1 to Dm include the frequency fmax ′. As a result, Δf, which is the difference between the maximum value and the minimum value of the frequencies f1 to fn associated with the frequency control data D1 to Dm, is equal to or greater than the frequency range R, and a distance resolution ΔR that is greater than or equal to the desired distance resolution is ensured. it can.

  Next, in the frequency range R ′ narrower than the frequency range R including the frequency f13 in which the reception intensity of a certain level or more is observed in the first interference wave detection operation, as shown in FIG. The reception operation is performed while changing the frequency discretely and sequentially at d2 (d2 <d1). Hereinafter, this reception operation is referred to as a second interference wave detection operation. By performing this second interference wave detection operation, as shown in FIG. 10D, the frequency at which the interference wave exists can be specified more precisely. The frequency range R ′ constitutes the second frequency range in the present embodiment.

  If necessary, the reception operation may be performed while changing the frequency discretely and sequentially at a narrower frequency interval in the vicinity of the frequency at which reception intensity of a certain level or more is observed in the second interference wave detection operation. Good. In this way, by performing the reception operation while gradually narrowing the reception range and the frequency interval, it is possible to specify the frequency where the interference wave exists in a short time and precisely.

  As a specific example, for example, when the frequency range R is 1 GHz, a first interference wave detection operation is performed in which the 1 GHz range is equally divided into 100 and a reception operation is performed in 10 MHz steps. Next, a second interference wave detection operation is performed in which a 10 MHz range centered on a frequency having a reception intensity of a certain level or more in the first interference wave detection operation is equally divided into 100, and the reception operation is performed in 100 kHz steps. Then, if necessary, the reception operation is performed in finer steps, centering on the frequency at which the reception intensity is observed in the second interference wave detection operation.

  Here, the reception duration at each frequency is determined according to the required frequency resolution. In other words, the same relationship between the output duration and the frequency spread described above also holds for the reception duration and the frequency spread. Therefore, if you want to specify the signal strength of the interference wave for each rough frequency step, receive at each frequency step. When it is desired to shorten the duration and specify the signal strength of the interference wave for each finer frequency step, the reception duration at each frequency step is increased.

  For example, in the first interference wave detection operation and the second interference wave detection operation described above, since the first frequency interval d1 is wider than the second frequency interval d2, reception in the first interference wave detection operation is performed. The duration is made shorter than the reception duration in the second interference wave detection operation.

  In addition, the reception duration at each frequency is determined so as to have a wider frequency range than the frequency interval in the interference wave detection operation. Taking the first interference wave detection operation shown in FIG. 10A as an example, the control unit 30 causes the frequency spread in the reception operation at each frequency f11, f12, f13, f14. Control the reception duration. At this time, for example, in the frequency range (frequency spread) received by the reception operation at the frequency f11 and the frequency range (frequency spread) received by the reception operation at the frequency f12, for example, the base portion of the frequency spread Will overlap. That is, there is no non-detection range where the interference wave detection operation is not performed between the frequency f11 and the frequency f12. Thereby, in each interference wave detection operation, the entire frequency range R and frequency range R ′ where the interference wave should be detected can be searched comprehensively without omission.

  As described above, when DAA processing is performed in the already occupied frequency band, interference waves may be detected in an unused band such as a guard band, and interference waves are not detected in a used band. May be. For example, the DAA process may be performed only around the candidate frequencies f1 to fk in the unused band. That is, if the frequencies f1 to fn are set at the center of the guard band, the presence or absence of interference waves within a certain range including the frequencies f1 to fn (for example, about 10% of the guard band) may be detected. .

  When the DAA process is performed as described above to detect the interference wave, the control unit 30 avoids the frequency control data corresponding to the frequency that may cause interference among the plurality of frequency control data D1 to Dm of the control data D. Thus, the transmission frequency of the transmission unit 10 and the reception frequency of the reception unit 20 are controlled. As a result, a collision with another device can be avoided, so that it is possible to coexist with another wireless system without separately providing a DAA circuit.

  Further, according to the result of the DAA process, the control unit 30 may newly generate the control data D or modify the existing control data D and store it in the memory 31.

  This is because the actual unused band detected in the DAA process is determined from the unused band in the usage rule / usage agreement / usage plan in the equipment or service to which the already occupied frequency band is assigned according to the actual usage situation. This is because there is a possibility of deviation. For example, in a frequency band used for mobile wireless communication, a Doppler shift is generated according to the moving speed of the mobile body. Therefore, when viewed from the observer side, the range and width are different from the usage rules / arrangements / usage plans. A guard band may appear.

  In such a case, the center frequency is set at an appropriate position according to each unused band actually detected by the DAA process, and an output having an appropriate frequency spread according to the actually detected unused bandwidth. It is desirable to generate the control data D in which the duration is set and store it in the memory 31. In this way, by setting the control data D according to the result of the DAA process, the radio wave sensor 100 performs the detection operation of the object with the optimum center frequency and output duration in accordance with the actual use situation. It is possible to reliably avoid problems such as interference, interference and interference with devices and services to which the already occupied frequency band is assigned.

  Since the actual usage status usually changes with time, the range and width of the unused band also change with time. Therefore, it is desirable that the generation and correction of the control data D is performed based on the probabilistic frequency usage situation created by statistically analyzing the result of the DAA process repeatedly performed for a certain period of time.

(3) Third embodiment:
Next, a radio wave sensor according to a third embodiment will be described. The radio wave sensor according to the third embodiment performs the time gate process (range gate process) at the time of phase detection in order to avoid the influence of the wraparound of the radio wave W1. Different from the embodiment. Note that the configuration of the radio wave sensor according to the present embodiment is the same as that of the radio wave sensor 100 according to the first embodiment described above, and thus the description thereof will be omitted. In the following description, the same reference numerals as those of the first embodiment are used. Do.

  FIG. 11 is a diagram for explaining range gate processing according to the present embodiment. As shown in FIG. 11A, the reflected wave W2 is received by the receiving unit 20 with a delay of time Δt corresponding to the distance from the transmitting unit 10 emitting the radio wave W1 to the target T. That is, the radio wave W1 emitted by the transmitter 10 while sequentially changing the frequency to f1, f2, f3, f4... Is transmitted to the receiver 20 with a time lag of time Δt corresponding to the distance to the object T. Received. At this time, there is a possibility that the radio wave W1 is reflected from an object other than the object T and reaches the receiving unit 20.

  Therefore, in the present embodiment, the range gates G1, G2, G3, G4,... That limit the reception time range so as to receive the reflected wave W2 of each frequency only within a time determined according to the distance from the object T. • is set. The range gates G1, G2, G3, G4,... Are set according to the following concept.

  As shown in FIG. 11B, the reflected wave from the object with a distance of 10 cm is received at time W10 with a delay of time Δt1 from the launch of the transmitter 10, and the reflected wave from the object with a distance of 20 cm is received by the transmitter 10. Is delayed by the time Δt2 from the launch of the current wave and received in the time range W20, and the reflected wave from the object with a distance of 30 cm is received by the time range W30 with a delay of the time Δt3 from the launch of the transmitter 10 and is received from the target with the distance of 40 cm. The reflected wave is received in the time range W40 with a delay of time Δt4 from the launch of the transmission unit 10, and the reflected wave from the object with a distance of 50 cm is received in the time range W50 with a delay of time Δt5 from the launch of the transmission unit 10, and the distance The reflected wave from the object of 60 cm is received in the time range W60 with a delay of time Δt6 from the launch of the transmitter 10, and the reflected wave from the object of distance 70cm is emitted from the transmitter 10. Is received in time Δt7 only delay time range W70 from. Each time range W10, W20,... Is equal to the output duration time of the radio wave of each frequency in the transmission unit 10. That is, the time required for the reflected wave W2 of the radio wave W1 emitted by the transmission unit 10 at a certain timing to reach the reception unit 20 varies depending on the distance between the radio wave sensor 100 and the object.

  Here, when the target T to be detected moves between about 30 cm to 50 cm from the radio wave sensor 100, the reflected wave W2 of the frequency f1 is within the range of the settable range Rg1 shown in FIG. The gate G1 can be set. This settable range Rg may be set at the time of shipment, or may be set by the user of the radio wave sensor 100.

  The control unit 30 includes a memory that stores a history of the distance at which the target T has been previously detected, and predicts the destination of the target T based on this history. For example, if the target T is detected in the order of 30 cm, 32 cm, and 34 cm in the latest history, the next detected distance is predicted to be 36 cm, and FIG. As shown, a range gate G1 is set in a time range W36 for receiving a reflected wave from an object having a distance of 36 cm. The motion prediction method is not limited to such a method, and various known methods may be used as appropriate.

  As described above, according to the radio wave sensor according to the present embodiment, the range gate setting range Rg1 is set, and the range gate setting range (range gate in FIG. 11B) is based on the motion prediction of the target T. By appropriately changing the range (G1) within the settable range Rg1, it is possible to prevent the influence of the reflected wave from a fixture or the like near the object T and to improve the detection accuracy of the object T. .

DESCRIPTION OF SYMBOLS 10 ... Transmission part, 11 ... Local oscillator, 20 ... Reception part, 21 ... Local oscillator, 22 ... Phase detector, 30 ... Control part, 31 ... Memory, 40 ... Object detection part, 100 ... Radio wave sensor, 100a ... Radio wave Sensor, 100b ... Radio wave sensor, 200 ... Display device, R ... Frequency range, R '... Frequency range, T ... Object, Δf ... Frequency, At1 ... Antenna, At2 ... Antenna, D ... Control data, D1-Dm ... Frequency control data, GB1 ... guard band, GB2 ... guard band, GB3 ... guard band, R1 ... already occupied frequency band, R2 ... already occupied frequency band, R3 ... already occupied frequency band, R4 ... already occupied frequency band, Sp1 ... spectrum , Sp2 ... Spectrum, Sp3 ... Spectrum, Sp4 ... Spectrum, W1 ... Radio wave, W2 ... Reflected wave, f1-fk ... Candidate frequency, f1-fn ... Frequency

Claims (15)

A transmitter that emits detection waves while discretely changing the frequency;
A receiver for receiving the reflected wave of the detection wave;
An object detection unit for detecting an object based on the reflected wave;
With
The radio wave sensor according to claim 1, wherein the frequency of the detection wave emitted by the transmitter includes at least a maximum frequency and a minimum frequency in a first frequency range corresponding to a distance resolution necessary for detecting the object. The first frequency range includes at least one occupied frequency band that has already been allocated,
The radio wave sensor according to claim 1, wherein the transmission unit emits the detection wave using an unused band in the already occupied frequency band. The first frequency range includes at least one occupied frequency band that has already been allocated,
The said transmission part transmits the said detection wave discretely to the whole area of the said 1st frequency range by transmitting the said detection wave using the guard band of the said occupied frequency band. The radio wave sensor described in 1. The first frequency range includes at least one occupied frequency band that has already been allocated,
The said transmission part transmits the said detection wave discretely throughout the said 1st frequency range by transmitting the said detection wave using the white space of the said occupied frequency band. The radio wave sensor according to any one of the above.   The object detection unit generates continuous pseudo reflected wave data over the entire first frequency range from the plurality of reflected waves obtained at discrete frequencies, and is based on the pseudo reflected wave data. The radio wave sensor according to any one of claims 1 to 4, wherein the object is detected.   The object detection unit performs inverse Fourier transform on each of the I phase signal and the Q phase signal obtained for each discrete frequency to convert them into a time space, and the I phase signal and the Q phase signal in the time space. The radio wave sensor according to claim 5, wherein the pseudo reflected wave data is generated by approximating a value using a likelihood function.   The transmission unit emits the detection wave of each frequency for an output duration in which a frequency spread of the detection wave emitted at each frequency is in a range narrower than a bandwidth of an unused band including the frequency. The radio wave sensor according to claim 6.   The transmitter transmits the detection wave of each frequency for an output duration in which a frequency spread of the detection wave emitted at each frequency is 10% or less of a bandwidth of an unused band including the frequency. The radio wave sensor described in 1.   The transmitter according to claim 7 or 8, wherein the transmitter emits the detection wave at each frequency so that a bandwidth of an unused band including the frequency of the detection wave and the output duration are in an inversely proportional relationship. The radio wave sensor described.   The radio wave sensor according to any one of claims 1 to 9, wherein the reception unit receives the reflected wave of the frequency at a reception duration corresponding to an output duration of the transmission unit at each frequency.   The radio wave sensor according to any one of claims 1 to 10, wherein the reception unit receives the reflected wave with a range gate determined based on motion estimation of an object. An interference wave detector for detecting the interference wave;
The interference wave detection unit stops output of the detection wave by the transmission unit, causes the reception unit to receive a radio wave at a first frequency interval in the first frequency range, and a reception intensity is equal to or higher than a certain level. A center frequency of an interference wave is specified by causing the receiver to receive a radio wave at a second frequency interval narrower than the first frequency interval in a second frequency range narrower than the first frequency range including the frequency. And
The radio wave sensor according to any one of claims 1 to 11, wherein the transmission unit emits the detection wave while avoiding a frequency in which the interference wave exists.   The interference wave detection unit causes the reception unit to receive the radio wave when the radio wave is received at the second frequency interval as compared to when the radio wave is received at the first frequency interval. The radio wave sensor according to claim 12, wherein the reception duration is increased. A transmission step of emitting detection waves while discretely changing the frequency;
Receiving a reflected wave of the detection wave;
An object detection step of detecting an object based on the reflected wave;
Including
The radio wave sensing method, wherein the frequency of the detection wave emitted in the transmission step includes at least a maximum frequency and a minimum frequency in a first frequency range corresponding to a distance resolution necessary for detection of the object. A transmission function that emits detection waves while discretely changing the frequency;
A receiving function for receiving the reflected wave of the detection wave;
An object detection function for detecting an object based on the reflected wave;
With
A radio wave sensing program characterized in that a frequency of a detection wave emitted by the transmission function includes at least a maximum frequency and a minimum frequency in a first frequency range corresponding to a distance resolution necessary for detecting the object.

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