JP2004040211A - Ring network system and apparatus for network - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a stable high speed data communication, in a ring network system. <P>SOLUTION: Electrical equipment, such as a CD changer 13 and an amplifier 14 in a ring network system 10 for making a data communication, in a fixed period has a modem 20 which modulates a carrier of data in a process about the transmission, and obtains time series data by subjecting the frequency component of the modulated carrier to IFFT at the same period as a transmission period. A transmission side electrical equipment transmits the obtained time series data enabling the communication with a lower frequency band than the transmission rate of the data and reducing the influence of radiated noises to ensure a stable communication. The modem 20 subjects the received time series data to FFT with the same period as the communication period, to obtain the frequency component and calculates original data from the frequency component, to receive the transmitted data. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to data communication between devices in a ring network system, and more particularly to a ring network system and network devices that secure stable high-speed data communication by changing a frequency band used for communication.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, there has been a ring network system in which electronic devices and electrical devices for various networks are connected in a ring, and data communication between the devices is performed at a constant cycle. Such a ring network system is constructed in various places, but recently, it is often constructed in a vehicle equipped with various electric equipment.
[0003]
FIG. 6A shows a conventional ring network system 1 built in the vehicle 2. In the ring network system 1, a CD changer 3, an amplifier device 4, a navigation device 5, a hands-free telephone device 6, a radio tuner 7, and a television tuner 8, which are electrical devices for a vehicle-mounted network, are daisy-chained by a metal cable connection line 1a. They are connected in a ring in a system. In the ring network system 1, the direction of data communication is constant, and data is communicated from one electrical device to another in the direction of the arrow (counterclockwise) in the figure.
[0004]
Each of these electrical devices has a common basic configuration, and includes a portion related to its own function and a portion related to communication. For example, as shown in FIG. 6B, the CD changer 3 includes a CD drive 3a for reading audio data of a CD (compact disk) as a part relating to its own function, and a communication unit 9 corresponding to a part relating to communication. I do. Further, the amplifier device 4 includes an amplifier 4a connected to the speaker 4b to amplify data and a communication unit 9 as a unit related to communication, as units related to its own function. The communication units 9 of the CD changer 3 and the amplifier device 4 have the same configuration, respectively, and are also provided in other electric devices such as the navigation device 5.
[0005]
Therefore, when the audio data of the CD is output from the speaker 4c, the audio data read by the CD drive 3 is sent to the communication unit 9 of the CD changer 3, and the communication unit 9 converts the audio data by a rectangular carrier wave shown in FIG. Serial transmission is performed at a constant cycle through the connection line 1a. On the other hand, the communication unit 9 of the amplifier device 4 receives the transmitted carrier wave and sends it out to the amplifying unit 4a, thereby outputting audio data from the speaker 4b.
[0006]
[Problems to be solved by the invention]
The ring network system 1 communicates data in the above-described configuration. However, when the data communication speed is increased, the frequency of the data carrier increases, and noise is radiated from the connection line 1a. The radiated noise has an adverse effect on other electric equipment, and for example, radiated noise is included in audio data of the radio tuner 7 and the television tuner 8 and the like, and there is a problem of deteriorating sound quality. Also, depending on the data transmission situation, such as when transmitting about 50 Mbits of data per second, the radio tuner 7 is more susceptible to the noise radiated from the relationship between the carrier frequency and the FM radio frequency band.
[0007]
Further, when such noise is radiated from a rectangular carrier, the noise is likely to be radiated, and the influence of the noise on surrounding electrical equipment is further increased. Further, since the frequency of the carrier wave is increased, crosstalk in which noise of one cable is mixed into the other cable between a plurality of cables of the twisted pair forming the connection line 1a occurs, or each data is transmitted. There is also a problem that a phenomenon called jitter, which makes accurate data transfer difficult due to the time shift, occurs.
[0008]
The present invention has been made in view of such circumstances, and by securing a required data communication speed and suppressing the frequency band of a carrier wave, electric equipment such as a radio tuner is affected by radiation noise. It is an object of the present invention to provide a ring network system and a network device that enable stable communication without using a network.
It is another object of the present invention to provide a ring network system and a network device in which the influence of noise radiated to the surroundings is reduced by forming a data carrier into a sine wave shape.
Furthermore, the present invention provides a ring network system and a network device that maintain stable communication by preventing the occurrence of crosstalk and jitter, which hinder good communication, by performing communication while keeping the frequency of a data carrier low. The purpose is to provide.
[0009]
[Means for Solving the Problems]
The ring network system according to the first invention is a ring network system in which a plurality of devices are connected in a ring, and one device and another device perform data communication at a constant cycle. A modulating means for modulating the carrier wave, a converting means for converting the frequency component of the carrier wave modulated by the modulating means to time-series data in the cycle, and transmitting the time-series data converted by the converting means in the cycle. Transmitting means for sampling the received time-series data at the cycle, and re-sampling the time-series data sampled by the sampling means to the frequency component at the cycle. Re-conversion means for performing conversion, and calculation means for calculating the data based on the frequency components subjected to re-conversion by the re-conversion means.
[0010]
In the ring network system according to the second invention, the one device further includes a first synchronization unit that synchronizes the conversion of the conversion unit and the transmission of the transmission unit, and the other device further performs transmission of the transmission unit. On the other hand, there is provided a second synchronizing means for synchronizing the sampling of the sampling means and the reconversion of the reconversion means.
[0011]
In the ring network system according to a third aspect, the one device further includes a dividing unit for dividing the original data into a plurality of divided data, and the modulating unit includes a carrier for the plurality of divided data divided by the dividing unit. Means for modulating, the converting means comprises means for converting the frequency components of the modulated plurality of carriers into time-series data, the re-conversion means, the frequency of the plurality of carrier waves Means for re-converting the plurality of frequency components, the calculating means comprises means for calculating the plurality of divided data based on the plurality of re-converted frequency components, the other device further, the plurality of calculated It is characterized by comprising a restoring means for combining the divided data and restoring the original data.
[0012]
A ring network system according to a fourth aspect is characterized in that the modulation means includes means for changing the amplitude and phase of the carrier.
[0013]
A network device according to a fifth aspect of the present invention is a network device that transmits data at a fixed period, comprising: a dividing unit that divides original data into a plurality of divided data; Modulating means for modulating a carrier; converting means for converting the frequency components of a plurality of carriers modulated by the modulating means into time-series data in the cycle; transmitting the time-series data converted by the converting means in the cycle; Means.
[0014]
A network device according to a sixth aspect of the present invention is a network device for receiving data transmitted from an external device at a fixed period, wherein the receiving device receives time-series data; Sampling means, sampling means, re-conversion means for re-converting the time series data sampled by the sampling means into a plurality of frequency components in the cycle, and a plurality of data based on the plurality of frequency components re-converted by the re-conversion means. And a restoring means for combining the plurality of data calculated by the calculating means and restoring the original data.
[0015]
According to the first aspect of the present invention, since a carrier of data transmitted by one device on the transmission side is modulated and converted into time-series data, the frequency band used for transmission can be changed. Therefore, even if the data communication speed is increased, the transmission frequency band can be suppressed low, so that the amount of radiated noise itself can be suppressed and the influence of radiated noise on peripheral devices can be prevented. Also, by converting the shape of the carrier wave of the time-series data into a waveform having no edge such as a sine waveform, it is possible to reduce the influence on the peripheral devices due to noise radiated from the connection line for transmitting the data.
[0016]
Further, by changing the transmission frequency band to be low, it is possible to suppress crosstalk, jitter, and the like, which have conventionally occurred during communication in a high frequency band, and maintain a good communication state. Note that the conversion and transmission by one device, and the sampling and reconversion by another device are all matched with the data communication cycle in the ring network system. Even if various processes are performed, reliable data transmission / reception can be performed.
[0017]
According to the second invention, the conversion and transmission processes are synchronized by the first synchronization means of one device, and the sampling and reconversion are also synchronized with the transmission by the second synchronization means of another device. In addition, it is possible to prevent problems such as duplication of data and unequal data intervals between data to be transmitted and data to be received, thereby ensuring stable and smooth communication.
[0018]
In the third invention, the fifth invention and the sixth invention, as the OFDM (Orthogonal Frequency Division Multiplexing) modulation, a carrier of a plurality of divided data divided from original data to be transmitted is modulated. , The transmission frequency band can be changed in various ways, and stable data communication can be ensured even if the data amount is large.
[0019]
Further, by creating the divided data, various modulation schemes can be applied to the modulating means. For example, PSK modulation (Phase ShiftKeying) that modulates by changing the phase of the carrier, and ASK modulation (Phase ShiftKeying) that modulates depending on the presence or absence of the amplitude of the carrier. Amplitude Shift Keying, FSK modulation (Frequency Shift Keying) that modulates using a plurality of amplitudes in a carrier, PSK modulation (Phase Shift Keying) that modulates by changing the phase of a carrier, and modulated waves having two different phases. QPSK (Quadrature PSK) modulation or the like, which synthesizes and converts the data, can be applied.
[0020]
In addition, by modulating the carrier of each divided data by various methods in this manner, the frequency use efficiency for data communication can be improved, and parallel communication can be performed with each frequency having a plurality of bits of data.
[0021]
The data communication described above is performed using a metal cable, but by setting the frequency band to be changed to be the same as the frequency band of the plastic optical fiber cable, the system that used the plastic optical fiber cable to perform communication will use a plastic optical fiber cable. High-speed communication using a metal cable instead of a fiber cable can be realized. Therefore, when the application of the plastic optical fiber cable is difficult, for example, when the laying point is narrow and the minimum bending rate of the plastic optical fiber cable cannot be ensured, the cable is laid on the moving member and the load accompanying the movement is large on the cable. In such a case, by introducing the system according to the present invention and performing communication using a metal cable, stable communication can be ensured.
[0022]
According to the fourth aspect, since the modulation is performed by changing the amplitude and the phase of the carrier, the occupied frequency of the plurality of divided data can be reduced to realize efficient data communication. As a method for performing such modulation, it is preferable to apply QAM (Quadrature Amplitude Modulation) modulation in which a value of a frequency amplitude value and a phase difference is changed to perform multi-level conversion.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described with reference to the drawings showing the embodiments.
FIG. 1 is a main part configuration diagram of a ring network system 10 constructed in a vehicle 12 according to an embodiment of the present invention. The overall configuration of the ring network system 10 is the same as the conventional system shown in FIG. 6A, and includes a CD changer 13, an amplifier device 14, a navigation device (not shown), a hands-free telephone device, a radio tuner, and a television tuner. The in-vehicle electrical equipment corresponding to the network equipment such as the above is connected in a ring shape by a connection line 11 of a twisted pair metal cable. In the ring network system 10, data communication is performed between one electrical device and another electrical device in a counterclockwise direction at a constant cycle.
[0024]
The electrical equipment such as the CD changer 13 and the amplifier device 14 according to the present invention is provided with a modulation / demodulation unit 20 as a part different from the conventional electrical equipment, and the CD changer 13 in FIG. In addition to the communication unit 19 composed of the drive 13a and the large-scale integrated circuit, a modulation / demodulation unit 20 connected to the communication unit 19 so as to be able to transmit and receive data is provided. The modulation / demodulation unit 20 is also connected to the input terminal 13b and the output terminal 13c of the CD changer 13.
[0025]
The modulation / demodulation unit 20 performs processing on data received by the CD changer 13 from the outside via the input terminal 13b, and performs processing on data transmitted from the output terminal 13c. The modulation / demodulation unit 20 provided in the CD changer 13 has the same configuration as that provided in other electric equipment such as the amplifier device 14, and the modulation / demodulation unit 20 in the other electric equipment is also the same as the CD changer 13 described above. Is the same as the connection configuration in.
[0026]
FIG. 2 is a block diagram showing the internal configuration of the modem unit 20. The modem unit 20 includes an input amplifier unit 21, an input low-pass filter 22, an A / D (analog / analog) in order from the side connected to the input terminal 13b. A digital) converter 23, a digital processing unit 24, a D / A (digital / analog) converter 25, an output-side low-pass filter 26, and an output amplifier unit 27 connected to the output terminal 13c are provided. Further, the modulation / demodulation unit 20 also includes a synchronization unit 28 connected to the A / D converter 23, the digital processing unit 24, and the D / A converter 25.
[0027]
The digital processing unit 24 connected to the communication unit 19 is configured by a large-scale integrated circuit, and performs OFDM conversion on data at the same cycle as that of data communication in the ring network system 10 to reduce the actual data communication speed. This enables communication in a lower frequency band.
[0028]
The digital processing unit 24 includes various processing units relating to data transmission and various processing units relating to data reception, and receives original digital data relating to a CD (Compact Disc) to be transmitted from the communication unit 19. The digital data received from the outside is processed by the digital processing unit 24 and then sent to the communication unit 19 or the D / A converter 25.
[0029]
The digital processing unit 24 functions as a unit that samples the data received from the communication unit 19, a dividing unit, a modulating unit, and a converting unit for the process related to data transmission. The sampling unit of the digital processing unit 24 performs sampling twice or more times as many times as the number of data divisions by the dividing unit described later in the reciprocal time of the data communication cycle of the ring network system 10. Therefore, for example, if the communication cycle is 44.1 kHz and the number of data divisions is 256, the sampling time per time is 1 / (44100 × 256 × 2) seconds.
[0030]
The dividing means of the digital processing unit 24 divides the data sequence of "0" and "1" of the sampled digital data into a plurality of sets of a plurality of bit sequences to generate a plurality of divided data. The dividing means can divide the original digital data in various division forms. For example, the original digital data in 1280-bit units can be divided to create a total of 256 sets of divided data of one set of 5 bit strings.
[0031]
The modulating means of the digital processing unit 24 modulates the carrier of the plurality of divided data divided by the dividing means according to the content of each divided data. The modulating means of the present embodiment includes means for performing QAM modulation for changing the amplitude value and phase difference value of a carrier wave as a modulation process, and this QAM modulation is performed according to the division method of the dividing means. ing.
[0032]
For example, when the dividing means creates a total of 256 sets of 5-bit divided data per set, the modulating means converts the contents of 5 bits of each of the 256 sets of divided data into the frequency f of each carrier of each divided data. ₁ , F ₂ , F ₃ , ~ F ₂₅₅ , F ₂₅₆ And the amplitude value and the phase difference value, which are the frequency components of each frequency, are calculated according to the 5-bit content of each divided data.
[0033]
By QAM-modulating a large number of divided data in this way, multi-bit (5 bits in the above example) data can be transmitted at one kind of frequency, and the frequency occupied per bit of data is suppressed to enable efficient communication. I have to. In addition, although all bits related to communication can be used for information communication, it is preferable to improve the reliability of communication by using any one bit for error correction of communication or for frequency diversity.
[0034]
By performing QAM modulation in this way, digital data can be changed to data related to the frequency axis. When QAM modulation is performed on a total of 256 sets of divided data, one set of which is 5 bits, as in the above-described example, as shown in FIG. _x For each frequency f having an amplitude value and a phase difference value corresponding to each divided data ₁ , F ₂ , F ₃ , ~ F ₂₅₅ , F ₂₅₆ Will be converted to a graph.
[0035]
The conversion means of the digital processing unit 24 converts the amplitude value and the phase difference value, which are the frequency components of the plurality of carriers modulated by the modulation means, into time-series data by IFFT (inverse fast Fourier transform). is there. This IFFT conversion is also performed at the same cycle as the data communication cycle of the ring network system 10, and the conversion time is synchronized with the data communication time by the synchronization unit 28.
[0036]
Therefore, each frequency f in FIG. ₁ , F ₂ , F ₃ , ~ F ₂₅₅ , F ₂₅₆ When the graph of the frequency component according to is converted, as shown in the graph of FIG. 3B, sine-wave time-series data on the time axis having time t as the horizontal axis is generated.
[0037]
By converting the frequency components into time-series data in this manner, it becomes possible to communicate each frequency component having multi-bit data as time-series data in a parallel state, thereby improving communication efficiency and securing a required communication speed. In addition, since the conversion is performed in synchronization with the data communication in the same cycle, there is no problem such as an overlap and an interval between the data to be communicated. Further, by making the shape of the carrier wave of the data to be transmitted a sinusoidal waveform, noise radiated from the connection line 11 is reduced, and adverse effects on devices located around the ring network system 10 are suppressed.
[0038]
Further, the time-series data generated as described above is sent from the digital processing unit 24 to the D / A converter 25 to be converted into analog data and then sent to the output side low-pass filter 26 as shown in FIG. Is done. The output-side low-pass filter 26 removes the high-frequency component of the transmitted analog data and sends it to the output amplifier 27. The output amplifier 27 adjusts the voltage of the sent analog data to an appropriate level, and 13c. This transmission is controlled so that the communication unit 19 corresponding to the transmission unit performs the transmission at a constant cycle based on the processing result of the digital processing unit 24 as in the related art.
[0039]
On the other hand, the data received by the digital processing unit 24 is analog time-series data transmitted from other electrical equipment as described above, and in the CD changer 13 of FIG. Has been received. The CD changer 13 adjusts the data received at the input terminal 13 b to a voltage suitable for data processing by the input amplifier unit 21, removes high-frequency components by the input-side low-pass filter 22, and sends the data to the A / D converter 23. ing.
[0040]
The A / D converter 23 functions as sampling means for receiving the transmitted analog time-series data and sampling the data received in the same cycle as the data communication cycle of the ring network system 10. The timing of performing this sampling is also synchronized with the data communication time by the synchronization unit 28, and the sampling time per time is also the reciprocal time of the value obtained by multiplying the communication cycle by a value twice or more the number of data divisions. become. The A / D converter 23 converts the sampled analog data into digital data, and sends out the converted digital time-series data to the digital processing unit 24.
[0041]
The digital processing unit 24 functions as a re-conversion unit, a calculation unit, and a restoration unit for the digital data received from the A / D converter 23 for the process related to the data reception.
[0042]
The re-conversion means re-converts the digital time-series data sampled and received by the A / D converter 23 into the above-mentioned frequency component of the carrier of the data using FFT transform (fast Fourier transform). The reconversion is also performed at the same cycle as the data communication cycle of the ring network system 10. The timing of performing the reconversion is synchronized with the timing of the data communication by the synchronization unit 28. By re-converting the time-series data in this manner, the amplitude value and the phase difference value, which are the frequency components of the original carrier, can be clarified, and even when the time-series data has the frequency components of a plurality of carriers, each carrier has its own frequency component. Can be determined.
[0043]
Therefore, the re-conversion means converts, for example, the time-series data on the time axis in FIG. 3B into a plurality of frequencies f on the frequency axis in FIG. ₁ , F ₂ , F ₃ , ~ F ₂₅₅ , F ₂₅₆ Is converted back to the frequency component of ₁ , F ₂ , F ₃ , ~ F ₂₅₅ , F ₂₅₆ The values of the amplitude value and the phase difference are clarified every time.
[0044]
Further, the calculating means of the digital processing unit 24 calculates by demodulating into a plurality of divided data generated by the above-mentioned dividing means based on the frequency components related to the frequencies of the plurality of re-converted carrier waves. For example, if the dividing unit of the transmission-side electrical device generates 5-bit divided data, the calculating unit calculates the content of 5 bits from the re-converted amplitude value and phase difference value for each frequency. I have.
[0045]
Further, the restoring means of the digital processing unit 24 sequentially combines the plurality of calculated divided data to restore continuous original digital data before division. Therefore, for example, if the dividing unit divides the original digital data of 1280-bit unit to create a total of 256 sets of 5-bit string divided data, the restoring unit will generate 256 sets of 5-bit string divided data. To restore the original digital data in 1280 bits.
[0046]
When the original digital data restored in this way is used in a portion related to the function of the restored electrical device, the portion related to the function of the electrical device is transmitted from the digital processing unit 24 via the communication unit 19. Sent to When the restored digital data is not used by the restored electrical device, the digital processing unit 24 performs processing related to transmission again and transmits the digital data from the output terminal 13c.
[0047]
The synchronizing unit 28 has an oscillator therein, and detects the period of the input data by being connected to a circuit that connects the input-side low-pass filter 22 and the A / D converter 23. Therefore, the synchronizing unit 28 is a first synchronizing unit and a second synchronizing unit that synchronize the respective units of the communication unit 19, the A / D converter 23, the digital processing unit 24, and the D / A converter 25 in accordance with the detected period. Functioning as
[0048]
The data communication between the respective electrical devices including the above-described modulation / demodulation unit 20 will be described using specific numerical values. For example, the data communication cycle in the ring network system 10 is determined by the CD drive 13a of the CD changer 13 in FIG. When the same setting is made as the CD reading cycle of 44.1 kHz and a total of 256 sets of divided data are created with 6 bits per set, theoretically, data that can be transmitted in one second is calculated from the following calculation from 44100 × 256 × 6. = About 64 Mbit.
[0049]
Furthermore, the frequency band related to communication at this communication speed is:
44.1kHz × 256 = about 11.2MHz
Thus, data communication can be performed in a frequency band of about 11.2 MHz, which is greatly deviated from the frequency band of the FM radio. The communication wave of the FM radio can be prevented from being affected by radiation noise, and the frequency band of the communication can be reduced. This is set lower than in the prior art to prevent the occurrence of crosstalk, jitter and the like.
[0050]
When data is actually communicated, it is preferable to increase the reliability of communication by using any one of a plurality of carrier frequencies of the divided data for error correction or the like. Therefore, even when data of a maximum of 64 Mbps can be communicated per second under the above-described communication conditions, it is preferable to set data to be actually communicated at about 50 Mbps.
[0051]
Next, as a specific data communication situation of the ring network system 10, a CD changer 13 corresponding to one electrical device is transferred from the CD changer 13 corresponding to another electrical device to a CD changer device 14 based on the time chart of FIG. The case where the voice data read in step 13 is communicated will be described.
[0052]
In this specific example, the data communication cycle is set to be the same as the CD reading cycle of 44.1 kHz of the CD drive 13a of the CD changer 13 in FIG. 1, and each time T1 to T6 in the time chart is a ring network. It means the time of the reciprocal of the data communication cycle in the system 10. Therefore, since the data communication cycle is 44.1 kHz, each time T1 to T6 is 1/44100 seconds.
[0053]
At the first time T1 in the time chart of FIG. 4, the communication unit 19 of the CD changer 13 outputs the data d1, which is the first data read by the CD drive 13a, and outputs the output first data d1 to the CD. The modulation / demodulation unit 20 of the changer 13 performs sampling. The modulation / demodulation unit 20 of the CD changer 13 creates divided data based on the sampled data d1, and then performs QAM modulation. At the next time T2, the modulation / demodulation unit 20 of the CD changer 13 performs the IFFT conversion of the QAM-modulated data d1, and simultaneously samples the second data d2 output from the communication unit 19 of the CD changer 13, performs division and QAM. Perform modulation. Note that the modulation and demodulation unit 20 performs conversion for the number of data division points by one operation related to IFFT conversion.
[0054]
At time T3, the modulation / demodulation unit 20 of the CD changer 13 outputs the converted data d1 subjected to the IFFT in an analog state, and the output converted data d1 is sampled and converted into digital by the modulation / demodulation unit 20 of the amplifier device 14. At this time T3, the modulation / demodulation unit 20 of the CD changer 13 performs the IFFT conversion on the data d2 in the same manner as described above, samples the third data d3 output from the communication unit 19, and performs division of the data d3 and QAM modulation. Do.
[0055]
At the next time T4, the modulation / demodulation unit 20 of the amplifier device 14 performs FFT conversion on the converted data d1, calculates the conversion result, and restores the original data d1. Note that the modulation / demodulation unit 20 of the amplifier device 14 performs conversion of the number of data division points by an operation related to one FFT conversion. Simultaneously with the restoration of the data d1, the modulation / demodulation unit 20 of the amplifier device 14 samples the converted data d2 output from the CD changer 13 and converts it into digital data. On the other hand, in the CD changer 13, the data d3 is IFFT-converted by the modulation / demodulation unit 20, and the fourth data d4 output from the communication unit 19 is sampled to perform division of the data d4 and QAM modulation.
[0056]
At the next time T5, the modem unit 20 of the amplifier device 14 outputs the restored data d1, and the data d1 is input to the communication unit 19 of the amplifier device 14. Further, the modulation / demodulation unit 20 of the amplifier device 14 performs sampling of the conversion data d3 output from the CD changer 13 and FFT conversion of the conversion data d2 to restore the original data d2. On the other hand, the CD changer 13 samples the fifth data d5 output from the communication unit 19 by the modem unit 20, performs division and QAM modulation, and performs IFFT conversion on the data d4.
[0057]
Further, at the next time T6, the communication unit 19 of the amplifier device 14 outputs the data d1, and the output data d1 is output as sound from the speaker 14d to the outside through the amplification unit 14a shown in FIG. The sound for the first data d1 is output from the speaker 14d in this manner after the lapse of the total time T1 to T6 since the communication unit 19 of the CD changer 13 outputs the data d1.
[0058]
Also, after time T6, voices for data d2, d3, d4, etc. are sequentially output from the speaker 14d at the same time cycle, and the outputs of these data d2, d3, d4, etc. are processed at each stage relating to data communication. Since the synchronization is performed in the same cycle, the sound is output from the speaker 14d in a smoothly continuous state without overlapping or interruption.
[0059]
In the actual ring network system 10, since data is output simultaneously from a plurality of electrical devices of the system, in addition to the above-described process, each electrical device also performs a process related to data output from the upstream side in the data communication direction. Will be done at the same time. An example of such a data communication processing situation is a case where the CD changer 13 transmits both its own data and data received from a television tuner connected to the upstream side of the CD changer 13 in FIG. This will be described based on the time chart shown in FIG.
[0060]
At the first time T10, the communication unit of the television tuner outputs the data d10 in analog, and the communication unit 19 of the CD changer 13 outputs the digital data d20 read by the CD drive 13a. The modulation / demodulation unit 20 of the CD changer 13 samples the output data d10 to make it digital, and samples and splits the data d20 to perform QAM modulation.
[0061]
At the next time T11, the modulation / demodulation unit 20 of the CD changer 13 performs FFT conversion on the digitized data d10 to restore the data d10, and performs IFFT conversion on the QAM-modulated data d20. At the same time as the conversion processing, the modulation / demodulation unit 20 of the CD changer 13 samples the data d11 output from the TV tuner and the data d21 output from the communication unit 19, and performs division and QAM modulation of the data d21.
[0062]
At the next time T12, the modulation / demodulation unit 20 of the CD changer 13 outputs the IFFT-converted converted data d20 in an analog state, and the output converted data d20 is sampled by the modulation / demodulation unit 20 of the amplifier device 14 and digitalized. Convert to The modulation / demodulation unit 20 of the CD changer 13 performs FFT conversion of the data d11 to restore the data d11, and performs IFFT by combining the restored data d10 and the QAM-modulated data d21.
[0063]
At this time T12, the modulation / demodulation unit 20 of the CD changer 13 samples the data d12 output from the television tuner and the data d22 output from the communication unit 19, and divides the data d22 and performs QAM modulation.
[0064]
At the next time T13, the modulation / demodulation unit 20 of the CD changer 13 combines the IFFT-converted converted data d10 and d21 into a plurality of slots of one frame, and outputs the data in an analog state. By outputting in this manner, data of the CD changer 13 and data of the television tuner are communicated without collision. The output conversion data d10 and d21 are sampled by the modulation / demodulation unit 20 of the amplifier device 14 and converted into digital data.
[0065]
Further, at this time T13, the conversion data d20 is FFT-transformed by the modulation / demodulation unit 20 of the amplifier device 14, and the conversion result is calculated to restore the original data d20. The processing of the amplifier device 14 after time T13 is basically the same as the processing after time T5 in the time chart of FIG. 4, but after time T13, both the data of the CD changer 13 and the data of the television tuner are used. Is sampled, so that only data corresponding to the data source whose output is set by the amplifier device 14 is output from the speaker 14d.
[0066]
At this time T13, the modulation / demodulation unit 20 of the CD changer 13 performs FFT conversion of the data d12 to restore the original data d12, while combining the data d11 restored at the time T12 and the QAM-modulated data d22 with an IFFT. On the other hand, the data d13 output from the television tuner and the data d23 output from the communication unit 19 are sampled, and the data d23 is divided and QAM modulated. In addition, the modulation / demodulation unit 20 of the CD changer 13 processes each data sequentially output after time T13 in the same manner as described above.
[0067]
As described above, in the ring network system 10, even when a plurality of electrical devices output data upward at the same time, the data can be smoothly communicated in an organized state without causing a collision or the like.
[0068]
It should be noted that the data communication is similarly performed between the other electronic devices other than the above-described television tuner, CD changer 13 and amplifier device 14. Further, although the ring network system 10 has been described as a system constructed in the vehicle 12, it can be constructed in another place such as a building, and the modem unit 20 shown in FIG. The converters 23 and the like may be integrated into one chip instead of being independent.
[0069]
【The invention's effect】
As described in detail above, in the first invention, since one device on the transmission side converts the data into time-series data, the frequency band used for transmission can be changed, and transmission is performed even when high-speed data communication is performed. The frequency band can be suppressed low, the emission of noise can be prevented, and the occurrence of crosstalk, jitter, and the like that hinder good communication can be prevented. Further, by converting the shape of the carrier of the time-series data into a sinusoidal waveform, it is possible to reduce the influence of noise radiated during transmission on other peripheral devices.
[0070]
According to the second aspect of the invention, since the respective units relating to conversion, transmission, sampling, and reconversion related to data communication are synchronized, smooth communication without continuous data interruption can be realized.
[0071]
In the third invention, the fifth invention, and the sixth invention, since each process related to transmission and the like is performed after modulating a carrier wave of a plurality of divided data divided by OFDM modulation, transmission based on the number of divided data is performed. The frequency band can be changed variously and data can be efficiently communicated.
According to the fourth aspect, since the modulation is performed by changing the amplitude and the phase of the carrier, the occupied frequency of the plurality of divided data can be suppressed to realize efficient data communication.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a main part of a ring network system according to an embodiment of the present invention.
FIG. 2 is a block diagram of a modem unit.
3A is a graph of a frequency axis subjected to QAM modulation, and FIG. 3B is a graph of a time axis subjected to IFFT conversion.
FIG. 4 is a time chart related to data communication from a CD changer to an amplifier device.
FIG. 5 is a time chart when each data of a TV tuner and a CD changer is communicated to an amplifier device.
FIG. 6 is a conventional ring network system, in which (a) is an overall configuration diagram and (b) is a main portion configuration diagram.
FIG. 7 is a schematic diagram showing a shape of a data carrier in a conventional ring network system.
[Explanation of symbols]
10. Ring network system
11 Connection line
13 CD Changer
14 Amplifier device
19 Communication Department
20 Modulation / demodulation unit
23 A / D converter
24 Digital processing unit
25 D / A converter
28 Synchronization unit

Claims (6)

In a ring network system in which a plurality of devices are connected in a ring and one device and another device perform data communication at a constant cycle,
The one device,
A modulating means for modulating a data carrier;
Conversion means for converting the frequency component of the carrier modulated by the modulation means to time-series data in the cycle,
Transmitting means for transmitting the time series data converted by the converting means in the cycle,
The other device is
Sampling means for sampling the received time-series data in the cycle,
Re-conversion means for re-converting the time series data sampled by the sampling means to the frequency component in the cycle,
And a calculating means for calculating the data based on the frequency components re-converted by the re-converting means. The one device further comprises:
A first synchronization unit that synchronizes the conversion of the conversion unit and the transmission of the transmission unit,
The other device further comprises:
The ring network system according to claim 1, further comprising a second synchronization unit that synchronizes the sampling of the sampling unit and the reconversion of the reconversion unit with the transmission of the transmission unit. The one device further comprises:
A dividing unit for dividing the original data into a plurality of divided data;
The modulation means,
Means for modulating a carrier of a plurality of divided data divided by the dividing means,
The conversion means,
Means for converting the frequency components of the modulated plurality of carriers into time-series data,
The re-conversion means,
Means for re-converting the time-series data into frequency components of the plurality of carriers,
The calculating means,
Means for calculating the plurality of divided data based on the re-converted plurality of frequency components,
The other device further comprises:
The ring network system according to claim 1, further comprising a restoration unit that combines the plurality of calculated pieces of divided data to restore the original data. The modulation means,
4. The ring network system according to claim 1, further comprising means for changing the amplitude and phase of the carrier. In network equipment that transmits data at a fixed cycle,
Dividing means for dividing the original data into a plurality of divided data;
Modulating means for modulating a carrier of a plurality of divided data divided by the dividing means,
Conversion means for converting the frequency components of the plurality of carrier waves modulated by the modulation means into time-series data in the cycle,
Transmission means for transmitting the time series data converted by the conversion means in the cycle. In a network device that receives data transmitted from the outside at a fixed cycle,
Receiving means for receiving time-series data;
Sampling means for sampling the time-series data received by the receiving means in the cycle,
Re-conversion means for re-converting the time-series data sampled by the sampling means into a plurality of frequency components in the cycle,
Calculation means for calculating a plurality of data based on the plurality of frequency components re-converted by the re-conversion means,
A restoring means for combining a plurality of data calculated by said calculating means and restoring the original data.

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