JP3818349B2 - Radar, radar signal processing method, radar communication method, and recording medium - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a radar, a radar signal processing method and a radar communication method, and a recording medium on which a program for executing the signal processing method and the communication method is recorded, and in particular, extends a detectable distance as a radar. In addition, it is possible to detect an accurate object when the distance is constant and improve the distance resolution, the radar signal processing method, the radar communication method and the recording medium, and the object detection using the radar sensor wave. The present invention relates to a radar capable of performing wireless communication, a radar signal processing method, a radar communication method, and a recording medium.
[0002]
[Prior art]
  Radar (radiar) emits radio waves, light, ultrasonic waves, etc. from an antenna or transducer, etc., and detects the presence of an object by receiving a reflected wave from an irradiated object or, in some cases, a radio wave re-emitted from the object. And a device for measuring the position. That is, the object detection by the radar is performed by emitting a radio wave, light, an ultrasonic wave, or the like from an antenna or a transducer, and detecting a reflected wave reflected from the object and returning. Hereinafter, a pulse radar (or impulse radar) that continuously emits radio waves or the like divided into pulse shapes will be described. Here, “pulse radar” uses a radio wave (carrier) of one frequency to radiate the carrier intermittently from the antenna with a pulse signal, and “impulse radar” has a pulse width of a time interval. Compared to the extremely narrow frequency range, the spectrum is infinitely widened, and it is different in that a specific carrier such as a pulse radar is not required to radiate the spectrum from the antenna.
[0003]
  By the way, when the object interval is a close distance, distance resolution is important. Taking an impulse emission interval as one period and sampling it at regular regular intervals is extremely high-speed sampling, which is technically impossible and impractical.
[0004]
  For example, if the maximum measurement distance is 50 cm, the time required for the reflected wave to return from the maximum distance is 3.3 ns. If this distance of 50 cm is measured with a distance resolution of 0.5 cm, 16.6 ps. Sampling is performed every time (with a sampling frequency of 60 GHz). The frequency of the impulse emission interval at this time is an arbitrary frequency of 300 MHz or less at maximum.
[0005]
  On the other hand, when the frequency of the impulse emission interval is 3 MHz, when the known time axis expansion sampling technique for sampling only once in one period is used, sampling with the same 3 MHz as the sampling frequency is sufficient, and 200 times is required. A received signal waveform whose time axis is expanded 200 times by sampling is obtained. The distance resolution at this time is ensured to be 0.5 cm. In this case, since the reflected wave is attenuated and becomes small and there is ambient noise, signal processing for improving the S / N is necessary.
[0006]
  Thus, the pulse (impulse) emission period of pulse radar (or impulse radar) is related to the measurement upper limit distance, which is larger than the time required for reciprocation, and the pulse (impulse) width is related to the measurement lower limit distance. In general, the time is shorter than the time required for the round trip.
[0007]
  Further, in the conventional general radar, in order to make it easy to process the received reflected wave, the time axis expansion sampling technique for expanding the time axis as described above is used. This time axis expansion sampling is a technique often used in the measurement field, and is different from sampling used in digitizing PCM communication, audio signals, and the like. In other words, “sampling” is performed at regular intervals and the analog signal to be sampled does not repeat with respect to the sampling, whereas “time-axis expanded sampling” is performed by slightly delaying the sampling timing. The analog signal to be sampled is of a nature that repeats with respect to the sampling. In other words, the time axis expansion sampling devise sampling timing using the repetitive nature of the analog signal to expand the time axis of the waveform, in other words, to reduce the frequency.
[0008]
  FIG. 19 shows a configuration diagram of a transmission unit and a reception unit of a conventional radar using a time axis expansion sampling technique. In the figure, the conventional radar includes a clock generation unit 501, a transmission unit 502, and a transmission antenna 503 as a transmission unit, a reception antenna 506, a control signal interface 504, a sampling control unit 505, and an amplifier 507 as reception units. And 508, a sampling unit 509, a hold unit 510, and an A / D conversion unit 511. In addition, this conventional example quoted what was indicated by "Chapter 3" Modulation techniques "pp103-115" of literature "" SURFACE-PENETRATING RADAR (surface permeation radar) "British Electrical Engineers publication".
[0009]
  FIG. 21 is a timing chart for explaining signal processing in the wave receiving section of the radar according to the conventional example. First, the transmission unit 502 emits a transmission signal from the transmission antenna 503 based on the reference clock CLK (see FIG. 21A) generated by the clock generation unit 501.
[0010]
  The wave receiving unit receives the reflected wave via the wave receiving antenna 506, and receives the received signal RFI (see FIG. 21C) as a sampling pulse SP generated by the sampling control unit 505 (see FIG. 21B). ) On the basis of (). As a result, the received signal sampled by the sampling unit 509 has a waveform as shown in FIG. This signal is held by the hold unit 510 and becomes a signal as shown in FIG. 21 (e), which is converted into a digital signal by the A / D conversion unit 511 (see FIG. 21 (f)) and output data of the receiving unit. It becomes.
[0011]
  Here, the sampling pulse SP is a signal for performing time axis expansion sampling, and is generated in the sampling control unit 505 with a circuit configuration as shown in FIG. That is, the clock generator 521, the high-speed ramp signal generator 522, the low-speed ramp signal generator 523, and the comparator 524 are included. The timing chart of FIG. 22 shows how the sampling pulse SP is generated with this circuit configuration. That is, as shown in FIG. 22A, when the clock CLK is output from the clock generation unit 521, the high-speed ramp signal generation unit 522 generates a high frequency (short cycle) as shown in FIG. The low-speed ramp signal RPF is generated, and the low-speed ramp signal generation unit 523 generates a low-frequency (long cycle) low-speed ramp signal RPS as shown in FIG. The comparator 524 compares these two signals RPF and RPS, and generates a sampling pulse at the timing when the voltage levels of both coincide with each other, as shown by the dotted line in FIG.
[0012]
  As described above, the sampling for expanding the time axis is performed while gradually delaying the time position so as to sufficiently include the width of the pulse (or impulse) reflected and returned. This is also related to the distance resolution. The time for sampling while shifting and returning to the original timing position is a detection time delay.
[0013]
  As an example of the impulse radar, when the impulse width is 100 ps and the impulse interval frequency is 2 MHz (cycle: 500 ns), the time axis expansion ratio is about 100,000 times. At this time, the reception impulse width is expanded to 10 μs and the impulse cycle time is expanded to 50 ms. Note that the enlarged received waveform is almost the same as the waveform received during one impulse period and magnified 100,000 times.
[0014]
[Problems to be solved by the invention]
  As described above, in pulse radar (or impulse radar), when a pulse (or impulse) radio wave or ultrasonic wave is emitted at a constant interval, the pulse (or impulse) hits an object and becomes a reflected wave at a constant interval. Will come back in a certain time. The magnitude of this reflected wave power is given as a function of transmission power, reflection cross section of the object, mutual distance, and antenna gain, and the reflected wave plus the thermal noise and ambient noise is received. It will be received as a signal.
[0015]
  However, in the conventional radar, when the distance to the object is away from the transmitting antenna, the received power of the reflected wave is inversely proportional to the fourth power of the mutual distance, and therefore the received signal voltage amplitude (from the receiving antenna ( There is a problem that S) is drastically reduced and buried in noise (N), and accurate distance measurement cannot be performed or the detectable distance cannot be extended.
[0016]
  The present invention has been made paying attention to such conventional problems, and the object of the present invention is to extend the detectable distance as a radar and to enable accurate object detection when the distance is constant. Another object of the present invention is to provide a radar with improved distance resolution, a radar signal processing method, a radar communication method, and a recording medium.
[0017]
  Another object of the present invention is to provide a radar, a radar signal processing method, a radar communication method, and a recording medium that can perform radio communication together with object detection using a radar sensor wave.
[0018]
[Means for Solving the Problems]
  In order to solve the above-described problem, the first invention of the present application is a radar that emits a pulse or impulse radio wave at a predetermined timing and receives and processes a reflected wave from an object, and is synchronized with the emission timing. Based on a first sampling clock that divides a fixed time interval within a periodic time interval, conversion means for converting a received signal by the reflected wave into digital received data, and M sampling times (M Is a data storage means comprising N + 1 storage means for holding digital received data of the first to N + 1 stages (N is an arbitrary positive integer), and the number of samplings within the period time interval. Are stored in the first stage storage means and then synchronized with the launch timing in the storage means from the first stage to the Nth stage. After the contents of the storage means at the i-th stage (i = 1 to N−1) are moved to the storage means at the (i + 1) -th stage, the contents of the storage means from the first stage to the N-th stage are added and the N + 1-th stage And a control means for storing in the storage means.
[0019]
  Further, the second invention of the present application is a radar that communicates by receiving a radio wave that is emitted from another radar at a predetermined timing and whose carrier is pulse-modulated or frequency-modulated, and is transmitted at a constant time interval within a predetermined period time interval. Conversion means for converting the received signal into digital received data based on a first sampling clock that engraves, and digital received data for M sampling times (M is an arbitrary positive integer) within the period time interval. N + 1 data storage means from the first stage to the (N + 1) th stage (N is an arbitrary positive integer), and digital received data for M times of sampling times within the period time interval. After being held in the first-stage storage means, in the storage means from the first stage to the N-th stage in synchronism with the firing timing, of the i-th (i = 1 to N−1) storage means Is transferred to the (i + 1) th stage storage means, and the control means for adding the contents of the storage means from the first stage to the Nth stage and storing them in the (N + 1) th stage storage means, and the (N + 1) th stage storage means And determining means for determining the content of communication data from the other radar based on the content of the radar.
[0020]
  The third invention of the present application isIn the first or second invention,A time-axis-enhanced sampling clock generating means for generating a second sampling clock obtained by phase-modulating a first sampling clock having a constant time interval within a periodic time interval synchronized with the emission timing, and a received signal by the reflected wave Sampling means for sampling the signal with the second sampling clock, and the conversion means converts the sampled signal into digital received data at a timing based on the first sampling clock.Also It is.
[0021]
  The fourth invention of the present application isIn the first or second invention,A time axis expansion sampling clock generating means for generating a second sampling clock obtained by phase-modulating a first sampling clock that divides a fixed time interval within a periodic time interval synchronized with the firing timing at a low frequency, and the converting means comprises: The received signal by the reflected wave is converted into digital received data at a timing based on the second sampling clock.Is.
[0022]
  In addition, according to a fifth invention of the present application, in the first, third, or fourth invention, when the first sampling clock or the second sampling clock divides a periodic time interval synchronized with the firing timing into L sections. When the M sampling timings are engraved within one interval, the control means synchronizes with the timing defining the L interval division in the storage means from the first stage to the Nth stage in the i-th stage (i = 1 to N−1) after the contents of the storage means are moved to the (i + 1) th storage means, the contents of the storage means from the first stage to the Nth stage are added and stored in the (N + 1) th storage means. It is characterized by doing.
[0023]
  Further, a sixth invention of the present application includes, in the fifth invention, a selection unit that selects and designates an arbitrary section of the divided L section, and the sampling unit, the conversion unit, or the control unit includes: Processing is performed on a section instructed to be selected by the selection means.
[0024]
  According to a seventh aspect of the present application, in a radar signal processing method for emitting a pulse or impulse radio wave at a predetermined timing and receiving and processing a reflected wave from an object, a period time synchronized with the emission timing. A conversion step of converting the received signal of the reflected wave into digital received data based on a first sampling clock that divides a fixed time interval within the interval, and M sampling times within the periodic time interval (M is an arbitrary number) (A positive integer) of digital received data in the first-stage storage means, and storage means from the first stage to the N-th stage (N is an arbitrary positive integer) in synchronization with the emission timing. , The contents of the storage means at the i-th stage (i = 1 to N−1) are moved to the storage means at the (i + 1) -th stage, and then the contents of the storage means from the first stage to the N-th stage are added to the N + 1-th stage. Note of steps In the signal processing method of the radar, characterized by comprising an adding step of storing the unit.
[0025]
  Further, an eighth invention of the present application is a radar signal processing method in which a radio wave which is emitted from another radar at a predetermined timing and a carrier is pulse-modulated or frequency-modulated and communicates is received. And a conversion step for converting the received signal into digital received data based on a first sampling clock that divides a predetermined time interval at M, and M sampling times within the period time interval (M is an arbitrary positive integer). The step of storing digital received data in the storage means of the first stage, and the storage means from the first stage to the Nth stage (N is an arbitrary positive integer) in synchronization with the launch timing, After the contents of the storage means i = 1 to N−1) are moved to the (i + 1) th stage storage means, the contents of the storage means from the first stage to the Nth stage are added to the N + 1th stage storage means. Add to store And step, based on the contents of the first N + 1 stages of the storage means, in the signal processing method of the radar, characterized by comprising a determination step of determining the contents of the communication data from the other radar.
[0026]
  According to a ninth aspect of the present application, in the seventh or eighth aspect, the second sampling is obtained by phase-modulating a first sampling clock that divides a fixed time interval within a periodic time interval synchronized with the firing timing at a low frequency. A time axis expansion sampling clock generation step for generating a clock; and a sampling step for sampling the received signal by the reflected wave with the second sampling clock, wherein the conversion step converts the sampled signal into the first signal. Converting to digital received data at timing based on sampling clockIs.
[0027]
  According to a tenth aspect of the present invention, in the seventh or eighth aspect, the second sampling is obtained by phase-modulating a first sampling clock having a constant time interval within a periodic time interval synchronized with the firing timing at a low frequency. A time axis expansion sampling clock generation step for generating a clock is provided, wherein the conversion step converts the reception signal by the reflected wave into digital reception data at a timing based on the second sampling clock.Is.
[0028]
  The eleventh invention of the present application is the seventh, ninth or tenth invention, wherein the first sampling clock or the second sampling clock divides a periodic time interval synchronized with the firing timing into L sections. When the M sampling timings are engraved within one interval, the adding step is performed at the i-th stage (i) in the storage means from the first stage to the N-th stage in synchronization with the timing defining the L-section division. = 1 to N−1) after the contents of the storage means are moved to the (i + 1) th storage means, the contents of the storage means from the first stage to the Nth stage are added and stored in the (N + 1) th storage means. It is characterized byIs.
[0029]
  The twelfth invention of the present application is the eleventh invention, further comprising a selection step of selecting and specifying an arbitrary section of the divided L section, wherein the sampling step, the conversion step, or the control step includes: Processing is performed for a section instructed to be selected in the selection step.Is.
[0030]
  In addition, in the thirteenth invention of the present application, as a result of processing for the jth section (j = 1 to L) in the eleventh or twelfth invention, the detection target object changes from the jth section to the j−1th section or When it is detected that the vehicle has moved to the j + 1th section, when moving from the jth section to the j−1th section, the jth section is moved in the direction of the j−1th section, and the jth section to the j + 1th section. When moving, a section shift step that shifts by 1/2 section in the direction of the (j + 1) th section and the storage means from the first stage to the Nth stage are divided into the first half and the second half, respectively. When moving to one section, the contents of the first half of the storage means of the i-th stage (i = 1 to N−1) are transferred to the second half of the storage means of the i-th stage, and the k-th stage (k = 1 to N−2). After shifting the contents of the latter half of the storage means to the first half of the k + 1-th stage storage means, The contents of the first half of the storage means of the first stage are cleared, and the contents of the second half of the storage means of the i-th stage (i = 1 to N−1) are stored in the i-th stage when moving from the j-th section to the j + 1-th section. In the first half of the means, the contents of the first half of the k-th stage (k = 2 to N−1) storage means are shifted to the second half of the k−1-th stage storage means, respectively, and then the N−1-th stage storage means. And the storage shift step of adding the contents of the storage means from the first stage to the Nth stage and then storing the contents in the storage unit of the (N + 1) th stage is executed, and then the jth section after the shift The conversion step, the storage step and the addition step are executed forIs.
[0031]
  Furthermore, the fourteenth invention of the present application is readable by a computer stored as a program for causing a computer to execute the radar signal processing method of the seventh, eighth, ninth, tenth, eleventh, twelfth or thirteenth invention. It is on a recording medium.
[0032]
  According to the first, seventh, or fourteenth invention, the conversion means (conversion step) converts the first sampling clock that has a predetermined time interval within a periodic time interval synchronized with the emission timing of the pulse or impulse radio wave. Based on this, the received signal from the reflected wave from the object is converted into digital received data, and the control means (storage step) digitally receives M samples (M is an arbitrary positive integer) the number of times of sampling within the period time interval. The wave data is held in the first-stage storage means, and the control means (addition step) is synchronized with the firing timing by the control means (addition step) in the storage means from the first stage to the N-th stage (N is an arbitrary positive integer). After the contents of the storage means of the stage (i = 1 to N−1) are moved to the storage means of the (i + 1) th stage, the contents of the storage means from the first stage to the Nth stage are added to store the N + 1th stage. Case To.
[0033]
  Thus, N sets are stored in the data storage means as one set from the transmission of the pulse or impulse radio wave to the next transmission, and the object detection or the object is detected based on the result of sequentially adding the reception data having the same time position. Therefore, thermal noise and noise that occurs randomly in the surroundings will be canceled out by the addition process, and even if the distance to the object is far from the transmitting antenna without increasing noise, In this way, the received signal voltage amplitude (S) obtained from the receiving antenna suddenly decreases and is buried in the noise (N) and does not reach the threshold value and cannot be detected. The noise-to-noise ratio S / N can be improved, and the received signal voltage amplitude (S) is increased and noise (N) is suppressed, so that the detectable distance as a radar can be greatly extended. Can, also to allow the accurate detection of the object when the distance constant, it is possible to improve the detection accuracy (distance resolution).
[0034]
  Further, according to the second, eighth, or fourteenth invention, the conversion means (conversion step) emits light from other radars at a predetermined timing based on a first sampling clock that ticks a predetermined time interval within a predetermined cycle time interval. Then, the received signal obtained by receiving the radio wave whose carrier is pulse-modulated or frequency-modulated is converted into digital received data, and the control means (storage step) performs M samplings (M is the number of sampling times within the period time interval). Arbitrary positive integer) digital received data is held in the first-stage storage means, and the control means (addition step) synchronizes with the emission timing from the first stage to the N-th stage (N is an arbitrary positive integer). ), The contents of the storage means in the i-th stage (i = 1 to N−1) are moved to the storage means in the i + 1-th stage, and then the contents of the storage means from the first stage to the N-th stage are transferred. Add Nth Stored in the first stage of the storage means, the determination means (determination step) determines contents of the communication data from other radar based on the content of the (N + 1) stage of the storage means. As a result, wireless communication can be performed together with object detection using radar sensor waves, and the detectable distance can be greatly extended in radar sensing, and accurate object detection can be performed when the distance is constant. Detection accuracy (distance resolution) can be improved.
[0035]
  Further, according to the third, ninth, or fourteenth invention, the time axis expansion sampling clock generation means (time axis expansion sampling clock generation step) records a predetermined time interval within a periodic time interval synchronized with the emission timing. A second sampling clock obtained by phase-modulating one sampling clock at a low frequency is generated, and the received signal by the reflected wave is sampled by the second sampling clock by the sampling means (sampling step), and the sampled signal is converted in the conversion step. Conversion to digital received data is performed at a timing based on the first sampling clock. As a result, the signal subjected to the time-axis expansion sampling by the time-axis expansion sampling clock is converted into a digital signal, and the operating frequency of the conversion means for performing signal processing, the data storage means, and the arithmetic means for performing addition is reduced. The circuit design can be improved and the circuit cost can be reduced.
[0036]
  According to the fourth, tenth, or fourteenth invention, the time axis expansion sampling clock generation means (time axis expansion sampling clock generation step) records the predetermined time interval within the periodic time interval synchronized with the emission timing. A second sampling clock obtained by phase-modulating one sampling clock at a low frequency is generated, and a reception signal based on the reflected wave is converted into digital reception data at a timing based on the second sampling clock in a conversion means (conversion step). As a result, the operating frequency of the data storage means excluding the conversion means and the arithmetic means for performing addition can be reduced, so that the circuit design can be realized and the circuit cost can be reduced.
[0037]
  According to the fifth, eleventh, or fourteenth invention, the first sampling clock or the second sampling clock is divided into M pieces within one section when the periodic time interval synchronized with the firing timing is divided into L sections. When the sampling timing is engraved, the control means (addition step) synchronizes with the timing defining the L section division, and the storage means from the first stage to the Nth stage in the i-th stage (i = 1 to N−1). The contents of the storage means are moved to the (i + 1) th stage storage means, and then the contents of the storage means from the first stage to the Nth stage are added and stored in the (N + 1) th stage storage means. If the accuracy of distance accuracy is to be ensured when the distance to the detection object is long, the capacity of the storage means at each stage of the data storage means becomes large and difficult to realize, but the object enters from the direction of travel. In this case, since the detection of the short distance portion is not necessary, the detection processing is performed from the upper limit of the detection range, thereby reducing the capacity of the storage unit. In addition, it is possible to reduce the delay of the object detection processing time while ensuring the distance accuracy.
[0038]
  According to the sixth, twelfth, or fourteenth invention, the selection means (selection step) selects and designates an arbitrary section of the divided L sections, and the sampling means (sampling step) and the conversion means (conversion step). ) Or the control means (control step), it is desirable to process the section designated by the selection means (selection step).
[0039]
  Further, according to the thirteenth or fourteenth invention of the present application, as a result of processing for the jth section (j = 1 to L) by the section shift step, the object to be detected is changed from the jth section to the j−1th section. Alternatively, when it is detected that the vehicle has moved to the j + 1th section, when moving from the jth section to the j−1th section, the jth section is directed to the j−1th section, and the jth section to the j + 1th section. When moving, a half shift is performed in the direction of the (j + 1) th section, and when the storage means from the first stage to the Nth stage is divided into two parts, the first half and the second half, respectively, from the jth section to the j-th section. When moving to one section, the contents of the first half of the storage means of the i-th stage (i = 1 to N−1) are transferred to the second half of the storage means of the i-th stage, and the k-th stage (k = 1 to N−2). Shift the contents of the second half of the storage means to the first half of the k + 1-th stage storage means. After that, the contents of the first half of the storage means of the first stage are cleared, and the contents of the second half of the storage means of the i-th stage (i = 1 to N−1) are transferred to the first stage when moving from the j-th section to the j + 1-th section. In the first half of the i-th storage means, the contents of the first half of the k-th (k = 2 to N-1) storage means are shifted to the second half of the k-1th storage means, respectively, and then the N-1th stage. The contents of the latter half of the storage means are cleared, then the contents of the storage means from the first stage to the Nth stage are added and stored in the storage means of the (N + 1) th stage, and then the j-th section after the shift is converted. Step, storage step and addition step are executed. As a result, it is possible to realize a follow-up function in accordance with the movement of the object when the periodic time interval is divided and processed.
[0040]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, the first embodiment, the second embodiment, and the third embodiment of the radar, radar signal processing method, radar communication method, and recording medium according to the present invention will be described. This will be described in detail with reference to the drawings in order.
[0041]
[First Embodiment]
  FIG. 1 is a configuration diagram of a radar according to a first embodiment of the present invention. FIG. 1A is an overall configuration diagram of the radar according to the embodiment, and FIG. 1B is a configuration diagram of a signal processing unit of the radar according to the embodiment.
[0042]
  1A, the radar according to this embodiment includes a clock generation unit 101, an impulse generation unit 102, a transmission antenna 103, a reception antenna 105, a signal processing unit 106, and a determination / image processing unit 107. ing.
[0043]
  The clock generation unit 101 generates a reference clock CLK, and the impulse generation unit 102 emits impulse radio waves via the transmission antenna 103 at regular intervals based on the reference clock CLK. Here, the impulse radio wave has a pulse width that is extremely narrow compared to the time interval and has an infinite spectrum that extends to a very high frequency range. In this embodiment, the impulse radar is illustrated. However, when the pulse radar is used, the impulse generator is replaced with a pulse generator, and the pulse generator uses a radio wave (carrier) of one frequency. The carrier is intermittently radiated from the antenna with a pulse signal based on the reference clock CLK.
[0044]
  The wave receiving antenna 105 receives a reflected wave from the object to be detected and supplies the wave receiving signal RFI to the signal processing unit 106. The signal processing unit 106 samples the received signal RFI, converts it into digital received data, and performs data processing. FIG. 1B shows a configuration diagram of the signal processing unit 106.
[0045]
  In FIG. 1B, the signal processing unit 106 includes an A / D conversion unit 111, a control unit 112, a data storage unit 113, and a calculation unit 114, and these components are connected via a bus 151. It is a configuration. The bus 151 is also connected to the determination / image processing unit 107 and supplies output data from the signal processing unit 106.
[0046]
  Further, FIG. 2 illustrates a configuration diagram of more specific first, second, and third embodiments of the signal processing unit 106. 2A, 2B, and 2C are configuration diagrams of the first, second, and third embodiments of the signal processing unit 106, respectively.
[0047]
  The first embodiment of the signal processing unit 106 shown in FIG. 2A shows the configuration of FIG. 1B more specifically. In the control unit 112, the reference clock CLK for marking the emission timing is used. A clock generation unit 115 that generates a synchronized sampling clock SCK for A / D conversion processing (a first sampling clock in the claims) is provided. In other words, in the first embodiment of the signal processing unit 106, the A / D conversion unit 111 digitally receives the received signal RFI based on the sampling clock SCK that ticks a fixed time interval within a periodic time interval synchronized with the emission timing. Convert to data.
[0048]
  A configuration diagram of the data storage unit 113 is shown in FIG. In FIG. 3, the data storage unit 113 stores storage means for holding digital received data for M times (M is an arbitrary positive integer) the number of times of sampling within a cycle time interval from the first stage to the N + 1th stage (N is the number N). It is a configuration provided with N + 1 numbers up to an arbitrary positive integer). That is, the storage means of each stage from the first stage to the (N + 1) th stage has a capacity corresponding to the number of samplings within the cycle time interval, and addresses A0 to AM-1 are allocated, and one sampling data is assigned to each address. Will be memorized.
[0049]
  In the control unit 112, first, M digital reception data of the number of samplings within the period time interval are sequentially stored in the first stage storage means, and the first stage to the Nth stage are synchronized with the emission timing. In the storage means up to the stage, the contents of the storage means in the i-th stage (i = 1 to N−1) are shifted to the next-stage i + 1-th storage means. That is, the contents of the first-stage storage means are stored in the second-stage storage means, the contents of the second-stage storage means are stored in the third-stage storage means,... It is moved to each of N stages of storage means. Immediately thereafter, the operation unit 114 is further used to add the contents of the storage means from the first stage to the Nth stage and store them in the (N + 1) th stage storage means. That is, for the address j (j = A0 to AM-1), the data from the first stage to the Nth stage are added and stored in the address j of the N + 1th stage storage means.
[0050]
  FIG. 4 is an explanatory diagram illustrating the contents of data stored in the storage means at each stage of the data storage unit 113. That is, FIG. 4A shows data stored in the first-stage storage means (from the transmission to immediately before the next transmission), and FIG. 4B stores in the second-stage storage means. FIG. 4C shows data stored in the (N + 1) th stage storage means from the first stage to the Nth stage (from the next transmission to immediately before the next transmission). The contents of the storage means up to the stage are added. FIG. 4 shows the signal waveform of the received signal RFI received by the receiving antenna 105, which includes not only the reflected wave but also the transmitted signal (the first large part in the figure is the transmitted signal). The part after that corresponds to the reflected wave). The vertical broken line in the figure is the sampling timing in A / D conversion (actually, sampling is performed more densely). To be precise, the storage means in each stage of the data storage unit 113 has the sampling timing at that sampling timing. Sampling (A / D conversion) data (digital value) is stored.
[0051]
  Further, the determination / image processing unit 107 sequentially reads the contents of the storage unit in the (N + 1) -th stage of the data storage unit 113 via the output data (bus 151), and detects an object by identifying with a predetermined threshold value. Do. In other words, the transmitted wave portion that appears first exceeds the threshold value, but is subsequently compared with the threshold value, and the reflected wave from the object is also detected exceeding the threshold value. It will be. Therefore, the actual distance to the object can be detected by multiplying the time difference from this transmitted portion to the reflected wave by the speed of light. To make the judgment process easier, start counting at the time of the transmission part, stop the counting operation at the part of the reflected wave, and select the clock for counting operation at a frequency considering high speed. Values can be read directly as distances.
[0052]
  The configuration of the radar according to the first embodiment (the first example of the signal processing unit 106) has been described in detail above. The signal processing method in this radar will be described together. That is, first, in the conversion step, the received signal RFI based on the reflected wave from the object is based on the sampling clock CLK that ticks the fixed time interval within the periodic time interval synchronized with the emission timing of the pulse or impulse radio wave by the A / D converter 111. Is then stored in the first stage storage means by the control unit 112 in the first stage storage means in the storing step, and then in the storing step, and in the adding step The control means 112 moves the contents of the i-th (i = 1 to N-1) storage means to the i + 1-th storage means in the storage means from the first stage to the N-th stage in synchronization with the firing timing. After that, the contents of the storage means from the first stage to the Nth stage are added and stored in the storage means of the (N + 1) th stage for further determination / image processing Detecting the distance to the object by 107.
[0053]
  As described above, in the radar according to the present embodiment, N sets are stored in the data storage unit 113 as one set from the impulse transmission to the next impulse transmission, and the reception data having the same time position (same address) are sequentially added. Since the object detection or the distance to the object is detected based on the result, thermal noise and noise generated randomly around the object are canceled out by the addition process, so that the noise does not increase and the distance to the object is transmitted. Even if it is away from the wave antenna, the received signal voltage amplitude (S) obtained from the receiving antenna is suddenly lowered and buried in the noise (N) as before, and it is detected without reaching the threshold value. Since the signal-to-noise ratio S / N can be improved without being disabled, the received signal voltage amplitude (S) is increased and the noise (N) is suppressed. Detecting distance can be extended greatly of, also to allow the accurate detection of the object when the distance constant, it is possible to improve the detection accuracy (distance resolution).
[0054]
  Next, the radar according to the first embodiment in the case where the signal processing unit is realized by the second embodiment, that is, the configuration shown in FIG. 2B will be described.
[0055]
  In FIG. 2B, the signal processing unit 106b includes a sampling unit 117b, an A / D conversion unit 111b, a control unit 112b, a data storage unit 113b, and a calculation unit 114b, and these components are connected via a bus 151b. Connected configuration. The control unit 112b includes a clock generation unit 115b and a time axis expanded sampling clock generation unit 116b.
[0056]
  In the control unit 112b, the clock generation unit 115 generates a sampling clock SCK (first sampling clock) for A / D conversion processing synchronized with the reference clock CLK that records the emission timing, and the time axis expanded sampling clock generation unit 116b performs sampling. A time axis expanded sampling clock SP (second sampling clock) obtained by phase-modulating the clock SCK at a low frequency is generated.
[0057]
  That is, in the second embodiment of the signal processing unit 106, the sampling unit 117b performs time axis expansion sampling of the received signal RFI at the timing of the time axis expansion sampling clock SP, and the A / D conversion unit 111b performs the sampling clock SCK. The sampled signal is converted into digital received data.
[0058]
  As described in the conventional example, the time axis expansion sampling clock SP generates a voltage waveform (ramp signal, that is, a triangular wave) that rises linearly in a range in which the time axis is to be expanded (for example, a time corresponding to 1000 pulses). Separately, a voltage that is a repetition of a triangular wave for one pulse is created, and when these two voltages are compared and coincident, a sampling pulse is generated. Since the phase of this time-axis-enlarged sampling clock SP is gradually shifted by a long-period triangular wave, the sampling timing gradually shifts from sampling to sampling (assuming one sampling with one pulse), and the next transmission from the transmission All the data up to the wave is collected (for example, by 1000 transmissions). Thus, the time from transmission to the next transmission (for example, 1 μs, 500 ns) is consequently expanded (for example, 1000 times) (1 ms, 500 μs), and the width of the transmission pulse or the impulse itself (for example, 1 ns) Is expanded to 1 μs) to lower the frequency.
[0059]
  In the configuration using the signal processing unit 106 of the first embodiment, when the transmission interval of the transmission pulse or impulse becomes high, the sampling frequency SCK becomes a super high frequency, and the A / D conversion unit 111, the control unit 112, and the data The circuit design of the storage unit 113 and the calculation unit 114 is required to be very fast, and problems arise in circuit feasibility, cost, etc., but A / D conversion is performed after performing time-axis expanded sampling. When the signal processing unit 106b of the example is used, the entire signal processing unit (A / D conversion unit 111b, control unit 112b, data storage unit 113b, and calculation unit 114b) can be slowed down, and circuit design can be realized. In addition, the circuit cost can be reduced.
[0060]
  For example, when the width of the transmitted impulse is less than nanoseconds, the reflected wave received will be the same width, but in order to sample without overlooking this, at least half the time of the width is reciprocal. Sampling clock SCK having a frequency (in the GHz range) is required, a commercial A / D conversion IC uses a clock of tens to hundreds of kHz, and an expensive A / D conversion IC for TV signal processing. However, in view of the current device technology using a clock of several tens of MHz, it is impossible to realize in reality. On the other hand, since the frequency can be lowered to the kHz range by performing the time axis expansion sampling, the device can be easily obtained, and the circuit can be realized.
[0061]
  Further, the operating frequency of the signal processing unit differs depending on whether the medium of the emitted radio wave is an electromagnetic wave or a sound wave, and also depends on the shortest distance that can be measured by each required specification. Considering specific numerical values, for example, the pulse width is 6.6 ns or less when 1 m is the shortest distance with radio waves, and 66 ns when radio waves are up to 10 m. Therefore, in the signal processing unit of the first embodiment, if it is desired to sample the reflected wave of 6.6 ns three times, the interval is 2.2 ns, and the frequency of the clock SCK of the A / D converter 111 is 450 MHz. Therefore, it is difficult to realize a circuit with respect to the specification of the shortest distance of 1 m, and it is necessary to introduce a time axis expansion sampling technique as in the second embodiment.
[0062]
  Next, the radar according to the first embodiment in the case where the signal processing unit is realized by the third embodiment, that is, the configuration shown in FIG. 2C will be described.
[0063]
  In FIG. 2C, the signal processing unit 106c includes an A / D conversion unit 111c, a control unit 112c, a data storage unit 113c, and a calculation unit 114c, and these components are connected via a bus 151c. It is a configuration. In addition, the control unit 112c includes a time axis expanded sampling clock generation unit 116c.
[0064]
  In the control unit 112c, the time-axis expanded sampling clock generation unit 116c generates a time-axis expanded sampling clock SP (second sampling clock) obtained by phase-modulating a signal synchronized with the reference clock CLK that marks the emission timing at a low frequency. In other words, in the third embodiment of the signal processing unit 106, the A / D conversion unit 111c converts the received signal RFI into digital received data based on the time axis expanded sampling clock SP.
[0065]
  Even in the signal processing unit 106c of the third embodiment, the signal processing units (the control unit 112c, the data storage unit 113c, and the calculation unit 114c) other than the A / D conversion unit 111c are slowed down as in the second embodiment. As a result, the circuit design can be improved and the circuit cost can be reduced.
[0066]
  Next, some modifications of the signal processing method in the radar according to the first embodiment will be described.
[0067]
  First, in the first modification, M sampling timings within one section when the sampling clock SCK or the time-axis-enlarged sampling clock SP of the signal processing unit 106 is divided into L sections of a periodic time interval synchronized with the firing timing. It is generated to engrave. In this case, in the control unit 112 (addition step), the i-th stage (i = 1 to N−1) of the storage means from the first stage to the N-th stage is synchronized with the timing defining the L section division. After the contents of the storage means are moved to the (i + 1) th stage storage means, the contents of the storage means from the first stage to the Nth stage are added by the calculation unit 114 and stored in the (N + 1) th stage storage means. .
[0068]
  If the distance accuracy is to be ensured when the distance to the detection object is long, the capacity (M) of the storage means at each stage of the data storage unit 113 becomes a large value. In the case of intrusion, a portion at a short distance is unnecessary, so that the capacity (M) of the storage means can be reduced if processing is performed from the upper limit of the detection range. In addition, it is possible to reduce the delay of the object detection processing time while ensuring the distance accuracy.
[0069]
  Originally, sampling must reliably sample a pulse or an expanded impulse, and this width is related to the shortest distance that can be detected, and the longest detection distance is determined by the pulse interval (assuming the firing power is sufficient). Involved. For example, if the shortest distance is 1 m and the longest distance is 100 m, each stage of storage means needs a capacity of 300 addresses when sampling three times with one pulse. Overall, a capacity of 300 × (N + 1) addresses is required. Also, the computation time for processing this is impossible because an ultra-high speed clock is required to finish the processing for each pulse.
[0070]
  By the way, when considering the radar, if it is started from a state where no object is detected, it is unlikely that the object will suddenly come into a short distance, and detection may be started from the point where it entered the maximum detection distance. Therefore, as shown in FIGS. 5A and 5B, when the cycle time interval is divided into the first to L-th L sections, as shown in FIGS. Since it can be seen from the L-th section near the detection distance, the capacity of the storage means at each stage may be 300 / L addresses. In generalized terms, the capacity for M / L addresses is sufficient.
[0071]
  Alternatively, since the sampling interval (three times in the above example) actually affects the distance accuracy, if all the storage capacity of the data storage unit 113 is allocated by L division, the distance resolution can be increased. Become. In any case, the operation clock of the arithmetic unit 114 and the like can be reduced.
[0072]
  Next, in the second modification, in the L section division as shown in FIG. 6A, sampling is performed for the jth section (j = 1 to L) as shown in FIGS. 6B and 6C. When it is detected from the result that the object to be detected has moved from the jth section to the j-1st section, as shown in FIG. 6 (d), the jth section is changed to the j-1th section direction. Storage means for the i-th stage (i = 1 to N-1) when the storage means from the first stage to the N-th stage is divided into two in the first half and the second half, respectively. Are shifted to the latter half of the i-th storage means and the latter half of the k-th (k = 1 to N−2) storage means are shifted to the first half of the k + 1-th storage means. The contents of the first half of the storage means of the first stage are cleared, and then the contents of the storage means from the first stage to the Nth stage are added and the N + Stored in the stages of the storage means (storage shift step), then, for the j interval after shifting, and executes a conversion step, storage step and addition step.
[0073]
  When processing is performed by dividing into L sections as in the first modification, only 1 / L section (area) of the entire distance measurement / detection area is seen, so that the object moves. A function to follow it is necessary. The second modification implements this follow-up function.
[0074]
  That is, when an object enters the Lth section, which is the farthest section, the object gradually moves and starts to enter the L-1 section. It can be seen from the change in the measurement distance that the object is approaching. Therefore, the sampling interval may be shifted based on the information indicating that it is approaching. However, since it is difficult to understand the boundary if moved by one section at a time, the sampling section is shifted by ½ section as described above. Further, as shown in FIG. 7, the content held in the data storage unit 113 in accordance with the interval shift is also shifted in accordance with the sampling interval shift, so that the changed sampling position and the content of the data storage unit 113 are unified. By doing so, it is possible to realize a tracking function that matches the movement of the object.
[0075]
  The storage shift operation in the data storage unit 113 shifts the contents of the addresses A0 to AM-1 of the storage means at each stage by M / 2. That is, the contents of the address A0 are moved to the address A0 + M / 2, the contents of the address A1 are moved to the address A1 + M / 2,..., And the contents of the address AM / 2-1 are moved to the address AM-1. Assuming that the storage units from the first stage to the Nth stage are arranged, the contents of all addresses are shifted to the right by M / 2 addresses. Thereafter, the contents of the first-stage addresses A0, A1,..., AM / 2-1 are cleared to “0”.
[0076]
  In this case, when the signal processing unit 106 is configured in the first embodiment, the sampling clock in this case is the time when the sampling start time and the end time are divided as shown in FIG. It only needs to coincide with the timing point shifted by two.
[0077]
  Further, when the signal processing unit 106 is configured in the second embodiment, as shown in FIG. 8, the start point of the long-period slow ramp waveform (triangular wave) (corresponding to the pulse or impulse emission interval) is a section. It suffices if it coincides with the divided time point or the timing time point shifted by M / 2 and the end time point is after the passage of one section.
[0078]
  The case of approaching has been described above, but when an object moves away, it is as follows. That is, when it is detected from the result of processing for the j-th section (j = 1 to L) that the detection target object has moved from the j-th section to the j + 1-th section, the j-th section is directed in the j + 1-th section direction. The storage means of the i-th stage (i = 1 to N-1) when the storage means from the first stage to the N-th stage is divided into the first half and the second half, respectively, is shifted by 1/2 section (section shift step). After shifting the latter half contents to the first half of the i-th stage storage means and shifting the first half contents of the k-th stage (k = 2 to N−1) storage means to the second half of the k−1-th stage storage means, The contents of the second half of the storage means of the (N-1) th stage are cleared, and then the contents of the storage means from the 1st stage to the Nth stage are added and stored in the storage means of the (N + 1) th stage (storage shift step). , For the jth section after the shift, the conversion step, the storage step, and the addition step Tsu to run up.
[0079]
  Further, along with the movement of the object, how the address (A0 to AM-1) when the object is detected in the data storage unit 113 is moved, and the direction of the storage shift operation (right shift or left shift) From the two viewpoints, the direction of whether the object is approaching or moving away can be determined, and since the sampling interval is time and can be converted into distance, the amount of change per unit time depends on the speed. Therefore, if the speed of change is measured in unit time, the speed can be determined, and the direction, distance, and relative speed can be determined. Therefore, in this case, the determination / image processing unit 107 can display an image of the moving direction, distance, and speed of the detected object.
[0080]
[Second Embodiment]
  Next, before describing the second and third embodiments, “communication sensing” will be briefly described. The conventional radar and the radar according to the first embodiment are used only as radar sensors, and a detection signal for detecting an object or a control signal based on the detection signal is transmitted by a separate communication system regardless of wired or wireless. For this reason, a communication line has been laid or a radio device having a different frequency has been required.
[0081]
  For example, if the presence of a vehicle is detected by a radar on a road with poor visibility, and there is an oncoming vehicle, a system that warns the driver by means of a vehicle-mounted device that there is an oncoming vehicle, or the road is wide and speed There is a system that detects the presence and speed of a vehicle with a radar at an accident-prone point where the curve cannot be bent too much, and warns the driver by a vehicle-equipped device if it is a dangerous speed. In such a system, a warning signal is transmitted using a wireless communication device as a separate means.
[0082]
  The radar according to the second and third embodiments of the present invention can perform wireless communication together with object detection using a radar sensor wave. That is, in the second embodiment, what normally communicates while sensing in a system called pulse radar is proposed, and in the third embodiment, what communicates while sensing in a system called FM-CW radar is proposed. ing. The FM-CW radar can measure speed and distance essentially, and the configuration is somewhat complicated. On the other hand, the pulse radar can measure distance essentially and has a somewhat simple configuration. There is a feature that it is secondarily obtained as a result of calculating the change in time. In addition, the direction can be obtained by combining the antennas (by making the radiation beam fine or shaking the beam).
[0083]
  FIG. 9 is an explanatory diagram illustrating a specific example in the field of ITS (Intelligent Transport System) to which the radars of the second and third embodiments are applied. ITS is a system for automobile transportation, etc. that realizes a much safer, quicker and more comfortable transportation system with information and communication technology.
  In FIG. 9, it is assumed that the host vehicle 201 and the rear vehicle 202 are equipped with a front radar and a rear radar, respectively, and the distance between the vehicles is being measured. That is, the host vehicle 201 sends a communication signal to the rear vehicle 202 using the same radio wave f1 while measuring the distance behind the radio wave f1, and the rear vehicle 202 communicates using the same radio wave f2 while measuring the distance ahead using the radio wave f2. A signal is sent to the vehicle 201. In the figure, a line crossing obliquely between the host vehicle 201 and the rear vehicle 202 represents a reflected wave. In this case, when the own vehicle 201 detects that the rear vehicle 202 has approached dangerously, it may be possible to communicate with the rear vehicle 202 so as to widen the distance between the vehicles.
[0084]
  Next, the “pulse radar system” to which the second embodiment is applied will be briefly described with reference to FIGS. 10 and 11.
[0085]
  A pulse radar normally emits a carrier by on / off keying (pulse modulation) with a pulse having a constant width and a constant interval. That is, when there is no data to be communicated, pulses are formed at regular intervals as shown in FIG. 10A, and when there is data to be communicated and the communication data is “0”, as shown in FIG. When the communication data is “1”, as shown in FIG. 10C, the pulse interval is 1.5 times as long as that of the communication data “0”. It is said. In this way, it is possible to send communication data while continuing the sensing operation. In addition, the numerical value of 1.5 times is an example, and it should just be changed, and has no particular meaning.
[0086]
  On the other hand, the receiver side receives and demodulates the pulse wave and verifies the pulse interval, thereby determining the data “0” and “1” and reproducing the received data. That is, if the received pulse is the pulse interval shown in FIG. 11A, the communication data is determined as “0”, and if the received pulse is the pulse interval shown in FIG. 11B, the communication data is determined as “1”. The The sensing operation is performed by the reflected wave shown in FIG.
[0087]
  12 and 13 are configuration diagrams of a radar according to the second embodiment of the present invention. 12 shows the configuration of the radar transmission unit 211 and the radar reception unit 212, and FIG. 13 shows the configuration of a radar wave receiving communication device including information. That is, the radar according to the present embodiment includes at least a radar transmission unit 211, a radar reception unit 212, and a radar wave reception communication device including information.
[0088]
  First, the radar transmission unit 211 includes a pulse generation unit 311, a pulse modulation unit 312, a pulse position control unit 313, a carrier generation unit 314, and an antenna 213. That is, a carrier of one frequency is used and the carrier is intermittently radiated from the antenna with a pulse signal. Since the function and operation of each component are well known, description thereof is omitted here.
[0089]
  Next, the radar receiving unit 212 includes an antenna 213, a front end 321, a detection circuit 322, a time axis expansion unit 323, an AD conversion unit 324, a storage unit / processing unit 325, a distance determination unit 326, a control unit 327, and a clock generation unit. (SGC) 328 is provided.
[0090]
  The antenna 213, the front end 321 and the detection circuit 322 are equivalent to those used in the reception or reception system of a normal radar or radio. Further, the description of other components will be simplified by making the signal processing unit correspond to the configuration of the third example (see FIG. 2C) in the radar of the first embodiment. That is, the time axis expansion unit 323 corresponds to the time axis expansion sampling clock generation unit 116c in FIG. 2C, the AD conversion unit 324 corresponds to the A / D conversion unit 111c in FIG. The processing unit 325 corresponds to the data storage unit 113c and the calculation unit 114c, the distance determination unit 326 corresponds to the determination / image processing unit 107 in FIG. 1A, and the control unit 327 includes the control unit 112c in FIG. The clock generation unit (SGC) 328 is configured in the control unit 112c in FIG.
[0091]
  Note that the radar receiver 212 of this embodiment differs from the first embodiment in the sampling range for signal processing. That is, in the first embodiment, the range is from a transmission pulse to the next transmission pulse, but in this embodiment, the transmission interval changes depending on the communication data “0” and “1”. Even in this case, the sampling range (target) is from the wave transmission to the time position corresponding to the maximum distance.
[0092]
  Further, in FIG. 13, the radar wave receiving communication device includes an antenna 213, a front end 331, a detection circuit 332, a time axis expansion unit 333, an AD conversion unit 334, a storage unit / processing unit 335, and a 1 determination unit 336. A unit 337 and a clock generation unit (SGC) 338 are provided.
[0093]
  The antenna 213, the front end 321 and the detection circuit 322 are the same as those used in a normal radio reception system. Further, the description of other components will be simplified by making the signal processing unit correspond to the configuration of the third example (see FIG. 2C) in the radar of the first embodiment. That is, the time axis expansion unit 333 corresponds to the time axis expansion sampling clock generation unit 116c in FIG. 2C, the AD conversion unit 334 corresponds to the A / D conversion unit 111c in FIG. The processing unit 335 corresponds to the data storage unit 113c and the calculation unit 114c, the 1, 0 determination unit 336 corresponds to the determination / image processing unit 107 in FIG. 1A, and the control unit 337 controls the control in FIG. The clock generation unit (SGC) 338 corresponds to the unit 112c and is configured in the control unit 112c in FIG.
[0094]
  The radar receiving unit 212 performs reflected wave processing as a radar sensor, whereas the radar wave receiving communication device receives a radar (sensor) wave transmitted by the other party as a direct wave and performs direct wave processing. It is different. Therefore, in the radar wave receiving communication device, the radar receiving unit 212 receives a signal transmitted and transmitted by another person, unlike when the radar receiving unit 212 sees a time corresponding to the maximum distance from the transmitted pulse. Is determined to be “0” or “1”, so that the sampling is continuously continuous, and the storage unit stores the time equal to or longer than the longer transmission interval of the pulse intervals representing “0” and “1”. The memory length of the storage means is required.
[0095]
  Next, a signal processing method in the radar receiver 212 of the radar according to the present embodiment will be described. Similar to the radar according to the first embodiment, first, in the conversion step, the reception by the reflected wave from the object is performed based on the time axis expansion sampling clock SP generated by the AD conversion unit 324 in synchronization with the emission timing of the pulse radio wave. The signal is converted into digital received data, and then in the storing step, digital received data for M times of sampling is held in the first-stage storage means by the control unit 327, and further in the adding step, the control means 327 By moving the contents of the storage means of the i-th stage (i = 1 to N−1) to the storage means of the i + 1-th stage in the storage means from the first stage to the N-th stage in synchronization with the launch timing, The contents of the storage means from the first stage to the Nth stage are added and stored in the storage means of the (N + 1) th stage. Determining the distance velocity direction data for detecting a direction.
[0096]
  A signal processing method in the radar wave receiving communication device of the radar according to this embodiment will be described. First, in the conversion step, the direct wave reception signal is converted into digital reception data based on the time-axis expanded sampling clock SP generated in synchronization with the emission timing of the pulse radio wave by the AD conversion unit 334, and then the storage step , The control unit 337 holds the digital reception data corresponding to the number of samplings Q in the first-stage storage means, and further, in the addition step, the control means 337 causes the control means 337 to synchronize with the firing timing from the first stage to the Nth stage. After the contents of the storage means of the i-th stage (i = 1 to N−1) are moved to the storage means of the i + 1-th stage in the storage means up to the stage, the contents of the storage means from the first stage to the N-th stage are transferred. Add and store in storage means in the (N + 1) th stage.
[0097]
  FIG. 14 is an explanatory diagram illustrating the contents of data stored in the storage means at each stage. Here, the storage means at each stage has a capacity capable of storing a data amount for a predetermined number of times of sampling, and addresses A0 to AQ-1 are assigned. That is, FIG. 14 (a) shows data stored in the first-stage storage means (from the transmission to a point just past the next transmission), and FIG. 14 (b) shows the second-stage storage. 14 (c) is data stored in the N + 1-th stage storage means (from the next transmission to around the next transmission). The contents of the storage means from the first stage to the Nth stage are added. FIG. 14 shows a signal waveform of a received signal received by the receiving antenna 213, and includes only direct waves from others. In addition, the vertical broken line in the figure is the sampling timing in A / D conversion (actually, sampling is performed more densely). To be exact, the storage means at each stage has sampling (A / D Conversion) data (digital value) will be stored.
[0098]
  Next, in the determination step, the 1, 0 determination unit 336 determines the content of communication data from other radars based on the content of the (N + 1) th stage storage means. That is, as shown in FIG. 15A, the communication data is determined to be "0" if a predetermined threshold value is exceeded at any two of the addresses A0 to AQ-1 of the (N + 1) th storage means. As shown in FIG. 16A, if a predetermined threshold value is exceeded at any one of the addresses A0 to AQ-1 of the storage means of the (N + 1) th stage, the communication data is determined to be "1". .
[0099]
  Further, if the determination process in the 1,0 determination unit 336 is improved, the address A0 in which the signal exceeds the threshold value in the above process (the smaller address if there are two) is used as the address A0. At the same time as subtracting A from the value of the address pointer, the data in the N-th stage storage means is shifted to the left by (A-A0). In this way, when the communication data is “0”, as shown in FIG. 15B, a location exceeding the threshold value appears at the address A 0 and the address B-A, and when the communication data is “1”, FIG. As shown in FIG. 5B, locations exceeding the threshold value appear at the address A0 and the address AQ-1. Therefore, since it is possible to perform the determination by excluding the data at the intermediate address and processing only the data of the address A0 and the address AQ-1, the reliability can be improved and the processing time can be shortened.
[0100]
  As described above, in the radar according to the present embodiment, it is possible to perform wireless communication together with object detection using radar sensor waves, and in radar sensing, the detectable distance is greatly increased and the distance is constant. An accurate object can be detected and detection accuracy (distance resolution) can be improved. In the radar according to the present embodiment, the first, second, and third examples described above can be applied to the signal processing unit of the radar according to the first embodiment. There is an effect.
[0101]
[Third Embodiment]
  Next, an embodiment in which communication is performed while sensing in a radar according to a third embodiment of the present invention, that is, an FM-CW radar system will be described.
[0102]
  FIG. 17 is an explanatory diagram for briefly explaining the “FM-CW radar system” to which the present embodiment is applied. In the FM-CW radar system, FM modulation is usually performed with a triangular wave. That is, on the transmitting side, as shown in FIG. 17A, the triangular wave repetition period is changed by “0” and “1” of data to be communicated, and on the receiving side, as shown in FIG. The communication is possible by obtaining the original triangular wave by FM demodulation and determining “0”, “1” of the communication data from the period of the triangular wave.
[0103]
  The configuration of the radar according to the present embodiment can also be realized by the configurations of FIGS. 12 and 13 as in the second embodiment. However, the radar transmission unit 211 performs FM modulation, and the radar reception unit 212 and the radar wave reception communication device differ in that FM demodulation is performed.
[0104]
  FIG. 18 is an explanatory diagram illustrating the contents of data stored in the storage means at each stage. Here, the storage means in each stage has a capacity capable of storing a data amount for a predetermined number of times of sampling. 18A shows data stored in the first-stage storage means, FIG. 18B shows data stored in the second-stage storage means, and FIG. The data stored in the (N + 1) th stage storage means is the sum of the contents of the storage means from the first stage to the Nth stage. FIG. 14 shows a signal waveform of a received signal received by the receiving antenna 213, and includes only direct waves from others. In addition, the vertical broken line in the figure is the sampling timing in A / D conversion (actually, sampling is performed more densely). To be exact, the storage means at each stage has sampling (A / D Conversion) data (digital value) will be stored.
[0105]
  As described above, in the radar according to the present embodiment, it is possible to perform wireless communication together with object detection using radar sensor waves, and in radar sensing, the detectable distance is greatly increased and the distance is constant. An accurate object can be detected and detection accuracy (distance resolution) can be improved. In the radar according to the present embodiment, the first, second, and third examples described above can be applied to the signal processing unit of the radar according to the first embodiment. There is an effect.
[0106]
  Further, in any of the pulse radar, FM-CW radar, or impulse radar described above, “0” and “1” of the transmission data are secondarily modulated by the PN code, and the PN code speed is matched with the radar emission period. It is possible to realize higher-quality communication by using so-called "spread spectrum communication" that is obtained by performing the above-described processing on the receiving side and correlating with the same PN code. .
[0107]
【The invention's effect】
  As is apparent from the above description, according to the present invention, the conversion means (conversion step) is based on the first sampling clock that ticks a fixed time interval within a periodic time interval synchronized with the emission timing of the pulse or impulse radio wave, A received signal by a reflected wave from an object is converted into digital received data, and digital received data for M sampling times within a period time interval is stored in the first-stage storage means by the control means (storage step). The contents of the storage means of the i-th stage (i = 1 to N−1) are stored in the storage means from the first stage to the N-th stage in synchronization with the firing timing by the control means (addition step). After moving to the storage means of the stage, the contents of the storage means from the first stage to the Nth stage are added and stored in the storage means of the (N + 1) th stage. The generated noise is canceled out by the addition process, and the signal-to-noise ratio S / N can be improved without increasing the noise, and the received signal voltage amplitude (S) is increased to increase the noise (N). Therefore, the detectable distance as a radar can be greatly increased, and an accurate object can be detected when the distance is constant, and the detection accuracy (distance resolution) can be improved.
[0108]
  Further, according to the present invention, the conversion means (conversion step) emits at a predetermined timing from another radar based on a first sampling clock that divides a predetermined time interval within a predetermined cycle time interval, and the carrier is subjected to pulse modulation or frequency. A received signal obtained by receiving the modulated radio wave is converted into digital received data, and the control means (storage step) stores M digital received data of the number of samplings within the period time interval in the first stage. The contents of the storage means of the i-th stage (i = 1 to N−1) are stored in the storage means from the first stage to the N-th stage in synchronization with the firing timing by the control means (addition step). After moving to the (i + 1) th stage storage means, the contents of the storage means from the first stage to the Nth stage are added and stored in the (N + 1) th stage storage means. Since the contents of communication data from other radars are determined based on the contents of the one-stage storage means, wireless communication can be performed together with object detection using radar sensor waves, and in radar sensing It is possible to greatly extend the detectable distance and to detect an accurate object when the distance is constant, and to improve the detection accuracy (distance resolution).
[0109]
  In addition, according to the present invention, the first sampling clock having a constant time interval within the periodic time interval synchronized with the emission timing is phased at a low frequency by the time axis expansion sampling clock generation means (time axis expansion sampling clock generation step). A modulated second sampling clock is generated, the received signal by the reflected wave is sampled by the second sampling clock by the sampling means (sampling step), and the sampled signal is converted at a timing based on the first sampling clock in the conversion step. As conversion to digital received data, a signal that has undergone time-axis expansion sampling with a time-axis expansion sampling clock is converted to a digital signal, so conversion means that performs signal processing, data storage means, and operations that perform addition, etc. hand It is possible to slow down the operating frequency for, to increase the feasibility of a circuit design, it is possible to reduce the circuit costs.
[0110]
  In addition, according to the present invention, the first sampling clock having a constant time interval within the periodic time interval synchronized with the emission timing is phased at a low frequency by the time axis expansion sampling clock generation means (time axis expansion sampling clock generation step). The modulated second sampling clock is generated, and the conversion means (conversion step) converts the received signal by the reflected wave into digital reception data at a timing based on the second sampling clock. The operating frequency of the storage means and the arithmetic means for performing addition can be reduced, so that the circuit design can be realized and the circuit cost can be reduced.
[0111]
  Further, according to the present invention, when the first sampling clock or the second sampling clock divides M sampling timings within one section when the periodic time interval synchronized with the firing timing is divided into L sections, the control means In the (addition step), the contents of the storage means in the i-th stage (i = 1 to N−1) are stored in the storage means from the first stage to the N-th stage in synchronization with the timing defining the L section division. After moving to the storage means of the stage, the contents of the storage means from the first stage to the Nth stage are added and stored in the storage means of the (N + 1) th stage, so that the detection process is performed from the upper limit of the detection range. It is possible to reduce the delay of the object detection processing time while suppressing the capacity of the storage means and ensuring the distance accuracy.
[0112]
  Further, according to the present invention, as a result of processing for the jth section (j = 1 to L) by the section shift step, the detection target object moves from the jth section to the j−1th section or the j + 1th section. When moving from the jth section to the j−1th section, the jth section is directed to the j−1th section, and when moving from the jth section to the j + 1th section, respectively, to the j + 1th section direction. When shifting from the jth section to the j-1th section when the storage means from the first stage to the Nth stage is divided into two parts, the first half and the second half, respectively, by shifting by 1/2 section and the storage shift step, The contents of the first half of the storage means of the i-th stage (i = 1 to N−1) are the latter half of the storage means of the i-th stage, and the contents of the second half of the storage means of the k-th stage (k = 1 to N−2) are After each shift to the first half of the k + 1 stage storage means, the first stage storage means The contents of the first half are cleared, and when moving from the jth section to the j + 1th section, the second half contents of the storage means of the i-th stage (i = 1 to N−1) are transferred to the first half of the storage means of the i-th stage. The contents of the first half of the k-th (k = 2 to N-1) storage means are shifted to the second half of the k-1th storage means, respectively, and then the latter half of the N-1th storage means is cleared. Thereafter, the contents of the storage means from the first stage to the Nth stage are added and stored in the (N + 1) th stage storage means, and then the conversion step, the storage step and the addition step are executed for the jth section after the shift. As a result, it is possible to realize a follow-up function in accordance with the movement of the object when the periodic time interval is divided into sections.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a radar according to a first embodiment of the present invention, FIG. 1 (a) is an overall configuration diagram of the radar of the embodiment, and FIG. 1 (b) is a signal processing unit of the radar of the embodiment. FIG.
FIGS. 2A, 2B, and 2C are configuration diagrams of first, second, and third embodiments of a signal processing unit, respectively.
FIG. 3 is a configuration diagram of a data storage unit.
FIG. 4 is an explanatory view illustrating the contents of data stored in the storage means at each stage of the data storage unit.
FIG. 5 is an explanatory diagram of a first modification (periodic time interval synchronized with the emission timing is divided into L sections);
FIG. 6 is an explanatory diagram of a second modification (follow-up function).
FIG. 7 is an explanatory diagram illustrating a relationship between a sampling clock and an address of a storage unit.
FIG. 8 is an explanatory diagram for explaining the relationship between generation of a time axis expanded sampling clock and interval movement;
FIG. 9 is an explanatory diagram illustrating a specific example of the ITS field to which the radar according to the second and third embodiments is applied.
FIG. 10 is an explanatory diagram for explaining a pulse radar system (transmitting side).
FIG. 11 is an explanatory diagram for explaining a pulse radar system (receiving side).
FIG. 12 is a configuration diagram of a radar (a radar transmitter and a radar receiver) according to a second embodiment of the present invention.
FIG. 13 is a configuration diagram of a radar (radar wave receiving communication device) according to a second embodiment.
FIG. 14 is an explanatory diagram illustrating the contents of data stored in storage means at each stage according to the second embodiment.
FIG. 15 is an explanatory diagram of communication data “0” determination in a 1, 0 determination unit (determination step).
FIG. 16 is an explanatory diagram of communication data “1” determination in a 1, 0 determination unit (determination step).
FIG. 17 is an explanatory diagram for explaining an FM-CW radar system;
FIG. 18 is an explanatory diagram illustrating the contents of data stored in the storage means of each stage according to the third embodiment.
FIG. 19 is a configuration diagram of a transmission unit and a reception unit of a conventional radar using a time axis expansion sampling technique.
FIG. 20 is a configuration diagram of a circuit that generates a time-axis-enlarged sampling pulse of a conventional example.
FIG. 21 is a timing chart illustrating signal processing in a wave receiving section of a conventional radar.
FIG. 22 is a timing chart for explaining generation of a time axis expanded sampling pulse;
[Explanation of symbols]
  101 Clock generator
  102 Impulse generator
  103 Transmitting antenna
  105 Receiving antenna
  106 Signal processor
  107 Judgment / Image Processing Unit
  CLK reference clock
  RFI received signal
  111, 111b, 111c A / D converter
  112, 112b, 112c control unit
  113, 113b, 113c Data storage unit
  114, 114b, 114c arithmetic unit
  115, 115b Clock generator
  116b, 116c Time axis expanded sampling clock generator
  151, 151b, 151c bus
  SCK sampling clock (first sampling clock)
  SP Time base expansion sampling clock (second sampling clock)
  201 Own car
  202 Rear vehicle
  211 Radar transmitter
  212 Radar receiver
  213 Antenna
  311 Pulse generator
  312 Pulse modulation unit
  313 Pulse position controller
  314 Carrier generator
  321,331 Front end
  322, 323 detector circuit
  323,333 Time axis expansion part
  324,334 AD converter
  325, 335 Storage unit / Processing unit
  326,336 Distance determination unit
  327,337 control unit
  328, 338 Clock generator (SGC)

Claims (8)

A transmission means for transmitting a pulse or impulse radio wave at a predetermined timing;
Receiving means for receiving a reflected wave from an object and generating a received signal;
Conversion means for converting a received signal by the reflected wave into digital received data based on a first sampling clock that divides a fixed time interval within a periodic time interval synchronized with the transmission timing;
There are provided N + 1 storage means for holding M digital reception data (M is an arbitrary positive integer) of the number of samplings within the period time interval from the first stage to the N + 1th stage (N is an arbitrary positive integer). Data storage means,
After the digital reception data for M sampling times within the cycle time interval is held in the first stage storage means, the first stage to the Nth stage are synchronized with the transmission timing. After the contents of the storage means in the i-th stage (i = 1 to N−1) are moved to the i + 1-th stage storage means in the storage means, the contents of the storage means from the first stage to the N-th stage are added. A radar comprising control means for storing in the N + 1-th stage storage means,
The first sampling clock is set so as to engrave M sampling timings within one section when a periodic time interval synchronized with the transmission timing is divided into L sections.
The control means synchronizes the content of the storage means of the i-th stage (i = 1 to N−1) in the storage means from the first stage to the N-th stage in synchronization with the timing defining the L section division. After moving to the (i + 1) th stage storage means, the contents of the storage means from the first stage to the Nth stage are added and stored in the (N + 1) th stage storage means. Comprising selection means for selecting and specifying an arbitrary section;
Before Symbol conversion means or the control means, for selecting the specified detection range limit of the interval is preferentially processed by the selecting means, radar, characterized in that. A time-axis-enhanced sampling clock generating means for generating a second sampling clock obtained by phase-modulating a first sampling clock that divides a fixed time interval within a periodic time interval synchronized with the transmission timing at a low frequency;
Sampling means for sampling the received signal by the reflected wave with the second sampling clock;
The radar according to claim 1, wherein the conversion unit converts the sampled signal into digital received data at a timing based on the first sampling clock. A time-axis expanded sampling clock generating means for generating a second sampling clock obtained by phase-modulating a first sampling clock that divides a fixed time interval within a periodic time interval synchronized with the transmission timing at a low frequency;
2. The radar according to claim 1, wherein the conversion unit converts a received signal by the reflected wave into digital received data at a timing based on the second sampling clock. A transmission step of transmitting a pulse or impulse radio wave at a predetermined timing;
A receiving step for receiving a reflected wave from an object and generating a received signal;
A conversion step of converting a received signal by the reflected wave into digital received data based on a first sampling clock that ticks a fixed time interval within a periodic time interval synchronized with the transmission timing;
A storage step of holding digital received data for M times (M is an arbitrary positive integer) of the number of samplings within the period time interval in the first-stage storage means;
In synchronism with the transmission timing, in the storage means from the first stage to the Nth stage (N is an arbitrary positive integer), the contents of the storage means of the i-th stage (i = 1 to N−1) are changed to the i + 1-th stage. And adding the contents of the storage means from the first stage to the Nth stage and storing them in the (N + 1) th stage storage means.
The first sampling clock is set so as to engrave M sampling timings within one section when a periodic time interval synchronized with the transmission timing is divided into L sections.
In the adding step, the contents of the storage means of the i-th stage (i = 1 to N−1) are stored in the storage means from the first stage to the N-th stage in synchronization with the timing defining the L section division. After moving to the (i + 1) th stage storage means, the contents of the storage means from the first stage to the Nth stage are added and stored in the (N + 1) th stage storage means. Comprising a selection step of selecting and specifying an arbitrary section;
Before Symbol conversion step or said adding step is preferentially processed for said selecting step in selecting the specified detection range limit of the interval, the signal processing method of the radar, characterized in that. A time-axis-enhanced sampling clock generation step of generating a second sampling clock obtained by phase-modulating a first sampling clock that divides a constant time interval within a periodic time interval synchronized with the transmission timing at a low frequency;
A sampling step of sampling the received signal by the reflected wave with the second sampling clock; and
5. The radar signal processing method according to claim 4, wherein the converting step converts the sampled signal into digital received data at a timing based on the first sampling clock. A time-axis-enhanced sampling clock generation step for generating a second sampling clock obtained by phase-modulating a first sampling clock that divides a fixed time interval within a periodic time interval synchronized with the transmission timing at a low frequency;
5. The radar signal processing method according to claim 4, wherein the converting step converts a received signal by the reflected wave into digital received data at a timing based on the second sampling clock. As a result of processing for the jth section (j = 1 to L), when it is detected that the object to be detected has moved from the jth section to the j−1th section or the j + 1th section, the jth section to the jth section a section shift step for shifting the jth section in the j-1 section direction when moving to the j-1 section, and a ½ section shift in the j + 1 section direction when moving from the jth section to the j + 1 section,
When the storage means from the first stage to the Nth stage is divided into the first half and the second half, respectively, when moving from the jth section to the j-1th section, the ith stage (i = 1 to N-1). The first half of the storage means is shifted to the second half of the i-th storage means, and the second half of the k-th storage means (k = 1 to N−2) is shifted to the first half of the k + 1-th storage means. Thereafter, the contents of the first half of the storage means of the first stage are cleared, and the contents of the latter half of the storage means of the i-th stage (i = 1 to N−1) are transferred to the i-th section when moving from the j-th section to the j + 1-th section. After shifting the contents of the first half of the storage means of the k-th stage (k = 2 to N−1) to the latter half of the storage means of the k−1th stage, respectively, The latter half of the storage means is cleared, then the contents of the storage means from the first stage to the Nth stage are added and stored in the (N + 1) th stage storage means A storage shift step,
7. The radar signal processing method according to claim 4 , wherein the conversion step, the storage step, and the addition step are executed for the j-th section after the shift. A computer-readable recording medium stored as a program for causing a computer to execute the radar signal processing method according to claim 4 .

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