JP2001007757A - On-vehicle communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the signal lines of a vehicle, to easily lighten the weight of a vehicle and save a space without deteriorating communication precision by transmitting/receiving a communication signal between an on-vehicle unit and an outer unit taken into the vehicle, with radio communication. SOLUTION: A signal transmitted from the signal transmitter 11 of a transmission source device 1 is modulated by a primary modulator 12, and a spectrum spreader 13 generates a spread modulation wave signal. The spread modulation wave signal is radio-transmitted by a radio transmitter 14 through an antenna 15. Related to a reception destination device 2, a radio receiver 22 receives a radio signal from the transmission source device 1 through an antenna 21. A reception signal is spread inversely by an inverse spreader 23. An inverse spread signal is demodulated by a demodulator 24 and an original signal transmitted from the signal transmitter 11 of the transmission source device 1 is extracted. A signal receiver 25 shows a prescribed characteristic function, based on a signal given from the demodulator 24.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-vehicle communication system for performing in-vehicle communication between on-vehicle units mounted on a vehicle or between on-vehicle units and various external devices.

[0002]

2. Description of the Related Art The number of electrical components (vehicle units) mounted on a vehicle, such as a car navigation system and a vehicle-mounted audio system, is increasing year by year. In addition, due to the diversification of consumer preferences, there are increasing examples of adding an in-vehicle unit according to the preference after purchasing a car, or attaching an original external device by customizing at the time of purchase.

[0003] With the increase of such in-vehicle units and external devices, power lines from a battery and signal lines from an instrument panel and the like arranged in the front part of the vehicle compartment are increasing. A bundle of such wirings is generally called a wire harness. In recent years, some luxury cars have a wire harness alone of 40 kg or more. This leads to increased fuel economy,
It is a problem that goes against the growing awareness of ecology in recent years. In addition, since the ratio of wiring materials such as signal lines occupying the space in the car increases, even if an attempt is made to install a new in-vehicle unit and an external device after purchasing the car, it is difficult to secure the space.
It is becoming commonplace to expose exposed wiring in the cabin in preparation for spoiling the aesthetics.

As a countermeasure against such a problem, reduction of a wire harness by multiplexing signal lines is being studied, and an automobile LAN (local area network) has been realized in some automobiles.

As signal line multiplexing methods, there are known a frequency division multiplexing method using different frequencies for each communication and a time division multiplexing method in which the same wiring is shared by dividing time.

[0006] In a recently developed system, there is also a spread spectrum communication system (SS) in which each signal is multiplied by a spreading code having a small cross-correlation value.
As disclosed in Japanese Patent No. 50619, a technique of superimposing a communication signal on a power supply line is also disclosed. As described above, in the method of superimposing the communication signal on the power line using the spread spectrum communication method, the number of wire harnesses can be significantly reduced,
It is possible to contribute to weight reduction and space saving of the automobile.

However, a starter motor connected to a power supply line and a vehicle-mounted air conditioner (air conditioner)
In such a blower, a surge current of several tens of volts or more may be generated, and when a noise component caused by the surge current is superimposed on a power supply line, sufficient reliability is ensured even in a spread spectrum communication system. Is uneasy.

In addition, various electric parts such as a capacitor and a surge absorber may be mounted for the purpose of stabilizing the power supply line. In this case, the communication signal in the power supply line is modulated by these parts. However, it is difficult to transmit and receive an accurate communication signal, and communication accuracy may be degraded.

Further, if various vehicle-mounted units and various external devices are installed in the vicinity of the power supply line, the degree of freedom in selecting a place can be restricted particularly when adding the vehicle-mounted units and external devices after purchasing the automobile. Problem.

Accordingly, an object of the present invention is to dramatically reduce the number of signal lines of a vehicle without deteriorating communication accuracy,
It is an object of the present invention to provide an in-vehicle communication system in which a vehicle can be reduced in weight and space, and an in-vehicle unit and an external device can be easily added after purchasing the vehicle.

[0011]

Means for Solving the Problems In order to solve the above problems,
The invention according to claim 1 is an in-vehicle communication system for transmitting and receiving a desired communication signal between on-vehicle units mounted on a vehicle or between on-vehicle units and various external devices,
The source device of the communication signal is a primary modulator that modulates desired information given from a predetermined signal transmitter and outputs an encoded modulated signal, and the modulation output from the primary modulator. A spread signal for generating a spread modulated wave signal by multiplying a wave signal by a predetermined spreading code having a code rate sufficiently higher than that of the modulated wave signal, and the spread generated by the spectrum spreader. A wireless transmitter for wirelessly transmitting the modulated wave signal, wherein a device for receiving a communication signal receives a wireless signal wirelessly transmitted from the wireless transmitter, and a wireless receiver for receiving the wireless signal. A despreader that generates a despread modulated wave signal by despreading by multiplying the spread signal by the same despread code as the spread code, and demodulating the despread modulated wave signal generated by the despreader. In which and a demodulator for input to a constant signal receiving unit.

According to a second aspect of the present invention, the signal transmitter and the signal receiver are irremovably installed in an automobile.

According to a third aspect of the present invention, the signal transmitting device is an external device that can be taken out of the vehicle, and the signal receiving device is non-removably installed in the vehicle.

According to a fourth aspect of the present invention, mutual communication is performed between an external device brought by a user into a vehicle compartment separately from a vehicle and one or more vehicle-mounted units irremovably installed in the vehicle. In the on-vehicle communication system to be performed, the external device and the on-vehicle unit each have both of a device that transmits the communication signal and a device that receives the communication signal.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment <Configuration> FIG. 1 is a block diagram showing a vehicle-mounted communication system according to a first embodiment of the present invention. As shown in FIG. 1, this in-vehicle communication system transmits and receives communication signals between an in-vehicle unit and an external device brought into a vehicle.
A wireless communication is performed between the transmission source apparatus 1 and the reception destination apparatus 2 by using a spread spectrum communication method, thereby simultaneously reducing a wire harness, securing a degree of freedom of a device mounting place, and improving communication accuracy. It is.

Specifically, the transmission source device 1 in the on-vehicle communication system includes a signal transmitter 11 for transmitting a desired signal.
A primary modulator 12 for converting a signal transmitted from the signal transmitter 11 into a coded signal of a predetermined format corresponding to a communication protocol of the destination device 2; and a primary modulator 1
A spectrum spreader 13 for further performing a spread spectrum process on the modulated wave signal modulated in step 2, and a radio transmission for converting the spread modulated wave signal output from the spectrum spreader 13 into a radio signal and wirelessly transmitting the radio wave signal to the receiving apparatus 2. Machine 14.

The signal transmitter 11 receives, for example, a signal related to a radio broadcast and transmits the signal, a headphone cassette tape player, a headphone compact disk (CD) player, or a headphone microdisk (MD) player. And any portable audio equipment such as a notebook personal computer or a mobile computer.

The primary modulator 12 converts a signal supplied from the signal transmitter 11 into a modulated wave signal of a predetermined format by performing amplitude modulation, frequency modulation, phase modulation, etc., in order to transfer information efficiently in a communication path. Is what you do.

The spectrum spreader 13 includes the primary modulator 12
Is further multiplied by a predetermined spreading code 13a by an integrator 13b with respect to the modulated wave signal given by

FIG. 2A shows a modulated wave signal supplied from the primary modulator 12, and FIG. 2B shows a spread code 13a.
FIG. 3C shows the spread modulated wave signal after the spread spectrum processing. Here, the modulated wave signal ((a) in the figure) given from the primary modulator 12 has a high state of "1" and a low state of "-1", and has a spreading code 13a (see FIG. b)) also takes two values, "1" and "-1", similarly to the modulated wave signal of FIG.
However, the code rate (hereinafter, referred to as “chip rate”) of the spreading code 13a is the code rate (hereinafter, referred to as “bit rate”) of the modulated wave signal ((a) in the figure) from the primary modulator 12.
It is set to be more than a certain factor faster than. Here, the ratio of the chip rate to the bit rate is generally a “spreading rate”.
This spreading factor is set to be much larger than “1”, for example, about 128 times. in this case,
When the value of the modulated wave signal (FIG. 13A) is “1” and the value of the spreading code 13a (FIG. 13B) is “1”,
The value of the spread modulated wave signal (FIG. 13 (c)) is “1”, the value of the modulated wave signal (FIG. 14 (a)) is “1”, and the value of the spread code 13a (FIG. 14 (b)). Is "-1",
The value of the spread modulated wave signal ((c) in the figure) is “−1”,
If the value of the modulated wave signal ((a) in the figure) is "-1" and the value of the spreading code 13a ((b) in the figure) is "1", the spread modulated wave signal ((c) in the figure) )) Is "-1", the value of the modulated wave signal (FIG. 14A) is "-1", and the value of the spreading code 13a (FIG. 14B) is "-1". In this case, the value of the spread modulated wave signal ((c) in the figure) is “1”.

As described above, in the spread spectrum device 13, the modulated wave signal (FIG. 2A) is added to the spread code 13a.
By multiplying ((b) in the figure), the “power density spectrum (state of power distribution for each frequency)” of the signal changes significantly. For example, if the distribution of the power density spectrum of the modulated wave signal provided from the primary modulator 12 falls within a relatively narrow frequency band, as indicated by a symbol L1 in FIG. 3, the power density spectrum is thin and widely distributed. The spread modulated wave signal, which is spread by the spectrum spreader 13 so that the power density spectrum is thin and widely distributed, is wirelessly transmitted to the receiving apparatus 2 through the antenna 15 by the wireless transmitter 14. .

The receiving device 2 includes a radio receiver 22 for receiving a radio signal given from the transmitting device 1 through an antenna 21, a despreader 23 for despreading a received signal received by the radio receiver 22, A demodulator 24 for demodulating the despread signal despread by the despreader 23, and a signal receiver 2 for receiving the demodulated signal demodulated by the demodulator 24 and performing predetermined processing.
5 is provided.

The despreader 23 multiplies the received signal received by the radio receiver 22 by a predetermined despreading code 23a by an integrator 23b, and spreads the spectrum by the spread spectrum unit 13 of the transmission source device 1. It is configured to return to the signal before processing (despread modulated wave signal). Here, the despreading code 23a is a spread code 13a (FIG. 2) obtained when the spread spectrum processing is performed by the spectrum spreader 13 of the transmission source apparatus 1.
(B) having the same waveform as that of (1) and "-1"
Therefore, when the value of the signal before despreading is “1” and the value of the despreading code 23a is “1”, the signal after despreading is “1”, When the value of the signal before despreading is “1” and the value of the despreading code 23a is “−1”, the signal after despreading is “−1”, and the value of the signal before despreading is “−”. 1 "and the value of the despreading code 23a is" 1 "
, The signal after despreading is “−1”, and when the value of the signal before despreading is “−1” and the value of the despreading code 23a is “−1”, the signal after despreading is “1”. Becomes “1”. The received signal received by the wireless receiver 22 is shown in FIG.
Since the spread modulated wave signal is nothing but the spread modulated wave signal shown in FIG.
a (the same code as the spreading code 13a shown in FIG. 2B)
The despread signal after the multiplication is the only modulated wave signal shown in FIG.

Thus, in this despreader 23,
Received signal received by the wireless receiver 22 (see FIG. 2C)
Is multiplied by the despreading code 23a (see FIG. 3B), the "power density spectrum (state of power distribution for each frequency)" of the signal changes greatly. For example, as shown by a symbol L2 in FIG.
In the case where the distribution of the power density spectrum of the received signal received in step 2 appears faintly in a wide frequency band, when the spread spectrum processing is performed on the distribution, as shown by a symbol L3 in FIG. Will fit in. Here, the despreading process in the despreader 23 performs exactly the same process as the spread spectrum process with the spread code 13a in the spread spectrum device 13 of the transmission source device 1. In the received signal received, the symbol N in FIG.
When a signal indicating a narrow power density spectrum distribution such as 1 appears, when such a signal is subjected to despreading processing, it is thin and wide as indicated by a symbol N2 in FIG. 5 just like the spread spectrum processing in the spectrum spreader 13. It will be converted into a power density spectrum distribution. And this despreader 23
Is designed to extract only a signal in a predetermined frequency band, which makes it easy to ignore the distribution of the code N2 with respect to the distribution of the code L3 in FIG. Even if a noise component like the symbol N1 in FIG. 4 is mixed, it can be easily removed.

The demodulator 24 performs a demodulation process by a predetermined method according to the modulation method used in the primary modulator 12 of the transmission source device 1, and outputs the original signal transmitted from the signal transmitter 11 of the transmission source device 1. It is designed to take out signals.

The signal receiver 25 is an information processing device having a predetermined specific function such as a radio tuner, an in-vehicle audio reproducer, or a car navigation device installed in an automobile, for example.

<Operation> The operation of the in-vehicle communication system having the above configuration will be described. First, the signal transmitted from the signal transmitter 11 of the transmission source device 1 is modulated by the primary modulator 12. At this time, a modulated wave signal which is an output signal (FIG. 2)
The distribution of the power density spectrum of (a)) falls within a relatively narrow frequency band as indicated by a symbol L1 in FIG.

An integrator 13b of the spectrum spreader 13 multiplies the modulated wave signal by a predetermined spreading code 13a (FIG. 2B) to generate a spread modulated wave signal (FIG. 2C).
Generate At this time, the spreading factor (the ratio of the chip rate to the bit rate) is set to, for example, about 128 times, so that the spread modulated wave signal becomes the code L2 in FIG.
The power density spectrum is thin and widely distributed as shown in FIG.

Here, when the value of the modulated wave signal (FIG. 2A) is "1" and the value of the spread code 13a (FIG. 2B) is "1", the spread modulated wave signal The value of ((c) in the figure) is "1", the value of the modulated wave signal ((a) in the figure) is "1", and the value of the spreading code 13a ((b) in the figure) is "-1". ”, A spread modulated wave signal ((c) in the same figure)
Is "-1", the value of the modulated wave signal ((a) in the figure) is "-1" and the value of the spreading code 13a ((b) in the figure) is "1". The value of the spread modulated wave signal (FIG. 13 (c)) is “−1”, the value of the modulated wave signal (FIG. 14 (a)) is “−1”, and the spreading code 13a (FIG. 13 (b)). Is "-1", the value of the spread modulated wave signal ((c) in the figure) is "1".

The spread modulated wave signal is wirelessly transmitted by the wireless transmitter 14 to the receiver 2 through the antenna 15.

In the receiving device 2, the radio receiver 22 receives the radio signal given from the transmitting device 1 through the antenna 21. The received signal at this time is despread by being multiplied by the despreading code 23a by the integrator 23b of the despreader 23, and is returned to a signal before the spread spectrum processing in the spread spectrum unit 13 of the transmission source apparatus 1.

Here, the despreading code 23a is the spreading code 13a used in the spectrum spreader 13 of the transmission source device 1.
When the value of the signal before despreading is "1" and the value of the despreading code 23a is "1", the signal after despreading is "1". And the value of the signal before despreading is “1” and the value of the despreading code 23a is “−1”.
, The signal after despreading is “−1”, and when the value of the signal before despreading is “−1” and the value of the despreading code 23a is “1”, the signal after despreading is “1”. When the value of the signal before despreading is "-1" and the value of the despreading code 23a is "-1", the signal after despreading is "1".

As described above, when the received signal (see FIG. 2C) received by the radio receiver 22 is multiplied by the despreading code 23a (see FIG. 2B), the "power density spectrum (frequency The state of the distribution of power for each) changes greatly. For example, when the distribution of the power density spectrum of the received signal received by the wireless receiver 22 appears faintly in a wide frequency band as indicated by a symbol L2 in FIG. , The power density spectrum falls within a narrow frequency band. here,
The despreading process performed by the despreader 23 is exactly the same as the spread spectrum process performed by the spread code 13 a in the spread spectrum device 13 of the transmission source device 1. When a signal having a narrow power density spectrum distribution such as the code N1 in FIG. 4 appears in the signal, when such a signal is subjected to despreading processing, the signal is spread in the same manner as in the spread spectrum processing in the spectrum spreader 13 in FIG. It is converted into a thin and wide power density spectrum distribution like the symbol N2 in the middle. The despreader 23 extracts only a signal in a predetermined frequency band, which makes it easy to ignore the distribution of the code N2 from the distribution of the code L3 in FIG. ,
Therefore, even if a noise component like the symbol N1 in FIG. 4 is mixed during the wireless communication, it can be easily removed.

The despread signal despread by the despreader 23 in this way is demodulated by the demodulator 24, and
The original signal transmitted from the signal transmitter 11 is extracted.

Thereafter, the signal receiver 25 is turned on by the demodulator 24.
Performs a specific function based on the signal given by

As described above, the transmission source device 1
Since information is transmitted from the receiver to the receiver device 2, the number of signal lines can be significantly reduced, the weight and space of the automobile can be reduced, and the installation location of the transmitter device 1 is not considered. Since the degree of freedom of installation is increased, it is easy to add an on-vehicle unit and an external device after purchasing a car.

In particular, since not only the primary modulation is performed in the transmission source device 1 but also a spread spectrum process is performed so that a spread modulated wave signal having a thin and wide power density spectrum distribution is wirelessly communicated to the reception destination device 2. Since the noise resistance can be greatly improved and the modulated wave signal can be prevented from being directly transmitted / received by the spread modulated wave signal communication, the confidentiality and confidentiality of the communication can be improved.

Further, as compared with the case of performing spread spectrum communication through a power supply line as disclosed in Japanese Patent Application Laid-Open No. 7-50619, noise components due to surge current of a blower of a starter motor or a vehicle air conditioner (air conditioner) are compared. It is possible to prevent unexpected modulation of a communication signal by a capacitor or a surge absorber for stabilizing a power supply line without a problem of mixing.

<< First Example >> Next, an example of the vehicle-mounted communication system according to this embodiment will be briefly described. An in-vehicle communication system according to a first example of this embodiment includes:
Source device 1 installed in a car so that it cannot be detached
Specifically, a signal related to radio broadcasting received by a radio receiving antenna of an automobile is transmitted to a signal transmitter 11 of the transmission source device 1.
Received by a radio broadcast receiver, and subjected to primary modulation and spread spectrum processing.
Wireless communication with the receiving device 2 including a radio tuner through

That is, as shown in FIG. 1, the transmission source device 1 transmits a radio broadcast receiver as a signal transmitter 11 and a signal transmitted from the signal transmitter 11 to a predetermined signal corresponding to the communication protocol of the reception destination device 2. Primary modulator 1 that converts the signal into a format signal
2, a spectrum spreader 13 for further performing spread spectrum processing on the modulated wave signal modulated by the primary modulator 12, and a spread modulated wave signal output from the spectrum spreader 13 converted into a radio signal to receive the signal. 2 and a wireless transmitter 14 for performing wireless transmission.

A radio receiver 22 for receiving a radio signal given from the transmission source device 1 through an antenna 21;
A despreader 23 for despreading the received signal received by the radio receiver 22, a demodulator 24 for demodulating the despread signal despread by the despreader 23, and a demodulated signal received by the demodulator 24. And a radio tuner as a signal receiver 25 for reproducing a radio broadcast.

The configuration of each element in the transmission source apparatus 1 and the reception destination apparatus 2 is as described above (see FIG. 1).

According to such an in-vehicle communication system, the noise resistance is strong, and the reduction in the number of communication lines can reduce the weight and space of the automobile.

Second Embodiment A vehicle-mounted communication system according to a second embodiment is installed in a vehicle so as to be non-detachable from a transmission source device 1 as an external device carried by a user into a vehicle compartment separately from a vehicle. The communication is performed with respect to the receiving device 2, and specifically, the signal transmitting device 11 of the transmitting device 1 reads and reproduces music information recorded on music media as the signal transmitting device 11. A portable audio device such as a portable headphone cassette tape player, a headphone compact disk (CD) player, or a headphone microdisk (MD) player is applied, and an audio signal output from a headphone signal output terminal of the portable audio device. After taking out
The primary modulator 12 converts the signal into a modulated wave signal of a predetermined format corresponding to the communication protocol of the reception destination device 2, and further performs a spread spectrum process in a spread spectrum device 13 to transmit the radio wave signal to the radio transmitter 1.
4 to the destination device 2 by radio.
Such a portable audio device can normally be driven for a long time by a built-in battery such as a lithium battery or an alkaline battery, and can be independently driven without being connected to a power supply of an automobile.

The receiving device 2 is an in-vehicle audio device that reproduces an audio signal given by wireless communication from the transmitting device 1.

When performing wireless communication from the transmission source device 1 to the reception destination device 2, it is desirable to provide a trigger signal for starting communication at the time of the start.

The configuration of each of the transmission source device 1 and the reception destination device 2 is as described above (see FIG. 1).

According to such an in-vehicle communication system, the noise resistance is high, and the reduction in the number of communication lines can reduce the weight and space of the automobile. In particular, when a portable audio device is used, the primary modulator 12 and the spread spectrum modulator 13 can be used for a portable audio device that is usually used without purchasing an audio device suitable for a power supply in a car. If a unit including the wireless transmitter 14 and the antenna 15 is connected, music can be reproduced by an in-vehicle audio device installed in a car in advance.

In addition, since the portable audio device is usually driven by a built-in battery, the portable audio device can be installed anywhere in the vehicle cabin without being restricted by the power supply wiring in the vehicle, and the reproduction operation and the operation can be performed at a desired place. Various operations such as a song feed operation can be performed.

Third Embodiment An on-vehicle communication system according to a third embodiment is provided between an external device brought into a vehicle compartment by a user separately from an automobile and an on-vehicle unit irremovably installed in the automobile. It is intended to realize not only mutual communication with each other but also mutual communication between a plurality of external devices through a vehicle-mounted unit.

Specifically, in the vehicle-mounted communication system according to this embodiment, as shown in FIG. 6, a portable notebook personal computer (external device) 31 as an external device is provided.
And a car navigation device 41 as an on-vehicle unit
To communicate with each other.

The personal computer (external device) 31 modulates and modulates the signal through an external connection port such as RS-232C formed in the personal computer 31.
It is connected to the demodulation unit 32. The modulation / demodulation unit 32 is connected to a spreading / despreading unit 33 and performs wireless communication with a car navigation device (vehicle unit) 41 through a wireless communication unit 34 and an antenna 35.

Here, the personal computer 31
The modulation / demodulation unit 32 has both functions of the primary modulator 12 and the demodulator 24, and has functions of both the signal transmitter 11 and the signal receiver 25.
The despreading unit 33 includes the spectrum spreader 13 and the despreader 23.
In addition, the wireless communication unit 34 has both functions of the wireless transmitter 14 and the wireless receiver 22. As a result, the data transmitted from the personal computer 31 is primary-modulated by the modulation / demodulation unit 32, and then subjected to spectrum spread processing by the spread / despread unit 33, and is transmitted as a radio signal from the wireless communication unit 34 and the antenna 35. While being wirelessly output, the wireless signal received by the antenna 35 and the wireless communication unit 34 is despread by the spreading / despreading unit 33, demodulated by the modulation / demodulation unit 32, and then input to the personal computer 31. ing.

The car navigation system (vehicle unit) 41 is connected to a modulation / demodulation unit 42 through a predetermined external connection port formed in the car navigation system 41.
The modulation / demodulation unit 42 is connected to a spreading / de-spreading unit 43, and is connected to a personal computer (external device) 3 through a wireless communication unit 44 and an antenna.
1 for wireless communication.

Here, the car navigation device 41
The modulation / demodulation unit 42 has both functions of the primary modulator 12 and the demodulator 24, and has functions of both the signal transmitter 11 and the signal receiver 25.
The despreading unit 43 includes the spectrum spreader 13 and the despreader 23.
The wireless communication unit 44 has both functions of the wireless transmitter 14 and the wireless receiver 22. As a result, the data transmitted from the car navigation device 41 is primary-modulated by the modulation / demodulation unit 42, then subjected to the spread spectrum processing by the spread / despread unit 43, and the radio signal is transmitted from the wireless communication unit 44 and the antenna 45. And the radio signal received by the antenna 45 and the radio communication unit 44 is despread by the spreading / despreading unit 43, demodulated by the modulation / demodulation unit 42, and then input to the car navigation device 41. It has become.

With such a configuration, this on-vehicle communication system is a car navigation device (vehicle unit) 41.
A variety of information handled in the vehicle can be shared by a plurality of personal computers (external devices) 31. Each personal computer can share the same information with the occupants of the rear seats of the automobile or the occupants of the bus seats. 31
Car navigation processing becomes possible.

In this embodiment, the car navigation device 41 is applied as the vehicle-mounted unit. However, the present invention is not limited to this, and various application software programs are shared between the vehicle-mounted unit and each personal computer 31. Then, simultaneous editing of data by a plurality of users in the automobile is possible. For this reason, for example, while a plurality of persons go on a business trip in one car, a plurality of occupants can jointly create the same material and perform an operation through wireless communication through the on-vehicle unit.

Further, in this embodiment, the modulation / demodulation unit 3
2. The spreading / despreading unit 33, the wireless communication unit 34, and the antenna 35 are configured separately from each personal computer 31, and the RS-2 of the personal computer 31
Although the external connection port such as 32C is connected to the modulation / demodulation unit 32, the modulation / demodulation unit 32, the spreading / despreading unit 33, the wireless communication unit 34, and the antenna 35 are mounted on one printed wiring board. If this is built in the personal computer 31 in advance by configuring a circuit, wireless communication can be directly performed with the on-vehicle unit without worrying about the connection wiring between them.

Further, since the spread spectrum processing is performed at the time of communication, it is possible to prevent the modulated wave signal from being directly transmitted / received, so that the confidentiality and confidentiality of the communication can be improved.

[0060]

According to the first aspect of the present invention, for example, in the communication between the on-vehicle units and the communication between the on-vehicle units and the external device as in the third and fourth aspects, Since the transmission of the communication signal from the transmission source device to the reception destination device is performed by wireless communication, the number of signal lines can be significantly reduced, and the weight and space saving of the vehicle can be realized. Since the degree of freedom of installation is increased without considering the installation location of the original device, it becomes easy to add the on-vehicle unit and the external device after purchasing the car.

In particular, since not only the primary modulation is performed in the transmission source apparatus, but also the spread spectrum is performed to spread the spread modulated wave signal having a thin and wide power density spectrum distribution to the reception destination apparatus by radio. Noise immunity can be greatly improved, and a modulated wave signal can be prevented from being directly transmitted / received by communication of a spread modulated wave signal, so that confidentiality and confidentiality of communication can be improved.

Further, compared to the case where spread spectrum communication is performed through a power supply line, there is no problem of noise components being mixed by a surge current of a starter motor or a blower of a vehicle-mounted air conditioner (air conditioner), and the power supply line is stabilized. Thus, there is an effect that unexpected modulation of a communication signal by a capacitor, a surge absorber or the like for the purpose can be prevented.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a vehicle-mounted communication system according to a first embodiment of the present invention.

FIG. 2 is a waveform chart showing respective waveforms of a modulated wave signal, a spread code, and a spread modulated wave signal.

FIG. 3 is a distribution diagram showing a difference in power density distribution of a signal before and after a spread spectrum device.

FIG. 4 is a diagram showing a state in which a noise component is added to a spread modulation wave signal.

FIG. 5 is a diagram illustrating a state in which a signal in a state where a noise component is added to a spread modulation wave signal is despread.

FIG. 6 is a block diagram illustrating a vehicle-mounted communication system according to a third example of the first embodiment of the present invention;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 source device 2 destination device 11 signal transmitter 12 primary modulator 13 spread spectrum device 13 a spreading code 13 b integrator 14 wireless transmitter 15 antenna 21 antenna 22 wireless receiver 23 despreader 23 a despread code 23 b integrator 24 Demodulator 25 Signal receiver 31 Personal computer (external device) 32 Demodulation unit 33 Despreading unit 34 Wireless communication unit 35 Antenna 41 Car navigation device (vehicle unit) 42 Modulation / decoding unit 43 Diffusion / despreading unit 44 Wireless communication unit 45 antenna

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Fumiaki Mizuno 1-7-10 Kikuzumi, Minami-ku, Nagoya-shi, Aichi F-term in Harness Research Institute, Inc. (reference) 5H180 AA01 BB05 BB13 CC12 FF03 FF22 FF32 5K022 EE02 EE21 EE31 5K067 AA41 BB21 BB43 CC10 EE02

Claims (4)

[Claims] An in-vehicle communication system for transmitting and receiving a desired communication signal in a vehicle between predetermined devices such as between on-vehicle units mounted on a vehicle or between on-vehicle units and various external devices. A signal transmission source device modulates desired information given from a predetermined signal transmitter, outputs a coded modulated wave signal, and a modulated wave output from the primary modulator. A spread spectrum generator for generating a spread modulated wave signal by multiplying a signal by a predetermined spreading code having a code rate sufficiently higher than that of the modulated wave signal to generate a spread modulated wave signal; and the spread modulation generated by the spectrum spreader. A wireless transmitter for wirelessly transmitting a wave signal, wherein a device for receiving a communication signal includes a wireless receiver for receiving a wireless signal wirelessly transmitted from the wireless transmitter; A despreader for despreading the signal received by the wireless transmitter by multiplying the same despreading code by the same despreading code to generate a despread modulated wave signal; and a despreading modulation generated by the despreader. A demodulator for demodulating a wave signal and inputting the demodulated signal to a predetermined signal receiver. 2. The in-vehicle communication system according to claim 1, wherein the signal transmitter and the signal receiver are on-vehicle units that are respectively irremovably installed in an automobile. system. 3. The in-vehicle communication system according to claim 1, wherein the signal transmitter is an external device that can be taken out of the vehicle, and the signal receiver is non-removably installed in a vehicle. An in-vehicle communication system, which is an in-vehicle unit. 4. An in-vehicle communication system for performing mutual communication between an external device carried by a user into a vehicle compartment separately from an automobile and one or more in-vehicle units irremovably installed in the automobile. 2. The in-vehicle communication system according to claim 1, wherein the external device and the on-vehicle unit each include both a device that is a transmission source of the communication signal and a device that is a reception destination of the communication signal. 3.