JP2003224509A - Short range radio communication equipment for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce mutual interference between short range radio communication equipment for a vehicle and a plurality of other radio equipment. <P>SOLUTION: This short range radio communication equipment for a vehicle has a limited characteristic so that spurious emission intensity may not be each maximum value or more with respect to each operating frequency and each frequency band where the each maximum value of spurious emission intensity is set in accordance with the each operating frequency and the each frequency band of portable telephones, a radio wave beacon receiver, a TV receiver and a GPS receiver as recognized from figure 3. The short range radio communication equipment for the vehicle has a limited reception characteristic that blocking performance may not be each minimum value or less so as to prevent transmission radio waves of the other radio equipment from interfering with the short range radio communication equipment. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a near field wireless communication device for a vehicle, and more particularly to a device for reducing wireless interference when a plurality of other wireless devices are present in a vehicle.

[0002]

2. Description of the Related Art In recent years, with the development of wireless communication, wireless communication has come to be carried out easily in offices, homes and the like. For example, it is a wireless LAN, such as a mobile phone.
And, such wireless communication is also attracting attention as a wireless interface in an automobile. For example, when a mobile phone is brought into a car, a hands-free call is made using a hands-free kit. ) Is under consideration. Further, not only a mobile phone but also a PDA (Personal Digital Assistant, Personal Digital Assistant) is provided with a wireless interface, and it is considered to transmit and receive data to and share data with a car navigation device of a vehicle, for example.

[0003]

The inventor of the present invention has found that the following situation occurs when the above short-distance wireless communication device is installed in a vehicle and experimentally studied.

When the short-distance wireless communication device is installed in the vehicle, when a GPS receiver of a car navigation device is already installed as another wireless communication device in the vehicle, or when the car navigation device is installed later. In the case where a keyless entry receiver is equipped, a plurality of wireless devices are arranged in a short distance in a narrow vehicle compartment space, as in the case where a mobile phone is brought into the vehicle as described above.

According to a study by the present inventor, since a plurality of wireless devices exist in a narrow space as described above, the radio waves transmitted by the short-range wireless communication device affect the reception of other wireless devices. It has been found that the radio waves transmitted from other wireless devices affect the reception of the short-range wireless communication device.

In view of the above problems, it is an object of the present invention to reduce interference between a plurality of other wireless devices in a vehicle short-range wireless communication device.

[0007]

In order to achieve the above object, in the invention according to claim 1, the transmission is performed from at least a portable wireless device carried in the vehicle or / and a wireless terminal device arranged in the vehicle. Depending on the transmission radio frequency to be transmitted, the reception characteristic is set so that the reception radio wave of the transmission radio frequency has a degree of reception interference that causes interference to the reception system, and the portable radio device and the radio It is characterized in that the transmission characteristics of the transmission system are set so that the degree of transmission interference that gives interference to each reception at the terminal device is below a predetermined level.

As a result, the radio waves transmitted from both the portable wireless device brought into the vehicle and the wireless terminal device arranged in the vehicle, or from one of the wireless terminal devices interferes with the receiving system of the vehicle short-range wireless communication device. In addition, it is possible to reduce the interference of both the mobile wireless device and the wireless terminal device by the radio wave transmitted from the vehicle short-range communication device.

As an example of claim 1, claim 2
As described in the invention, the degree of reception interference is equal to or less than a predetermined level,
The blocking performance of the receiving system is such that the input power level to the receiving system at each transmission radio frequency is limited to a predetermined power level or less, or the transmission interference degree and Is the spurious emission intensity, and it is preferable to limit the emission intensity of the spurious at each transmission radio frequency so as to be equal to or lower than a predetermined power level.

By the way, in recent years, the spread of car navigation devices in vehicles has been remarkable. Among these, there is one in which an antenna for receiving GPS signals from satellites can be arbitrarily arranged on a dashboard located between the front seat and the windshield in the vehicle. When the vehicle short-distance wireless device of the present invention is attached to a car navigation device, the vehicle short-distance wireless device and the antenna may be installed in close proximity to each other, increasing radio interference. There is a problem.

Therefore, the present invention is particularly suitable for the mode as the invention according to claim 6.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a short-range wireless device 1 for a vehicle.
Car navigation device 10 with a built-in (installed)
0 (hereinafter, referred to as a car navigation device 100) represents a state in which the car navigation device 100 is mounted inside the vehicle.

The car navigation system 100 is capable of calculating the current position of the vehicle and displaying it, and by setting a destination and the like, a known device for guiding the occupant from the current position to the destination. Is. Car navigation system 100
Are arranged in the center portion in the vehicle width direction (left-right direction in the drawing) as shown in FIG. The mounting position of the car navigation device 100 is, for example, a meter device 101 that displays a vehicle speed and the like.
It may be of a type that is integrally built in an instrument panel 102 that accommodates the vehicle, or a dashboard 113 that is located between the vehicle front seat and the windshield 103 and that forms a design surface in the vehicle interior. It may be of a type that is attached to a stay or an adhesive sheet.

The near field wireless device 1 for a vehicle of this embodiment is
As shown in FIG. 1, it is built in the car navigation system 100. FIG. 2 shows details of the car navigation device 100 and the vehicle short-range wireless device 1.

First, the hardware configuration of the car navigation system 100 will be described. The car navigation system 100 includes an antenna 104 for receiving GPS signals from GPS satellites (not shown) of the global positioning system (GPS),
It has a GPS receiver 105 connected to this antenna by a flexible cable member such as a coaxial cable. Antenna 1
Since 04 is connected by such a flexible cable, it can be installed at any position. For example, it may be attached to the roof outside the vehicle compartment with a magnet or the like, or may be attached to any position on the dashboard 113 as shown in FIG.

The dashboard 113 is located between the front seat and the windshield of the vehicle and serves as a design surface inside the vehicle.

The GPS receiver 105 (the wireless terminal device of the present invention) is connected to each GP from a plurality of satellites via the above antenna.
The S signal is received and the GPS signal is demodulated. The GPS signal demodulated by the GPS receiver is sent to the CPU
The data is input to 106 and the CPU 106 calculates the position of the own device 1 by obtaining the distance between each satellite and the own device and using a method such as trigonometry. Note that this arithmetic processing is performed by the memory 107.
It is performed by a program stored in.

The car navigation system 100 has map data 108 stored and stored in a storage means, a storage medium such as a CD-ROM or a DVD-ROM, and the calculated position is the map corresponding to this map data. Is searched and displayed on the display 114 (display unit). It should be noted that the program for performing the above search and display is stored in the memory 107.
Remembered in. The memory 107 also stores a program that achieves a function of calculating and guiding a route from the user's position to the destination when the operator sets the destination.

The car navigation system 100 includes a TV receiver 109.
(Wireless Terminal Device of the Present Invention) and Radio Beacon Receiver 1
10 (the wireless terminal device of the present invention). That is, as is well known, the car navigation device 100 can watch television images. The radio wave beacon receiver 110 detects the position error in order to improve the position detection accuracy.
To notify 00, improve the convenience of the driver, eliminate or alleviate traffic congestion, etc.
It is for receiving road traffic information relating to traffic regulations from a broadcaster installed on the road and providing information to the car navigation system 100.

Here, the car navigation system 100 of this embodiment
Has a microphone 111 and a speaker 112. This is for making a hands-free call with a mobile phone 200 (see FIG. 1, the mobile wireless device of the present invention) brought in a vehicle. These microphone 111 and speaker 1
12 is a car navigation system 1 as a hands-free kit.
It may be configured to be attachable / detachable to 00. Also, these microphones 111 may be used for voice recognition when the car navigation system 100 has a voice recognition function.
In addition, the speaker 112 may be used to output a guidance sound such as “turn right” to the driver by synthetic voice during route guidance.

Next, the vehicle short-range radio apparatus 1 will be described. The vehicle short-range radio apparatus 1 of the present embodiment directly communicates with the mobile phone 200 shown in FIG. 1 without using a base station (not shown) connected to a public or private telephone line network. In other words, the mobile phone 200 also has a built-in device similar to the above-mentioned vehicle short-range wireless device 1, so that bidirectional communication between the two is performed. The mobile phone 200 is, as is well known, a cellular type wireless phone that communicates with a base station installed in each communication area.

The short-range wireless communication device 1 for vehicles is GFSK.
It uses a wireless communication system (Bluetooth) that allows frequency-hopping of the modulated data. As a frequency to be used, bidirectional data communication is performed by the TDD method by transmitting and receiving a transmission radio wave in the 2.4 GHz band.

The short-range wireless communication device 1 for vehicles is 2.4G.
An antenna 10 for transmitting and receiving a radio wave in the Hz band, a transmission unit 12 for converting data to be transmitted (transmission data) into a transmission signal in the 2.4 GHz band and outputting the signal to the antenna 10, and a 2.4 GHz input from the antenna 10. The reception unit 14 that demodulates the reception signal of the band and extracts the data (reception data) transmitted from the mobile phone 200, the antenna 10 and the transmission unit 1
2, an antenna changeover switch 16 for switching between connection to the receiver 2 and a receiver 14, inputting transmission data to the transmitter 12 at a predetermined transmission timing, and receiving data demodulated by the receiver 14 at a predetermined reception timing. It is composed of a control device 18 which performs a process of fetching data.

The control device 18 converts the voice signal input from the microphone 111 into a voice code signal, inputs the voice code signal to the DSP / baseband unit 19 in the control device 18 as voice data (call data), and receives the voice data. The call data in the received data demodulated by the unit 14 is taken out from the DSP / baseband unit 19, the call data is converted into a voice signal, and the speaker 112 is passed via the CPU 22 → CPU 106.
It has a voice processing function to output to.

Then, the control device 18 causes the CPU 22 to generate communication control data (control data) to be transmitted to the mobile phone 200 in accordance with a preset communication procedure, and demodulate the reception data by the receiving unit 14. The control data in the data is taken in, the transmission / reception timing and the like are controlled according to the control data, and the communication state and the operation state of the device are arithmetically controlled. Further, the control device 18 has a memory 24 for storing programs and various data necessary for the CPU 22 to execute various controls.

A local oscillator 32 for generating a transmission signal in the transmission unit 12 and a local oscillation signal of a predetermined frequency for frequency conversion of the reception signal in the reception unit 14 are provided.

Here, the transmitter 12 includes a modulator 30 for GFSK-modulating the transmission data input from the DSP / baseband unit 19 at a predetermined transmission timing, and a local oscillator 3.
A transmission amplifier 36 that amplifies the transmission signal output from the antenna 2 and outputs the amplified transmission signal to the antenna 10, and a filter 37 that removes an extra frequency (spurious component) from the frequency-converted signal.

On the other hand, the receiving unit 14 includes a filter 35 for removing unnecessary frequency components from the 2.4 GHz band received signal input from the antenna 10 and a filter 35.
A reception amplifier 38 that amplifies the reception signal that has passed through, and a mixer 40 that mixes the reception signal amplified by the reception amplifier 38 with a local oscillation signal from the local oscillator 32 to convert the reception signal into an intermediate frequency signal. The mixer 40 demodulates the reception signal converted into the intermediate frequency signal to extract the reception data,
It is composed of a demodulation section 42 which is input to the DSP / baseband section 19.

Further, the control device 19 is also adapted to drive the antenna changeover switch 16, and normally, when the antenna changeover switch 16 is connected to the receiving section 14 side and communication is performed, the control switch 19 is provided at predetermined time intervals. Antenna switch 16
Are alternately switched to the transmitting unit 12 side and the receiving unit 14 side.
Then, the channel multiplexing TDD is realized by outputting the transmission data and receiving the reception data in one slot designated by the CPU 22 in the predetermined slots divided by the predetermined time.

C of the car navigation system 100 described above
The PU 106 and the CPU 22 of the vehicle short-range wireless apparatus 1 are connected by a bus 51 (data and control), and the sound from the microphone 111 is sent to the vehicle short-range wireless apparatus 1 via the CPU 106. The CPU 22,
A mobile phone 200 through the transmitter 12 and the antenna 10.
Sent to. Then, the mobile phone 200 transmits these audio data to a communication partner through a base station (not shown). On the other hand, the sound from the mobile phone 200 is transmitted to the antenna 1
0 and received by the receiving unit 14, CPU22 → CPU
Sound is output from the speaker 112 via 106. As a result, in the call using the mobile phone 200, the hands-free function using the microphone 111 and the speaker 112 on the car navigation device 100 side can be executed by the near field wireless devices 1 for both vehicles.

Next, the transmission characteristic of the transmission unit 12 in the present invention will be described with reference to FIG. FIG. 3 shows the transmission characteristics of the vehicle short-range wireless device 1 according to the present embodiment. The transmission characteristic here means a spurious emission intensity characteristic generated in the transmission unit 12 (strictly including the antenna 10). Spurious emission intensity is the output power level of the spurious.

Since the vehicle short-range wireless device 1 wirelessly communicates with the mobile phone 200 in the vehicle as described above,
It is necessary to limit the transmission interference degree, that is, the spurious emission intensity at the frequency used by the mobile phone 200 to a predetermined value or less so that the mobile phone 200 does not interfere with the wireless communication with the base station.

Further, as described above, since the vehicle short-range wireless device 1, the TV receiver, and the radio wave beacon receiver are built-in, they are arranged close to each other. Therefore, even if the transmitter 12 generates spurious signals, it is necessary to limit the reception to the extent that they do not interfere with reception. In particular, as described above, the antenna 104 that receives the GPS signal can be arranged at any position on the dashboard 113, so that the antenna 104 may also be arranged close to the vehicle short-range wireless apparatus 1. is there.

Therefore, in the present embodiment, the transmitting unit 12 has the mobile phone 200 and the radio wave beacon receiver 1 as shown in FIG.
10, the TV receiver 109 and the GPS receiver 105 are set to have transmission characteristics that do not interfere with reception.
Specifically, the transmission characteristic is adjusted by adjusting the frequency characteristic of the filter 37 while considering the characteristic of the transmission unit 12 when the antenna 10 and the transmission unit 12 are regarded as a transmission system.

As shown in FIG. 3, the transmission characteristic of the mobile phone 200, the radio wave beacon receiver 110, T
The maximum value of the spurious emission intensity is set in accordance with each used frequency and each frequency band in the V receiver 109 and the GPS receiver 105 so that the spurious emission intensity does not exceed each maximum value. As a characteristic limited to. It should be noted that the four mobile phones 200 are described because the mobile phone 200 has a different usage frequency / frequency band depending on the communication method, and therefore in the present example, considering the four mobile phones, the transmission characteristics are It is set.
Further, according to a study by the present inventor, a keyless entry receiver (not shown) that wirelessly unlocks or locks the door of the vehicle and an ETC communication device (two-way communication) also need to be considered. It is shown in FIG. In addition,
ETC communication equipment is a non-stop automatic fee payment system by bidirectionally communicating with a roadside radio installed at the entrance of a highway, eliminating congestion at toll gates on toll roads, and improving convenience by managing cashless In order to reduce costs, the tolls are automatically paid without stopping at toll gates on toll roads.

Next, the reception characteristic of the receiving section 14 in the present invention will be described with reference to FIG. Here, since the vehicle short-range wireless device 1 wirelessly communicates with the mobile phone 200 in the vehicle as described above, it is necessary to limit the degree of reception interference so as not to interfere with wireless communication by the radio waves transmitted from the mobile phone 200. There is. Therefore, in the present invention, the reception characteristic of the reception unit 14 is set so that the above interference does not occur.

FIG. 4 shows the reception characteristics of the vehicle short-range radio apparatus 1 in this embodiment. And
The reception characteristic here means the blocking performance in the reception unit 14 (strictly including the antenna 10). The blocking performance means that the maximum transmission power (specified in the communication standard) of each of the frequencies used by the wireless devices (110, 105, 109, 200) other than the vehicle short-range wireless device 1 is used for the vehicle near range. When input to the range wireless device 1, it means an index indicating how much interference occurs.

Specifically, the vehicle short-range radio apparatus 1 uses a bit error rate (BER) or a frame error rate as an index indicating interference from other devices, as a minimum condition required for communication with the apparatus 1. (FER)
Is usually specified. Therefore, when the maximum transmission power is input, it is measured whether or not the minimum condition is satisfied, and when the minimum transmission power is not satisfied, the maximum transmission power at each operating frequency is attenuated by the receiving unit 12, thereby effectively Therefore, it is set to satisfy the above regulations. Therefore, the blocking performance in FIG. 4 can be said to be the maximum input power level of another device satisfying the above-mentioned minimum condition. In other words, the vehicle short-range wireless device 1 has a blocking performance characteristic so as not to fall below the maximum input power level (minimum level).

Therefore, in the present embodiment, the receivers 14 of the four types of mobile phones are set so as to have the reception characteristics that do not interfere with the reception of the device 1 as shown in FIG. Specifically, the reception characteristic is adjusted by adjusting the frequency characteristic of the filter 35 while considering the characteristic of the receiving unit 14 when the antenna 10 and the receiving unit 14 are regarded as a receiving system.

As described above, in the present embodiment, the transmission transmitted from any one or more of the mobile phone 200 brought into the vehicle, the GPS receiver arranged in the vehicle, the radio wave beacon receiver 110, the TV receiver 109. It is possible to reduce radio waves from interfering with the receiving system of the vehicle short-range wireless communication apparatus 1. Further, the radio waves transmitted from the vehicle short-range communication apparatus 1 allow the mobile phone 200 and each receiver. Can be reduced.

(Modification) In the above embodiment, separate filters 35 and 37 are provided for the transmission system and the reception system, but one or both of them are eliminated and one common filter is used as the antenna 10 and the antenna changeover switch 16. It may be placed between and.

Further, in the above-mentioned embodiment, only one example of the wireless device used in the vehicle is given, and the present invention may be any one that can be used in the vehicle, for example, FM of VICS.
It may be applied to a receiver or IEEE 802. 11b
Or a new wireless system that will increase in the future, and various combinations are possible.

[Brief description of drawings]

FIG. 1 is a diagram in which a vehicle short-range wireless device according to an embodiment of the present invention is mounted in a vehicle.

FIG. 2 is a block diagram showing a configuration of a vehicle short-range wireless communication apparatus according to the above embodiment.

FIG. 3 is a diagram showing characteristics of a transmission system in the above embodiment.

FIG. 4 is a diagram showing characteristics of a receiving system in the above embodiment.

[Explanation of symbols]

1 ... Short-range wireless device for vehicle, 12 ... Transmitter, 14 ... Receiver, 35, 37 ... filter, 100 ... Car navigation system, 104 ... antenna, 109 ... TV receiver, 110 ... Radio beacon receiver.

Claims (6)

[Claims] 1. A short-range wireless communication device for a vehicle, which is disposed in a vehicle and has a receiving system for receiving a wireless signal and a transmitting system for transmitting a wireless signal, the portable wireless device being carried in the vehicle and / or , A reception characteristic such that the degree of reception interference that causes the transmission radio wave of this transmission radio frequency to interfere with the reception system is below a predetermined level according to the transmission radio frequency transmitted from the radio terminal device arranged in the vehicle. And a transmission characteristic of the transmission system is set so that the degree of transmission interference that interferes with each reception at the portable wireless device and the wireless terminal device is less than or equal to a predetermined value. Short-range wireless communication device. 2. The reception interference degree being less than or equal to the predetermined level is a blocking performance of the reception system, and is limited so that an input power level to the reception system at each transmission radio frequency is less than or equal to a predetermined power level. The short-range wireless communication device for a vehicle according to claim 1, wherein 3. The transmission interference degree is the spurious emission intensity, and is limited so that the emission intensity of spurious at each transmission radio frequency is equal to or lower than a predetermined power level. 2. The vehicle short-range wireless communication device according to 2. 4. The vehicle proximity device according to claim 1, wherein the mobile wireless device is a cellular mobile phone that communicates with a base station installed in each communication area. Range wireless communication device. 5. The vehicle according to claim 1, wherein the wireless communication device is a GPS receiver that receives GPS signals from satellites of a global positioning system (GPS). Short-range wireless communication device. 6. The GPS receiver receives the GPS signal from an antenna, and the antenna can be arbitrarily arranged on a dashboard located between a front seat and a windshield in the vehicle, and further, The short distance for vehicle according to claim 5, wherein the antenna and the GPS receiver are used in a car navigation device used to calculate the position of the vehicle and are attached to the car navigation device. Wireless communication device.