JP5682965B2 - Vehicle detection device, communication device, and vehicle detection system - Google Patents

Description

  The present invention relates to a vehicle detection device, a communication device, and a vehicle detection system, and in particular, a vehicle detection device and communication suitable for use in detecting a distance from a vehicle using RSSI (Received Signal Strength Indication). The present invention relates to an apparatus and a vehicle detection system.

  Conventionally, a method of receiving a transmission signal from a vehicle by a portable device and detecting a distance from the portable device to the vehicle based on the received intensity is known. For example, as disclosed in Patent Document 1, the distance and direction between the vehicle and the portable device are detected according to the reception strength of the signal between the vehicle and the portable device, and the distance and direction in which the vehicle exists is set in the portable device. Displaying (a so-called car finder system) is known.

  FIG. 1 shows an example of the characteristics of an RSSI (Received Signal Strength Indication) circuit for detecting the reception strength of a signal. The horizontal axis indicates the input signal level (unit: dBm) indicating the strength of the received signal input to the RSSI circuit, and the vertical axis indicates the RSSI value (unit: V) output from the RSSI circuit with respect to the input signal level. Is shown.

  As shown in this figure, when the input signal level is within a predetermined effective range, the RSSI value is substantially proportional to the input signal level. On the other hand, when the input signal level falls below the effective range and the RSSI value falls below the lower limit threshold, the RSSI value is saturated and becomes almost constant. Similarly, when the input signal level exceeds the effective range and the RSSI value exceeds the upper threshold, the RSSI value is saturated and becomes almost constant. Therefore, when the input signal level falls within the effective range and the RSSI value falls within the range of the unsaturated region, the distance to the vehicle can be accurately detected based on the RSSI value.

  For example, when a portable device is present in the region R2 indicated by the oblique lines in FIG. 2, the input signal level to the RSSI circuit of the portable device for the transmission signal from the vehicle 1 is within the effective range, and the distance to the vehicle 1 is accurately Can be detected. On the other hand, when the portable device exists in the region R1 inside the region R2, the input signal level to the RSSI circuit of the portable device exceeds the effective range, and the distance to the vehicle 1 cannot be accurately detected. Similarly, when a portable device is present in the region R3 outside the region R2, the input signal level to the RSSI circuit of the portable device is below the effective range, and the distance to the vehicle 1 cannot be detected accurately.

  The region R2 moves according to the intensity of the transmission signal transmitted from the vehicle 1. More specifically, the region R2 is farther from the vehicle 1 as the intensity of the transmission signal becomes stronger, and closer to the vehicle 1 as the intensity of the transmission signal becomes weaker.

  Thus, the range in which the distance to the vehicle 1 can be detected is limited by the characteristics of the RSSI circuit and the intensity of the transmission signal from the vehicle 1.

  On the other hand, it is desired to expand the range in which the distance to the vehicle 1 can be detected. Further, it is desired to improve the detection accuracy of the distance to the vehicle.

  On the other hand, in a conventional passive keyless entry system, when a portable transmitter / receiver receives a transmission signal from an in-vehicle transmitter / receiver, the received signal level exceeds the input allowable value of the detector of the portable transmitter / receiver. It has been proposed to control the transmission signal level from the vehicle-mounted transceiver to be reduced (see, for example, Patent Document 2).

  However, in the invention described in Patent Document 2, it is not particularly considered to improve the detection accuracy of the distance to the vehicle.

JP 2010-38684 A JP 2005-171720 A

  The present invention improves the detection accuracy of the distance to the vehicle.

  A vehicle detection device according to a first aspect of the present invention is a vehicle detection device that detects a distance to a vehicle by performing wireless communication with a communication device provided in the vehicle, for detecting the distance to the vehicle. A reception unit that receives a plurality of detection signals having different transmission intensities from a communication device, a reception intensity detection unit that detects a reception intensity of each detection signal, and a reception detected by the reception intensity detection unit An effective signal determination unit that determines whether the strength is within a predetermined effective range, a transmission strength command unit that instructs the communication device to adjust the transmission strength of the detection signal whose reception strength is outside the effective range, and the reception strength And a distance detection unit that detects the distance to the vehicle based on the reception intensity of two or more predetermined number of detection signals within the effective range.

  In the vehicle detection device according to the first aspect of the present invention, a plurality of detection signals having different transmission intensities, which are detection signals for detecting the distance to the vehicle, are transmitted from a communication device provided in the vehicle. Received, the reception intensity of each detection signal is detected, it is determined whether the detected reception intensity is within a predetermined effective range, and the transmission intensity of the detection signal whose reception intensity is outside the effective range is adjusted. The distance to the vehicle is detected based on the reception intensity of two or more predetermined number of detection signals that are commanded to the communication device and the reception intensity is within the effective range.

  Therefore, the detection accuracy of the distance to the vehicle can be improved.

  This communication device is constituted by, for example, a vehicle-mounted communication device. The vehicle detection device is configured by, for example, a portable communication device. For example, the receiving unit includes an antenna and a receiving circuit. The reception intensity detection unit is configured by, for example, an RSSI circuit. The valid signal determination unit is configured by, for example, a control device such as a CPU, an arithmetic device, an analog or digital comparison circuit, and the like. The transmission intensity command unit is configured by, for example, a control device such as a CPU, an arithmetic device, an antenna, a transmission circuit, and the like. This distance detection part is comprised by control apparatuses and arithmetic units, such as CPU, for example.

  In the distance detection unit, in the detection signals received at the same time, the reception intensity of the detection signals equal to or greater than a predetermined number of two or more that has a reception intensity within the effective range. The distance can be detected.

  Thereby, the detection accuracy of the distance to a vehicle can be improved more.

  The transmission intensity command unit can be instructed to increase or decrease the transmission intensity of a detection signal whose reception intensity is outside the effective range.

  As a result, the transmission intensity of the detection signal can be quickly adjusted to an appropriate value.

  In this vehicle detection device, based on the distance to the vehicle, the reception intensity of which is calculated based on the detection signal within the effective range, the set value of the transmission intensity of the detection signal whose reception intensity is outside the effective range is calculated. A setting intensity calculation unit is further provided, and the command unit can be instructed to set the transmission intensity of the detection signal whose reception intensity is outside the effective range to a set value.

  As a result, the transmission intensity of the detection signal can be adjusted to an appropriate value more quickly.

  The set strength calculation unit is configured by a control device such as a CPU or an arithmetic device, for example.

  The transmission intensity command unit can be instructed to adjust the transmission intensity of the detection signal whose reception intensity is out of the effective range when the detection intensity within the effective range is less than a predetermined number.

  As a result, the amount of communication can be reduced and the transmission intensity of the detection signal can be adjusted only when necessary.

  A vehicle detection system according to a second aspect of the present invention is a vehicle detection system including a communication device provided in a vehicle, and a vehicle detection device that performs wireless communication with the communication device and detects a distance to the vehicle. The communication device is a detection signal for detecting a distance to the vehicle, and receives a command from the vehicle detection device and a transmission unit that transmits a plurality of detection signals having different transmission intensities to the vehicle detection device. A first receiving unit; and a transmission control unit that adjusts the transmission intensity of each detection signal based on a command from the vehicle detection device, wherein the vehicle detection device receives each detection signal. A reception intensity detection unit that detects the reception intensity of each detection signal, an effective signal determination unit that determines whether the reception intensity detected by the reception intensity detection unit is within a predetermined effective range, and the reception intensity is Detection signal out of range A distance to the vehicle is detected based on a transmission intensity command unit for instructing the communication apparatus to adjust the transmission intensity and a reception intensity of two or more predetermined number of detection signals whose reception intensity is within an effective range. A distance detection unit.

  In the vehicle detection system according to the second aspect of the present invention, a plurality of detection signals having different transmission intensities, which are detection signals for detecting a distance to the vehicle by a communication device provided in the vehicle. The signal is transmitted to the vehicle detection device, the command from the vehicle detection device is received, the transmission intensity of each detection signal is adjusted based on the command from the vehicle detection device, and each detection signal is received by the vehicle detection device. The reception intensity of each detection signal is detected, it is determined whether or not the detected reception intensity is within a predetermined effective range, and the adjustment of the transmission intensity of the detection signal whose reception intensity is outside the effective range is performed by the communication device The distance to the vehicle is detected based on the reception intensity of two or more predetermined number of detection signals whose reception intensity is within the effective range.

  Therefore, the detection accuracy of the distance to the vehicle can be improved.

  This communication device is constituted by, for example, a vehicle-mounted communication device. The vehicle detection device is configured by, for example, a portable communication device. For example, the transmission unit includes an antenna and a transmission circuit. The first receiving unit includes, for example, an antenna, a receiving circuit, and the like. This transmission control part is comprised by control apparatuses and arithmetic units, such as CPU, for example. The second receiving unit includes, for example, an antenna and a receiving circuit. The reception intensity detection unit is configured by, for example, an RSSI circuit. The valid signal determination unit is configured by, for example, a control device such as a CPU, an arithmetic device, an analog or digital comparison circuit, and the like. The transmission intensity command unit is configured by, for example, a control device such as a CPU, an arithmetic device, an antenna, a transmission circuit, and the like. This distance detection part is comprised by control apparatuses and arithmetic units, such as CPU, for example.

  A vehicle detection device according to a third aspect of the present invention is a vehicle detection device that detects a distance to a vehicle by performing wireless communication with a communication device provided in the vehicle, and detects the distance to the vehicle. A reception unit that receives a plurality of detection signals having different transmission intensities from a communication device, a reception intensity detection unit that detects a reception intensity of each detection signal, and a reception detected by the reception intensity detection unit An effective signal determination unit that determines whether or not the strength is within a predetermined effective range; a reception state notification unit that notifies the communication device of the reception state of each detection signal; and two or more reception strengths that are within the effective range A distance detection unit that detects a distance to the vehicle based on a reception intensity of a predetermined number or more of detection signals.

  In the vehicle detection device according to the third aspect of the present invention, a plurality of detection signals having different transmission intensities, which are detection signals for detecting a distance to the vehicle, are transmitted from a communication device provided in the vehicle. Received, the reception intensity of each detection signal is detected, it is determined whether or not the detected reception intensity is within a predetermined effective range, the reception state of each detection signal is notified to the communication device, and the reception intensity is The distance to the vehicle is detected based on the reception intensity of two or more predetermined number of detection signals within the effective range.

  Therefore, the detection accuracy of the distance to the vehicle can be improved.

  This communication device is constituted by, for example, a vehicle-mounted communication device. The vehicle detection device is configured by, for example, a portable communication device. For example, the receiving unit includes an antenna and a receiving circuit. The reception intensity detection unit is configured by, for example, an RSSI circuit. The valid signal determination unit is configured by, for example, a control device such as a CPU, an arithmetic device, an analog or digital comparison circuit, and the like. The reception state notification unit is configured by, for example, a control device such as a CPU, an arithmetic device, an antenna, a transmission circuit, and the like. This distance detection part is comprised by control apparatuses and arithmetic units, such as CPU, for example.

  This reception state can include information indicating whether the reception intensity of each detection signal is within the effective range, strong, or weak.

  As a result, the transmission intensity of the detection signal can be quickly adjusted to an appropriate value.

  This reception state can further include the reception intensity of each detection signal.

  As a result, the transmission intensity of the detection signal can be adjusted to an appropriate value more quickly.

  The reception state notifying unit can be made to notify the reception state of the detection signal when the detection intensity within the effective range is less than a predetermined number.

  Thereby, it is possible to reduce the amount of communication and adjust the transmission intensity of the detection signal only when necessary.

  A communication device according to a fourth aspect of the present invention is a communication device that is provided in a vehicle and performs wireless communication with a vehicle detection device that detects the distance to the vehicle, and a detection signal for detecting the distance to the vehicle. A transmission unit that transmits a plurality of detection signals having different transmission intensities to the vehicle detection device, a reception unit that receives a notification of a reception state of each detection signal in the vehicle detection device from the vehicle detection device, and each detection And a transmission control unit that adjusts the transmission intensity of each detection signal based on the reception state of the signal.

  In the communication device according to the fourth aspect of the present invention, a plurality of detection signals having different transmission intensities, which are detection signals for detecting the distance to the vehicle, are transmitted to the vehicle detection device. A notification of the reception state of each detection signal is received from the vehicle detection device, and the transmission intensity of each detection signal is adjusted based on the reception state of each detection signal.

  Therefore, the detection accuracy of the distance to the vehicle can be improved.

  This communication device is constituted by, for example, a vehicle-mounted communication device. The vehicle detection device is configured by, for example, a portable communication device. For example, the transmission unit includes an antenna and a transmission circuit. For example, the receiving unit includes an antenna and a receiving circuit. This transmission control part is comprised by control apparatuses and arithmetic units, such as CPU, for example.

  The reception state includes information indicating whether the reception intensity of each detection signal is within a predetermined effective range, strong or weak, and the transmission control unit includes a detection signal having a high reception intensity. It is possible to decrease the transmission intensity and increase the transmission intensity of the detection signal having a low reception intensity.

  As a result, the transmission intensity of the detection signal can be quickly adjusted to an appropriate value.

  The reception state further includes the reception strength of each detection signal, and the transmission control unit detects that the reception strength is out of the effective range based on the reception strength of the detection signal within the effective range. It is possible to set the transmission intensity of the signal for use.

  As a result, the transmission intensity of the detection signal can be adjusted to an appropriate value more quickly.

  A vehicle detection system according to a fifth aspect of the present invention is a vehicle detection system including a communication device provided in a vehicle, and a vehicle detection device that performs wireless communication with the communication device and detects a distance to the vehicle. The communication device is a detection signal for detecting a distance to the vehicle, and transmits a plurality of detection signals having different transmission intensities to the vehicle detection device, and each detection signal in the vehicle detection device A first reception unit that receives a notification of a reception state from the vehicle detection device; and a transmission control unit that adjusts the transmission intensity of the detection signal based on the reception state of the detection signal. A second receiving unit that receives the detection signal, a reception intensity detection unit that detects the reception intensity of each detection signal, and whether the reception intensity detected by the reception intensity detection unit is within a predetermined effective range Valid signal determination unit A reception state notifying unit for notifying a communication device of a reception state of each detection signal, and a distance to the vehicle based on reception strengths of two or more predetermined numbers of detection signals whose reception intensity is within an effective range And a distance detection unit for detecting.

  In the vehicle detection system according to the fifth aspect of the present invention, a plurality of detection signals having different transmission intensities, which are detection signals for detecting the distance to the vehicle by a communication device provided in the vehicle. Transmitted to the vehicle detection device, a notification of the reception state of each detection signal in the vehicle detection device is received from the vehicle detection device, the transmission intensity of each detection signal is adjusted based on the reception state of each detection signal, Each detection signal is received by the vehicle detection device, the reception intensity of each detection signal is detected, it is determined whether or not the detected reception intensity is within a predetermined effective range, and the reception state of each detection signal Is notified to the communication device, and the distance to the vehicle is detected based on the reception strengths of the detection signals of two or more predetermined reception strengths within the effective range.

  Therefore, the detection accuracy of the distance to the vehicle can be improved.

  This communication device is constituted by, for example, a vehicle-mounted communication device. The vehicle detection device is configured by, for example, a portable communication device. For example, the transmission unit includes an antenna and a transmission circuit. The first receiving unit includes, for example, an antenna, a receiving circuit, and the like. This transmission control part is comprised by control apparatuses and arithmetic units, such as CPU, for example. The second receiving unit includes, for example, an antenna and a receiving circuit. The reception intensity detection unit is configured by, for example, an RSSI circuit. The valid signal determination unit is configured by, for example, a control device such as a CPU, an arithmetic device, an analog or digital comparison circuit, and the like. The reception state notification unit is configured by, for example, a control device such as a CPU, an arithmetic device, an antenna, a transmission circuit, and the like. This distance detection part is comprised by control apparatuses and arithmetic units, such as CPU, for example.

  According to the 1st thru | or 5th side surface of this invention, the detection accuracy of the distance to a vehicle can be improved.

It is a graph which shows an example of the characteristic of an RSSI circuit. It is a figure which shows an example of the detectable range of the distance to a vehicle. It is a block diagram which shows 1st Embodiment of the car finder system to which this invention is applied. It is a flowchart for demonstrating 1st Embodiment of the vehicle detection process performed with a portable machine. It is a figure for demonstrating the validity determination of the signal for distance detection. It is a table | surface which shows the example of the adjustment method of the transmission strength of the signal for distance detection. It is a flowchart for demonstrating 1st Embodiment of the signal transmission process for distance detection performed by the communication apparatus for vehicles. It is a block diagram which shows 2nd Embodiment of the car finder system to which this invention is applied. It is a flowchart for demonstrating 2nd Embodiment of the vehicle detection process performed with a portable device. It is a flowchart for demonstrating 2nd Embodiment of the signal transmission process for distance detection performed by the communication apparatus for vehicles. It is a block diagram which shows 3rd Embodiment of the car finder system to which this invention is applied. It is a flowchart for demonstrating 3rd Embodiment of the vehicle detection process performed with a portable device. It is a flowchart for demonstrating 3rd Embodiment of the signal transmission process for distance detection performed by the communication apparatus for vehicles.

Hereinafter, modes for carrying out the present invention (hereinafter referred to as embodiments) will be described. The description will be given in the following order.
1. First Embodiment (Example in which the strength of transmission strength of a distance detection signal is commanded from a portable device)
2. Second Embodiment (Example of setting transmission intensity of distance detection signal from portable device)
3. Third Embodiment (Example of Notifying Reception Status of Distance Detection Signal from Portable Device)
4). Modified example

<1. First Embodiment>
[Configuration example of car finder system]
FIG. 3 is a block diagram showing a first embodiment of a car finder system to which the present invention is applied.

  The car finder system 101 includes a portable device 111 and a vehicle communication device 112, and is a system that uses the portable device 111 to detect a distance to a vehicle in which the vehicle communication device 112 is provided.

  The portable device 111 includes a portable communication device, performs wireless communication with the vehicle communication device 112, and based on the reception strength of the distance detection signal transmitted from the communication device, the distance from the portable device 111 to the vehicle. Is detected.

  The portable device 111 is configured to include an operation unit 121, a transmission unit 122, a reception unit 123, a reception intensity detection unit 124, an effective signal determination unit 125, a transmission intensity command unit 126, a distance detection unit 127, and a notification unit 128. Is done.

  The operation unit 121 includes operation means such as buttons and switches, for example, and is operated by the user when detecting the distance to the vehicle using the portable device 111, for example. When operated by the user, the operation unit 121 supplies an operation signal indicating the operation content to the transmission unit 122.

  The transmission unit 122 performs wireless communication by a predetermined method with the reception unit 131 of the vehicle communication device 112 and transmits a command or the like to the vehicle communication device 112.

  The reception unit 123 performs wireless communication with the transmission unit 133 of the vehicle communication device 112 using a predetermined method, and receives a distance detection signal for detecting the distance from the vehicle from the vehicle communication device 112. The reception unit 123 supplies the received distance detection signal to the reception intensity detection unit 124.

  The vehicle communication device 112 transmits a plurality of types of distance detection signals having different transmission intensities. In the following description, a case where distance detection signals having three different transmission intensities are used will be described as an example. Hereinafter, the distance detection signal 1, the distance detection signal 2, and the distance detection signal 3 will be referred to in order from the strongest transmission intensity.

  The reception strength detection unit 124 is configured by, for example, an RSSI (Received Signal Strength Indication) circuit, and detects the reception strength of the distance detection signal. More specifically, the reception intensity detection unit 124 converts the input signal level of the distance detection signal supplied from the reception unit 123 into a voltage representing the RSSI value. The reception intensity detection unit 124 supplies a voltage signal representing the RSSI value (hereinafter referred to as RSSI signal) to the valid signal determination unit 125 and the distance detection unit 127.

  The valid signal determination unit 125 determines whether each distance detection signal is valid based on the RSSI value for each distance detection signal. The valid signal determination unit 125 supplies the determination result to the transmission intensity command unit 126 and the distance detection unit 127.

  The transmission strength command unit 126 sends a command for adjusting the transmission strength of the distance detection signal determined to be invalid based on the determination result by the valid signal determination unit 125 via the transmission unit 122 to the vehicle communication device. 112. In addition, the transmission intensity command unit 126 supplies the content of the command transmitted to the vehicle communication device 112 to the distance detection unit 127.

  The distance detection unit 127 detects the distance to the vehicle using the RSSI value for the distance detection signal determined to be valid. For example, the distance detection unit 127 stores a correspondence table in which the RSSI value and the distance to the vehicle are associated in advance for each transmission intensity of the received distance detection signal (for example, the distance detection signal 1). deep. And the distance detection part 127 detects the distance between vehicles using the correspondence table. Here, as will be described later, an initial value of the transmission intensity is set for each of the plurality of distance detection signals transmitted from the vehicle communication device 112. When the portable device 111 first detects the distance to the vehicle using the correspondence table corresponding to the initial value, and then instructs the vehicle communication device 112 to change the transmission intensity of the distance detection signal, The distance to the vehicle is detected using a correspondence table according to the change. The distance detection unit 127 supplies the detection result thus detected to the notification unit 128.

  The notification unit 128 includes, for example, a display unit such as a display, a light emitting unit such as an LED (Light Emitting Diode), or an audio output unit such as a speaker or a buzzer. And the notification part 128 notifies a user of the detection result of the distance to a vehicle by a predetermined method.

  The vehicle communication device 112 is configured to include a reception unit 131, a transmission control unit 132, and a transmission unit 133.

  The receiving unit 131 receives a command to the vehicle communication device 112 transmitted from the transmitting unit 122 of the portable device 111 and supplies the command to the transmission control unit 132.

  The transmission control unit 132 controls the transmission timing, transmission strength, and the like of the distance detection signal from the transmission unit 133 based on a command from the portable device 111 and the like.

  The transmission unit 133 transmits a plurality of types of distance detection signals with different transmission intensities to the portable device 111 under the control of the transmission control unit 132.

[Vehicle detection processing]
Next, a vehicle detection process executed by the portable device 111 will be described with reference to the flowchart of FIG. In this process, for example, the user operates the operation unit 121 of the portable device 111 to instruct the detection of the distance to the vehicle, and the operation signal is supplied from the operation unit 121 to the transmission unit 122 and the distance detection unit 127. It starts when it is done.

  In step S <b> 1, the transmission unit 122 requests the vehicle communication device 112 to transmit a distance detection signal by transmitting a transmission request signal.

  The vehicle communication device 112 that has received the transmission request signal transmits a distance detection signal in step S53 of FIG.

  In step S2, the distance detection unit 127 starts a timer.

  In step S3, the distance detection unit 127 determines whether or not a predetermined time has elapsed since the timer was started. If it is determined that the predetermined time has not elapsed, the process proceeds to step S4.

  In step S4, the reception unit 123 determines whether a distance detection signal has been received. If it is determined that the distance detection signal has not been received, the process returns to step S3.

  Thereafter, the processes in steps S3 and S4 are repeatedly executed until it is determined in step S3 that a predetermined time has passed or until it is determined in step S4 that a distance detection signal has been received.

  On the other hand, if it is determined in step S4 that the distance detection signal has been received, the process proceeds to step S5.

  In step S5, the reception intensity detector 124 detects the reception intensity of the distance detection signal. Specifically, the reception unit 123 supplies the distance detection signal received from the vehicle communication device 112 to the reception intensity detection unit 124. The reception intensity detection unit 124 detects the reception intensity of the distance detection signal by converting the input signal level of the distance detection signal into a voltage representing the RSSI value. Then, the reception intensity detection unit 124 supplies the RSSI signal representing the converted RSSI value to the valid signal determination unit 125.

  When a plurality of types of distance detection signals are received, the reception intensity detection unit 124 converts each distance detection signal into an RSSI signal and supplies the RSSI signal to the effective signal determination unit 125.

  In step S6, the valid signal determination unit 125 determines the validity of the distance detection signal. Specifically, the valid signal determination unit 125 determines that the distance detection signal whose RSSI value is within the unsaturated region is valid, and the distance detection signal whose RSSI value does not fall within the unsaturated region. Is determined to be invalid.

  Here, a specific example of the determination result will be described with reference to FIG. FIG. 5 shows an example of the characteristics of the RSSI circuit that constitutes the reception intensity detection unit 124, and has the same characteristics as the characteristics of FIG. 1 described above. The input signal levels L1 to L3 indicate the input signal levels for the distance detection signals 1 to 3, respectively.

  In this case, since the input signal level L1 of the distance detection signal 1 is larger than the effective range, the RSSI value exceeds the upper limit threshold. Therefore, it is determined that the distance detection signal 1 is invalid. Similarly, since the input signal level L3 of the distance detection signal 3 is smaller than the effective range, the RSSI value falls below the lower limit threshold value. Therefore, it is determined that the distance detection signal 3 is invalid. On the other hand, the input signal level L2 of the distance detection signal 2 is within the effective range, and the RSSI value for the distance detection signal 2 is within the unsaturated region. Therefore, it is determined that the distance detection signal 2 is valid.

  In step S7, the valid signal determination unit 125 determines whether or not a plurality of distance detection signals are valid based on the determination result in step S6. If it is determined that a plurality of distance detection signals are not valid, that is, if there are less than two valid distance detection signals, the process proceeds to step S8.

  In step S8, the transmission strength command unit 126 determines a method for adjusting the transmission strength of the invalid distance detection signal. Specifically, the valid signal determination unit 125 supplies the determination result to the transmission intensity command unit 126. In addition to whether or not each distance detection signal is valid, the determination result includes a strong reception strength (RSSI value exceeds the upper limit threshold) or weakness (RSSI value is the lower limit) for invalid distance detection signals. Information indicating whether the value is less than the threshold) is included. Then, the transmission intensity command unit 126 determines an invalid adjustment method for the distance detection signal based on the acquired determination result.

  In step S <b> 9, the transmission strength command unit 126 transmits a transmission strength adjustment command for commanding adjustment of the transmission strength of the invalid distance detection signal via the transmission unit 122 to the vehicle communication device 112. Command adjustment of invalid distance detection signal. The transmission intensity adjustment command includes, for example, a distance detection signal to be adjusted and information indicating whether the transmission intensity of the signal is increased or decreased.

  Further, the transmission strength command unit 126 supplies the content of the transmission strength adjustment command transmitted to the vehicle communication device 112 to the distance detection unit 127. Thereby, the distance detection part 127 can grasp | ascertain the transmission intensity | strength of each signal for distance detection after adjustment.

  The vehicle communication device 112 receives a transmission strength adjustment command in step S54 of FIG. 7 described later, and adjusts the transmission strength of the distance detection signal based on the command in step S56.

  Here, a specific example of a method for adjusting the distance detection signal will be described with reference to FIG. FIG. 6 is a table summarizing the adjustment method of each signal when the portable device 111 has received all the distance detection signals 1 to 3, and from pattern 1 to pattern 8 depending on the determination result of each signal. It is divided into adjustment methods.

  In the figure, the column written as unsaturated indicates that the RSSI value of the target distance detection signal is within the unsaturated region and the signal is valid. Further, the column written as “saturated (strong)” indicates that the RSSI value of the target distance detection signal exceeds the upper limit threshold and the signal is invalid. Furthermore, the column written as “saturated (weak)” indicates that the RSSI value of the target distance detection signal is below the lower limit threshold value, and the signal is invalid.

  In the case of pattern 1, that is, when the distance detection signals 1 to 3 are all too strong, the transmission strength of the distance detection signals 2 and 3 is weakened so that the two signals of the distance detection signals 2 and 3 are effective. It is done.

  In the case of pattern 2, that is, when the distance detection signal 3 is valid and the distance detection signals 1 and 2 are too strong, the distance detection signal 2 and 3 are valid so that the distance detection signals 2 and 3 are valid. 2 transmission strength is weakened.

  In the case of pattern 3, that is, when the distance detection signal 2 is valid, the distance detection signal 1 is too strong, and the distance detection signal 3 is too weak, either the distance detection signal 1 or 2 and the distance detection signal The transmission intensity of the distance detection signal 1 is weakened or the transmission intensity of the distance detection signal 3 is increased so that the two signals 2 are effective.

  In the case of the patterns 4 to 6, since two or more distance detection signals are effective, the transmission intensity of the distance detection signal is not adjusted.

  In the case of the pattern 7, that is, when the distance detection signal 1 is valid and the distance detection signals 2 and 3 are too weak, the distance detection signals 1 and 2 are valid so that the two signals are effective. The transmission intensity of 2 is increased.

  In the case of the pattern 8, that is, when the distance detection signals 1 to 3 are all too weak, the transmission strength of the distance detection signals 1 and 2 is increased so that the two signals of the distance detection signals 1 and 2 are effective. It is done.

  Thereafter, the process returns to step S3, and in steps S3 to S9 until it is determined in step S3 that a predetermined time has passed or until it is determined in step S7 that a plurality of distance detection signals are valid. The process is executed repeatedly. That is, the portable device 111 commands the vehicle communication device 112 to adjust the transmission strength of invalid distance detection signals until a plurality of distance detection signals become valid or a predetermined time elapses.

  On the other hand, if it is determined in step S7 that a plurality of distance detection signals are valid, the process proceeds to step S10.

  In step S10, the distance detection unit 127 detects the distance to the vehicle. Specifically, as described above, the distance detection unit 127 holds in advance data (correspondence table) indicating the relationship between the transmission intensity of the distance detection signal and the RSSI value, and the distance to the vehicle. The distance detection unit 127 uses the data based on the transmission strength and RSSI value of each of a plurality of effective distance detection signals received at the same time (for example, between several milliseconds to several seconds). Find the distance to the vehicle. Here, when the vehicle communication device 112 is instructed to change the transmission intensity of any one of the plurality of distance detection signals, the distance detection unit 127 displays data corresponding to the change of the transmission intensity (correspondence table). ) To find the distance to the vehicle. Thus, a plurality of distances to the vehicle are detected based on a plurality of distance detection signals received at the same time.

  Furthermore, the distance detection unit 127 obtains a final detection result of the distance to the vehicle based on the detection results of the distance to the plurality of vehicles. For example, an average value of detection results for all distances may be used as the final detection result. Alternatively, when three detection results are obtained, for example, an intermediate value may be used as the final detection result.

  Then, the distance detection unit 127 supplies the detection result of the distance to the vehicle to the notification unit 128.

  In step S11, the notification unit 128 notifies the detection result by an arbitrary method. For example, the notification unit 128 displays the distance to the vehicle with a numerical value, a scale, or the like, notifies with a voice, or notifies with the color, number of lights, brightness, etc. of the light emitting means.

  Thereafter, the vehicle detection process ends.

  On the other hand, if it is determined in step S3 that the predetermined time has elapsed, that is, if a plurality of effective distance detection signals cannot be received within the predetermined time, the process proceeds to step S12.

  In step S12, the notification unit 128 notifies a detection error. Specifically, the distance detection unit 127 supplies information indicating that the detection of the distance to the vehicle has failed to the notification unit 128. The notification unit 128 notifies the detection error by an arbitrary method, similarly to the case of notifying the detection result of the distance to the vehicle.

  Thereafter, the vehicle detection process ends.

[Distance detection signal transmission processing]
Next, a distance detection signal transmission process executed by the vehicle communication device 112 corresponding to the vehicle detection process of the portable device 111 of FIG. 4 will be described with reference to the flowchart of FIG.

  In step S51, the transmission control unit 132 determines whether transmission of a distance detection signal is requested. This determination process is repeatedly executed at predetermined intervals until it is determined that transmission of a distance detection signal is requested. The transmission control unit 132 determines that the transmission of the distance detection signal is requested when the transmission request signal transmitted from the portable device 111 in step S1 of FIG. Advances to step S52.

  In step S52, the transmission control unit 132 starts a timer.

  In step S53, the transmission unit 133 transmits a distance detection signal. For example, under the control of the transmission control unit 132, the transmission unit 133 transmits the distance detection signals 1 to 3 sequentially at predetermined intervals with a predetermined interval. Note that the transmission strengths of the distance detection signals 1 to 3 at this time are set to predetermined initial values, respectively. Further, the interval for transmitting the distance detection signals 1 to 3 is set to a short time (for example, about several milliseconds to several seconds) such that the signals are not interfered with each other.

  In step S54, the transmission control unit 132 determines whether or not transmission intensity adjustment has been commanded. If the transmission control unit 132 has not received the transmission strength adjustment command from the portable device 111, the transmission control unit 132 determines that the transmission strength adjustment is not commanded, and the process proceeds to step S55.

  In step S55, the transmission control unit 132 determines whether a predetermined time has elapsed since the timer was started. If it is determined that the predetermined time has not yet elapsed, the process returns to step S54.

  Thereafter, the processing of step S54 and step S55 is repeatedly executed until it is determined in step S54 that transmission intensity adjustment has been commanded or until it is determined in step S55 that a predetermined time has elapsed.

  On the other hand, when the transmission control unit 132 receives the transmission intensity adjustment command transmitted from the portable device 111 in step S9 of FIG. 4 via the reception unit 131 in step S54, the transmission control unit 132 determines that the transmission intensity adjustment is instructed. Then, the process proceeds to step S56.

  In step S56, the transmission control unit 132 adjusts the transmission intensity. Specifically, when there is a distance detection signal instructed by the portable device 111 to increase the transmission intensity, the transmission control unit 132 increases the transmission intensity of the signal by a predetermined value from the current value. The transmission unit 133 is set. On the other hand, when there is a distance detection signal instructed by the portable device 111 to weaken the transmission intensity, the transmission control unit 132 transmits the signal to the transmission unit 133 so that the transmission intensity of the signal is decreased from the current value by a predetermined value. Set up.

  Note that the transmission control unit 132 increases or decreases the transmission intensity by a predetermined value when the portable device 111 is instructed to change the transmission intensity. Therefore, the portable device 111 can determine which transmission strength signal the distance detection signal received after instructing to change the transmission strength. In other words, the portable device 111 can grasp in advance that a signal whose transmission intensity has been increased or decreased by a predetermined value will arrive, and data (correspondence table) indicating the RSSI value corresponding to the transmission intensity and the distance to the vehicle. ) Can be used.

  Thereafter, the process returns to step S53, and the processes of steps S53 to S56 are repeatedly executed until it is determined in step S55 that a predetermined time has elapsed. Thereby, the process of adjusting the transmission intensity of the invalid distance detection signal and transmitting each distance detection signal is repeated according to the command from the portable device 111 until a predetermined time elapses.

  On the other hand, if it is determined in step S55 that the predetermined time has elapsed, the process proceeds to step S57.

  In step S57, the transmission control unit 132 resets the transmission intensity. That is, the transmission control unit 132 sets the transmission unit 133 so that the transmission intensity of each distance detection signal becomes an initial value.

  Thereafter, the process returns to step S51, and the processes after step S51 are executed.

  As described above, by adjusting the transmission intensity of the distance detection signal transmitted from the vehicle communication device 112 in accordance with the command from the portable device 111, the distance to the vehicle can be compared with the case where the adjustment is not performed. The detection range can be expanded.

  Further, since it is instructed whether to increase or decrease the transmission intensity based on the reception state at the portable device 111, the transmission intensity of the distance detection signal can be quickly adjusted to an appropriate value, and the user's waiting time Can be shortened.

  Furthermore, since the distance to the vehicle is detected using the distance detection signals having two or more types of transmission strength, the accuracy of detecting the distance to the vehicle is improved.

<2. Second Embodiment>
[Configuration example of car finder system]
FIG. 8 is a block diagram showing a second embodiment of a car finder system to which the present invention is applied. This car finder system 201 allows the transmission intensity of the distance detection signal of the vehicle communication device 212 to be set from the portable device 211.

  In the figure, parts corresponding to those in FIG. 3 are denoted by the same reference numerals, and description of parts having the same processing will be omitted as appropriate because the description will be repeated.

  The car finder system 201 includes a portable device 211 and a vehicle communication device 212.

  The portable device 211 is different from the portable device 111 of FIG. 3 in that a transmission strength command unit 222 is provided instead of the transmission strength command unit 126 and a set strength calculation unit 221 is added.

  The setting intensity calculation unit 221 acquires the RSSI signal for each distance detection signal from the reception intensity detection unit 124. In addition, the setting intensity calculation unit 221 acquires a determination result as to whether or not each distance detection signal is effective from the effective signal determination unit 125. Further, the set strength calculation unit 221 acquires the detection result of the distance to the vehicle from the distance detection unit 127. Then, the setting strength calculation unit 221 calculates a setting value (hereinafter referred to as setting strength) of the transmission strength of the invalid distance detection signal. The setting intensity calculation unit 221 supplies the calculated setting intensity and information indicating the target distance detection signal to the transmission intensity command unit 222.

  The transmission strength command unit 222 sends a command to the vehicle communication device 212 via the transmission unit 122 to set the transmission strength of the invalid distance detection signal to the setting strength obtained by the setting strength calculation unit 221. Send. Further, the transmission intensity command unit 222 supplies the content of the command transmitted to the vehicle communication device 212 to the distance detection unit 127.

  The vehicle communication device 212 is different from the vehicle communication device 112 in FIG. 3 in that a transmission control unit 231 is provided instead of the transmission control unit 132.

  The transmission control unit 231 controls the transmission timing of the distance detection signal from the transmission unit 133 based on a command from the portable device 211 or sets the transmission strength to the set strength commanded from the portable device 211. To do.

[Vehicle detection processing]
Next, a vehicle detection process executed by the portable device 211 will be described with reference to a flowchart of FIG.

  The vehicle detection process in FIG. 9 differs from the vehicle detection process in FIG. 4 in the processes in step S108 and step S109.

  Specifically, in step S108, the portable device 211 calculates the set strength of the invalid distance detection signal. The process of step S108 is performed when it is determined in step S107 that a plurality of distance detection signals are not valid, that is, when the number of effective distance detection signals is one or zero.

  Therefore, when there is one effective distance detection signal, the distance detection unit 127 calculates the distance to the vehicle based on the RSSI value of the distance detection signal, and calculates information indicating the calculated distance as a set strength calculation. To the unit 221.

  If the distance to the vehicle is known, it is possible to estimate how much the transmission strength of the invalid distance detection signal is set and the reception strength is within the effective range. Therefore, the set intensity calculation unit 221 is assumed that the reception intensity falls within the effective range based on the distance to the vehicle obtained by the distance detection unit 127 for at least one of the invalid distance detection signals. The transmission strength is calculated as the set strength. Then, the set strength calculating unit 221 supplies the calculated set strength and information indicating the target distance detection signal to the transmission strength command unit 222.

  In addition, even when there is no effective distance detection signal, if all the distance detection signal reception strengths are too strong (in the case of pattern 1 in FIG. 6), the distance to the vehicle may be within a predetermined range. I understand. Therefore, the setting strength calculation unit 221 calculates, as the setting strength, the transmission strength that is estimated that the reception strength falls within the effective range for at least two of the invalid distance detection signals. Then, the set strength calculating unit 221 supplies the calculated set strength and information indicating the target distance detection signal to the transmission strength command unit 222.

  On the other hand, when all the reception strengths of the distance detection signals are too weak (in the case of pattern 8 in FIG. 6), it can be seen that the distance to the vehicle exceeds the predetermined range, but it is unclear how much it exceeds. . Accordingly, the set strength calculation unit 221 calculates a value obtained by adding a predetermined value from the current transmission strength for each distance detection signal. Then, the set strength calculating unit 221 supplies the calculated set strength and information indicating the target distance detection signal to the transmission strength command unit 222.

  In step S109, the transmission intensity command unit 222 transmits a transmission intensity adjustment command for instructing adjustment of the transmission intensity of the invalid distance detection signal via the transmission unit 122, to the vehicle communication device 212. Command adjustment of invalid distance detection signal. The transmission intensity adjustment command includes, for example, a distance detection signal to be adjusted and information indicating the set intensity of the signal.

  Further, the transmission intensity command unit 222 notifies the distance detection unit 127 of the content of the transmission intensity adjustment command transmitted to the vehicle communication device 212. Thereby, the distance detection part 127 can grasp | ascertain the transmission intensity | strength of each signal for distance detection after adjustment.

  Then, the portable device 211 instructs the vehicle communication device 212 to set the transmission strength of the invalid distance detection signal to the set strength until a plurality of distance detection signals become valid or a predetermined time elapses. Is done.

[Distance detection signal transmission processing]
Next, a distance detection signal transmission process executed by the vehicle communication device 212 corresponding to the vehicle detection process of the portable device 211 of FIG. 9 will be described with reference to the flowchart of FIG.

  The distance detection signal transmission process of FIG. 10 differs from the distance detection signal transmission process of FIG. 7 in the process of step S156.

  Specifically, in step S156, the transmission control unit 231 sets the transmission intensity to the commanded value. That is, based on the transmission intensity adjustment command received from the portable device 211, the transmission control unit 231 transmits the transmission unit so that the transmission intensity of the distance detection signal to be adjusted becomes the set intensity commanded from the portable device 211. 133 is set.

  Then, until a predetermined time elapses, in accordance with a command from the portable device 211, the transmission strength of the invalid distance detection signal is set to the commanded set strength, and the process of transmitting each distance detection signal is repeated.

  As described above, in the car finder system 201, compared with the car finder system 101, the transmission intensity adjustment time can be shortened and the waiting time of the user can be shortened.

<3. Third Embodiment>
[Configuration example of car finder system]
FIG. 11 is a block diagram showing a third embodiment of a car finder system to which the present invention is applied. The car finder system 201 notifies the vehicle communication device 312 of the reception state of the distance detection signal from the portable device 311 and the vehicle communication device 312 sets the transmission strength of the distance detection signal based on the reception state. It is what you want to do.

  In the figure, parts corresponding to those in FIG. 3 are denoted by the same reference numerals, and description of parts having the same processing will be omitted as appropriate because the description will be repeated.

  The car finder system 301 includes a portable device 311 and a vehicle communication device 312.

  The portable device 311 is different from the portable device 111 of FIG. 3 in that the reception state notification unit 321 is added and the transmission intensity command unit 126 is deleted.

  The reception state notifying unit 321 acquires an RSSI signal for each distance detection signal from the reception intensity detection unit 124. In addition, the reception state notification unit 321 acquires a determination result as to whether or not each distance detection signal is valid from the valid signal determination unit 125. The reception state notification unit 321 notifies the vehicle communication device 312 of the reception state of the distance detection signal via the transmission unit 122.

  The vehicle communication device 312 is different from the vehicle communication device 112 of FIG. 3 in that a transmission control unit 331 is provided instead of the transmission control unit 132.

  The transmission control unit 331 controls the transmission timing of the distance detection signal from the transmission unit 133 based on a command from the portable device 311 or the distance detection signal based on the reception state notified from the portable device 311. Adjust the signal transmission strength.

[Vehicle detection processing]
Next, a vehicle detection process executed by the portable device 311 will be described with reference to the flowchart of FIG.

  The vehicle detection process of FIG. 12 differs from the vehicle detection process of FIG. 4 in the process of step S208.

  Specifically, in step S208, the reception state notification unit 321 notifies the vehicle communication device 312 of the reception state of the distance detection signal by transmitting a reception state notification signal via the transmission unit 122. The reception state notification signal includes, for example, information indicating whether the reception intensity of each distance detection signal is appropriate (within an effective range), strong, or weak.

  Then, the reception state of the distance detection signal is notified from the portable device 311 to the vehicle communication device 312 until a plurality of distance detection signals become effective or a predetermined time elapses.

[Distance detection signal transmission processing]
Next, a distance detection signal transmission process executed by the vehicle communication device 312 corresponding to the vehicle detection process of the portable device 311 of FIG. 12 will be described with reference to the flowchart of FIG.

  The distance detection signal transmission process of FIG. 13 differs from the distance detection signal transmission process of FIG. 7 in the process of step S256.

  Specifically, in step S256, the transmission control unit 331 adjusts the transmission strength based on the reception state of the portable device 311. For example, when there is a distance detection signal that is notified that the transmission intensity is too strong, the transmission control unit 331 sets the transmission unit 133 so that the transmission intensity of the signal is decreased from the current value by a predetermined value. . On the other hand, when there is a distance detection signal notified that the transmission strength is too weak, the transmission control unit 331 sets the transmission unit 133 to increase the transmission strength of the signal by a predetermined value from the current value. .

  Then, when the reception state of the portable device 311 is notified until a predetermined time elapses, the transmission intensity of the invalid distance detection signal is adjusted based on the reception state, and each distance detection signal is transmitted. This process is repeated.

  In this case, it is desirable to include information indicating the transmission intensity in each distance detection signal.

  As described above, in the car finder system 301, the processing of the portable device 311 can be lightened compared to the car finder system 101 and the car finder system 201.

<4. Modification>
Hereinafter, modifications of the embodiment of the present invention will be described.

  In the above description, an example using three types of distance detection signals with different transmission intensities has been shown, but two types or four or more types of distance detection signals may be used.

  In the above description, an example in which the distance to the vehicle is detected based on the reception strength of two or more types of effective distance detection signals has been described. The distance to the vehicle may be detected based on the reception strength of the effective distance detection signal.

  Furthermore, for example, even when the number of effective distance detection signals is less than a predetermined number, if one or more effective distance detection signals exist when a time-out occurs in step S3 in FIG. Based on this, the distance to the vehicle may be detected.

  Further, for example, in the car finder system 301, the actual reception intensity may be included in the reception state notified from the portable device 311 to the vehicle communication device 312. Then, in the vehicle communication device 312, based on the reception strength of the effective distance detection signal, the transmission strength may be calculated and set so that the reception strength of the invalid distance detection signal falls within the effective range. Good. As a result, the transmission intensity of the detection signal can be adjusted to an appropriate value more quickly.

  In this specification, the system means a set of a plurality of components (devices, modules (parts), etc.), and it does not matter whether all the components are in the same housing. Accordingly, a plurality of devices housed in separate housings and connected via a network and a single device housing a plurality of modules in one housing are all systems. .

  The embodiments of the present invention are not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 101 Car finder system 111 Portable machine 112 Vehicle communication apparatus 122 Transmission part 123 Reception part 124 Reception intensity detection part 125 Effective signal determination part 126 Transmission intensity command part 127 Distance detection part 131 Reception part 132 Transmission control part 133 Transmission part 201 Car finder System 211 Mobile device 212 Vehicle communication device 221 Setting strength calculation unit 222 Transmission strength command unit 231 Transmission control unit 301 Car finder system 311 Mobile device 312 Vehicle communication device 321 Reception state notification unit 331 Transmission control unit

Claims (14)

In a vehicle detection device that performs wireless communication with a communication device provided in a vehicle and detects a distance to the vehicle,
A detection unit for detecting a distance to the vehicle, wherein the reception unit receives a plurality of detection signals having different transmission intensities from the communication device;
A reception intensity detector that detects the reception intensity of each of the detection signals;
An effective signal determination unit that determines whether or not the reception intensity detected by the reception intensity detection unit is within a predetermined effective range;
A transmission intensity command unit that instructs the communication apparatus to adjust the transmission intensity of the detection signal whose reception intensity is outside the effective range;
A vehicle detection apparatus comprising: a distance detection unit that detects a distance to the vehicle based on reception intensity of two or more predetermined number of detection signals whose reception intensity is within the effective range. . The distance detection unit is configured to detect the distance to the vehicle based on the reception intensity of the detection signals that are equal to or more than a predetermined number of reception strengths within the effective range in the detection signals received at the same time. The vehicle detection device according to claim 1, wherein: The vehicle detection device according to claim 1, wherein the transmission intensity command unit instructs the transmission intensity of the detection signal whose reception intensity is outside the effective range to be increased or decreased. A setting strength for calculating a setting value of the transmission strength of the detection signal whose reception intensity is outside the effective range, based on the distance to the vehicle whose reception intensity is calculated based on the detection signal within the effective range A calculation unit,
The vehicle detection device according to claim 1, wherein the command unit instructs the transmission intensity of the detection signal whose reception intensity is outside the effective range to be set to the set value. The transmission strength command unit commands the adjustment of the transmission strength of the detection signal whose reception strength is outside the effective range when the detection signal within the effective range is less than the predetermined number. The vehicle detection device according to claim 1, wherein the vehicle detection device is a vehicle detection device. In a vehicle detection system including a communication device provided in a vehicle, and a vehicle detection device that performs wireless communication with the communication device and detects a distance to the vehicle,
The communication device
A transmission unit that detects a distance to the vehicle and transmits a plurality of detection signals having different transmission intensities to the vehicle detection device;
A first receiving unit for receiving a command from the vehicle detection device;
A transmission control unit that adjusts the transmission intensity of each detection signal based on a command from the vehicle detection device;
The vehicle detection device includes:
A second receiving unit for receiving each detection signal;
A reception intensity detector that detects the reception intensity of each of the detection signals;
An effective signal determination unit that determines whether or not the reception intensity detected by the reception intensity detection unit is within a predetermined effective range;
A transmission intensity command unit that instructs the communication apparatus to adjust the transmission intensity of the detection signal whose reception intensity is outside the effective range;
A vehicle detection system comprising: a distance detection unit that detects a distance to the vehicle based on reception intensity of two or more predetermined number of detection signals whose reception intensity is within the effective range. . In a vehicle detection device that performs wireless communication with a communication device provided in a vehicle and detects a distance to the vehicle,
A detection unit for detecting a distance to the vehicle, wherein the reception unit receives a plurality of detection signals having different transmission intensities from the communication device;
A reception intensity detector that detects the reception intensity of each of the detection signals;
An effective signal determination unit that determines whether or not the reception intensity detected by the reception intensity detection unit is within a predetermined effective range;
A reception state notification unit for notifying the communication device of the reception state of each detection signal;
A vehicle detection apparatus comprising: a distance detection unit that detects a distance to the vehicle based on reception intensity of two or more predetermined number of detection signals whose reception intensity is within the effective range. . The vehicle detection device according to claim 7, wherein the reception state includes information indicating whether a reception intensity of each detection signal is within the effective range, strong, or weak. The vehicle detection device according to claim 8, wherein the reception state further includes reception intensity of each of the detection signals. 10. The reception state notifying unit notifies the reception state of the detection signal when the detection intensity within the effective range is less than the predetermined number. The vehicle detection device according to any one of the above. In a communication device that is provided in a vehicle and performs wireless communication with a vehicle detection device that detects a distance to the vehicle,
A transmission unit that detects a distance to the vehicle and transmits a plurality of detection signals having different transmission intensities to the vehicle detection device;
A receiving unit for receiving a notification of a reception state of each detection signal in the vehicle detection device from the vehicle detection device;
A communication apparatus comprising: a transmission control unit that adjusts transmission intensity of each detection signal based on a reception state of each detection signal. The reception state includes information indicating whether the reception intensity of each detection signal is within a predetermined effective range, strong, or weak,
The communication apparatus according to claim 11, wherein the transmission control unit lowers the transmission intensity of the detection signal having a high reception intensity and increases the transmission intensity of the detection signal having a low reception intensity. The reception state further includes reception intensity of each of the detection signals,
The transmission control unit sets the transmission strength of a detection signal whose reception strength is outside the effective range based on the reception strength of the detection signal whose reception strength is within the effective range. 12. The communication device according to 12. In a vehicle detection system including a communication device provided in a vehicle, and a vehicle detection device that performs wireless communication with the communication device and detects a distance to the vehicle,
The communication device
A transmission unit that detects a distance to the vehicle and transmits a plurality of detection signals having different transmission intensities to the vehicle detection device;
A first receiving unit that receives a notification of a reception state of each detection signal in the vehicle detection device from the vehicle detection device;
A transmission control unit that adjusts the transmission intensity of the detection signal based on the reception state of the detection signal;
The vehicle detection device includes:
A second receiving unit for receiving each detection signal;
A reception intensity detector that detects the reception intensity of each of the detection signals;
An effective signal determination unit that determines whether or not the reception intensity detected by the reception intensity detection unit is within a predetermined effective range;
A reception state notification unit for notifying the communication device of the reception state of each detection signal;
A vehicle detection system comprising: a distance detection unit that detects a distance to the vehicle based on reception intensity of two or more predetermined number of detection signals whose reception intensity is within the effective range. .

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