JP2007329786A - Portable device and radio apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem that a processing time for detecting an area with a good accuracy is long. <P>SOLUTION: A portable device includes either the first code signal or the second code signal in a request signal, and an invalidating means 29 which invalidates results of a determination means 28 in a control circuit 21. When it is determined by the determining means 28 that the control circuit 21 includes the first code signal, the request signal is made valid. When it is determined by the determination means that the control circuit 21 includes the second code signal, a correction detecting voltage is calculated from a detection voltage for the request signal input from antennas 23 and 24. When the value of the correction detecting voltage is equal to or less than a predetermined threshold, the invalidating means has a function of invalidating the results of the determination means. In case of the first request signal, the signal is determined to be valid, and only in case of the second request signal, the correction detecting voltage is calculated. Therefore, the processing time can be reduced, and an area can be determined with a good accuracy. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a portable device that performs area detection in a keyless entry device for a vehicle, for example, and a wireless device using the portable device.

  Hereinafter, when the portable device receives a request signal from the base station, the conventional wireless device has a detector that detects the received signal level of the request signal, and returns the received signal level information to the base station. The base station side determines the position of the portable device according to the received signal level information.

As prior art document information related to the invention of this application, for example, Patent Document 1 is known.
JP 2002-77972 A

  However, in such a conventional wireless device, the portable device always measures the reception level when receiving the request signal and transmits the reception signal information to the base station. Therefore, even when area detection is not required, the measurement of the reception level and the reception level information There is a problem that an extra processing time is required for transmitting the message, and the time until the communication is established becomes longer.

  Accordingly, the present invention has been made to solve this problem, and an object of the present invention is to provide a radio apparatus having an area detection function and shortening the processing time when the area detection is unnecessary.

  In order to achieve this object, the radio apparatus of the present invention includes a request signal that includes either the first code signal or the second code signal, and the control circuit invalidates the result of the determination means. And the control circuit determines that the request signal is valid and the determination means includes the second code signal when the determination means determines that the first code signal is included. In this case, when the correction detection voltage is calculated from the detection voltages for the request signals input from all the antennas, and the value of the correction detection voltage is equal to or less than a predetermined threshold value, the invalid means is the determination means. This has the function of invalidating the result of the above, and thereby the intended purpose can be achieved.

  As described above, according to the present invention, a portable device to which a request signal transmitted from a base station is input, the portable device includes a plurality of antennas provided in different directions, and these antennas. A receiver to which an antenna is connected, and an output of the receiver, and a control circuit for controlling the receiver, the receiver demodulating a request signal; and Level detection means for detecting the signal level of the request signal for each antenna and generating a detection voltage, and determination means provided in the control circuit and for determining a signal from the receiver, In a portable device in which a control circuit controls the switching unit according to the request signal and the detected voltage, any one of the request signals input to the plurality of antennas is selectively controlled. A switching means for supplying to the circuit and an invalid means provided in the control means and invalidating the result of the determination means are provided, and either one of the first code signal and the second code signal is provided in the request signal The control circuit determines that the request signal is valid when the determination means determines that the first code signal is included, and determines that the determination means includes the second code signal. If the correction detection voltage is calculated from the detection voltages for the request signals input from all antennas, and the value of the correction detection voltage is equal to or less than a predetermined threshold value, the invalidation means This is a portable device that invalidates the result of the determination means.

  As a result, when the request signal includes the first code signal, it is determined to be valid, and the correction detection voltage is calculated only when the request signal includes the second code signal, thereby shortening the processing time. There is an effect that can be.

  In the case of the second request signal, the corrected detection voltage is calculated from the detection voltages for the request signals input from all the antennas. Therefore, when the area is determined using the request signal, the determination can be made with high accuracy. . Furthermore, stable area determination is possible regardless of the attitude of the portable device.

  Embodiments of the present invention will be described below.

(Embodiment 1)
FIG. 1 is a block configuration diagram of a radio apparatus according to the first embodiment.

  In FIG. 1, the radio apparatus includes a base station 10 and a portable device 20. The base station 10 is connected to the control circuit 11, a transmitter 12 connected to the control circuit 11, and the transmitter 12. When the communication with the portable device 20 is performed, the base station 10 outputs the AM-modulated request signal in the 125 kHz band from the transmission antenna 13.

  On the other hand, the portable device 20 includes a control circuit 21, a receiver 22 connected to the control circuit 21, a reception antenna 23 and a reception antenna 24 connected to the receiver 22. In addition, although it demonstrates using two antennas for convenience of explanation here, you may use three or more antennas actually.

  The request signal transmitted from the transmission antenna 13 is received by the reception antennas 23 and 24. The reception antennas 23 and 24 are formed of loop coils, and when the request signal is received, an induced voltage is generated according to the received electric field strength. Generated and input to the receiver 22. The receiving antennas 23 and 24 have different directivities by being arranged in different directions. For example, when the receiving antennas 23 and 24 are arranged so as to be orthogonal to each other as shown in FIG. The induced voltage at the receiving antenna 23 in the direction is high, and the induced voltage at the orthogonal receiving antenna 24 is low. However, when the portable device 20 is rotated at the same position, the induced voltage at the receiving antenna 23 decreases, and the induced antenna 24 is induced. The voltage rises. Further, the receiver 22 can select one of the receiving antennas 23 and 24 by the switching means 27 and can select which signal of the receiving antennas 23 and 24 is input by a signal from the control circuit 21. In addition, the induced voltage increases as the distance between the transmitting antenna 13 and the receiving antennas 23 and 24 decreases.

  In the receiver 22, the AM-modulated signal is demodulated into a digital signal by the demodulating means 25 and transmitted to the control circuit 21. At the same time, the level of the received signal is measured by the level detecting means 26, and the received signal strength display voltage (Received Signal) Strength Indicator (hereinafter referred to as RSSI voltage, which is used as an example of the detection voltage) and transmitted to the control circuit 21.

  In the control circuit 21, the received digital signal and RSSI voltage are determined by the determination unit 28. At this time, the digital signal is converted to a 1/0 bit data string and matched with the determined data string, and the RSSI voltage is digitized using an AD converter, and the numeric value is determined to be a threshold value. If the determination result is invalid, the invalidation means 29 invalidates the received data.

  The portable device 20 uses the transmitter 30 connected to the control circuit 21 and the transmission antenna 31 connected to the transmitter 30 to transmit the determination result using a radio wave in the 300 MHz band, and the base station 10 The determination result is received using the receiver 14 connected to the receiver 14 and the receiving antenna 15 connected to the receiver 14, and the subsequent control is changed according to the result. Here, when the determination result is invalid, the portable device 20 does not transmit the determination result, and since the base station 10 cannot receive the determination result, it may be determined that the determination is invalid.

  Next, the determination operation of the portable device 20 will be specifically described with reference to FIGS.

  FIG. 2 shows an induced voltage waveform at the time of receiving a request signal and a demodulated digital signal waveform in the present embodiment, and FIG. 3 is a processing flowchart of the determination means in the present embodiment.

  In FIG. 2, 40, 42, 44, and 46 are induced voltage waveforms when a request signal is received, and 41, 43, 45, and 47 indicate demodulated digital signal waveforms. In addition, 40 and 41 are first request signals, 42 and 43 are valid second request signals, 44 and 45 are invalid second request signals, and 46 and 47 are second signals in a noise environment. Indicates a request signal. Here, the second request signal is a request signal for recognizing that the portable device 20 is within a certain area, and the first request signal is specified by the portable device 20 by the second request signal. This is a request signal for recognizing that it is outside the area. In the present embodiment, the first request signal is transmitted at a level larger than that of the second request signal, and the first request signal can be determined even at a position far from the transmission antenna 13. The transmitter alternately outputs the first and second request signals at predetermined time (T) intervals.

  In this embodiment, the areas are divided by changing the levels of the first and second request signals. However, this may be done by changing the frequencies. In other words, the fact that the reach of the signal differs depending on the frequency is used.

  When the portable device 20 receives the request signal, first, the receiver 22 starts operating during the burst signal period 50. Here, the AGC circuit is included in the receiver 22, and the receiver 22 switches between the antenna 23 and the antenna 24 by the switching means 27 during the burst signal period 50, detects the respective AGC voltages, and detects this AGC. Although the antenna having the better sensitivity according to the voltage is selected, the processing speed is increased by omitting processing such as RSSI voltage measurement and calculation of a plurality of antennas. The receiver 22 converts the first half 51 of the request signal, which is the first half of the request signal input following the burst signal, into a 1/0 bit data string. In this embodiment, a short pulse (for example, 150 μs or less) is determined as bit 0, and a long pulse (for example, 150 μs or more) is determined as bit 1. The determination means 28 determines whether or not the bit string after conversion is 0010. If so, the process proceeds to the next determination process, and otherwise determines that the request signal is invalid (60).

  Next, the determination means 28 determines the bit string of the latter half 52 or 53 of the request signal. When the bit string is 010 (010 is used as an example of the first code signal), it is determined that the request signal is the first request signal.

  Here, the determination means 28 checks a flag to be described later, and determines whether or not the second request signal is determined within a time (T) before the determination of the first request signal and before the determination time. Check. When the flag is detected, it is determined that the first request signal is invalid. On the other hand, if the determination means does not detect the flag, it is determined that the request signal is valid (61). Thereby, it can be determined that the portable device 20 is outside the area specified by the second request signal.

  Next, when the bit string of the second half of the request signal 52 or 53 is not 010, the determination unit 28 uses the bit string of the second half 52 or 53 of the request signal as 001 (001 is an example of the second code signal). If so, it is determined that the request signal is the second request signal, and the process proceeds to the next determination process. Otherwise, it is determined that the request signal is invalid (62). When the determination unit 28 determines the second request signal, a flag indicating that the second request signal has been determined is set. This flag is maintained for a time (T). When this time (T) elapses, the flag is reset. With such a configuration, it is possible to perform area determination with one transmission antenna 13.

  When it is determined that the request signal is the second request signal, the control circuit 21 uses the switching unit 27 to sequentially switch the receiving antenna connected to the level detection unit 26 and during the burst signal period 54 or 55. The RSSI voltage of the receiving antennas 23 and 24 is measured (63).

  Thereafter, the determination unit 28 performs arithmetic processing on the RSSI voltage of the receiving antenna 23 and the RSSI voltage of the receiving antenna 24 to calculate a corrected RSSI voltage (used as an example of a corrected detection voltage) (64).

  As a calculation method at this time, for example, a method of performing vector calculation, a method of using the maximum value of each antenna as a corrected RSSI voltage, a method of correcting the maximum value by a ratio of the maximum value of each antenna to other values, and the like can be considered.

  Thereafter, the determination means 28 determines whether or not the calculated corrected RSSI voltage is equal to or higher than a certain threshold value (65). If the calculated correction RSSI voltage is equal to or higher than the threshold value, the request signal is valid (66). The signal becomes invalid (67).

  As described above, the validity / invalidity determination of the request signal is corrected by using the RSSI voltages from a plurality of antennas so that the sensitivity of the antenna is substantially constant with respect to the distance from the portable device (or the transmission antenna 13). The position (area) determination can be accurately measured regardless of the attitude of the portable device.

  Here, in order to obtain the corrected RSSI voltage, the time for stabilizing the transmission level detecting means 26, the time for reading with the AD converter of the determining means 28, and the processing time for calculating the corrected RSSI voltage are 10 ms or more in total. Time is required, and the response during communication decreases. Therefore, in the present embodiment, when the position determination is unnecessary, the processing time can be shortened by transmitting the first request signal.

  Further, as shown in 46 and 47 of FIG. 2, the second request signal includes a corrected RSSI voltage threshold value information 56 as a part thereof, and the determination unit 28 determines the threshold information 56 according to the value of the threshold information 56. By changing the determination threshold value of the corrected RSSI voltage, the communication area between the base station and the portable device can be adjusted from the base station side.

  Further, in a noisy environment, the induced voltage waveform received by the receiving antenna 23 may be buried in noise and cause a communication error. However, the base station side has a function of changing the level of the transmission signal, and the signal level Accordingly, by changing the threshold value information included in a part of the request signal, for example, when the first time is transmitted at the level of the request signal 44 and the determination result cannot be received, as shown in the second request signal 46, By raising the threshold level at the same time as raising the signal level, the communication area can be kept constant even if the transmission power is changed, so it is usually possible to communicate with less power and increase the power only in a noisy environment. Has the effect of reducing power consumption.

  Furthermore, in the present embodiment, the correction of the antenna sensitivity is corrected using the RSSI voltage, but this may be performed using the AGC voltage output from the AGC circuit of the receiver 22.

  Furthermore, although the antenna 23 and the antenna 24 are used in this embodiment, they may be provided in three orthogonal directions. As a result, area detection can be performed with higher accuracy, and stable area detection can be performed regardless of the attitude of the portable device.

(Embodiment 2)
FIG. 4 is a conceptual diagram of the area detection apparatus according to the second embodiment.

  In FIG. 4, reference numeral 70 denotes a base station having the same meaning as 10, and includes a first transmission antenna 71 and a second transmission antenna 72 having the same meaning as 13. Reference numeral 73 denotes a room where area detection is desired, such as the interior of an automobile, and is an area where communication is performed by the second transmission antenna 72. The first transmitting antenna 71 is attached to the door 74, and its communication area is 75.

  Although it is desirable that the first transmitting antenna 71 can communicate only outdoors, when it is attached to the door 74, a communication area is formed in the room due to radio wave leakage, and it is difficult to clearly define the area. On the other hand, the area where the second transmitting antenna 72 communicates is arranged in the center of the room, for example, so that only the room can communicate.

  In FIG. 4, 80 is a portable device having the same meaning as 20, and the receiving antennas 81 and 82 are arranged so as to be orthogonal to each other. Here, the receiving antenna 81 is provided to receive a magnetic field from the X direction shown in the figure (shown in FIG. 4), and the directivity has a shape like a dotted line 83, for example. As an index indicating directivity, in FIG. 4, when the output level of the transmission antenna is kept constant and the portable device is rotated 360 °, the transmission antenna when a constant induced voltage (for example, 10 mV) is induced in the reception antenna. When the loop antenna is used, the distance between the mobile device and the portable device is approximately eight. The receiving antenna 82 is provided to receive a magnetic field from the Y direction shown in FIG. 4 (shown in FIG. 4), and the directivity is, for example, a dashed-dotted line 84, which complements the directivity of the receiving antenna 81. It comes to meet each other.

  When a communication area is formed by the portable device 80 having such directivity and the transmission antennas 71 and 72, a position where the transmission antenna and the reception antenna are opposed or orthogonal to each other, and a position having an inclination of 45 ° In this embodiment, the communication area differs depending on the angle of the portable device, but in this embodiment, the RSSI voltage of the receiving antenna 81 and the receiving antenna 82 is vector-calculated to obtain a corrected RSSI voltage, and the value is constant. Since it is determined whether or not the threshold value is exceeded, for example, the calculation method of the corrected RSSI voltage is a square root of (the square of the receiving antenna 81 + the square of the receiving antenna 82), and as indicated by a solid line 85, By correcting the directivity so that the reception sensitivity with respect to the distance is substantially constant or the maximum communication distance between the transmission antenna and the portable device is substantially constant, It can reduce the fluctuation of the communication area at the time when the angle of the machine has changed.

  Regarding the calculation method and threshold value of vector calculation and correction RSSI, for example, assuming an inclination of 45 °, when the induced voltage of the receiving antenna 81 is 10 mV and the induced voltage of the antenna 82 is 10 mV, (the square of 10 + 10 From the square root of (square) = 14.1 mV, a method of setting the threshold to 14.1 mV or higher is conceivable.

  Also, if the antenna directivity is different, the ratio of the induced voltage of the antenna from which the maximum induced voltage was obtained and the induced voltage of the other antenna is obtained, and the coefficient up to a maximum of 1.4 times is calculated as the induced voltage. A calculation method of multiplying the maximum value of can also be considered.

  Further, in this embodiment, since the correction RSSI is not performed when the first request signal is transmitted, in order to detect whether the portable device 76 is in the room 73, the second request signal is transmitted from the transmission antenna 72. By transmitting, errors in the communication area are reduced, and erroneous transmission of portable devices outside the room can be prevented. Furthermore, by communicating with the portable device 76 in the room 73 first using the second request signal, and then transmitting the first request signal from the transmission antenna 71 and communicating with the portable device 77 in the outdoor room. Whether or not the portable device is in the room 73 can be classified, and when the first request signal is transmitted, the processing time for calculating the corrected RSSI voltage is not required. In use such as locking / unlocking, there is an effect that the operation response becomes faster.

  Furthermore, since the directivity when communicating using the first request signal is larger than the directivity 85 when using the corrected RSSI, as shown by 83 and 84, the communication area is not clearly defined, When it is desired to communicate with a farther mobile device, there is an effect that the possibility of communication is increased.

  Further, in FIG. 4, assuming that there is a noise source in the room 73 and the transmitting antenna 72 and the indoor portable device 76 communicate with each other, the threshold of the corrected RSSI voltage is included in a part of the second request signal. It is configured to include value information, the first time is transmitted with less power, and the threshold information of the corrected RSSI voltage is decreased at the same time, and the second time the transmission power is increased and the threshold information of the corrected RSSI voltage is increased. Thus, while keeping the communication area constant, it is possible to use such that noise is transmitted with high power and the S / N ratio is improved.

  In addition, the first request signal is transmitted with low power at the first time, and the second request signal with the threshold value of the corrected RSSI voltage increased at the same time as increasing the transmission power at the second time, Communication at the time is performed at high speed, and it is also possible to use high power only when noise countermeasures are taken.

  The portable device according to the present invention and the wireless device using the portable device have an effect that the area determination can be quickly and accurately determined, and are useful when used for a vehicle keyless entry device or the like.

Configuration diagram of radio apparatus according to Embodiment 1 of the present invention Schematic diagram of request signal Same as above, processing flowchart of the determination means Configuration diagram of area detection apparatus according to Embodiment 2 of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Base station 20 Portable machine 21 Control circuit 22 Receiver 23 Antenna 24 Antenna 25 Demodulation means 26 Level detection means 27 Switching means 28 Judgment means 29 Invalidation means

Claims (8)

A portable device to which a request signal transmitted from a base station is input. The portable device includes a plurality of antennas provided in different directions, a receiver to which these antennas are connected, and An output of the receiver is connected, and a control circuit for controlling the receiver is provided. The receiver has a demodulating unit for demodulating the request signal, and the request signal for the respective antennas. Signal level detection means for detecting a signal level and generating a detection voltage; and determination means provided in the control circuit and determining a signal from the receiver, wherein the control circuit includes the request signal and the detection In a portable device that controls the switching means according to a voltage, a switch for selectively supplying any one of request signals inputted to the plurality of antennas to the control circuit. A changing means, and an invalid means that is provided in the control means and invalidates the result of the determination means, and is a signal that includes one of the first code signal and the second code signal in the request signal, The control circuit validates the request signal when it is determined by the determination means to include the first code signal, and all when the determination means determines that the second code signal is included. When the correction detection voltage is calculated from the detection voltage with respect to the request signal input from the antenna, and the value of the correction detection voltage is not more than a predetermined threshold value, the invalidation means invalidates the result of the determination means Portable machine. The threshold value information of the corrected detection voltage is included in a part of the request signal from the base station, and the portable unit invalidates the result of the determination unit based on the threshold information. Portable machine. The mobile device according to claim 2, wherein the base station has a function of changing a level of a signal to be transmitted, and changes threshold information included in a part of the request signal according to the level of the signal. . The portable device according to claim 1, wherein the corrected detection voltage is calculated by vector synthesis of detection voltages for request signals input from all antennas. In a portable device that receives a request signal from a transmission antenna of a base station and transmits a response signal corresponding to the request signal when it is determined that the request signal includes the first code signal, the portable device includes: When it is determined that the request signal includes the second code signal, the reception sensitivity of the request signal is corrected to be substantially constant with respect to the distance from the portable device regardless of the posture of the portable device, A portable device that transmits a response signal corresponding to the request signal when the corrected reception sensitivity is equal to or higher than a predetermined value. A portable device that receives a request signal including a first or second code signal generated by a base station, and the portable device receives the first code without receiving the second code signal; In the portable device that determines that the portable device is in the first area and determines that the portable device is in the second area when the second code is received, the portable device is: When it is determined that the second code signal is included in the request signal, the reception sensitivity of the request signal is corrected as much as possible with respect to the distance from the portable device regardless of the posture of the portable device. A portable device that determines that it is in the second area when the corrected reception sensitivity is equal to or higher than a predetermined value. A base station that generates a request signal including the first or second code signal, a first antenna that transmits the first code signal, and a predetermined distance from the first antenna are arranged. A second antenna that transmits the second code signal; and a portable device that receives the request signal transmitted from these antennas and transmits a response signal corresponding to the request signal to the base station; The base station determines that the portable device is in the first area when there is a response to the response signal by transmitting the first code, and transmits the second code. In the area determination device that determines that the portable device is in the second area when the response signal is received by the portable device, the portable device determines that the second code signal is included in the request signal If The signal reception sensitivity is corrected so that the maximum communication distance from the second antenna to the portable device is substantially constant regardless of the direction of the portable device, and the corrected reception sensitivity is equal to or greater than a predetermined value. In some cases, a wireless device that transmits a response signal corresponding to the request signal. A base station that generates a request signal including the first or second code signal, an antenna that transmits the request signal, the request signal transmitted from the antenna, and the base station according to the request signal The base station transmits the second code signal, and transmits the first code signal after elapse of a predetermined time after transmission of the second code signal. When the response signal is transmitted during the predetermined time, it is determined that the portable device is in the first area, and the response signal is transmitted by transmitting the first code. If the portable device determines that the second code signal is included in the request signal, the wireless device determines that the portable device is in the second area. Request signal reception sensitivity Correction is made to be substantially constant with respect to the distance from the transmission antenna regardless of the direction of the portable device, and when the corrected reception sensitivity is equal to or less than a predetermined value, the second code signal is invalidated. Wireless device to do.

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