JPS6314539B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a multiplex signal transmission device that transmits multiple signals in a time-division manner using a single transmission path, and in particular, transmission information is a simple waveform signal such as an ON/OFF signal. suitable for certain cases.

When transmitting a large amount of information between two or more distant points, transmitting this information in parallel would require many transmission lines, which would be extremely uneconomical. A so-called time-division multiplex transmission method is often adopted, which allows multiple pieces of information to be sent by dividing the information into multiple pieces of information and sharing them.

In addition, in cases where information sources are scattered throughout the vehicle, such as in a car, stations are installed to cover the information sources in appropriate ranges, and time-division multiplex transmission is performed between these stations and the main receiver. It is desirable to do so. In addition, if you want to configure the transmission equipment at a low cost, you can configure it with the same single transmission path between the stations and between the receivers, and also use separate dedicated transmission lines for the synchronization signal and clock signal required for time division multiplex transmission. The transmission path can be simplified by simultaneously sending information to the information transmission path without providing a path.

The present invention has been made in response to these demands, and an object of the present invention is to provide a time division multiplexing transmission apparatus suitable for a case where the transmission information is relatively simple, such as an ON-OFF signal.

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, 1 is a main transmitter, 2 is a sub-transmitter,
3 is a receiver, and these three units are connected by one transmission line 4. The transmitter 1 is provided with four information input sections a1 to a4.
Similarly, the sub transmitter 2 is provided with four information input sections b1 to b4. Input information from these eight information input sections in total is outputted to eight information output sections ca1 to ca4 provided in the receiver 3, respectively.

Next, the operation will be explained. FIG. 2 is an example of an operation timing chart of the multiplex transmission apparatus according to the present invention. The operation will be explained below using FIGS. 1 and 2. First, reference numeral 11 shown in FIG. 1 is an oscillator, and its output, a pulse of a constant frequency, is input to a synchronizing signal generator 12 and a clock signal generator 13. Here, FIG. 2A shows the output waveform of the clock signal generator 13.

Next, the respective outputs, a synchronization signal (not shown) and a clock signal A, are sent to a modulated signal generator 14.
is input to the modulation signal generator 15. The modulated signal (low), which is the output waveform of the modulated signal generator 14, is shown in FIG. The modulated signal LO consists of a channel consisting of pulses with a time width Tc, and a synchronization signal with a pulse width 1/4Tc is assigned to channel "O" (hereinafter referred to as CHO, and the nth channel is also referred to as CHn). Pulse width 3/4Tc from CH1 to CH8 below
Assign the reference pulse. Therefore, one frame consists of nine channels from CH0 to CH8.

Also, from CH1 to CH4 can be used as main transmitter 1, and
It is assumed that CH5 to CH8 are assigned to the sub transmitter 2. It is also assumed that the leading edges of each pulse including the synchronization signal are aligned in timing.

Next, the modulation signal generator 15 has input information sections a1 to
Information to be transmitted is input from a4.
Generally, there are many types of information, but when considering the information used in automobiles, ON-OFF signals of switches are the most common, and other information includes information on changes in low resistance values and information on changes in frequency. By the way, the frequency change information can also be considered as a repeating pulse of "1" and "0", and instantaneously, the change information of a switch can be interpreted as
It can be regarded as an ON-OFF signal. Further, resistance value change information can be easily converted into frequency change information by incorporating the resistance into a simple oscillator time constant setting circuit. Therefore, most of the information can be expressed by turning the switch on or off, so for the sake of simplicity here, we will assume that the input information is the ON or OFF state of the switch. I can't help it.

Now, as a form of information transmission, as shown in the modulated signal B, the channel assigned to each information transmission consists of one bit.
It is sufficient to modulate the pulse width, but if we define the pulse width of 3/4Tc as an OFF signal and the pulse width of 2/4Tc as an ON signal, the modulated signal locus shown in Figure 2 (b) has the information of OFF signals from CH1 to CH8, therefore, only when the information input to the information input section _a1 to _a4 is an ON signal, the pulse width of the corresponding channel is set to 2/4Tc. It will be fine if you cut it. 15 is a modulation signal generator, and if ON signals are now input to information input sections _a2 and _a4 , each pulse of the corresponding channel, that is, CH2 and CH4, is 2/4 as described above.
To modulate Tc, the modulation signal C (shown in Figure 2 C)
occurs. Therefore, the modulated signal B and the modulated signal C are input to the modulation circuit 16, and the transmission signal D (shown in FIG. 2D) appears at its output.

Next, the transmission signal D is sent out onto the transmission line 4 via the transmission circuit 17. Assuming that the transmitting circuit 17 does not cause any change in the waveform, the signal waveform appearing on the transmission path will be exactly the same as the transmission signal 2.

The transmission signal 2 sent out onto the transmission line 4 then enters the receiving circuit 21 of the sub transmitter 2. The received waveform is the same as the transmission signal 2, assuming that the receiving circuit does not change the waveform at all, and is input to the synchronization signal regenerator 22 and the clock signal regenerator 23. As is well known, in order to reproduce a clock signal or a synchronization signal from a transmission signal, the leading edges of each pulse must be generated at the same timing.
This can be easily done using a PLL (Phase Locked Loop) circuit, several counters, and logic circuits. The regenerated synchronization signal (not shown) and the clock signal (second
(shown in Figure E) is input to the modulation signal generator 25. The modulated signal generator 25 receives information input sections b ₁ to b ₄ in the same manner as in the main transmitter 1 described above.
Only when the signal to the channel is an ON signal, a modulation signal is generated that cuts the pulses of the corresponding channels, that is, CH5 to CH8. Now, information input section
If the input information of b ₁ and b ₃ is an ON signal,
A modulation signal (shown in FIG. 2) is generated to modulate the CH5 and CH7 pulses to a pulse width of 2/4Tc.
The modulated signal enters the transmitting circuit 27, and the transmitting circuit 27
cuts the transmission signal D on the transmission line 4 at a predetermined timing according to the modulation signal to create a transmission signal G.

That is, the transmission signal d on the first transmission line 4 is
This is used for convenience to explain the operation of the sub transmitter 2; in reality, these operations are performed in real time, and as a result, there is no transmission signal 2 on the transmission path 4, and there is no transmission signal 2. There will only be one. However, it goes without saying that the output waveform of the modulation circuit 16 of the main transmitter 1 is the transmission signal D.

Next, the reception circuit 31 of the receiver 3 receives the transmission signal on the transmission path 4, and in the same manner as described in the operation explanation of the sub-transmitter 2, the synchronization signal regenerator 32 and the clock signal regenerator 33 are activated. A synchronizing signal (not shown) and a clock signal are respectively reproduced through the reproducing circuit. Further, the output of the receiving circuit 31 is similar to the transmitting signal G, and these three signals are input to the signal demodulator 35. The demodulator 35 receives a clock signal (second
At the eight check points indicated by arrows in Figure H), the presence or absence of a pulse in the transmission signal is checked, and if there is a pulse at that timing, that is, if it is "1", it is an OFF signal, and if there is no pulse. For example, if it is “0”, it is an ON signal, and the result is decoded and the information on CH1 is
1, information on CH2 is output to ca2, and so on, from ca1 to cb4 according to each channel.

The pulse width modulation time division multiplexing transmission device configured as described above simultaneously superimposes the synchronization signal component and the clock signal component on the transmission path that transmits the information component, so it can completely transmit information using one transmission path. Can send and receive. In addition, the circuit configuration is relatively simple, and it is highly effective when applied to information transmission and reception signals where the signal frequency is not so high, especially for automobiles.

In the above embodiment, the pulse width of the reference modulated signal is set to a wide pulse width of 3/4Tc, and then the trailing edge is cut off according to the input information and modulated to a pulse width of 2/4Tc. However, by reversing this, in other words, the pulse width of the modulated signal is set to 2/4Tc from the beginning, and then a new pulse is added to the trailing edge of the pulse according to the modulation signal to create a pulse of 3/4Tc. It is clear that the same effect can be obtained even if the structure of the transmitting circuit is slightly changed.

Furthermore, if a demodulator having the same function as the demodulator 35 provided in the receiver 3 is provided in the sub-transmitter 2, the information from the main transmitter 1 can be reproduced in the sub-transmitter 2 as well. Needless to say, it can be output.

By the way, in the above embodiment, the configuration is such that a complete rectangular wave pulse such as the transmission signal T is sent from the main transmitter 1 and the sub transmitter 2 onto the transmission line 4.
As is well known, the waveform of the transmission signal G includes many high-order harmonics, and a large amount of electromagnetic waves are generated from the transmission path 4. As a result, if there is a radio or other electronic equipment near the transmission line 4, such as when used in a car, the electromagnetic waves may cause noise to enter the radio or cause the equipment to malfunction. etc., resulting in an inconvenient situation.

In such a case, transmitting circuits 17 and 27
It is necessary to provide a low-pass filter in order to attenuate harmonic components on the transmission line 4.

In this case, when the transmission signal is received in the sub-transmitter, the waveform is blunted, so the timing of the recovered clock signal is different from the clock signal in the main transmitter, and as a result, the sub-transmitter A situation arises in which information from the network cannot be accurately sent to the transmission path. This will be explained using FIG. FIG. 3A shows a clock signal, and FIG. 3D shows a transmission signal, whose waveforms are exactly the same as those shown in FIGS. 2A and 2D. Note that FIG. 3 shows the time axis enlarged twice. The transmission signal D is sent out onto the transmission line 4 via a low-pass filter in the transmission circuit of the main transmitter 1, and has a blunt waveform as shown in FIG. When this is received by the sub transmitter 2 and passed through a waveform shaping circuit provided in the receiving circuit 21, the received waveform becomes as shown in FIG. At this time, the received waveform N is delayed by Td compared to the transmitted waveform D. The clock signal (shown in Figure 3) is reproduced based on the received waveform N delayed as described above, and the modulated signal (O shown in Figure 3) is directly generated based on this clock signal. Once created, the waveform on the transmission line 4, that is, the transmission waveform, is modulated as shown in FIG. In other words, the transmission signal wave is delayed by CH5 and CH7.
If the signal is not sufficiently modulated by Td and is received by the receiver 3, it will have a waveform as shown in FIG. 3F. That is, for CH5 and CH7, the pulse width does not become the predetermined value 2/4Tc, and the pulse width becomes wider by the time width Td. If information is demodulated from such a waveform at the check points shown in FIG.

Therefore, in the present invention, when creating the modulated signal of the sub transmitter 2, an operation is performed to advance the timing by a time corresponding to the operation delay time Td of the received waveform. In other words, if we create a modulated signal advanced by Td as shown in Figure 3 Y instead of the cut signal shown in Figure 3 O, the transmitted signal waveform on the transmission line 4 will become as shown in Figure 3 T. Then, the received waveform at receiver 3 becomes as shown in Figure 3, and CH5
The pulse width of CH7 is 2/4Tc. Here, the method of accelerating the timing when creating the modulation signal is to use a PLL circuit, several counters, and logic circuits in advance in the receiving circuit 21 in the same way as when creating the clock signal, and use a timing pulse with a higher frequency than the clock signal. (shown in Figure 3), and while actually measuring the time delay of the transmitting and receiving system,
The modulation signal generation circuit 25 is adjusted using the timing pulse so that the effect of correcting the delay time is maximized.

As described above, according to the present invention, a plurality of information transmission/reception systems can be configured using a relatively simple circuit configuration and a single transmission path. Furthermore, even when it is desired to dull the signal waveform on the transmission path in order to prevent harmonic interference to other electronic devices, accurate information reception can be achieved by adding a simple circuit.

In the above embodiment, the main transmitter 1 also has an information input section a ₁ ~
A ₄ is provided, and the modulated signal of the assigned channel is shaped and sent to the transmission line. However, the main transmitter is configured to simply send only the modulated signal to the transmission line, and the information The input section may be divided into a plurality of sub transmitters 2. This has the advantage that the configuration of the main transmitter is simplified, and that a multiplex transmission device with the required number of channels can be configured simply by increasing the number of sub-transmitters 2.

In addition, in the embodiment described here, the number of information transmission channels is eight in total, but it is also possible to expand this to eight or more, and to provide not one but multiple sub-transmitters. period and
Within the range that allows the maximum frequency relationship of input information,
Needless to say, it is easy to do.

Furthermore, in the above embodiment, the synchronization signal, the OFF signal,
To express three types of information of the ON signal, the time width of the 1-bit pulse is 1/4Tc, 2/4Tc, and 2/4Tc, respectively.
Although the configuration is configured to use three types of 3/4Tc, in principle, the three types of information may be defined as any of the three types of pulse widths, and furthermore, the three types of pulse widths can be defined as 1 type of pulse width. It goes without saying that almost the same effect can be obtained even if pulse widths other than /4Tc, 2/4Tc, and 3/4Tc (for example, 1/5 ^Tc ₁ , 2/5 ^Tc ₁ , and 3/5Tc) are used.

Note that the frequency of the modulated pulse, the number of channels, and the frequency of input information are mutually related, and especially when used for automobiles, the frequency of input information is at most several hundred Hz, and the number of input information is several hundred Hz. The number of channels is 7 to 31, and the frequency of the modulated pulse is 5KHz to 20K.
Hz, and it is appropriate to set the pulse width modulation amount in steps of 1/4 to 1/5.

As described above, this invention prevents harmonic interference on the transmission path and also prevents harmonic interference caused by this in a transmission method in which a single transmission path is divided in time and shared to send multiple pieces of data. Accurate information transmission can be achieved by correcting timing deviations in the transmitter and performing data superimposition.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a timing diagram showing operating waveforms of each part.
FIG. 3 is a timing diagram in another embodiment of the invention. In the figure, 1 is the main transmitter, 2 is the sub-transmitter, 3
is a receiver, 4 is a transmission line, 11 is an oscillator, 12 is a synchronization signal generator, 13 is a clock signal generator, 14
is a modulated signal generator, 15 and 25 are modulated signal generators, 16 is a modulation circuit, 17 and 27 are transmission circuits, 2
1 and 31 are receiving circuits, 22 and 32 are synchronous signal regenerators, 23 and 33 are clock signal regenerators, and 35 is a signal demodulator. The same reference numerals in the drawings indicate corresponding parts.

Claims (1)

[Claims] 1. The following main transmitter (a), a plurality of sub-transmitters (b),
A pulse width time division multiplex transmission device comprising a receiver (c) and a common transmission line. (b) A clock signal generator, a synchronization signal generator that sends out a synchronization signal synchronized with this clock signal, and a clock signal generator that sends out a synchronization signal synchronized with this clock signal, and a plurality of time-divided channels in synchronization with this synchronization signal and the above clock signal, each with a predetermined pulse width. A modulated signal generator that sends out a modulated signal; a modulated signal generator that sends out a modulated signal that modulates the modulated signal of the assigned channel; and a modulated signal generator that inputs the modulated signal and the modulated signal, and A modulation circuit that obtains a transmission signal modulated according to input information, a transmission circuit that sends this transmission signal to a transmission line, a transmission circuit that sends this transmission signal to the transmission line, and a A main transmitter equipped with a low-pass filter that removes harmonic components on the transmission line. (b) A receiving circuit that shapes the waveform of a transmission signal train received via a transmission line, a clock signal regenerator that regenerates a clock signal from the received signal train obtained by this receiving circuit, and a synchronization signal from the received signal train. It has a synchronization signal regenerator for reproducing and an information input section for each of a predetermined number of allocated channels, and a modulation signal for changing the pulse width of the modulated signal according to the input information of each channel is transmitted to the regenerated clock. a modulation signal generator that generates a modulation signal at a timing earlier than the timing determined by the signal and the reproduction synchronization signal by an operation delay time of the received signal train relative to the transmission signal train, and a transmission circuit that sends the modulation signal to a transmission line; A sub-transmitter including a low-pass filter that is inserted into the transmission circuit and removes high-frequency components on the transmission line. (c) A clock signal regenerator that regenerates a clock signal from a signal train received via a transmission line, a synchronization signal regenerator that regenerates a synchronization signal from the signal train, and a clock signal regenerator that regenerates a synchronization signal from the clock signal and synchronization signal received from the clock signal and synchronization signal. A receiver comprising a signal demodulator that identifies the width of each channel pulse signal, discriminates the content of transmission information of each channel, and sends the content to an information output section of each channel. 2. The pulse width modulation time division multiplex transmission apparatus according to claim 1, which is configured to generate a modulated signal that cuts or adds 1/2 to 1/5 of the pulse width of the modulated signal.