RADAR CIRCUIT, RADAR SYSTEM AND RADAR PROGRAM

Abstract

Radar circuit (10) which detects the distance (D) from a target and the relative velocity (V) of the target using a frequency modulation method, wherein the radar circuit (10) comprises: a signal generation unit (20) which generates a transmit signal (ST) for a transmit wave, a modulation control unit (22) which controls the frequency modulation of the transmit signal (ST), a receiving circuit unit (32, 33, 34) which detects a detection signal (SF) based on a difference frequency between a received signal (SR) of a receiving wave with respect to the transmit wave and the transmit signal (ST), and a signal processing unit (11) which performs analysis processing based on the detection signal (SF) and calculates the distance and the relative velocity (V), wherein a frequency modulation waveform of the transmit signal (ST) comprises a number (n) of sub-waveforms.in which the slope of the modulation frequency is positive or negative, and for adjacent partial waveforms of the number (n) of partial waveforms, the initial frequency of a subsequent partial waveform is greater than the final frequency of a preceding partial waveform when the slope is positive, and the initial frequency of the subsequent partial waveform is less than the final frequency of the preceding partial waveform when the slope is negative, characterized in that the radar circuit (10) further comprises: an output control unit (24) which controls the switching on / off of the output of the transmitting wave, wherein the output control unit (24) controls the output of the transmitting wave such that it is in an on state when a PLL circuit (21) of the signal generation unit (20) is in a latched state, and controls the output of the transmitting wave such that it is in an off state,when the PLL circuit (21) is in an unlocked state.

Description

Technical field The present invention relates to a radar (radio detecting and ranging) technology and an effective technology for improving the distance resolution of a millimeter wave radar. Technical background An example of radar technology for measuring the distance from a target object (which can be referred to as a target) involves a radar system mounted on a vehicle or the like. A radar circuit of such a system transmits a signal based on a transmit signal, for example, using frequency modulation (FM), and receives a signal using a wave reflected from a target. The radar circuit calculates the distance from the target using the frequency difference between the transmitted and received signals. An example of a general radar modulation technique is frequency-modulated continuous-wave (FMCW) radar. In the FMCW technique, the waveform of a predefined frequency modulation is continuously repeated over time. Examples of prior art relating to a radar using frequency modulation include WO2016 / 184850 (PTL 1) and US Patent 9,134,415 (PTL 2). PTL 1 discloses a vehicle-mounted radar system combining multiple FMCW modulations. PTL 2 discloses an imaging synthetic aperture radar (SAR) that covers a wide band by combining multiple FMCW modulations (linear frequency modulation: LFM). Document JP 2004 - 333 269 A discloses a radar circuit according to the preamble of claim 1. Further prior art is disclosed in DE 102 28 583 A1, DE 698 16 687 T2, DE 10 2007 046 480 A1 and DE 10 2007 051 190 A1. Literature on the state of the art Patent literature PTL 1: WO2016 / 184850PTL 2: US Patent 9,134,415 ( US9 134,415 B2 ) Summary of the invention Technical problem In a radar device for measuring distance or relative velocity using a frequency modulation method, as an example of the prior art, problems arise with regard to distance resolution and the signal-to-noise ratio (SN ratio), particularly when measuring the distance or relative velocity of a target at a relatively short range. With the general FMCW method (a first method of the comparative example) from the prior art, simply increasing the distance resolution is insufficient because the frequency band is narrow. In a radar system using the FMCW method, a technique (the second method in the comparative example) is used to generate a transmitted signal in a wide frequency band by combining and linking several modulation frequency waveforms in order to increase the range resolution. However, in the aforementioned method, when a received signal is processed based on a transmitted signal, the problem arises that the noise increases, the signal-to-noise ratio deteriorates, and the detection sensitivity and accuracy of the range or relative velocity decrease. That is, the signal-to-noise ratio decreases as the range resolution is increased. In other words, it is difficult to increase the range resolution without decreasing the signal-to-noise ratio. One object of the invention is to provide a radar technology for measuring distance or relative speed using a frequency modulation method, which can increase the distance resolution while preventing the deterioration of the signal-to-noise ratio. Solution to the problem The problem according to the invention is solved by a radar circuit according to claim 1, a radar system with such a radar circuit, and by a radar program according to claim 14. Advantageous embodiments are described in the dependent claims. A representative embodiment of the invention provides a radar circuit or the like having the following configuration. A radar circuit according to one embodiment detects the distance from a target and its relative velocity using a frequency modulation method. The radar circuit comprises: a signal generation unit that generates a transmit signal for a transmit wave; a modulation control unit that controls the frequency modulation of the transmit signal; a receiving circuit unit that detects a detection signal based on a difference frequency between a received signal of a receiving wave with respect to the transmit wave and the transmit signal; and a signal processing unit that performs analysis based on the detection signal and calculates the distance and relative velocity. The frequency modulation waveform of the transmit signal has a number (n) of sub-waveforms where the slope of the modulation frequency is positive or negative.For adjacent partial waveforms of the number (n) of partial waveforms, the initial frequency of a subsequent partial waveform is greater than the final frequency of a preceding partial waveform if the slope is positive, and the initial frequency of the subsequent partial waveform is less than the final frequency of the preceding partial waveform if the slope is negative. Beneficial effect According to the representative embodiment of the invention, a radar technology for measuring distance or relative speed is provided using a frequency modulation method, which increases the distance resolution while preventing the deterioration of the signal-to-noise ratio. Brief description of the drawings Figure 1 shows the configuration of a vehicle-mounted system with a radar circuit and a radar system, as well as the distance from a target, according to a first embodiment of the invention. Figure 2 shows a diagram mainly showing a configuration of an RF circuit unit in the radar circuit according to the first embodiment. Figure 3 shows a frequency modulation waveform, a received signal characteristic, and a received signal characteristic of a first modification example according to the first embodiment. Figure 4 shows configuration examples of continuous waves with multi-cycle waveforms according to the first embodiment. Figure 5 shows a signal from a transmit wave output switch-off control according to the first embodiment. Figure 6 shows effects and the like compared with comparative examples according to the first embodiment. Figure 7 shows design examples of a waveform according to the first embodiment and the comparative examples.8 Waveform designs according to a second modification of the first embodiment, Fig. 9 Waveform designs according to a third modification of the first embodiment, Fig. 10 a waveform design according to a fourth modification of the first embodiment, Fig. 11 a configuration of a radar circuit according to a second embodiment of the invention, Fig. 12 a configuration of a radar circuit according to a third embodiment of the invention, Fig. 13 a design of a frequency modulation waveform in each mode according to the third embodiment, Fig. 14 a transmit wave output switch-off control according to the third embodiment, Fig. 15 examples of a mode switching control according to the third embodiment, Fig. 16 a configuration of a radar circuit according to a comparative example not included in the invention, Fig. 17 Waveforms of a continuous wave and a differential signal, a radar circuit according to the comparative example and Fig.18 waveforms of a first and a second radar circuit method according to the comparative example. Description of embodiments Embodiments of the invention are described in detail below with reference to the drawings. In all drawings illustrating the embodiments, the same components are generally designated with the same reference numerals, and repeated descriptions of them are omitted. [Problem] Technological requirements, problems and the like of the radar circuit and the like according to the embodiments of the invention are additionally described using the radar technology of a comparative example. Fig. 16 shows a configuration of a radar circuit 90 according to a comparative example. A radar system comprising the radar circuit 90 measures and detects the distance to a target and the target's relative velocity using an FMCW modulation method. The radar system comprises the radar circuit 90, a transmitting antenna 41, and a receiving antenna 42. The radar circuit 90 includes a signal processing unit 91, a modulation control unit 92, a signal generation unit 20 with a PLL circuit 21, an amplifier 31, a low-noise amplifier 32, a step-down converter 33, an analog-to-digital converter (ADC) 34, and the like. The signal processing unit 91 consists of a CPU or the like and controls the measurement and acquisition of distance and relative velocity using frequency modulation according to the FMCW modulation method. The signal processing unit 91 provides a frequency modulation control signal C1 to the modulation control unit 92. The modulation control unit 92 provides the signal generation unit 20 with a modulation control signal SM corresponding to the control signal C1, which controls the frequency modulation. The signal generation unit 20 generates a transmit signal ST with a predetermined frequency corresponding to the modulation control signal SM using the PLL circuit 21 and outputs it. The transmit signal ST is fed into the amplifier 31 and the step-down converter 33. The amplifier 31 outputs a signal (transmit wave output signal) TXOUT, obtained by amplifying the transmit signal ST, to the transmitting antenna 41.The transmitting antenna 41 emits the signal TXOUT as a transmission wave in the form of a radio wave. A portion of the transmitted wave returns as a reflected wave, specifically the reflected radio wave that reaches the target. The receiving antenna 42 receives the reflected wave as a received wave and outputs it as a signal (receive wave input signal) RXIN. The low-noise amplifier 32 amplifies the signal RXIN and outputs it as a received signal SR. The step-down converter 33 receives the received signal SR and the transmitted signal ST and generates a difference signal SD, representing the frequency difference between the received signal SR and the transmitted signal ST, by multiplying the received signal SR and the transmitted signal ST. The ADC 34 converts the difference signal SD, which is an analog signal, into a digital signal and outputs the digital signal as a detection signal SF.The signal processing unit 91 receives the detection signal SF and calculates and records the distance from the target and the target's relative velocity based on the result (frequency spectrum) obtained by performing an analysis process similar to a fast Fourier transform (FFT). The signal processing unit 91 outputs detection information such as the detected distance, the detected relative velocity, and the like. As described above, when the distance and relative velocity of the target are detected in the radar circuit 90 according to the comparative example, a modulation method is used in which frequency modulation of the output signal of the PLL circuit 21 of the signal generation unit 20 is performed. In the prior art, important modulation methods include CW modulation, FMCW modulation, step modulation, 2FCW modulation, and the like. In the comparative example and in the first embodiment, the most widely used FMCW modulation method is employed. Fig. 17 shows designs of the transmit signal in which FMCW modulation is used in the radar circuit 90 according to the comparative example. Fig. 17(A) shows a frequency-time characteristic of an FMCW modulation waveform (modulation frequency waveform). The solid line indicates the characteristic of a transmit signal 910 corresponding to the transmit signal ST, and the dashed line indicates the characteristic of a receive signal 920 corresponding to the receive signal SR. The transmit signal 910 is subjected to FMCW modulation by the signal generation unit 20. The characteristic curve (A) indicates a time transition of the frequency (F) in the signal. In the transmit signal 910, frequency modulation is performed in one modulation period TM, such that the frequency increases linearly with time. Although not shown, frequency modulation in which the frequency decreases proportionally with time is also possible. The radar circuit 90 transmits the transmit wave based on the frequency-modulated transmit signal 910 and receives the reflected wave from the target as a receive signal 920. Due to its propagation delay, the receive signal 920 is delayed by a delay time TD relative to the transmit signal 910. The delay time TD is the time between the transmission of the transmit wave and the reception of the received wave reflected from the target. In the FMCW modulation method, the frequency modulation waveform, as described above, is repeated as a continuous wave along the time axis. In example (A), after a first modulation period TM and a predetermined pause time TR, a frequency-modulated signal is output similarly in the next modulation period TM. The frequency modulation waveform in each of several modulation periods TM has the same predetermined frequency band W0.Fig. 17(B) shows a difference signal with a difference frequency (FD) between the received signal 920 and the transmitted signal 910 in Fig. 17(A). The step-down converter 33 outputs the difference signal SD by multiplying the received signal 920 and the transmitted signal 910. This difference signal SD represents the difference frequency FD between the frequency of the received signal 920 and the frequency of the transmitted signal 910. The difference frequency FD is proportional to the delay time TD. Therefore, the signal processing unit 91 can calculate the distance from the target by knowing the difference frequency FD based on the difference signal SD. The signal processing unit 91 performs the analysis processing in the form of an FFT on the acquisition signal SF based on the difference signal SD and identifies the peak frequency from the FFT spectrum of the result. The distance can then be calculated from the peak frequency of the FFT.Accordingly, the spacing information for each signal in each modulation period TM is extracted. On the other hand, the relative velocity of the target can be calculated by detecting a known Doppler shift (Doppler effect). Several calculation methods exist. Here, a calculation method using a secondary FFT is described. If a relative velocity with respect to the target is given, i.e., if the target's velocity differs from the velocity of radar circuit 90, and the relative velocity is to be calculated, the continuous wave repeated several times along the time axis, as in the transmitted signal 910 from (A), is used. The respective times are represented as (1), (2), ..., (N). First, each distance can be calculated from each frequency modulation signal, as described above. If a relative velocity exists, the respective distance gradually changes along the time axis. This changes the phase of the complex number, which is the value of the peak frequency of the resulting FFT.The signal processing unit 91 can calculate the relative velocity by detecting the phase change. The present example illustrates a case in which the relative velocity does not change. The maximum detection range of the target, which can be calculated by the FMCW modulation method described above, is D_MAX, the range resolution is RES_D, the maximum relative velocity is V_MAX, and the relative velocity resolution is RES_V. D_MAX, RES_D, V_MAX, and RES_V are represented by the following formulas (1) to (4). [Formula 1] [Formula 2] [Formula 3] [Formula 4] Here, fs is the sampling frequency [Hz] of the FFT. fc is the center frequency [Hz] of a signal output by the signal generation unit 20 (the transmit signal ST). Δf is the modulation bandwidth [Hz]. c is the speed of light [m / s]. Tmod is the modulation time [s]. Trest is the modulation delay (pause time) [s]. Nchirp is the number of chirps [Male]. Note that one chirp indicates that the frequency increases over time, as in the waveform of the transmit signal 910 shown in Fig. 17(A). Fig. 18 shows a first and a second method for waveform design for radar circuit 90 according to the comparative example. Fig. 18(A) shows a design example where the relatively narrow frequency band W0 is used in the first method of the comparative example. This is similar to that in Fig. 17(A), and the same repeated frequency modulation waveforms are contained in a number (n) of modulation times Tm {Tm1, Tm2, ​​..., Tmn} corresponding to the modulation period TM. Straight sections 901, 902, ..., 90n as waveforms are contained in each modulation time Tm. The respective pause times Tr {Tr1, Tr2, ..., Trn} are present between the modulation times Tm. The waveform of each modulation time Tm and the frequency band W0 are the same. For example, the frequency of the linear section 901 of the first modulation time Tm1 increases over time from the initial frequency Fs1 to the final frequency Fe1 with a predetermined slope. Similarly, the frequency of the linear section 902 of the next modulation time Tm2 increases with the same slope from an initial frequency Fs2 to a final frequency Fe2. The initial frequency Fs2 and the final frequency Fe2 of the linear section 902 are the same as the initial frequency Fs1 and the final frequency Fe1 of the linear section 901. By repeatedly transmitting and receiving on the time axis as a continuous wave, distance and relative velocity measurements can be performed multiple times, and the signal-to-noise ratio can be increased. As described above, the distance and relative speed can be calculated and detected by the radar circuit 90. Such a radar system is used, for example, for collision avoidance and driver assistance in the automotive field. Against this background, the need for a radar device to detect the distance to an object located at a relatively short distance with a high distance resolution of, for example, 10 cm or less, has become increasingly recognized in recent years. An example is a function for performing parking control by detecting the distance to an object such as another vehicle located in a parking space near the host vehicle. To enable the detection of short distances compared to the prior art, the distance resolution must be increased.For example, in the prior art method the distance resolution unit is 10 cm or larger, whereas a distance resolution unit of less than 10 cm or less than 5 cm is desirable. As shown in the preceding formula (2), the distance resolution can be increased essentially by increasing the modulation bandwidth (Δf). In the future, for example, a modulation bandwidth of 4 GHz will be acceptable for a radar system using a frequency of 77 to 81 GHz. If such frequency modulation is performed at 4 GHz, a distance resolution of 4 cm or less can be achieved with a simple calculation. However, to perform frequency modulation in a broadband of 4 GHz, the frequency modulation range of the signal generation unit 20, which includes the PLL circuit 21, must be increased to 4 GHz or more. Increasing the frequency modulation range in this way carries the risk of adverse effects such as deterioration of the phase noise and instability of the locked state of the PLL. An example of the prior art for achieving a wide frequency modulation range with respect to frequency band W0 is a chirp-stitching technology disclosed in PTL 2. In this technology, a modulation band required for the design is divided into several modulation bands. A signal of each frequency modulation is provided in each modulation band, and these signals are combined and used as the transmit signal. At the receiving end, several received signals corresponding to the respective frequency modulation signals are combined to generate a signal for the required modulation band. The spacing, or similar parameters, are then calculated using this signal. Fig. 18(B) shows a design example of the transmit signal 910 in the second method of the comparative example, corresponding to the prior art example. This achieves a relatively wide frequency band W0. The waveform (modulation frequency waveform) of (B) shows a section corresponding to the modulation period TM. The waveform has a linear section (a partial waveform), which is a waveform segment of a number (n) of frequency modulations on the time axis. Similar to (A), the pause time Tr and the modulation time Tm are repeated on the time axis. The linear sections 901, 902, ..., 90n are included as linear sections at each modulation time Tm. A number (n) of linear sections have different frequency bands.For example, the frequency of the linear section 901 of the first modulation time Tm1 increases linearly from the initial frequency Fs1 to the final frequency Fe1 with a predetermined slope. The linear section 902 of the next (second) modulation time Tm2 increases with the same slope from the initial frequency Fs2 to the final frequency Fe2. The initial frequency Fs2 of the second linear section 902 is equal to the final frequency Fe1 of the first linear section 901. Unlike the frequency range of the first linear section 901, the frequency range of the second linear section 902 has a higher band. In the overall waveform of the modulation period TM, the frequency band W0 is achieved by a combination of several (n) linear sections in a wider band than in the first method of (A). By using such a second method, the required wide frequency modulation band (frequency band W0) can be achieved with respect to the design. That is, the distance resolution can be increased with the second method compared to the first method. However, it was found that even when the distance resolution is increased by the second method, a problem arises with regard to the signal-to-noise ratio if the target has a relative velocity. If the distance and relative velocity are calculated using the received signal based on the transmitted signal of the second method, a calculation in the manner of an FFT must be performed using a signal obtained by combining a number (n) of signals of the waveform of (B).When relative velocity occurs, the spacing changes even during an interval (the pause time Tr) between the multiple frequency modulations in the received signal, and the phase shifts. This means that coherence on the time axis is not maintained in the multiple signals within the received signal. As a result, a discontinuous point appears in a region where multiple signals are combined. If the signal processing unit 91 performs FFT-type analysis using a capture signal with such discontinuous points, the background noise is increased, and the signal-to-noise ratio in the FFT spectrum is degraded. Consequently, the capture sensitivity and the accuracy of the spacing and relative velocity are reduced.As described above, with the radar technology of the comparison example, it is difficult to increase the distance resolution without worsening the signal-to-noise ratio. (First embodiment) A radar circuit and the like according to the first embodiment of the invention are described with reference to Figures 1, 2, 3, 4, 5, 6, 7, 8, 9 to 10. The radar circuit according to the first embodiment complements a method by which the distance resolution can be increased while preventing the deterioration of the signal-to-noise ratio. [System mounted on a vehicle and radar system] Fig. 1 shows the configuration of a vehicle-mounted system 100, consisting of a radar circuit 10 and a radar system 1 according to the first embodiment. The vehicle-mounted system 100 is shown on the left side of Fig. 1. The distance between a host vehicle and a target is shown on the right side of Fig. 1. The vehicle-mounted system 100 is attached to the host vehicle. The target is another vehicle used for measuring and detecting a distance or the like. The position M1 of the host vehicle, the position M2 of the other vehicle, the distance D between the radar circuit 10 and the target, and the relative speed V between the target and the host vehicle are shown. The vehicle-mounted system 100 comprises an engine control unit (ECU) 101, a sensor unit 102, a communication unit 103, a vehicle navigation unit 104, an output unit 105, an operating unit 106 and a power supply unit (not shown) connected by a vehicle bus and a vehicle area network (CAN) 110. The ECU 101 is an engine control unit, in other words a vehicle control unit, and controls the entire host vehicle and the vehicle-mounted system 100, including the engine control unit. The ECU 101 can control radar system 1 to obtain the distance between radar system 1 and the target as detection information and use this distance to control the host vehicle. An example of the ECU 101's control is described below. The ECU 101 receives the distance D, the direction, the relative speed V, and other parameters between radar system 1 and a target such as another vehicle. Based on this information, the ECU 101 controls the steering, the application / deactivation of the brakes, and other functions.One control example includes controlling the parking to avoid contact with an object such as another vehicle located at a short distance by using the distance D to the other vehicle when parking in a parking space, as well as automatic braking control and warning output control according to the relative speed V with respect to another vehicle located at a medium distance while driving. Sensor Unit 102 comprises a well-known sensor group mounted on the vehicle and outputs acquisition information. ECU 101 performs control using this acquisition information. Examples of sensor devices included in Sensor Unit 102 are a vehicle speedometer, an accelerometer, a gyroscopic sensor, a geomagnetic sensor, an engine start sensor, and a temperature sensor. The accelerometer and gyroscopic sensor detect the acceleration, angular velocity, angle, and similar characteristics of the host vehicle. It should be noted that radar system 1, because it has a function for measuring distance, direction, or the like, can also be referred to as a radio wave distance sensor. The communication unit 103 has a communication interface device that communicates with a mobile network outside the vehicle, the internet, and the like. For example, the communication unit 103 can communicate with a server on the internet based on control from the ECU 101, the radar system 1, and the like. The vehicle navigation unit 104 has a GPS receiver and is part of an existing vehicle navigation system installed in the vehicle. The vehicle navigation unit 104 performs well-known navigation processing using map information, position information received from the GPS receiver (e.g., latitude, longitude, altitude), or the like. The output unit 105 has a display device, an audio output device, and the like, and performs information display and audio output to a user, such as the driver.The operating unit 106, for example, has a control panel, a control button and the like, and receives an operating input from the user. The function of the radar system 1 is to detect the distance D between the host vehicle and the target, the relative speed V of the target, the direction of the target, and the like. The radar system 1 comprises the radar circuit 10, the transmitting antenna 41, and the receiving antenna 42. The radar system 1 may, for example, include a communication interface unit for the ECU 101 or the like and a user interface unit for the user, and these interface functions may be functions of the vehicle-mounted system 100. Although, according to the first embodiment, the radar system 1 is connected as part of the vehicle-mounted system 100, the invention is not limited thereto and can be implemented as an independent device. Furthermore, the radar system 1 is not limited to being mounted on a vehicle and can also be applied to other applications of the vehicle type.Furthermore, the radar system 1 may have a function to execute a predetermined control using the detected distance D or the like. The radar circuit 10 comprises a signal processing unit 11, an RF circuit unit 12, a memory 13, an environmental interface unit 14, and the like. The radar circuit 10 is a radar device mounted on a semiconductor chip or the like. The radar circuit 10 measures the distance D and similar parameters using the frequency modulation method. The signal processing unit 11 is implemented by hardware such as a CPU, ROM, and RAM, and by corresponding software, and its function is complemented by software program processing. The signal processing unit 11 can be implemented by hardware such as a microcomputer or an FPGA. The function of the signal processing unit 11 includes calculating and determining the distance D from the target, the relative velocity V, and similar parameters based on the transmission and reception of radio waves, particularly using the FMCW modulation method. For example, the signal processing unit 11 reads a program stored in memory 13 via the CPU 16 and performs processing in accordance with the program, thus complementing a processing unit corresponding to its function.The signal processing unit 11 stores data and information as needed in internal or external memory and performs read and write operations. The signal processing unit 11 is electrically connected to the RF circuit unit 12 and other units, and is communicatively connected to the ECU 101 or the like via the vehicle-mounted bus and the CAN 110. The signal processing unit 11 controls the measurement of distance D and similar values ​​from the ECU 101. The signal processing unit 11 provides a control signal to the RF circuit unit 12 and controls the transmission of a transmit wave from the transmit antenna 41 based on the transmit signal from the RF circuit unit 12. Furthermore, the signal processing unit 11 calculates the distance D and similar values ​​based on the reception of the receive wave at the receive antenna 42 and outputs acquisition information, including the distance D and similar values, to the ECU 101 and similar values ​​using the received acquisition signal based on the received signal from the RF circuit unit 12. The RF circuit unit 12 is a high-frequency circuit unit that processes signals with a relatively high frequency and a wide frequency band. Controlled by the signal processing unit 11, the RF circuit unit 12 generates a frequency-modulated transmit signal and causes the transmitting antenna 41 to send a transmit wave. Part of the transmit wave reaches the target and is reflected, and the reflected wave returns as a received wave. The RF circuit unit 12 receives a detection signal based on the frequency difference between the received signal of the received wave received by the receiving antenna 42 and the transmitted signal, and outputs the detection signal to the signal processing unit 11. The signal processing unit 11 performs frequency analysis based on the detection signal to calculate the distance D and other parameters. For example, a program and environmental information are pre-stored in memory 13 before product shipment. The program corresponds to a radar program according to the first embodiment and causes the radar circuit 10 to perform processing to complement the specified function. The program contains environmental information. Alternatively, the environmental information is described within the program. The environmental information includes information that defines a frequency modulation design described below. The environment information can include user environment information. The program and environment information can be design information defined by a manufacturer or the like, and can be defined by the manufacturer or the user themselves after the product has been shipped. In this case, the environment, i.e., the program and environment information, can be updated using the environment interface unit 14. The program and environment information can be defined by downloading or the like from a server or the like on the communication network. If the manufacturer or the like defines the program and environment information, the definition processing for radar system 1 is performed by the operating unit 106, the output unit 105, the communication unit 103, and the like of the vehicle-mounted system 100.Responding to the aforementioned setting process, the radar circuit 10, for example, receives the program and environment information for environment update and updates the program and environment information of memory 13 via the environment interface unit 14. It should be noted that only the program and environment information can be updated. The signal processing unit 11 completes the function using the updated program and environment information. Furthermore, the ECU 101 can set the program and environment information of the radar circuit 10 as needed. [Radar circuit] Fig. 2 mainly shows the configuration of the RF circuit unit 12 in the radar circuit 10 of the radar system 1. As an example of the implementation of the configuration of the radar circuit 10 in Fig. 2 according to the first embodiment, the signal processing unit 11 is implemented on a first semiconductor chip TP1, and the RF circuit unit 12 is implemented on a second semiconductor chip TP2, and both are interconnected. According to the present embodiment, functions are complemented by the signal processing unit 11 controlling the RF circuit unit 12. According to the present embodiment, an interface circuit 17 is provided in the second semiconductor chip TP2. The interface circuit 17 connects the signal processing unit 11 and the RF circuit unit 12 and performs communication processing using a predefined communication interface, which exchanges signals between them.As another example of the implementation configuration, a configuration is also possible in which the signal processing unit 11 and the RF circuit unit 12 are integrated into a single semiconductor chip. In this case, the interface circuit 17 would be unnecessary. The signal processing unit 11 has a CPU 16. The CPU 16 has a timer 15. The timer 15 measures time based on the clock signal of the CPU 16. The CPU 16 performs a control action based on the time signal from the timer 15. The CPU 16 performs the control action by reading information 201, for example, a command from the ECU 101 or the like from the vehicle-mounted system 100 as the host system. The CPU 16 outputs detection information 202, including the detected distance D, the relative velocity V, and the like, to the ECU 101 and the like. The CPU 16 controls the RF circuit unit 12 via the interface circuit 17. Through the interface circuit 17, the CPU 16 provides a control signal C1 to a modulation control unit 22 and a control signal C2 to an output control unit 24. The CPU 16 receives the signal from the RF circuit unit 12 via the interface circuit 17.The CPU 16 receives a status sensing signal SS from a status sensing unit 23 via the interface circuit 17 and receives the sensing signal SF from the ADC 34. The individual processing performed by the CPU 16 of the signal processing unit 11 includes the processing of the control of the entire measurement, the processing of the transmit control, the processing of the receive control, the processing of the distance and relative velocity calculation, the processing of the output of acquired information, and the like. The RF circuit unit 12 comprises the signal generation unit 20 including the PLL circuit 21, the modulation control unit 22, the state detection unit 23, the output control unit 24, the amplifier 31, the low-noise amplifier 32, the buck converter 33, and the analog-to-digital converter (ADC) 34. The transmit-side circuit unit comprises the signal generation unit 20, the amplifier 31, and the like. The receive-side circuit unit comprises the low-noise amplifier 32, the buck converter 33, the ADC 34, and the like. The modulation control unit 22 generates the modulation control signal SM, which controls the frequency modulation of the signal generation unit 20 in accordance with the control signal C1 from the CPU 16, and outputs the signal to the PLL circuit 21. The modulation control signal SM is, for example, a PLL setting signal of the PLL circuit 21 and contains waveform data. The PLL circuit 21 sets the frequency of the PLL according to the PLL setting signal of the modulation control signal SM. The signal generation unit 20 generates the frequency-modulated transmit signal ST using the PLL circuit 21 based on the modulation control signal SM from the modulation control unit 22. The transmit signal ST is a frequency-modulated signal and is fed into the amplifier 31 and the buck converter 33. The PLL circuit 21 has the function of outputting a PLL state signal SP. The PLL state signal SP is, for example, a binary signal that represents a locked or unlocked state in the PLL. For instance, a value of 1 is output in the locked state, and a value of 0 is output in the unlocked state. In other words, the unlocked state is a transition state or a state with an unstable output. Amplifier 31 amplifies the transmit signal ST and outputs it as the transmit wave output signal TXOUT. The transmit antenna 41 radiates the transmit wave output signal TXOUT as a transmit wave. Part of the transmit wave reaches the target and is reflected back as a reflected wave. The receive antenna 42 receives the reflected wave as a receive wave and outputs it as the receive wave input signal RXIN. The low-noise amplifier 32 amplifies the receive wave input signal RXIN and outputs the amplified signal as the receive signal SR. The step-down converter 33 receives the receive signal SR and the transmit signal ST and outputs the difference signal SD, representing the difference frequency, by multiplying the receive signal SR and the transmit signal ST. The ADC 34 performs an analog-to-digital conversion on the difference signal SD and outputs the result as a detection signal SF, which is a digital signal, to the CPU 16. The state detection unit 23 detects the locked or unlocked state of the PLL circuit 21 based on the PLL state signal SP from the PLL circuit 21 and outputs the state detection signal SS representing the state to the CPU 16. In other words, the state detection unit 23 is a lock detection unit. The state detection signal SS is, for example, a binary signal representing the locked or unlocked state. The state detection unit 23 can be omitted. The CPU 16 detects the state of the PLL circuit 21 via the state detection signal SS and executes a transmit wave output shutdown control according to the state, as described below. The CPU 16 provides the output control unit 24 with the control signal C2 for the transmit wave output shutdown control. The output control unit 24 generates an output control signal SO for transmit wave output switch-off control according to the control signal C2 from the CPU 16 and provides the output control signal SO to the amplifier 31. The output control signal SO is a signal to switch the output (transmission) of the transmit wave from the transmitting antenna 41 on / off by switching the output (amplification) of the amplifier 31 on / off. For example, if the output control signal SO has a value of 1, the output of the amplifier 31 is in a normal on state and the transmit wave is emitted based on the transmit signal ST. If the output control signal SO has a value of 0, the output of the amplifier 31 is in an off state and the transmit wave is not emitted. CPU 16 receives the acquisition signal SF from ADC 34, performs an FFT-type analysis on the acquisition signal SF, and thereby obtains an FFT spectrum and a peak frequency. Based on the peak frequency and other parameters, CPU 16 calculates the distance D from the target and the relative velocity V of the target at any given time. CPU 16 outputs the acquisition information 202, including the distance D and the relative velocity V obtained through the calculation, to ECU 101 or similar. [Frequency modulation (1)] Fig. 3 shows a design sketch of a frequency modulation waveform in the radar circuit 10 according to the first embodiment. Fig. 3(A) shows a characteristic curve of frequency F [Hz] - time [second] of the waveform of the transmitted signal ST. The waveform corresponds to a waveform obtained by amplifying a portion of a modulation period TM in the comparative example from Fig. 17. The waveform has several straight sections, which are several secondary frequency modulation waveforms subdivided for the respective number (n) of modulation times Tm (referred to in the description as partial waveforms), and it is formed by a combination of the several straight sections. n is an integer of 2 or greater. The waveform exhibits a repetition of a pause time Tr, which is a modulation delay, and a modulation time Tm on the time axis. This means that a pause time Tr {Tr1, Tr2, ..., Trn} and a modulation time Tm {Tm1, Tm2, ​​..., Tmn} are provided. During modulation time Tm, a straight segment indicated by a solid line is provided, and a gap is provided at pause time Tr. When modulation time Tm is present, straight segments 301, 302, ..., 30n are provided. A straight line 300, indicated by a dashed line, is a reference line for frequency modulation control. The frequency of line 300 increases linearly with a predetermined slope over time. A number (n) of straight segments 301, 302, ..., 30n overlap on line 300. Each straight segment has the same slope as line 300, a modulation time Tm with the same time width, and a range Fx, which is the same predetermined frequency range. The interval, corresponding to the pause time Tr, has a range Fy, which is the same predetermined frequency range. The specific configuration in the waveform design of the transmitted signal ST according to the first embodiment has the following features. In the number (n) of linear sections (partial waveforms), the initial frequency of a subsequent linear section is greater than the final frequency of the preceding linear section, and a predetermined range Fy is provided. For example, a relationship is considered between a first linear section 301 and a second linear section 302. The linear section 301 has an initial frequency Fs1, which is the starting point in the time direction, and a final frequency Fe1, which is the endpoint. Similarly, the linear section 302 has an initial frequency Fs2 and a final frequency Fe2. The initial frequency Fs2 of the second linear section 302 is greater than the final frequency Fe1 of the first linear section 301 (Fs2 > Fe1).The difference between the initial frequency Fs2 and the final frequency Fe1 lies in the range Fy (Fs2 - Fe1 = Fy). With such a design, the distance resolution of the radar circuit 10 according to the first embodiment can be increased and ensured compared to the design of the comparison example described above, while preventing the deterioration of the signal-to-noise ratio when the target has a relative velocity and thus improving the signal-to-noise ratio. In the waveform design of the comparative example in Fig. 18, the initial frequency of a subsequent straight section (for example, the second straight section) is equal to or lower than the final frequency of a given straight section (for example, the first straight section) in the multiple straight sections of the first and second methods (for example, Fs2 ≤ Fe1). For example, the initial frequency Fs2 of the second straight section 902 in the first method is lower than the final frequency Fe1 of the first straight section 901 and is equal to the initial frequency Fs1 (Fs2 = Fs1). In the second method, the initial frequency Fs2 of the second straight section 902 is equal to the final frequency Fe1 of the first straight section 901 (Fs2 = Fe1). As described above, the waveform design of the first embodiment differs from the comparative example. In the above design, the radar circuit 10, according to the first embodiment, controls the modulation frequency waveform of the transmitted signal ST so that it is linear. That is, as shown in Fig. 3(A), the straight sections of the respective multiple waveforms are controlled so that they ideally overlap the reference line 300 in time. The modulation control unit 22 provides the modulation control signal SM, corresponding to the waveform design, to the PLL circuit 21 of the signal generation unit 20. In the PLL circuit 21, the frequency of the PLL is set according to the PLL setting signal. Therefore, the transmitted signal ST, which is the output of the signal generator 20, has a linear waveform, as described above. In the waveform design according to the first embodiment, a wide frequency band W1 is complemented by a combination of several linear sections (partial waveforms) that correspond to the respective modulation period TM at any given time. The frequency of the range Fy of each interval is not used in the frequency band W1. By using the wide frequency band W1, the distance resolution can be increased even when a short distance is being detected. The frequency modulation design according to the first embodiment is preferably a completely linear design on the reference line 300, as shown in Fig. 3(A). However, the design is not limited to this, and various designs are possible, as described below. It is also acceptable in which the actual signal waveform deviates from the line 300 to some degree due to signal fluctuations on an implementation circuit or the like. [Frequency modulation (2)] Fig. 3(B) shows a characteristic curve of the voltage [V] - time [s] of a received signal corresponding to the received signal SR according to the first embodiment (if there is no interpolation function as described below). The received signal has individual waveform segments, which are obtained according to each of the several straight segments and the modulation time Tm of the waveform of Fig. 3(A), and is represented as signal IF {IF1, IF2, ..., IFn}. The signal IF of the received signal maintains coherence (phase alignment) with respect to the transmitted signal even if the target has a relative velocity and a phase shift occurs due to a Doppler shift. Throughout the entire modulation time Tm, the several signals IF travel on a predetermined wave (typically represented by Asinωt) and coherence on the time axis is maintained. That is, the phases of the signals IF are aligned on the time axis.In this state, the multiple IF signals are defined as corresponding acquisition signals SF and output to CPU 16. Because the coherence of the respective IF signals of the received signal is maintained over time, CPU 16, when calculating the distance or similar value from the acquisition signal SF through analysis processing in the manner of an FFT, can calculate the distance or similar value at a predetermined distance resolution while preventing a degradation of the signal-to-noise ratio. Because all of the multiple partial waveforms according to the first embodiment are controlled to lie on the straight line 300, as shown in Fig. 3(A), a gap is created between adjacent partial waveforms. During the pause time Tr corresponding to this gap, no transmit wave is sent. In other words, no meaningful frequency is provided on the transmit wave. Therefore, as shown in Fig. 3(B), a corresponding gap is also created in the multiple signals IF of the received signal. No received wave is received in the gap of the signal IF. In other words, no meaningful frequency is provided on the received wave. Meanwhile, a portion corresponding to a whole wave (Asinωt) is indicated by a dotted line. In Fig. 3 and similar figures, a radio wave propagation delay is omitted. As described above, the acquisition signal SF used in the analysis processing by CPU 16 must be connected to the multiple signals IF of the received signal because there is a gap between these signals. This means that the signal to be analyzed by CPU 16 is obtained by connecting multiple IF signals. It should be noted that, in this connection process, CPU 16 can perform part of the processing, or a circuit unit that connects the IF signals can be provided in the RF circuit unit 12. According to the first embodiment, the content of the connection is not restricted. [Frequency modulation (2)] Fig. 4 shows control and design examples where the transmit signal ST is repeated several (N) times in the time direction based on the waveform design from Fig. 3. That is, a continuous wave of the FMCW system is represented. The same waveform is repeated N times for each modulation period TM. Fig. 4(A) shows a case where, as a first design example, a waveform with a positive slope from Fig. 3(A) for each modulation period TM is repeated N times in the same way. The waveforms of the N cycles are identical and have the same frequency band W1. The modulation periods TM1, TM2, ..., TMN are represented as their respective modulation periods TM. Waveforms 401, 402, ..., 40N are provided as waveforms for each modulation period TM. The contents of waveform 401 and the like are as shown in Fig. 3.The slope of the reference line 300 and the slope of each sub-waveform are positive. Therefore, the relative velocity V can be determined using the continuous wave of N cycles of waveforms on the time axis. Fig. 4(B) shows a second design example. In the second design example, unlike the first, the slope of the straight section is negative. For example, in the waveform design, the initial frequency Fs2 of the second straight section 302 is lower than the final frequency Fe1 of the first straight section 301 in the relationship between the first straight section 301 and the second straight section 302. The same effect can be obtained by this control. A corresponding result is obtained with radar, except that the direction of the phase shift due to the Doppler shift is opposite, regardless of whether the slope of the frequency modulation is positive or negative. Fig. 4(C) shows, as another design example, a third design example in which a waveform with a positive slope (A) and a waveform with a negative slope (B) are repeated alternately for each modulation period TM. The same effect can be obtained by this control. [Transmit Wave Output Off Control (1)] If a relatively wide frequency band is ensured by combining several partial waveforms in frequency modulation, as in the second method of the comparative example or the first embodiment, the distance resolution suitable for detecting small distances can be enhanced. However, because the frequency modulation is enhanced using the PLL circuit 21, a problem arises with respect to the signal-to-noise ratio. Generally, frequency modulation is performed using the phase-locked loop (PLL) circuit. According to the first embodiment, as described above, the transmit signal ST, to which the frequency modulation is applied in a given design, is generated by the modulation control at the PLL circuit 21. To implement the modulation frequency control of the waveform, as shown in Fig. 3, the PLL setting of the PLL circuit 21 must be changed for each partial waveform (the straight segments) of the respective modulation time Tm. Because the frequency range of the respective partial waveforms is different, the PLL setting state must be changed. In general, the unlocked PLL state in PLL circuit 21 exists during the transition until the output is stable, and the output frequency in the unlocked state is unstable. However, when the modulation frequency is changed by the PLL setting, a predetermined transition time is required. This transition time is necessary for the PLL to move from the unstable unlocked state to a stable locked state. The partial waveform gap (the pause time Tr) is related to the PLL transition time. PLL circuit 21 is in an unlocked state where the frequency is unstable during the transition time, and the frequency in the unlocked state cannot be controlled with absolute stability. Therefore, in the unlocked state, an unstable frequency other than a predetermined frequency can be output by the signal generation unit 20.Although there are differences depending on the country and region, usable frequency ranges, output powers, and the like are regulated by the radio wave laws and standards of the respective countries and regions. Outputting the unstable frequency signal in the non-locked state of the PLL circuit 21 is problematic because there is a possibility that the radio wave law or similar regulations will not be fulfilled. Therefore, the transmitted wave with an unstable frequency must not be output during the non-locked state. [Transmit Wave Output Off Control (2)] Therefore, according to the first embodiment, the radar circuit 10 also has the function of controlling the switching on and off of the output (transmission) of the transmit wave according to the waveform design of the transmit signal ST. The function consists of controlling the output of the transmit wave so that it assumes a switched-off state during the transition time (pause time Tr) corresponding to the undocked state of the PLL circuit 21. With this function, a stable transmit wave can be output that satisfies the radio wave law and the like when the radar system 1 is implemented. According to the first embodiment, the frequency of the transmit wave is assumed to be, for example, 77 to 81 GHz, in accordance with the radio wave law and radio wave standards.According to the first embodiment, the transmit wave output shutdown control is implemented to send a transmit wave with a frequency within the frequency range and to prevent the transmission of an unstable transmit wave outside the frequency range. In Fig. 2, the function is implemented based on the control of the CPU 16 described above, using the state detection unit 23 and the output control unit 24. Fig. 5 shows a configuration and timing diagram of each signal for the transmit wave output turn-off control according to the first embodiment. Similar to Fig. 3, the modulation time Tm and the pause time Tr are provided on the time axis. Fig. 5 shows the state detection signal SS, the output control signal SO, and the transmit wave output signal TXOUT from top to bottom. The CPU 16 receives the locked and unlocked states of the PLL circuit 21 by referencing the value of the state sensing signal SS from the state sensing unit 23. When the PLL circuit 21 is in the unlocked state, the CPU 16 generates the control signal C2 to prevent the transmit wave from being emitted. Specifically, the CPU 16 provides the control signal C2 to the output control unit 24 to switch the transmit wave output signal TXOUT from the on state to the off state in response to the change in the state sensing signal SS from the locked state (value 1) to the unlocked state (value 0). The output control unit 24 switches the output control signal SO from the on state (value 1) to the off state (value 0) in accordance with the control signal C2.In amplifier 31, the amplification is switched off according to the switched-off state of the output control signal SO, and the transmit wave output TXOUT is in the switched-off state. Accordingly, the transmit wave in the transmit signal ST is not emitted (transmitted) by the transmitting antenna 41 during the pause time Tr. Naturally, the receive wave input signal RXIN is not generated during the pause time Tr in the corresponding receive wave. Accordingly, in the radar circuit 10 according to the first embodiment, the transmission of a transmit wave with an unstable frequency corresponding to the unlatched state of the PLL circuit 21 is prevented by the transmit wave output switch-off control. This reliably prevents radio waves (transmit waves) from being emitted during the unlatched state, thus preventing violations of the radio wave law and the like, and allowing a suitable measurement to be performed using a transmit wave with a stable frequency. Furthermore, Fig. 5 shows a preferred control example relating to on / off time control. This means that, in this control example, the output control signal SO is switched from the on state with the value 1 to the off state with the value 0 at a time (e.g., t3) that is before a time at which the state detection signal SS is in the unlocked state with the value 0 (e.g., t4). Furthermore, the output control signal SO is switched from the off state with the value 0 to the on state with the value 1 at a time (e.g., t6) that is after a time at which the state detection signal SS is in the locked state with the value 1 (e.g., t5). Details of the control system, which includes the transmit wave output switch-off control, are described below. When the measurement is initiated by frequency modulation in the radar circuit 10, a modulation start signal is sent from the CPU 16 via the interface circuit 17 as one component of the control signal C1 to the modulation control unit 22. Based on the modulation start signal, the modulation control unit 22 controls the modulation frequency of the PLL circuit 21. Based on the time of the timer 15, the CPU 16 sends the control signal C2, which switches the transmit wave output signal TXOUT to the off state, to the output control unit 24 before the modulation frequency waveform from Fig. 3 ends. The output control unit 24 provides the amplifier 31 with the output control signal SO corresponding to the control signal C2. Therefore, the transmit wave output signal TXOUT is in the off state. During the transition time (pause time Tr) when the modulation frequency waveform is switched, the PLL circuit 21 is in the unlatched state. The state detection unit 23 detects the unlatched state based on the PLL state signal SP from the PLL circuit 21 and outputs the corresponding state detection signal SS. The CPU 16 provides the control signal C2, which switches off the transmit wave output signal TXOUT, based on the state detection signal SS, according to the change from the locked to the unlatched state. When the PLL circuit 21 is in the locked state again during the transition period, the state detection unit 23 detects the locked state and outputs the corresponding state detection signal SS. Based on the state detection signal SS, the CPU 16 provides the control signal C2, which activates the transmit wave output signal TXOUT, according to the change from the unlocked state to the locked state. If the output control signal SO, which switches the output (gain) of amplifier 31 on / off, is switched on / off rapidly, the spectrum broadens due to AM modulation (amplitude modulation), and a signal outside a specified frequency band may be output. To prevent this, the output must be switched on / off carefully over time. Therefore, the output control signal SO exhibits a slope at the time of switching between the on and off states. [Effects] As described above, the radar circuit 10 according to the first embodiment and the like can increase the distance resolution when measuring the distance D and the relative velocity V using the frequency modulation method, while preventing the deterioration of the signal-to-noise ratio. In particular, according to the first embodiment, a small distance can be suitably detected using a wide frequency band based on the waveform design shown in Fig. 3. Figures 6 and 7 are diagrams illustrating the effects and the like of the first embodiment compared with the comparative example. Figure 6 shows FFT spectra of the results of the frequency modulation designs according to the first embodiment, the first comparative example, and the second comparative example. The horizontal axis of the FFT spectra in Figure 6 shows a value (distance BIN) that is proportional to the distance to be measured from the target, with the left side of the figure showing a small distance and the right side showing a large distance. The vertical axis shows the FFT power [dB] of the result of the frequency analysis in the signal processing unit 11, which is the FFT signal intensity with the FFT peak value set to 0 dB. Fig. 6(A) shows the results of the first and second comparison examples. Result 601, indicated by a solid line, represents the first comparison example and shows a characteristic curve for the waveform from Fig. 7(A). Result 602, indicated by a dashed line, represents the second comparison example and shows a characteristic curve for the waveform from Fig. 7(B). The second comparison example shows an ideal characteristic curve obtained through simulation. Near a distance value of approximately 32, an FFT power peak (frequency peak) occurs. In the waveform design from the first comparative example in Fig. 7(A), a first linear section 701 and a second linear section 702 are provided as n = 2 partial waveforms (linear sections) within the modulation period TM. The initial frequency Fs2 of the second linear section 702 is equal to the final frequency Fe1 of the first linear section 701 (Fs2 = Fe1). Both partial waveforms have the same slope g0. In the waveform design of the second comparative example in Fig. 7(B), a linear section 700 and the same slope g0 are present within the same modulation period TM. The waveform is not subdivided into partial waveforms; rather, it is an ideal waveform that can be defined by a straight line. As shown in Fig. 6(A), the FFT performance of result 601 of the first comparison example is higher than that of the ideal result 602 of the second comparison example, except at the peak. In result 601 of the first comparison example, the noise floor is increased at high frequency, i.e., at large distances, compared to the ideal result 602 of the second comparison example. As a result of the increased noise floor, the signal-to-noise ratio of the first comparison example deteriorates when a target at a large distance is detected. Similarly, the noise floor is increased at small or medium distances. In the first comparison example, the noise floor is broader and the signal-to-noise ratio is lower than in the second comparison example. Fig. 6(B) shows the results of the first embodiment and the first comparative example. A result 603, indicated by a solid line, occurs with the radar circuit 10 according to the first embodiment and with a characteristic curve of the waveform from Fig. 7(C) without an interpolation function. In the waveform design shown in Fig. 7(C) according to the first embodiment, in the modulation period TM n = 2, partial waveforms (straight-line sections) comprise the first straight-line section 301 and the second straight-line section 302. The design corresponds to the case described above, in which n = 2 is shown in Fig. 3. The two straight-line sections lie on the reference line 300 and have the same slope g0. The initial frequency Fs2 of the second straight-line section 302 is greater than the final frequency Fe1 of the first straight-line section 301 (Fs2 > Fe1). As shown in Fig. 6(B), the FFT power in result 603 according to the first embodiment is lower than in result 601 of the first comparative example at a high frequency, i.e., a large distance, and an increase in the background noise is prevented. Similarly, the background noise is prevented even at a small or medium distance. That is to say, in the radar circuit 10 according to the first embodiment, unlike in the first comparative example, a deterioration of the signal-to-noise ratio is prevented. However, in the result 603 according to the first embodiment, a side lobe 605 is generated, as shown near the peak. Specifically, the side lobe can be observed as three "peaks," including a peak. Therefore, depending on the analysis processing of the CPU 16, it is possible that the three "peaks" will be determined as three peaks. Although the influence of the side lobe 605 is not considered a problem in the analysis processing of the CPU 16, an improvement must be made if a problem arises. The interpolation function of the first modification of the first embodiment can be used as an improvement method. [Modification (1) - Waveform interpolation function] The radar circuit 10 is described below according to a modification of the first embodiment. The function of the radar circuit 10 according to the first modification is to interpolate the waveform of the gap connecting the multiple IF signals of the received signal in Fig. 3. The interpolation function is performed, for example, by software processing of the CPU 16. Alternatively, a circuit unit for performing interpolation processing can be additionally provided in the RF circuit unit 12. Fig. 3(C) shows a waveform after interpolation as multiple signals IF of the received signal in the radar circuit 10 according to the first modification. The radar circuit 10 according to the first modification interpolates waveform data in the interval at the time of combination of the multiple signals IF. The interval of each signal IF in relation to the pause time Tr has an interpolated waveform. Interpolated waveforms are represented as signals IP1, IP2, ..., IPn. When the acquisition signal SF is processed based on the received signal SR, the CPU 16 interpolates the waveform, as shown in (C), and generates a signal obtained by combining the portions of the multiple signals IF using the post-interpolation signal. The CPU 16 then performs FFT-type analysis using the combined signal to calculate the distance D, the relative velocity V, and other parameters. This eliminates the discontinuous connection point of the multiple signals IF, even if the target has a relative velocity and a phase shift occurs due to Doppler shift, while maintaining coherence.Accordingly, in the analysis processing of the CPU 16, the distance D and the like can be calculated with a high distance resolution using the signal of the wide frequency band W1, while preventing the deterioration of the signal-to-noise ratio. Several methods can be applied to interpolate the waveform data. For example, a method for interpolating waveform data using previous waveform data, a spline interpolation method, and a method for predicting and interpolating future waveforms by machine learning the previous waveform data are applicable. For instance, if a method for interpolating waveform data using previous waveform data is applied, the following operations can be performed. CPU 16 temporarily holds a capture signal corresponding to each signal IF of the received signal in one of the memories. Using the waveform of signal IF held in memory, CPU 16 generates an interpolation waveform to interpolate the waveform of the subsequent interval (pause time Tr).For example, CPU 16 sequentially holds the waveform of signal IF1 corresponding to the first modulation time Tm1 and the waveform of signal IF2 corresponding to the second modulation time Tm2. The waveform of signal IF comprises waveforms of various frequencies, which are not shown in detail. Based on the waveform of signal IF1 and the waveform of signal IF2, CPU 16 generates, for example, a signal IP1 of the interpolated waveform of the interval. CPU 16 generates the interpolated waveform signal IP1 using the waveform of signal IF1, connects the interpolated waveform signal IP1 after signal IF1 so that there is no discontinuous point, and connects the interpolated waveform signal IP1 before signal IF2 so that there is no discontinuous point. CPU 16 performs the analysis processing in the manner of an FFT using the combined and interpolated signals.Fig. 6(C) shows, as the first modification of the first embodiment, a comparison result obtained when interpolation is performed. The result 604, indicated by a solid line, shows a characteristic curve obtained in the first modification. In result 604 according to the first modification, the waveform design is identical to that in Fig. 7(C), and the waveform data in the received signal are interpolated. A method is used for interpolating the waveform data in which an interpolation waveform is generated by reusing the previous waveform. Because no side lobe 605 is generated near the peak in result 604, adverse effects on the distance calculation during analysis processing by the CPU 16 can be avoided.In result 604, the FFT performance lies at any interval between result 601 (indicated by the dashed line) of the first comparison example and result 603 (indicated by the dashed line) of the first comparison example, and, unlike in the first comparison example, the background noise is prevented. With the first modification, the degradation of the signal-to-noise ratio and side lobes can be prevented, with these two effects being achieved in a balanced way. [Modification (2) - Step-shaped waveform] A modification of the radar circuit 10, relating to the design of the modulation frequency waveform of the transmit signal ST, is described below as a modification of the first embodiment. Fig. 8 shows a frequency-time characteristic curve for the design of the modulation frequency waveform of the transmitted signal ST in the radar circuit 10 according to the second modification as in Fig. 3. The reference line 300 is the same as that in Fig. 3. The straight sections 301, ..., 30n are provided as a number (n) of partial waveforms on the straight line 300. Each straight section is shown enlarged in (A) and (B). (A) shows the case of the waveform from Fig. 3 according to the first embodiment described above, where it is a straight line with a predetermined slope g0. (B) shows the case of the second modification with a step waveform. In the waveform design of the second modification, a predetermined time period with a horizontal width h1 of the step waveform and a predetermined frequency range with a vertical width h2 are defined.The straight sections of the staircase shape essentially run along line 300 and have the same slope g0 as in (A). Similarly, a staircase shape with a negative slope is also possible. The first embodiment of (A) is advantageous with respect to distance resolution. The second modification of (B) is advantageous with respect to the detection performance of the relative velocity V. When the modulation in (B) is used, the Doppler shift can be detected more easily than with the modulation shown in (A) (linear frequency modulation), so that the relative velocity V can be detected with high accuracy. [Modification (3) - Essentially linear waveform] The design of the frequency modulation waveform is not limited to a completely linear characteristic curve as shown in Fig. 3, and it can exhibit a substantially linear characteristic curve that closely approximates this, while achieving the same and corresponding effects. The multiple straight sections of the waveform can essentially run along the reference line 300 and exhibit a certain frequency deviation from the line 300 within a permissible range. The multiple straight sections of the waveform can be arranged in a substantially linear fashion with respect to the line 300 within the reference region of a given frequency range. Fig. 9 shows a waveform design for radar circuit 10 according to a third modification. Fig. 9(A) shows a schematic linear design example, where the degree of frequency increase of each of the several straight sections is less than in the fully linear design according to the first embodiment of Fig. 3. In this design, the straight sections gradually deviate slightly downwards from the reference line 300. In this design, the region corresponding to the amount of frequency increase in the interval between the several straight sections (pause time Tr) is smaller than the region in the case of Fig. 3. Each of the several straight sections has the same slope, and the relationship between adjacent straight sections is the same as that according to the first embodiment.For example, the initial frequency Fs2 of the second straight section 302 satisfies the condition described above (Fs2 > Fe1) with respect to the final frequency Fe1 of the first straight section 301. In the design, the frequency range of the gap is defined as Fy2. The range Fy2 is smaller than the range Fy in Fig. 3 (Fy2 < Fy). Therefore, the second straight section 302 lies slightly below the straight line 300. The increment and the deviation are within a predetermined permissible range. The frequency range corresponding to the permissible range is specified by Fz. The initial frequency can lie within the aforementioned range Fz. Throughout the entire modulation period TM, the several straight sections 301 to 30n are essentially linear. A region 350, indicated by a dashed triangle, denotes a region of a feasible area (reference region) corresponding to the line 300 and the region Fz. A number of straight sections can be formed within region 350. Fig. 9(B) shows an essentially linear design example, where the degree of frequency increase of each of the several straight segments is greater than in the case of Fig. 3, as another design example. In this design, the straight segments gradually deviate slightly from and lie above the reference line 300. In this design, the frequency range of the interval is defined as Fy3. The range Fy3 is larger than the range Fy in Fig. 3 (Fy3 > Fy). As a result, the second straight segment 302 lies slightly above line 300. The increment and deviation are within a predetermined range Fz. [Modification (4) - Waveform with a changing slope] Fig. 10 shows a waveform design for radar circuit 10 according to a fourth modification. Fig. 10(A) shows a design example in which the slopes in a number (n) of straight sections of the modulation period TM are different and the slopes gradually increase along the time axis. In this design, the number (n) of straight sections generally forms a gradually increasing quadratic curve. The relationship between the frequencies of the adjacent straight sections is the same as described above. The slope of each straight section gradually increases. For example, the first straight section 301 has a slope g1, and the second straight section 302 has a slope g2 that is greater than the slope g1 (g2 > g1). The multiple straight sections lie within a predetermined region 350. Similarly, a design is also possible in which the slope of the straight section decreases. The program and environment information in memory 13 can be used to determine which of the waveform designs of the respective embodiments and modifications is to be applied. Furthermore, several types of waveform design programs and environment information can be stored in memory 13 and selected and used according to the user's settings and controls. (Second embodiment) A radar circuit and the like according to the second embodiment of the invention are described with reference to Fig. 11. The basic configuration of the second embodiment and the like is the same as that of the first embodiment, and components that differ from those of the first embodiment are described below. The second embodiment shows a form of sequence control implemented in the RF circuit unit 12, which differs from the transmit wave output switch-off control function according to the first embodiment. [Transmit wave output shutdown control] Fig. 11 shows a configuration of the RF circuit unit 12 and the like in the radar circuit 10 according to the second embodiment. In this configuration, the switching off of the transmit circuit output during a non-latched state of the PLL circuit 21 is primarily controlled by the RF circuit unit 12 instead of the CPU 16. The above configuration includes a sequence control unit 26 and a timer 25 in the RF circuit unit 12 as elements different from the configuration shown in Fig. 2. The state detection unit 23 mentioned above is not required in the above configuration. The timer 25 receives a clock CLK2 generated by the RF circuit unit 12 and measures the time relative to the clock CLK2. According to the second embodiment, because the control must be based on the operating time of the PLL circuit 21 in the RF circuit unit 12, the timer 25 in the RF circuit unit 12 is used instead of the timer 15 of the CPU 16. The sequence control unit 26 is a sequencer that controls the frequency modulation sequence relative to the time of the timer 25. The sequence control unit 26 performs sequence control of the control contents of the modulation control unit 22 and the output control unit 24 on a time axis based on the time of the timer 25. The sequence control unit 26 generates a control signal C4 that controls the frequency modulation of the signal generation unit 20 and the switching off of the transmit wave output on the time axis. The sequence control unit 26 generates the control signal C4 relative to the time of the timer 25 and sends the control signal C4 to the modulation control unit 22 and the output control unit 24 according to a sequence predetermined by a program and environmental information. The sequence control unit 26 can also generate and send the control signal C4 according to an instruction (a control signal) from the CPU 16 relative to the time of the timer 25.The content of the control signal C4 includes a control signal for the modulation control unit 22 and a control signal for the output control unit 24. The configuration of the sequence control signals for the transmit wave output switch-off control in the radar circuit 10 according to the second embodiment matches the waveform of the transmit signal ST from Fig. 3(A), the output control signal SO from Fig. 5, the transmit wave output signal TXOUT, and the like. This means that the output control signal SO is switched off at the beginning of the pause time Tr, corresponding to the unlocked state of the PLL circuit 21, and that the output control signal SO is switched on at the end of the pause time Tr. Accordingly, during the pause time Tr corresponding to the unlocked state, the transmit wave output signal TXOUT is in an off state and no transmit wave is sent. [Setting the sequence control] In the radar circuit 10 according to the second embodiment, the sequence control content can be set (or programmed) by the sequence control unit 26 using a setting function that refers to the program and the environment information of the memory 13. The content and timing of the control signal C4 from the sequence control unit 26 to the modulation control unit 22 and to the output control unit 24 can be set. The characteristic curve of the PLL circuit 21 specifies the time and transition time at which a PLL state switches between an locked and an unlocked state. A sequence is set based on the obtained characteristic curve. For example, the manufacturer sets the sequence during production. Similarly, the on / off timing of the output control signal SO from Fig. 5 can be set. As shown in Fig.As shown in Figure 5, the transmit wave output signal TXOUT can, for example, be switched off shortly before the end of the partial waveform (at a time shortly before the transition to the unlocked state). Furthermore, the transmit wave output signal TXOUT can be switched on at a time shortly after the beginning of the partial waveform (a time after the transition to the locked state). The sequence control unit 26 receives the current PLL state based on a predefined sequence and the time from the timer 25 and outputs the control signal C4 with a value corresponding to the PLL state. The modulation control unit 22 controls the frequency modulation in the same manner as described above, according to the value and timing of the control signal C4, using the modulation control signal SM. The output control unit 24 controls the switching on / off of the transmit wave output in the same manner as described above, according to the value and timing of the control signal C4, using the output control signal SO. [Effects] As described above, the radar circuit 10 and the like, according to the second embodiment, can achieve the same effects as the first embodiment. According to the second embodiment, the radio wave law or similar requirements can be met by ensuring, through sequence control, that no transmit wave with an unstable frequency is emitted during the unlocked state of the PLL circuit 21. According to the second embodiment, distance detection can be achieved, in particular, by reducing the communication between the signal processing unit 11 and the RF circuit unit 12. As in the first embodiment, a radar circuit 10 can employ a method, as in the first embodiment, in which the PLL state of the PLL circuit 21 is detected and recorded using the state detection unit 23 (or the sequence control unit 26 itself). In this case, the sequence control unit 26 similarly controls the prescribed sequence according to the detected PLL state. Furthermore, as with the radar circuit 10 according to a modification of the second embodiment, an output switch-off circuit 29 from Fig. 11 can be provided at a later stage of the output of the signal generation unit 20 and the PLL circuit 21, or at a position within the signal generation unit 20 and the PLL circuit 21. The output switch-off circuit 29 can switch the on / off state of the output signal of the PLL circuit 21. In this case, the output control unit 24 provides the output control signal SO for the output switch-off circuit 29 to switch off the transmit signal ST to the output of the PLL circuit 21. (Third embodiment) A radar circuit and the like according to the third embodiment of the invention are described with reference to Figures 12, 13, 14 to 15. The radar system 1 and the radar circuit 10 according to the third embodiment have, on the transmitting side, several transmitting channels and a function for switching a transmitting channel to be used according to a mode relating to distance measurement. Furthermore, the third embodiment has a phased-array antenna configuration on the receiving side. That is to say, the third embodiment shows a phased-array radar. [Radar circuit] Fig. 12 shows a configuration of the radar system 1 and the radar circuit 10 according to the third embodiment. In the radar circuit 10 according to the third embodiment, a configuration in which the control is performed using the sequence control unit 26 is applied as the basic configuration in the same way as in the radar circuit 10 (Fig. 11) according to the second embodiment. However, the configuration is not limited to this, and the radar circuit 10 according to the third embodiment can be controlled by the CPU 16 in the same way as the radar circuit 10 according to the first embodiment (Fig. 2). Radar system 1 has two transmitting antennas corresponding to two transmitting channels on the side of transmitting antenna 41. The two transmitting channels comprise a first transmitting channel CH1 and a second transmitting channel CH2. A first transmitting antenna TXA1 for the first transmitting channel CH1 and a second transmitting antenna TXA2 for the second transmitting channel CH2 are provided. Corresponding to the transmitting channel, amplifier 31 comprises a first amplifier PA1 and a second amplifier PA2. The first transmitting antenna TXA1 is connected to the first amplifier PA1, and the second transmitting antenna TXA2 is connected to the second amplifier PA2. The first transmitting channel CH1 has the first amplifier PA1 and the first transmitting antenna TXA1. The second transmitting channel CH2 has the second amplifier PA2 and the second transmitting antenna TXA2. The transmit wave output signals TXOUT1 and TXOUT2 are provided according to the transmitting channel.The transmit signal ST from the PLL circuit 21 is fed into the first amplifier PA1, the second amplifier PA2, and a number (k) of step-down converters 33. The output control signal SO from the output control unit 24 comprises output control signals SO1 and SO2. The radar system 1 according to the third embodiment has two range-measuring modes and a control function for the appropriate use of the two transmit channels according to the modes. The modes correspond to the amount of the detected range from the target. According to the third embodiment, the first and second modes are provided, and the first transmit channel CH1 and the second transmit channel CH2 are provided according to the first and second modes, respectively. The first mode is a short-range detection mode (short-range radar mode) and uses the first transmit channel CH1. The first mode is suitable for detecting a short distance (close range) from the target compared to the second mode, and in particular, a short distance can be detected with higher resolution than in the second mode. The first mode uses the design of the first waveform.The second mode is a medium-range detection mode (medium-range radar mode) and uses the second transmission channel, CH2. This second mode is suitable for detecting a medium distance from a target, unlike the first mode. The second mode uses the second waveform design. The modulation control unit 22 provides a modulation control signal (SM) with a waveform corresponding to the mode, according to the sequence control of the PLL circuit 21. The direction and output power of the transmitting antenna 41 differ for the respective modes. As shown in Fig. 12, a radar system 1 can perform two types of distance measurements in two modes as a configuration of two transmitting channels. This means that, according to the third embodiment, both short and medium distances can be suitably detected. According to the third embodiment, the receiving antenna 42 has the configuration of a phased-array antenna 500. The phased-array antenna 500 has a number (k) of receiving antennas RXA1 to RXAk. The radar circuit 10 has a number (k) of low-noise amplifiers 32 {LNA1 to LNAk}, a number (k) of step-down converters 33 {DC1 to DCk}, and a number (k) of ADCs 34 {ADC1 to ADCk} corresponding to the number (k) of receiving antennas. A number (k) of receive-wave input signals RXIN1 to RXINk, a number (k) of receive signals SR1 to SRk, a number (k) of difference signals SD1 to SDk, and a number (k) of detection signals SF1 to SFk are provided corresponding to the number (k) of receiving antennas. A number (k) of detection signals SF1 to SFk is sent as detection signal SF to signal processing unit 11. The phased-array antenna 500 has blocks of a number (k) of receive channels, and each receive channel has the receive antenna 41, the low-noise amplifier 32, the step-down converter 33, and the ADC 34. It should be noted that the receive channel and the transmit channel are distinct concepts. In the configuration of the phased-array antenna 500, the angle of a received wave (incoming wave) can be estimated according to a well-established technology by processing the detection signal SF, thereby enabling the detection of the target's direction. The signal processing unit 11 of the radar system 1 calculates the target's direction using the phased-array antenna 500 based on the detection signal SF. The detection information 202 includes information about the direction.With an increasing number of receiving channels of the Phased-Array Antenna 500, angular separation of a number of targets can be performed, so that the angle (direction) of the target can be detected with higher accuracy. The configuration of the phased-array antenna 500 can be applied similarly to the first embodiment and the like. [Frequency modulation] Fig. 13 shows a waveform projection of the frequency modulation in the modulation period TM of the transmit signal ST for the respective modes according to the third embodiment. Fig. 13(A) shows a first waveform for the first mode. Fig. 13(B) shows a second waveform for the second mode. The configuration of the first waveform in (A) is the same as that of the waveform according to the first embodiment in Fig. 3(A). On the reference line 300, the straight sections 301 to 30n are provided as several partial waveforms, and the entire frequency band W1 is provided. The configuration of the second waveform from (B) is the same as that of the waveform of the first method of the comparison example in Fig. 18(A). The straight sections 901 to 90n are provided as several partial waveforms, and the entire frequency band W0 is provided. The frequency band W1 is wider than the frequency band W0 (W1 > W0). Because the waveform of the first mode has a wider band than the waveform of the second mode, the distance resolution can be increased, making it possible to detect small distances. [Mode control (1)] The radar system 1 according to the third embodiment controls the mode switching, such that the first transmitting channel CH1 is in the switched-on state when the first mode is used, and the second transmitting channel CH2 is in the switched-on state when the second mode is used. Figure 14 is a timing diagram relating to the control of switching between two modes. Figure 14 shows an example of the output control signal SO and the transmit wave output signal TXOUT with respect to the transmit wave output turn-off control for each mode. Figure 14 shows, from top to bottom, an output control signal SO1 of the first transmit channel CH1 in the first mode, an output control signal SO2 of the second transmit channel CH2 in the second mode, a transmit wave output signal TXOUT1 of the first transmit channel CH1 in the first mode, and a transmit wave output signal TXOUT2 of the second transmit channel CH2 in the second mode. The example shows signals for controlling the first mode so that the on state (valid) is assumed, and the second mode so that the off state (invalid) is assumed. When the first mode is used, the output control signal SO1 of the first transmit channel CH1 is on for each modulation period Tm corresponding to each of the partial waveforms, and off for each pause time Tr. Consequently, for each modulation period Tm, the transmit wave output signal TXOUT1 from the first amplifier PA1 is on, and off during the pause time Tr corresponding to the unlatched state of the PLL. The control signal is the same as shown in Fig. 5. Conversely, the output control signal SO2 of the second transmit channel CH2 is off, so the transmit wave output signal TXOUT2 from the second amplifier PA2 is off. Thus, when the first mode is used, the transmit wave is radiated only from the first transmit antenna TXA1. Although not shown, the reverse signal when the second mode is used is similar to the one described above. That is, when the second mode is used, the output control signal SO2 of the second transmit channel CH2 is repeatedly switched on and off, while the output control signal SO1 of the first transmit channel CH1 remains off. Therefore, the transmit wave is emitted only from the second transmit antenna TXA2. The second mode is designed, for example, so that it is not necessary to detect such small distances as in the first mode, and the same distance resolution as in the first mode is not required when detecting medium distances. Therefore, the same design as in the comparison example is applied to the waveform of the second mode.In the second mode, however, a waveform that differs from that of the comparison example can be applied, depending on the intended distance from the detection target or similar factors. For example, in the second mode, a waveform similar to that of the first embodiment or modification, but with different settings such as slope and frequency band than in the first mode, can be used. The sequence control unit 26 or the CPU 16 can generate a control signal representing a current mode to be used and control the mode switching. As a modification of the third embodiment, not only is a configuration of two modes and transmit channels possible, but also a configuration of three or more modes and transmit channels. For example, a long-range detection mode and a corresponding third transmit channel can be provided as an additional third mode. In this case, the third transmitting antenna is one with a high antenna gain suitable for long-range detection. Other modes and transmitting antennas can be used, such as a narrow-angle irradiation mode in which the irradiation beam is narrowed. Accordingly, by switching the waveform and the transmit channel according to each mode, different distances can be detected by a radar system 1, thus providing the radar system 1 with a sophisticated function. [Mode control (2)] The radar system 1 according to the third embodiment can employ the following mode-switching methods. First, a method is possible in which several modes are predefined using a program or environmental information, and these modes are to be switched sequentially. For example, the sequence control unit 26 (or the CPU 16) generates a control signal to switch the mode at a predetermined time or at a predetermined point in time on the time axis based on the aforementioned settings. Fig. 15 shows an example of a mode switching control. Fig. 15(A) shows, as a first example, a time transition where two modes are switched separately based on a predefined setting. For example, the first mode and the second mode are used alternately at their respective predefined times. The mode duration and the like are predefined as the first and second mode periods, with their settings being variable. A predefined switching transition time Tsw is provided between the two modes. During the switching transition time Tsw, the frequency modulation waveform setting and the transmit channel setting to be used are switched. By implementing such a time-separated mode switching control, two distance types, namely a short distance and a medium distance, can be detected almost simultaneously with a predefined accuracy. Fig. 15(B) shows a case in which the mode is switched by a timer corresponding to a command from a host system or the like, as a second example of mode switching control. For example, a mode relating to a distance measurement, a command, or other information is input from the ECU 101 of the vehicle-mounted system 100, which is a host system, to the signal processing unit 11 of the radar system 1. The CPU 16 switches the several modes according to the input information. In the example from (B), CPU 16 receives information in the form of a command from ECU 101 at a certain first time tx1. This information might be, for example, a command to use the second mode. Responding to this command, CPU 16 provides RF circuit unit 12 with a control signal to switch to the second mode. As a result, the second mode is switched on after the specified switching transition time Tsw. Subsequently, at a second time tx2, CPU 16 receives information in the form of a command from ECU 101. This information might be, for example, a command to use the first mode. Responding to this command, CPU 16 provides RF circuit unit 12 with a control signal to switch to the first mode. As a result, the first mode is switched on after the specified switching transition time Tsw.Such a mode switching control allows distance measurement to be performed at any time, as required by the host system, at short and medium distances. The information input from the host system is not limited to direct mode commands. For example, based on information input from the ECU 101, such as vehicle speed, the CPU 16 can determine which mode to use and switch modes. Furthermore, even without a command input from the host system, the CPU 16 can switch modes itself based on its own assessment. It is also possible to use a specific mode from among several options, depending on the command or settings. Fig. 15(C) shows, as a third example of mode switching control, a control example in which the CPU 16 automatically determines a mode and switches between the two modes based on the vehicle speed information (host vehicle speed) input by the ECU 101. In (C), a time transition example of the vehicle speed [m / s] is shown on the top side, and a corresponding mode switching example is shown on the bottom side. CPU 16 switches between the two modes according to the input vehicle speed as a reference. In this example, CPU 16 switches between the two modes using hysteresis control and a vehicle speed threshold. The example shows a first threshold H1 and a second threshold H2 (H1 < H2). If the vehicle speed exceeds the second threshold H2 from the first mode state, CPU 16 uses the second mode, and it switches back to the first mode when the vehicle speed drops below the first threshold H1 from the second mode state. To avoid frequent mode switching between increases and decreases in vehicle speed near a threshold, a well-known hysteresis control is used.In this example, a medium distance is recorded in the second mode because the vehicle speed is relatively high at the beginning. At a specific time ty1, the vehicle speed is below the first threshold H1. Therefore, the second mode switches to the first mode, and a small distance is recorded in the first mode. Subsequently, the vehicle speed exceeds the second threshold H2 at a specific time ty2. Therefore, the first mode switches back to the second mode. Such a mode-switching control allows for precise distance detection by adjusting the distance of the detection target according to the vehicle's speed while driving. During relatively slow driving, a short distance can be detected in the first mode, and during relatively fast driving, a medium distance can be detected in the second mode. For example, when the host vehicle is parking in a parking lot, a short distance to an object such as another vehicle at a close range can be detected with relatively high distance resolution. The vehicle-mounted system 100 can, for instance, use information about the short distance detected by radar system 1 to control the brakes or similar actions during parking.The input information to be used is not limited to vehicle speed, and the mode switching control can be performed similarly using information from other sensors or the like. [Effects] As described above, the radar circuit 10 and the like according to the third embodiment can achieve the same effects as according to the first and second embodiments. According to the third embodiment, suitable distance detection can be carried out, in particular using a mode of a suitable waveform corresponding to the magnitude of the distance from the detection target. Furthermore, suitable control can be carried out in a host system using the detection distance. The relationship between distance and modulation frequency is further elaborated. As in the example of the first mode, when a relatively small distance is to be detected, it is desirable to increase the distance resolution as much as possible. For example, when a small distance is to be detected from an object such as another vehicle located at a relatively short distance from the host vehicle while the vehicle is moving at a relatively low speed, the distance resolution in the prior art example is a few tens of centimeters to a few centimeters. On the other hand, a distance resolution of several centimeters or less can be achieved by using the first to third embodiments. As shown in Fig.As shown in Figure 3, a wide frequency modulation band can be ensured and the distance resolution increased by composing the waveform from a combination of several partial waveforms. As with the example of the second mode, when a medium distance is to be detected, a distance resolution like that required in the first mode for short distances is not necessary. Therefore, a waveform similar to the comparison example described above can also be used. Because the modulation frequency is narrowband in the second mode, this offers the advantage of reducing the frequency modulation time. If the relative velocity V of the target is high, the second mode is more likely to detect the relative velocity. As a modification of radar circuit 10 and the like according to the third embodiment, the following is also possible. An independent circuit unit can be provided for each mode and for each transmission channel. For example, a first PLL circuit and a tuning circuit for it can be provided for the first mode, and a second PLL circuit and a tuning circuit for it can be provided for the second mode. The outputs of the circuit units of several systems are combined into a single output. The output is switched according to the mode. The design of the multiple partial waveforms of the modulation period TM can also be achieved by using several parallel circuit units.For example, the frequency modulation of the first straight section is achieved by a first PLL circuit or the like, and the frequency modulation of the second straight section is achieved by a second PLL circuit or the like. Although the invention has been described in detail based on the embodiments, it is not limited to them, and various modifications can be made without deviating from the scope of protection of the invention. Components of the embodiments can be added, omitted, separated, joined, replaced, combined, or the like. Some or all of the functions and the like of the embodiments can be implemented by hardware in the form of an integrated circuit or by software program processing. Each component of the software can be pre-stored in the device before product shipment or obtained after product shipment by communication from an external device. Numerical values ​​and shapes of specific examples of the embodiments are examples. The invention is applicable not only to a system mounted on a vehicle but also to other applications. Reference symbol list 1 Radar system 10 Radar circuit 11 Signal processing unit 12 RF circuit unit 13 Memory 14 Environmental interface unit 15 Timer 16 CPU 17 Interface circuit 20 Signal generation unit 21 PLL circuit 22 Modulation control unit 23 State detection unit 24 Output control unit 31 Amplifier 32 Low-noise amplifier 33 Buck converter 34 ADC 41 Transmitting antenna 42 Receiving antenna 100 Vehicle-mounted system

Claims

Radar circuit (10) which detects the distance (D) from a target and the relative velocity (V) of the target using a frequency modulation method, wherein the radar circuit (10) comprises: a signal generation unit (20) which generates a transmit signal (ST) for a transmit wave, a modulation control unit (22) which controls the frequency modulation of the transmit signal (ST), a receiving circuit unit (32, 33, 34) which detects a detection signal (SF) based on a difference frequency between a received signal (SR) of a receiving wave with respect to the transmit wave and the transmit signal (ST), and a signal processing unit (11) which performs analysis processing based on the detection signal (SF) and calculates the distance and the relative velocity (V), wherein a frequency modulation waveform of the transmit signal (ST) comprises a number (n) of sub-waveforms.in which the slope of the modulation frequency is positive or negative, and for adjacent partial waveforms of the number (n) of partial waveforms, the initial frequency of a subsequent partial waveform is greater than the final frequency of a preceding partial waveform when the slope is positive, and the initial frequency of the subsequent partial waveform is less than the final frequency of the preceding partial waveform when the slope is negative, characterized in that the radar circuit (10) further comprises: an output control unit (24) which controls the switching on / off of the output of the transmitting wave, wherein the output control unit (24) controls the output of the transmitting wave such that it is in an on state when a PLL circuit (21) of the signal generation unit (20) is in a latched state, and controls the output of the transmitting wave such that it is in an off state,when the PLL circuit (21) is in an unlocked state. Radar circuit (10) according to claim 1, wherein the transmit signal (ST) realizes a predetermined frequency band by a combination of the several partial waveforms of the waveform in one modulation period and the waveform is repeated a number (n) of times. Radar circuit (10) according to claim 1, wherein the multiple partial waveforms of the waveform are arranged on a reference line or are arranged substantially linearly in a reference region of a predetermined frequency range with respect to the reference line. Radar circuit (10) according to claim 3, wherein a pause time (Tr) corresponding to the unlocked state is provided between adjacent partial waveforms and the output control unit (24) controls the output of the transmitting wave such that it is in a switched-off state at the pause time. Radar circuit (10) according to claim 1, wherein the signal processing unit (11) generates a control signal (C1) that controls the frequency modulation based on the time of a timer (15) and provides the signal to the modulation control unit (22). Radar circuit (10) according to claim 1, which further comprises: a sequence control unit (26) which controls the frequency modulation, wherein the sequence control unit (26) generates a control signal (C4) which controls the frequency modulation on the basis of the time of a timer (25) in a high-frequency circuit unit (12) different from the signal processing unit (11) and provides the signal to the modulation control unit (22). Radar circuit (10) according to claim 1, wherein the waveform data of the interval of a number of signals is interpolated according to the number of partial waveforms in the received signal (SR) and the signal processing unit (11) performs the analysis processing using a signal obtained by combining the number of signals. Radar circuit (10) according to claim 1, wherein the partial waveforms have a step shape with a predetermined time width and frequency width as units. Radar circuit (10) according to claim 1, which further comprises: a transmit-side circuit unit with a number of transmit channels (CH1, CH2) corresponding to the number of transmit antennas (TXA1, TXA2), wherein the modulation control unit (22) controls a number of waveform types including a first waveform and a second waveform as the waveform of the transmit signal (ST), and in a first mode the transmit wave is emitted from a first transmit antenna based on the transmit signal (ST) with the first waveform, and in a second mode the transmit wave is emitted from a second transmit antenna based on the transmit signal (ST) with the second waveform. Radar circuit (10) according to claim 9, wherein the transmitting wave with the first waveform has a first frequency band, the transmitting wave with the second waveform has a second frequency band and the first frequency band is wider than the second frequency band and the first and second modes are switched according to the distance from the detection target or information input from a host system. Radar circuit (10) according to claim 9, wherein the transmitting wave with the first waveform has a first frequency band, the transmitting wave with the second waveform has a second frequency band and the first frequency band is wider than the second frequency band and the first mode and the second mode are switched separately in time. Radar circuit (10) according to claim 9, wherein the transmitting wave with the first waveform has a first frequency band, the transmitting wave with the second waveform has a second frequency band, and the first frequency band is wider than the second frequency band, and the first and second modes are switched according to information input by a host system, including the vehicle speed. Radar system (1) which detects the distance from a target and the relative velocity (V) of the target using a frequency modulation method, wherein the radar system comprises a radar circuit (10) according to one of the preceding claims, a transmitting antenna and a receiving antenna. Radar program which causes a radar circuit (10), which detects the distance from a target and the relative velocity (V) of the target using a frequency modulation method, to perform processing, wherein the processing performed by the radar circuit (10) comprises: a signal generation processing for generating a transmit signal (ST) for a transmit wave, a modulation control processing for controlling the frequency modulation of the transmit signal (ST), a receive processing for acquiring a detection signal (SF) based on the difference frequency between a received signal of a receive wave with respect to the transmit wave and the transmit signal (ST), a signal processing for performing an analysis processing based on the detection signal (SF) and for calculating the distance and the relative velocity (V),wherein a frequency modulation waveform of the transmit signal (ST) has a number (n) of sub-waveforms where the slope of the modulation frequency is positive or negative, and for adjacent sub-waveforms of the number (n) of sub-waveforms, the initial frequency of a subsequent sub-waveform is greater than the final frequency of a preceding sub-waveform if the slope is positive, and the initial frequency of the subsequent sub-waveform is less than the final frequency of the preceding sub-waveform if the slope is negative, characterized in that the processing performed by the radar circuit (10) further comprises: an output control processing for controlling the switching on / off of the output of the transmit wave, wherein the output control processing controls the output of the transmit wave such that it is in an on state,when a PLL circuit (21) of the signal generation unit (20) is in a locked state, and controls the output of the transmitting wave so that it is in a switched-off state when the PLL circuit (21) is in a non-locked state.

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