JP2006205838A - In-vehicle receiver - Google Patents

Abstract

Even if different modulation schemes coexist, it is possible to demodulate with one receiver.
A radio signal transmitted from an RKE portable device 11 by either one of the ASK or FSK modulation schemes and a radio signal transmitted from the TPMS transceivers 12A to 12D by either one of the modulation schemes are received. The ASK demodulator 31 and the ASK demodulator 31 are connected in parallel to the shared antenna unit 24, the ASK demodulator 31 that demodulates the signal received by the shared antenna unit 24 according to the ASK method, and determines whether the header of the demodulated data is valid. The FSK demodulator 32 that demodulates the signal received by the shared antenna unit 24 according to the FSK system and determines whether the header portion of the demodulated data is valid, and is valid by the ASK demodulator 31 or the FSK demodulator 32 And an output unit 33 that outputs one of the demodulated data determined.
[Selection] Figure 2

Description

  The present invention relates to a vehicle-mounted receiver, and more particularly to a device that can demodulate a plurality of types of radio signals modulated by different methods with a single receiver.

Conventionally, there has been provided a remote keyless entry system capable of locking and unlocking a vehicle door without inserting and operating a key into a keyhole.
For example, assuming that the keyless entry system has been used from the beginning when it was put into practical use, the door is unlocked / locked by wirelessly communicating with the vehicle by operating a button on an RKE (Remote Keyless Entry) portable device attached to the key. There is something. When the user presses the transmission button of the RKE portable device within a certain distance range from the vehicle, a signal encrypted with a different ID code is transmitted wirelessly and received by the RKE receiver. On the vehicle side, it is confirmed whether or not the ID code of the received signal matches that of its own, and if it matches, a door unlock signal is transmitted to the door ECU to unlock the door.

On the other hand, vehicles equipped with a tire pressure monitoring device (TPMS) for ensuring safety during traveling are also becoming popular. In the tire pressure monitoring apparatus, a TPMS transmitter is built in each of the front and rear wheels, and tire pressure information is periodically transmitted from the TPMS transmitter to the TPMS receiver for monitoring during engine operation.
In Japanese Patent Application Laid-Open No. 2004-189072, a keyless entry system and a tire pressure monitoring device are integrated, but a keyless entry receiving unit and a tire pressure monitoring receiving unit are provided separately. Since it is useless if there are two wireless receivers in one vehicle, it is efficient if they can be shared by one wireless receiver.

However, even if the RKE and TPMS are used in the same frequency band, the modulation schemes are different. For example, the RKE modulation scheme is FSK (Frequency Shift Keying) and the TPMS modulation scheme is ASK (Amplitude Shift Keying). However, there is a problem that a receiver for demodulating the received signal must be provided individually. At present, FSK is adopted as the RKE modulation method in Japan, but ASK is adopted in the United States. Even for RKE receivers with the same function, each modulation method can be used for domestic and overseas use. There is also a problem that two types must be prepared. Furthermore, even if RKE or TPMS is exchanged after the purchase of a vehicle, it must be exchanged including the receiver if the modulation method is different. In particular, data communication standards are not unified among tire manufacturers in TPMS. Currently, there is a possibility that bothering of changing the receiver in accordance with the modulation method may occur every time the tire is changed.
In addition, even if the modulation method is the same, the data rate of the radio signal may be different between RKE and TPMS. However, in this case as well, a separate receiver must be provided for each data rate. It is.
JP 2004-189072 A

  The present invention has been made in view of the above problems, and an object of the present invention is to enable demodulation by a single receiver even when different modulation schemes and different data rates coexist.

In order to solve the above problems, the present invention firstly includes a radio signal from a remote keyless entry portable device possessed by a user and a radio signal from a transceiver for monitoring the pressure of tires mounted on a vehicle. An in-vehicle receiver for receiving,
A shared antenna unit that receives a radio signal that is modulated and transmitted from the portable device, and a wireless signal that is modulated by a modulation scheme different from that of the portable device and transmitted from the transceiver,
A first demodulator that demodulates the signal received by the shared antenna unit according to the modulation method of the portable device and determines whether the header of the demodulated data is valid;
A second demodulator connected in parallel with the first demodulator and demodulating a signal received by the shared antenna unit according to a modulation scheme of the transceiver, and determining whether a header part of demodulated data is valid;
An in-vehicle receiver is provided, comprising: an output unit that outputs one of the demodulated data determined to be valid by the first demodulator or the second demodulator.

With the above configuration, even if different modulation schemes are mixed in the radio signal received by the receiver, the first demodulator and the second demodulator once perform the demodulation process in parallel and examine the header of the demodulated data Therefore, it is possible to correctly demodulate radio signals having different modulation schemes with one receiver by determining that the data having the correct data arrangement is valid and outputting the data. In particular, RKE (Remote Keyless Entry) works when the engine is stopped, and TPMS (Tire Pressure Monitoring)
System) operates while the engine is running, and the operation timing of each other does not overlap. Therefore, it is possible to make effective use of resources by coexisting both systems with a single receiver.

It is preferable that the first demodulator and the second demodulator are determined to be valid when the preamble of a frame of the demodulated data is a specified value.
That is, by selecting a preamble that always takes a constant binary value as a determination target regardless of the data content in the header portion of the frame, it is possible to easily determine the modulation method on the correctly demodulated side. Note that the preamble is data in which 1 and 0 are alternately arranged to notify transmission of a frame and to synchronize.

  It is preferable that either one of the portable device or the transceiver is an ASK modulation method and the other is an FSK modulation method. However, other modulation schemes such as a PSK (Phase Shift Keying) modulation scheme may be used.

Secondly, the present invention receives a radio signal from a keyless entry portable device possessed by a user and also receives a radio signal from a transceiver for monitoring the pressure of tires mounted on a vehicle. Machine,
A shared antenna unit that receives a wireless signal transmitted from the portable device at a constant data rate and a wireless signal transmitted from the transceiver at a data rate different from the portable device;
A data rate determining unit for determining a data rate of a signal received by the shared antenna unit;
An in-vehicle receiver is provided that includes a demodulation unit that demodulates a reception signal based on a determination result of the data rate determination unit.

  With the above-described configuration, the data rate is determined by determining the data rate of the received data and performing the demodulation process in the data cycle even when the modulation method having different data rates is mixed in the radio signal received by the receiver. It is possible to correctly demodulate different radio signals with one receiver.

  As is clear from the above description, according to the first invention, even if different modulation schemes are mixed, the first demodulator and the second demodulator perform demodulation processing in parallel, and the header portion of the demodulated data By checking the above and outputting the data having the correct data arrangement, it is possible to correctly select and demodulate radio signals having different modulation schemes with one receiver. According to the second aspect of the invention, even when modulation schemes having different data rates are mixed, one radio signal having a different data rate is obtained by determining the data rate of received data and performing demodulation processing according to the data cycle. Can be correctly sorted and demodulated by the receiver.

Embodiments of the present invention will be described with reference to the drawings.
1 and 2 show the RKE / TPMS system 10 according to the first embodiment, which is incorporated in the RKE portable device 11 for remote keyless entry possessed by the user and the four-wheel tire of the vehicle, and detects the tire air pressure. TPMS transceivers 12A to 12D, and a vehicle-mounted receiver 13 that is mounted on the vehicle and receives radio signals from the RKE portable device 11 and radio signals from the TPMS transceivers 12A to 12D.
The vehicle C constructs an in-vehicle LAN using the wire harness W / H as a transmission medium. The LAN includes a door ECU 34 for driving and controlling the door lock device 35, and an alarm device 37 and a display device 38 for TPMS. The ECU 36 is connected, and the in-vehicle receiver 13 is connected to the LAN via the door ECU 34.

The RKE portable device 11 includes an ID storage unit 14 that stores an ID code for performing an authentication operation with the door ECU 34, a transmission unit 15 that modulates a signal including the ID code using an ASK modulation method and wirelessly transmits the radio wave using radio waves. And an input operation unit 16 which is a transmission button for the user to press and serves as a trigger for the transmission operation of the transmission unit 15.
The TPMS transceivers 12A to 12D include a tire pressure sensor 18, an arithmetic control unit 19 that manages transmission / reception, a reception antenna 21 and a reception unit 20 that receive a request signal from an onboard transmitter (not shown), and a tire. It includes a transmission unit 22 and a transmission antenna 23 that wirelessly transmit the tire air pressure information detected by the pressure sensor 18 after modulating the tire air pressure information by the FSK modulation method.

  The in-vehicle receiver 13 transmits from the local transmitter 27 the analog data received by the shared antenna unit 24, the amplifier 25, and the shared antenna unit 24 that receives radio signals from the RKE portable device 11 and the TPMS transceivers 12A to 12D. The mixer unit 26 that outputs the IF (intermediate frequency) signal by mixing and differing the frequencies to be processed, the amplifier 28, the filter unit 29 for removing noise, the A / D conversion unit 30, and the demodulation processing according to the ASK modulation method ASK demodulator 31 (first demodulator) to perform, FSK demodulator 32 (second demodulator) arranged in parallel with ASK demodulator 31 to perform demodulation processing according to the FSK modulation method, and output demodulated data to door ECU 34 Output unit 33.

Next, the processing procedure of the in-vehicle receiver 13 will be described.
First, a processing procedure of a signal transmitted from the RKE portable device 11 will be described.
When the user presses the input operation unit 16 of the RKE portable device 11 within a predetermined area around the vehicle C while the engine is stopped, the signal including the ID code is modulated by the ASK modulation method and wirelessly transmitted using a carrier wave having a frequency of 300.1 MHz. Sent. This wireless signal is received by the shared antenna unit 24 of the in-vehicle receiver 13 and input to the mixer unit 26 via the amplifier 25.
The mixer unit 26 outputs a 100 kHz IF signal, which is an intermediate frequency, by taking a difference between the received signal and a signal having a frequency of 300 MHz inserted from the local transmitter 27.

  The IF signal is noise-removed by the filter unit 29 via the amplifier 28, and converted from analog data to digital data by sampling at a sampling frequency of 400 KHz in the A / D conversion unit 30. At this time, the sampling frequency is preferably set to be twice or more the IF frequency. The A / D converted data is input to both the ASK demodulator 31 and the FSK demodulator 32.

As shown in FIG. 3, the ASK demodulator 31 first acquires A / D conversion data (S1), detects the maximum value (S2), and determines whether the carrier period is one type or not. (S3). If it is not one type, the processing is stopped and the process waits until the next data frame comes (S4). The received data is of the ASK modulation method, and as shown in FIGS. 5 and 6A, since there is only one type of carrier cycle Tc1, the time (= 10 μsec) of the carrier cycle Tc1 is calculated (S5). ).
Next, the data period Td for each “1” and “0” indicating the data rate is detected. For example, if the data rate is 10 kbps, it is determined whether Td = 100 μsec (S6). If it is not Td = 100 μs, the process is stopped and the process waits until the next data frame arrives (S7). If Td = 100 μsec, “1” is written to the register (S8).

  Next, it is determined whether the carrier-free time Te is also 100 μs (S9). If Te = 100 μs is not satisfied, the processing is stopped and the process waits until the next data frame comes (S10). If Te = 100 μsec, “0” is written in the register (S11). Next, it is determined whether or not the preamble of the header portion of the data frame has been correctly received by determining whether the register value is “1” “0”... In this case, the process is repeated from S2. If it matches the specified value, demodulation processing is performed by the ASK method (S13), and the demodulated data is sent to the output unit 33.

  On the other hand, as shown in FIG. 4, the processing in the FSK demodulator 32 first acquires A / D conversion data (S20), detects the maximum value (S21), and determines whether there are two types of carrier cycles. Determine (S22). The received data is of the ASK modulation method, and as shown in FIGS. 5 and 6A, there is only one type of carrier cycle Tc1, so the processing is stopped and the process waits for the next data frame (S24). . That is, no data is sent from the FSK demodulator 32 to the output unit 33.

  By the above procedure, only data correctly demodulated by the in-vehicle receiver 13 is input to the door ECU 34 via the output unit 33. The door ECU 34 checks whether or not the ID code included in the received demodulated data matches its own ID code, and if it matches, instructs the door lock device 35 to unlock the door lock.

Next, a processing procedure of signals transmitted from the TPMS transceivers 12A to 12D will be described.
During engine operation, the TPMS ECU 36 transmits a request signal to each of the four TPMS transceivers 12A to 12D via a transmitter (not shown) in order, and signals with the TPMS transceivers 12A to 12D. The timing of sending and receiving is shifted. The TPMS transceiver 12A that has received the request signal at the reception antenna 21 and the reception unit 22 modulates a signal including the air pressure data detected by the tire pressure sensor 18 by the FSK method in the transmission unit 22, and sets “1” to the frequency 300. A 1 MHz carrier wave, “0”, is wirelessly transmitted from the transmission antenna 23 using a carrier wave having a frequency of 300.05 MHz. This wireless signal is received by the shared antenna unit 24 of the in-vehicle receiver 13 and input to the mixer unit 26 via the amplifier 25. The mixer unit 26 outputs an IF signal having an intermediate frequency by taking a difference between the received signal and a signal having a frequency of 300 MHz inserted from the local transmitter 27. That is, the IF frequency is 100 kHz when “1” and 50 kHz when “0”.
Next, as described above, the IF signal flows in the order of the amplifier 28 → filter unit 29 → A / D conversion unit 30, and the A / D converted data is input to both the ASK demodulation unit 31 and the FSK demodulation unit 32. .

As shown in FIG. 3, the ASK demodulator 31 first acquires A / D conversion data (S1), detects the maximum value (S2), and determines whether the carrier cycle is one type or not. (S3).
The received data is an FSK modulation method, and there are two types of carrier periods Tc1 and Tc2 as shown in FIGS. 5 and 6A and 6B. Therefore, the processing is stopped and the process waits until the next data frame arrives. (S24). That is, no data is sent from the ASK demodulator 31 to the output unit 33.

On the other hand, as shown in FIG. 4, the processing in the FSK demodulator 32 first acquires A / D conversion data (S20), detects the maximum value (S21), and determines whether there are two types of carrier cycles. Determine (S22). The received data is an FSK modulation system, and there are two types of carrier cycles Tc1 and Tc2 as shown in FIGS. 5 and 6A and 6B. Next, the time interval between adjacent maximum values is set to the carrier. The periods Tc1 and Tc2 are calculated (S25, S26). Since the frequency of “1” is 100 kHz, signal detection is performed with Tc1 = 10 μsec as “1”, and since the frequency of “0” is 50 kHz, signal detection is performed with Tc2 = 20 μsec as “0”.
Next, the data period Td for each “1” and “0” indicating the data rate is detected. For example, if the data rate is 10 kbps, it is determined whether Td = 100 μsec (S27, S28). If it is not Td = 100 μsec, the process is stopped and the process waits until the next data frame arrives (S29, S30). When Td = 100 μsec, “1” is written to the register when Tc1 = 10 μsec (S31), and “0” is written to the register when Tc2 = 20 μsec (S32).

  Next, it is checked whether the carrier-free time Te is not longer than 10 μs (S33, S34). If it is longer than 10 μm, it is determined that the data is not FSK data, and the process is stopped and waits until the next data frame comes ( S35, S36). If the carrier-free time Te is less than 10 μs, whether or not the preamble of the data frame header has been correctly received by determining whether the register value is “1” “0”... (S37), and if it is different from the specified value, the process is repeated from S21. If it matches the specified value, demodulation processing is performed by the FSK method (S38), and the demodulated data is sent to the output unit 33.

  By the above procedure, only data correctly demodulated by the in-vehicle receiver 13 is input to the door ECU 34 via the output unit 33. The door ECU 34 transmits the demodulated data to the destination TPMS ECU 36 via the LAN. The TPMS ECU 36 determines that the tire pressure is abnormal when the received tire pressure is less than or equal to a predetermined threshold value, and instructs the alarm device 37 to sound an alarm alarm and instructs the display device 38 to display a warning. Do.

  According to the above configuration, even if a different modulation scheme of ASK or FSK is mixed in the radio signal received by the in-vehicle receiver 13, the ASK demodulator 31 and the FSK demodulator 32 perform the demodulation process once in parallel. By examining the preamble of the demodulated data and determining that the data having the correct data arrangement is valid and outputting it, a single in-vehicle receiver 13 can correctly demodulate a radio signal having a different modulation method. it can. In addition, even if there is a change in the modulation system or the like, it is sufficient to rewrite the programs of the demodulation units 31 and 32 afterwards, so that the flexibility of the in-vehicle receiver 13 is improved and the running cost of the system can be reduced. .

7 to 9 show a second embodiment.
The difference from the first embodiment is that signals having different data rates can be discriminated and demodulated using the same modulation method.
In the in-vehicle receiver 13 ′ of the present embodiment, the ASK data rate determination unit 40 is disposed in front of the ASK demodulation unit 31 ′, and the FSK data rate determination unit 41 is disposed in front of the FSK demodulation unit 32 ′. is doing.

  The ASK data rate determination unit 40 determines the data rate by measuring the data period Td, which is the time required for one binary value. For example, as shown in FIGS. 8A and 8B, even when the RKE portable device and the TPMS transceiver are the same ASK modulation method, when the RKE data cycle Td1 and the TPMS data cycle Td2 are different, The data rate determination unit 40 determines the data periods Td1 and Td2, and informs the ASK demodulator 31 ′ of which data period it is. The ASK demodulator 31 'performs demodulation processing based on the data period.

  For example, as shown in FIGS. 9 (A) and 9 (B), the FSK data rate determination unit 41 uses the RKE data period Td1 and TPMS even if the RKE portable device and the TPMS transceiver use the same FSK modulation method. When the data period Td2 is different, the data rate determining unit 41 determines the data periods Td1 and Td2, and notifies the FSK demodulating unit 32 ′ which data period it is. The FSK demodulator 32 'performs demodulation processing based on the data period.

  With the above-described configuration, even if modulation methods having different data rates are mixed in the radio signal received by the in-vehicle receiver 13 ′, the data rate is determined by determining the data rate of the received data and performing demodulation processing in the data cycle Can be correctly demodulated by one in-vehicle receiver 13 '. Since other configurations are the same as those of the first embodiment, the same reference numerals are given and description thereof is omitted.

1 is a perspective view showing a vehicle according to a first embodiment of the present invention. It is a system configuration figure containing the receiver of a 1st embodiment. It is a flowchart explaining the process sequence in an ASK demodulation part. It is a flowchart explaining the process sequence in a FSK demodulation part. It is drawing explaining each modulation system. (A) is a waveform representing 1 in the ASK and FSK modulation schemes, and (B) is a waveform representing 0 in the FSK modulation schemes. It is a system block diagram containing the receiver of 2nd Embodiment. (A) and (B) are drawings showing signals having different data rates in the ASK modulation method. (A) and (B) are drawings showing signals having different data rates in the FSK modulation method.

Explanation of symbols

11 RKE portable devices 12A to D TPMS transceiver 13 On-vehicle receiver 24 Shared antenna unit 31 ASK demodulator (first demodulator)
32 FSK demodulator (second demodulator)
33 Output section

Claims (4)

An in-vehicle receiver that receives a radio signal from a portable device for remote keyless entry possessed by a user and a radio signal from a transceiver for monitoring the pressure of tires mounted on a vehicle,
A shared antenna unit that receives a radio signal that is modulated and transmitted from the portable device, and a wireless signal that is modulated by a modulation scheme different from that of the portable device and transmitted from the transceiver,
A first demodulator that demodulates the signal received by the shared antenna unit according to the modulation method of the portable device and determines whether the header of the demodulated data is valid;
A second demodulator connected in parallel with the first demodulator and demodulating a signal received by the shared antenna unit according to a modulation scheme of the transceiver, and determining whether a header part of demodulated data is valid;
An in-vehicle receiver comprising: an output unit that outputs one of the demodulated data determined to be valid by the first demodulator or the second demodulator.   The in-vehicle receiver according to claim 1, wherein the first demodulator and the second demodulator are configured to be valid when a preamble of a frame of the demodulated data is a specified value.   The in-vehicle receiver according to claim 1 or 2, wherein either one of the portable device or the transceiver is an ASK modulation method, and the other is an FSK modulation method. A vehicle-mounted receiver that receives a radio signal from a remote keyless entry portable device possessed by a user and receives a radio signal from a transceiver for monitoring the pressure of a tire mounted on a vehicle,
A shared antenna unit that receives a wireless signal transmitted from the portable device at a constant data rate and a wireless signal transmitted from the transceiver at a data rate different from the portable device;
A data rate determining unit for determining a data rate of a signal received by the shared antenna unit;
A vehicle-mounted receiver comprising: a demodulator that demodulates a received signal based on a determination result of the data rate determiner.

Images