JPH01276849A - Bus type time division multiplex transmitting method - Google Patents

Abstract

PURPOSE:To unify the phase of the time slot of data at respective device receiving edges through all data channels and frame synchronizing signals by specifying the providing interval of respective devices on a bus type transmission line so that a signal propagation delaying time between respective devices can become the integer-fold of the time of one time slot width of the data. CONSTITUTION:One center device 1 and plural terminal devices 2, 3 and 4 are connected on a bus type transmission line, the center device q receives a frame synchronizing signal transmitted at a constant period and phase- synchronizes to this. For the frame to provide a guard time larger than a cyclic propagation delaying time, the data are transmitted to the data channel assigned to the self-device and in other device, the data are received accompanied by the propagation delaying time by a bus type transmission line 5 in other device. At this time, the providing interval of respective devices on the bus type transmission line 5 is set so that the propagation delaying time of the signal between respective devices can be the integer-fold of the time of one time slot width of data. Thus, all data channels received in the receiving edge of the arbitrary device and the data phase of a frame synchronizing signal can be made coincident.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a bus-type time division multiplex transmission method used for communication between a center device and a plurality of terminal devices connected in a bus-type manner.

(Prior Art) FIG. 3 is a block diagram of a transmission system to which a conventional bus type time division multiplex transmission method is applied. At □ in Figure 3,
The center device 1 is connected to a bus type transmission line 5 along with terminal devices 2, 3, and 4. The connection intervals between the devices on the bus-type transmission line 5 are arbitrary, but for the sake of explanation, it is assumed that the devices are connected at the distance intervals shown in FIG. Here, the distance Q is during the time T0 corresponding to the width of 1 tie and 11 slots of data.
(This indicates the distance that the C signal propagates on the bus-type transmission path.

Therefore, the maximum round trip delay time (Round Trip Delay Tim
e) is the distance 1114. The round trip propagation time of Q is 8T.
It becomes o.

FIG. 4 shows a frame configuration diagram of a conventional bus type time division multiplex transmission method. In FIG. 4, one frame consists of frame synchronization A4F and N data channels chi to chN. A guard time larger than the maximum circular propagation delay time on the bus type transmission path is provided between each data channel.

The frame synchronization signal F is transmitted only by the center device, and each data channel is transmitted only by the devices to which each data channel is assigned. Therefore, multiple terminal devices do not transmit on one data channel. All devices can also receive frame synchronization signals and any data channels.

FIG. 5 is an explanatory diagram of the operation of the conventional bus-type time division multiplex transmission method, and is based on the configuration of the transmission system shown in FIG. 3 and the frame structure shown in FIG. 4.

Next, the operation of the above conventional example will be explained using FIG. 5. In FIG. 5, each terminal device uses the reception phase of the frame synchronization signal transmitted by the center device as its own time base.
Send data to a pre-assigned data channel. - As an example, the length of the frame synchronization signal is 4T0. Set the length of the data channel to 8T0. Guard time length 10
T0, and one frame consists of four data channels. Now, the center device 1 and the terminal device 3. It is assumed that the terminal device 2 and the terminal device 4 perform full-duplex communication. In addition, the data channel chi is sent to the terminal device 4 in advance, and the data channel
It is assumed that channel 3 is assigned to center device 1, channel 3 is assigned to terminal device 2, and channel 4 is assigned to terminal device 3. Center device 1
transmits the frame synchronization signal F and ch2 to the bus-type transmission line, the terminal device 3 receives them, and the channel transmitted by the terminal device 3
4 is received by the center device ei1. Communication between the terminal devices 2 and 4 is also performed using ch3 and chi, respectively.

In this case, the frame synchronization signal F sent from the center device 1 on [14 is reached in FIG. 3, where the distance between the center device 1 and the terminal device 4 is 4Q, so the propagation delay time is 4T. Since the terminal device 4 transmits to chi based on the frame synchronization signal F, the transmission start of chl starts with a propagation delay time of 4T0 and a length of frame synchronization signal 44 of 4.
T0, as shown in FIG. 4, starts from the sum of the frame synchronization signal F and the chl interval 2T0, that is, t=10T. When chi reaches the receiving end of the center device 1, a propagation delay time of 4T is added, and the result is t=14T. What the center device 1 transmits to ch2 is t=271'I''O(4'ro+2'r,+8
T, +lOT,). Also, what the terminal device 2 transmits to ch3 is:

The terminal device 2 starts transmitting the frame synchronization signal F 42T0 after receiving it. That is, it takes T6 for the frame synchronization signal F to reach the receiving end of the terminal device 2, so the total t =
43T, is transmitted to ch3.

Similarly, what terminal device 3 sends to ch4 is
starts transmitting 60T0 after receiving the frame synchronization signal F. That is, the frame synchronization signal F is sent to the receiving end of the terminal device 3.
It takes 2.2T to reach t, so the total t is 62.
The signal is transmitted from 2To to ch4, resulting in the operation shown in FIG.

In this way, even with the conventional bus-type time division multiplex transmission method described above,
By providing a guard time greater than the maximum circular propagation delay time between each data channel, time division multiplex transmission by multiple access on a bus-type transmission path is possible without overlapping signal waveforms.

(Problem to be Solved by the Invention) However, in the conventional bus-type time division multiplex transmission method described above, since the distance between each device is arbitrary, the phase of the data time slot at the receiving end of each device d is different for each channel. It becomes random. Therefore, as a clock extraction method, a method that is weak against noise such as start-stop synchronization or a phase-locked loop that is resistant to noise is used, but it is necessary to apply phase synchronization to each channel, which corresponds to the number of channels. There was a problem in that a method using many phase-locked loops was required.

The present invention solves these conventional problems,
It is an object of the present invention to provide an excellent bus-type time division multiplex transmission method that can make the phase of data time slots at each device receiving end constant through all data channels and frame synchronization signals.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a bus-type transmission line so that the signal propagation delay time between each device is an integral multiple of the time of one time slot width of data. The installation interval for each device is determined.

(Function) Therefore, according to the present invention, the installation interval of each device on a bus-type transmission path is set so that the signal propagation delay time between each device is an integral multiple of the time of one time slot width of data. This has the effect that the phases of all data channels and frame synchronization signals received at the receiving end of any device can be matched.

(Embodiment) FIG. 1 is a configuration diagram of a transmission system to which an embodiment of the present invention is applied. In FIG. 1, a center device 1 is connected to a bus type transmission path 5 along with terminal devices 2, 3, and 4. The connection interval of each device on the bus type transmission line 5 is set to be an integral multiple of the distance Q. Distance Q is 1 of the data
Indicates the distance that a signal propagates on a bus type transmission line during the time T0 corresponding to the time slot width, and the length of the transmission line connecting the bus type transmission line and each device is sufficiently shorter than the distance Q. shall be. For example, NRZ (NonReturn
to Zero) with a transmission speed of 10 Mbit/se
If communication is performed using e, the width of one time slot of data T 0 = 100 n see. Assuming that the propagation delay time of (M) on the bus-type transmission path is 5 n see/m, Q = (100 nsec)/ (5n5ec
/ m) = 20m.

Therefore, taps may be provided at 20 m intervals on the bus-type transmission path, and each device may be connected to any of the installed taps.

FIG. 2 is a diagram illustrating the operation of an embodiment of the present invention.

Note that the frame structure in this embodiment is the same as the frame structure in the conventional example shown in FIG. The operation of this embodiment will be explained using FIG. 2. The length of the frame synchronization signal is 4T, the length of the data channel is 8T0, and the guard time is 1.
．． The following description assumes that the settings of data channels for OTo and full-duplex communication are the same as in the conventional example shown in FIG. Therefore, in FIG. 2, it takes 4T0 for the frame synchronization signal F transmitted from the center device 1 when 1=0 to reach the terminal device 4 since the distance is 4Q. The terminal device 1 transmits to chi based on the frame synchronization signal F.

Transmission starts from t=10"l". chl reaches the receiving end of center device 1 at t=14T0, and center device 1 starts transmitting ch2 at t=24T0.
It is time to start transmission from terminal device 2 = 43T0. It is 63T0 when the terminal device 3 starts transmitting on ch4. That is, in the case of this embodiment, as is clear from FIG. 2, the data change points at the receiving ends of all devices are integral multiples of To, and the phases are aligned.

As described above, according to the above embodiment, the data propagation delay time between each device is the time T corresponding to the data time slot width. Since the data is transmitted on the data channel assigned to each device, the phase of all data change points is Can be matched.

(Effects of the Invention) As is clear from the above embodiments, the present invention provides a bus-type transmission path so that the propagation delay of a signal between each device is an integral multiple of the time corresponding to the width of one time slot of data. By setting the installation interval of each device, it is possible to match the data phases of all data channels and frame synchronization signals received at the receiving end of any device.

Therefore, when extracting a clock for identifying data in a received data channel, stable data reproduction can be achieved simply by providing one noise-resistant phase-locked loop in each device.

Furthermore, even if signal reflection occurs at the transmitting/receiving end of each device, the reflected signal will reach the transmitting/receiving end of other devices in the same phase as the data change point, suppressing deterioration of the signal eye pattern. It has the effect of being able to.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a transmission system to which a bus-type time division multiplex transmission method according to an embodiment of the present invention is applied, FIG. 2 is an explanatory diagram of the operation of this embodiment, and FIG. FIG. 4 is a block diagram of a transmission system to which the multiplex transmission method is applied, FIG. 4 is a frame structure diagram of the conventional transmission method, and FIG. 5 is an explanatory diagram of the operation of the conventional method. 1...Center device, 2,3.4...Terminal device,
5...Bus type transmission line. Patent applicant: Matsushita Electric Industrial Co., Ltd. Agent: Hisashi Hoshino ml';'1 No. 1
Figure 3

Claims (1)

[Claims] One center device and multiple terminal devices (hereinafter, the center device and terminal devices are collectively referred to as devices) are connected to a bus-type transmission path, and each device receives a frame synchronization signal that the center device transmits at regular intervals. For frames in which a guard time greater than the maximum one-round propagation delay time is provided between the frame synchronization signal and multiple data channels, data is transmitted to the data channel assigned to the own device. In a time division multiplex transmission system in which the data of each data channel is received by another device with a propagation delay time through a bus-type transmission line, the propagation delay time of the signal between each device is one time of the data. By setting the installation interval of each device on the bus-type transmission path so that it is an integral multiple of the slot width time, bus-type time division enables reception with the changing points of the received data in each device always being in the same phase. Multiplex transmission method.