JP2005277666A - In-vehicle transmitter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately and inexpensively detect spike noise. <P>SOLUTION: The transmitter 11 which is connected to a power line W to be cabled to a vehicle has a modulator 13 which modulates an input signal entered from an input signal generator 12 by the power line carrier by making the power line W as a transmission path 29, and transmits it. The transmitter 11 is provided with a demodulator 15 for inspection, which is connected to the power line W and demodulates a signal on the transmission path 29, and a comparator 16 for comparing a signal for inspection demodulated by the demodulator 15 for inspection with the input signal. When it is determined that the signal for inspection and the input signal are different by the comparator 16, it is decided to be a communication error. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vehicle-mounted transmission device, and more particularly to a device that modulates and transmits a signal to a vehicle-mounted electrical component through a power line of a wire harness wired in a vehicle.

In recent years, automobile manufacturers have been making efforts to reduce the weight of vehicles by reducing the wire harnesses routed to the vehicle body in order to reduce exhaust gas and improve fuel efficiency in response to environmental problems. Attempts have been made to reduce communication lines by introducing a power line carrier technology that superimposes signals by time division or frequency division.
However, wiring harnesses in automobiles are installed in a limited body space, and all electrical equipment is installed near the power lines. May cause a communication error.

As countermeasures against the spike noise, it is possible to cut off the noise by electromagnetically shielding the power line, but if the shield line is used for the power line, the wire cost increases and the vehicle weight also increases. There's a problem.
As another countermeasure, it may be possible to provide a band-pass filter that cuts the frequency of the specific noise on the side that receives the signal from the power line. However, spike noise that occurs in the vehicle is abrupt and occurs in advance. Since it is difficult to know the noise frequency outside the setting, the noise frequency passes without being filtered, which causes a serious problem in terms of reliability.

In Japanese Patent Laid-Open No. 5-63458, the digital modulation method and the analog modulation method are appropriately distributed and combined to reduce the number of units of the power amplifying unit and improve characteristic deterioration due to quantization noise. Thus, it is disclosed that a highly efficient and high quality modulated wave can be obtained. However, there is no change in that there is no noise detection means on the modulation circuit side and spike noise generated on the transmission path cannot be detected.
JP-A-5-63458

  This invention is made | formed in view of the said problem, and makes it a subject to detect the spike noise which arises in the vehicle-mounted power line which transmits / receives a signal by power line conveyance accurately and at low cost.

In order to solve the above-mentioned problem, the present invention is a transmission having a modulation unit that is connected to a power line routed in a vehicle, modulates an input signal from an input signal generation unit by a power line carrier using the power line as a transmission path, and transmits the modulated signal. A device,
A demodulator for inspection that is connected to the power line and demodulates a signal on a transmission line;
Comparing the inspection signal demodulated by the inspection demodulator with the input signal,
An in-vehicle transmission device is provided in which a communication error is determined when the comparison unit determines that the inspection signal and the input signal are different.

  With the above configuration, the signal transmitted from the modulation unit of the in-vehicle transmission device onto the power line is re-acquired by the in-vehicle transmission device itself and demodulated by the inspection demodulation unit, and the demodulated inspection signal has the same code state as the input signal. A communication error can be easily detected on the transmission side by determining whether the comparison is maintained. That is, it is possible to provide a self-diagnosis function related to error detection of transmission signals in the in-vehicle transmission device.

  When the comparison unit determines that a communication error has occurred, it is preferable that the input signal is modulated by the modulation unit and retransmitted.

  As described above, since a communication error can be detected on the transmission side, automatic transmission error correction can be achieved by retransmitting at the time of the communication error as in the above configuration.

  Further, in this case, it is preferable that the modulation unit transmits a signal to a body-type or information-type in-vehicle electrical component connected to the power line.

With the above configuration, when the destination is a body-type or information-type in-vehicle electrical component that does not require real-time high speed and high reliability like a control system (powertrain system, safety system, etc.) When a communication error due to spike noise is detected, appropriate communication can be maintained by retransmitting.
Examples of body-based in-vehicle electrical components include door mirror devices, power window devices, wipers, and lighting devices. Examples of information-based in-vehicle electrical components include a car navigation device, an audio device, a front / back camera device, and the like.

  The modulation unit is configured to connect the input signal generation unit via a transistor to a ground line that grounds the power line, and to carry a transmission signal obtained by modulating the input signal on the power line.

  With the above configuration, the configuration of the modulation unit that modulates the input signal and places the signal as a carrier wave on the power line can be formed at low cost. In this case, since the signal is not different from the noise of the power source connected to the power line, the above-described retransmission function at the time of a communication error is effective.

The modulation unit performs amplitude modulation and transmits a transmission signal to the power line,
The inspection demodulator is configured to detect an envelope of the amplitude-modulated transmission signal.

  With the above configuration, the inspection demodulator uses envelope detection to compare with the input signal, so that the configuration can be made inexpensive.

  As is clear from the above description, according to the present invention, whether the signal transmitted from the in-vehicle transmission device to the power line is taken in again by the in-vehicle transmission device and demodulated by the inspection demodulator, and the same code state as the input signal is maintained. Therefore, it is possible to easily perform a communication error self-diagnosis on the transmission side.

Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a state in which an in-vehicle transmission device 11 is mounted on a vehicle, and a power line W that constitutes a wire harness is connected to a power source 10 that is mounted in the vehicle. And connected. The transmission signal transmitted from the in-vehicle transmission device 11 is transmitted to the in-vehicle reception device 30 by power line conveyance using the power line W as the transmission path 29.

  The in-vehicle transmission device 11 includes an input signal generation unit 12 that is a generation source of an input signal to be transmitted to the in-vehicle reception device 30, a modulation unit 13 that amplitude-modulates a signal from the input signal generation unit 12, and a cup to the transmission path 29. Ring capacitor 20, reception amplifier 14 that extracts an amplitude signal from transmission path 29, coupling capacitor 21 for coupling reception amplifier 14 and transmission path 29, and demodulator for inspection that demodulates the amplitude signal from reception amplifier 14 15 and a comparator 16 that compares the signal of the demodulator 15 for inspection with the input signal.

  The modulation unit 13 includes a control unit 17 that gives a command of magnitude according to the sign (1 or 0) of the digital input signal received from the input signal generation unit 12, an oscillation circuit 19 that generates a carrier wave, and the oscillation circuit 19. And a transmission amplifier 18 that superimposes the carrier wave on the power line W as an amplitude signal that is amplitude-modulated based on a command from the control unit 17.

  As shown in FIG. 2, the inspection demodulator 15 includes a diode 23 and a low-pass filter 26 including a resistor 24 and a capacitor 25 and performs envelope detection. And a resistor 28 are provided. The amplitude signal shown in FIG. 3A obtained by blocking the direct current component is cut off by the diode 23 as shown in FIG. 3B, and the envelope shown in FIG. It is detecting.

  The in-vehicle receiving device 30 includes a capacitor 31 for coupling with the transmission path 29, a receiving amplifier 32 that amplifies the received carrier wave, a demodulator 33 that demodulates the received amplitude signal into a digital signal, and the digital signal. And a main body processing unit 34 for performing predetermined processing. The vehicle-mounted receiving device 30 is a body-mounted vehicle-mounted electrical component such as a door mirror device, a power window device, a wiper, a lighting device, or the like, or an information-based vehicle-mounted electrical component such as a car navigation device, an audio device, or a front / back camera. Equipment etc.

Next, the communication error self-detection function of the in-vehicle transmission device 11 will be described.
When the input signal from the input signal generation unit 12 is “0”, the modulation unit 13 of the in-vehicle transmission device 11 transmits a low-amplitude signal having an amplitude less than a predetermined threshold to the transmission path 29 according to a command from the control unit 17. While transmitting as a signal, when the input signal is “1”, a high-amplitude signal having an amplitude equal to or greater than the threshold is transmitted to the transmission path 29. When there is no input signal from the input signal generator 12, no signal with an amplitude of zero is assumed.

  The demodulator 33 of the in-vehicle receiver 30 determines “0” when the signal received from the transmission path 29 is a low-amplitude signal, while it determines that the signal received from the transmission path 29 is a high-amplitude signal. It is determined as “1” and demodulated into a digital signal. Upon receiving the digital signal, the main body processing unit 34 performs a predetermined process.

The inspecting demodulator 15 of the in-vehicle transmitter 11 takes out the amplitude signal transmitted from the modulator 13 to the transmission path 29 from the power line W via the capacitor 21 and the reception amplifier 14 and receives it, and the received signal has a low amplitude. When it is a signal, it is set to “0”, and when it is a high amplitude signal, it is demodulated as a digital inspection signal as “1”.
The comparator 16 compares the test signal demodulated by the test demodulator 15 with the input signal transmitted by the input signal generator 12, that is, the difference between these signals is a predetermined value or more. In this case, it is determined that the communication error is caused by disturbance spike noise. On the other hand, when the test signal matches the input signal, that is, when the difference between these signals is less than a predetermined value, it is determined that the signal is normal.

  If the comparison unit 16 determines that a communication error has occurred, the control unit 17 is instructed to modulate and retransmit a correct input signal by the modulation unit 13. At this time, it is also preferable to transmit a message to the in-vehicle receiving device 30 that the previously transmitted signal is an error and should be discarded.

FIG. 4 shows a modification of the modulation unit 40 of the in-vehicle transmission device 11.
The modulation unit 40 of the modified example connects the input signal generation unit 12 to a ground line that grounds the power line W via a resistor 42 and a transistor 41 (which may be a field effect transistor), and outputs from the input signal generation unit 12. The input signal may be modulated and carried on the power line W.
In this case, the configuration of the modulation unit 40 can be formed at a low cost, but since the signal is not different from the noise of the power supply 10 connected to the power line W, the above-described retransmission function at the time of a communication error becomes effective.

It is a block diagram which shows the vehicle-mounted modem device of embodiment of this invention. It is a circuit diagram which shows the demodulation part for a test | inspection. (A)-(C) are explanatory drawings of envelope detection. It is drawing which shows the modulation | alteration part of a modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Power supply 11 Car-mounted transmitter 12 Input signal generation part 13 and 40 Modulator 15 Demodulator 16 for inspection 16 Comparison part 30 Car receiver 41 Capacitor W Power line

Claims (5)

A transmission device connected to a power line routed in a vehicle, and having a modulation unit that modulates and transmits an input signal from an input signal generation unit by power line carrier using the power line as a transmission path,
A demodulator for inspection that is connected to the power line and demodulates a signal on a transmission line;
A comparison unit that compares the test signal demodulated by the test demodulation unit with the input signal;
An in-vehicle transmission device characterized by determining that it is a communication error when the comparison unit determines that the inspection signal and the input signal are different.   The in-vehicle transmission device according to claim 1, wherein when the comparison unit determines that a communication error has occurred, the input signal is modulated by the modulation unit and retransmitted.   The in-vehicle transmission device according to claim 2, wherein the modulation unit transmits a signal to a body-type or information-type in-vehicle electrical component connected to the power line.   The said modulation | alteration part connects the said input signal generation | occurrence | production part via the transistor to the ground line which earth | grounds the said electric power line, It is set as the structure which carries the transmission signal which modulated the said input signal on the said electric power line. The in-vehicle transmission device according to any one of items 3. The modulation unit performs amplitude modulation and transmits a transmission signal to the power line,
5. The in-vehicle transmission device according to claim 1, wherein the inspection demodulator is configured to detect an envelope of the transmission signal subjected to amplitude modulation. 6.

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