JPS6112141A - Synchronizing signal system - Google Patents

Abstract

PURPOSE:To transmit simulaneously information and a synchronizing signal by the same code by using a Bi-L code as an information transmission code and adding violation to a bit set for transmitting the synchronizing signal. CONSTITUTION:When a signal T1r toward a terminal device T1 from a signal transmission terminal OUT of a bus terminator M is transmitted to a bus B, the terminal device T1 receives the signal T1r, and the signal T1t for the device M is transmitted from the terminal device T1 to the bus B in a prescribed timing. The operation is applied similarly to terminal devices T2-Tn to constitute the frame of the Bi-phi-L code, the frame passes through the bus B and is inputted to a reception terminal IN of the device M. A frame synchronizing bit adding violation to the 1st bit of the 1st code string of an outgoing signal is provided to the 1st bit of the 2nd code string in the multi-frame system and a multi- frame synchronizing bit MS added with violation separately from the FS is provided. The violation is added by an NRZ code when the length of bus line is short and by the phase shift in the bit cell when longer.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention provides a system for performing time division multiplexed signal transmission.
The present invention relates to a synchronization signal system that uses an information transmission code Bi-φ-L code and adds violations to setting bits to simultaneously transmit information and a frame synchronization signal with the same code.

(Technical Background and Prior Art of the Present Invention) A system in which the present invention is implemented is configured as shown in FIG. 4, for example. That is, the bus B is connected to the signal (information) sending end OUT of the bus termination device M that terminates the bus B.
A plurality of terminals T1 to Tn are coupled to this bus B, which is connected at both ends to a receiving end IN.

The downlink signal from the bus termination device M to the terminal 'rl-Tn is sent out from the sending end OUT of the bus termination device M, and
The upstream signal from l-Tn to the bus termination device M is input to the receiving end IN of the bus termination device M.

The terminals Tl to Tn in the system of FIG. 4 receive their own downlink signals sent by the bus terminal M, acquire synchronization with the downlink signals, and send out uplink signals at predetermined timings.

For this reason, a bi-phase code that can easily obtain bit synchronization is suitable as the code used for transmission.

OMI (CodedM
ark Inversion) code and Bi-φ-L
A synchronization signal system is known in which a frame synchronization signal is transmitted using a MD (Modified Dipucse) code, which is an OM code with a violation added thereto. As is well known, in the OM engineering code, which is the original form of the MD code, the past transmission code is related to the assembly of the current transmission code during the code generation process, and when adding a violation, the past transmission code is also related. There is. Therefore,
In bus-coupled time division multiplex transmission equipment, which requires multiple independent devices (terminals) to share and generate a frame, which is a set of code strings, as described above, it is possible to The above MD code without independence cannot be used.

Indeed, if a bit for sending a synchronization signal is provided independently of a bit for information transmission, the number of bits for information transmission will decrease by the number of bits for the synchronization signal.

(Object of the present invention) In view of the problems of the conventional method, the present invention provides a synchronization signal configuration method that is suitable for a cross-coupled time division multiplex signal transmission device and that allows information to be included in the synchronization signal bits. The goal is to obtain

(Summary of the present invention) For the above purpose, the present invention uses Bi-φ-
Using the L code, a new type of violation is added to the bit set to send the synchronization 1g signal, so that information and frame synchronization signals are simultaneously transmitted using the same code.

(Embodiment of the present invention) FIG. 1 shows a code form according to an embodiment of the present invention. Bi-
The φ-L code is a binary code as shown in Figure 1 (a).
For binary code ``0'', the signal whose level falls from H (--low level) to L (low level) in the middle of the bit cell (time allocated to 1 bit) is the signal that falls in the middle of the bit cell (time allocated to 1 bit). Signals whose level rises from L to H in the middle are assigned to each other.

As a method of adding a violation to the above Bi-φ-L code, in the present invention, the violation addition bit B
A method of replacing the i-φ-L code with an NT (Z code) (this is called the NRZ coding method), or a method of replacing the i-φ-L code with the NT (Z code), or changing the phase of the Bi-φ-code of the violation addition bit to 1/1 of the pit cell.
A method of shifting by four periods (this is called a phase shift method) was adopted.

In the NRZ coding system, as shown in Figure 1 (b), by replacing the falling signal with an H-level signal and the rising signal with an L-level signal, the level is maintained over the entire bit cell for a binary code "1". A signal whose level is H is associated with the binary code "0", and a signal whose level is L throughout the entire bit cell is associated with the binary code "0".

In the phase shift method, by shifting the Bi-φ-L code by 1/4 synchronization of the bit cell, the binary code "1"
”, a positive pulse-like signal whose level changes as L −* ) (-+ L, and a negative pulse signal whose level changes as H-+L-+H for a binary code Assign pulse signals to each other.

Note that the amount of phase shift in the phase shift method can be set arbitrarily. Also, in the above, the binary codes "1" and "0"
Figure 1 (a), (b), (c) shows the correspondence between `` and the signal level.
The opposite relationship to the relationship shown in (For example, regarding the Bi-φ-ri sign of tar (a), the signal changes from L-+H for l1ljl, and changes from H to L for "0". ) may also be set.

Information is transmitted in the system shown in FIG. 4 in the format shown in FIG. That is, the signal is sent from the signal sending end OUT of the bus terminal device M toward the terminal T1. This operation is similarly performed for the terminals T2 to Tn to form a frame shown in FIG. In FIG. 2, signals are sent and received to and from the terminals T1 to Tn in an orderly manner, but generally this order may be random.

Since the above signal has a transmission delay on the bus B, it is not possible to identify the code of the signal input to the receiving terminal N based on the signal applied to the transmitting terminal OUT of the bus terminal M.

That is, for example, the total length of bus B is lKm, and the code speed is I.
If Mbit/s, the signal propagation speed of bus B is approximately 2×
Since it is 108 rIV' days, it takes about 5 times for the signal sent from the transmitting end OUT to reach the receiving end IN, and the frame shown in Figure 2 reaches the receiving end IN with a delay of about 5 bits. . The delay of this signal is not constant due to changes in the characteristics of the cable over time, changes in environmental temperature, etc. Therefore, it is necessary to extract the bit synchronization signal and frame synchronization signal from the signal that has arrived at the receiving end IN.

In a multi-frame system in which information is exchanged as a set of multiple frames, it becomes necessary to extract a multi-frame synchronization signal from the received signal in addition to the frame synchronization signal described above.

Therefore, as shown in Fig. 2, a violation is added to the appropriate bits constituting the frame (in the embodiment, the first bit of the first code string of the downlink signal is added, and the bit shown as FS in Fig. 2), and the multi-frame In this method, in addition to the frame synchronization bit FS, a violation is added to an appropriate bit separate from the frame synchronization bit FS (in the embodiment, the first bit of the second code string of the downlink signal). (Figure 2, bit designated MS). At least one frame synchronization bit FEI is required for one frame, but its position can be set arbitrarily. still,
The multiframe synchronization bit MS requires at least one bit for one multiframe, but its position can be set arbitrarily as long as it can be distinguished from the frame synchronization bit FS.

FIG. 3 shows an example of a signal format when transmitting information using a binary code string. In Figure 3, the bits with asterisks indicate the bits to which a violation has been added to include a frame synchronization signal, and the dotted arrows indicate the rising edge or rising edge of the signal when no violation is added to the bit. It shows the descent.

As is clear from FIG. 1 or 3, in the present invention, even when a violation is added, the binary codes "1" and "0#" are
Since it becomes a separate signal for Bi-φ, it is possible to transmit information even with the violation additional bit.
- Since each bit cell in the L code and the code with a violation added thereto is mutually independent (for example, in the CM code, the signal indicating the binary code "1" is determined by the previous bit, H or L, and there is no independence between bits.)
, is the most suitable encoding method when a frame is composed of information from mutually independent terminals.

When the above-mentioned NRZ coding method is adopted as the violation addition method, the bus terminal device M and the terminal Tl-
When the distance between the bus B and Tn is short, that is, when the length of the bus B is short, the violation added bit does not disturb the subsequent bits to the extent that they become indistinguishable, as shown in the photograph in Figure 5. (approximately 500 m), but as the length of bus B becomes longer, the violation added bit disturbs the succeeding bits as shown in FIG. 6, making it impossible to identify them. However, when the above-mentioned phase shift method is adopted as the method of adding pi-orage, the photograph in Fig. 7 (this Fig. 7 is
This photo was taken under the same conditions as the figure. ), the violation addition bit hardly disturbs the subsequent bits.

Examining the above causes, as is clear from Figure 1, the information signal (a) and the phase shift type violation addition signal (c) are at the H level and L level in the bit cell for the same amount of time, so the direct current Equilibrium (D
C balanced), but the violation added signal (b) of the NRZ coding system is DC unbalanced (DC
This causes disturbances to subsequent bits in the NRZ coding scheme.

Considering the above two methods in terms of cost, the phase soft method requires more complicated signal processing2 than the NRZ code method, and is therefore more expensive.

Therefore, in implementing the present invention, the NRZ coding method may be adopted in a system where the bus B is relatively short (approximately 500 m or less), and the phase shift method may be adopted in a system where the bus B is relatively long.

(Effects of the Present Invention) As is clear from the above detailed explanation, according to the present invention, information can be synchronized while maintaining code independence in a bus-coupled time division multiplex signal transmission system. Because signals can be transmitted simultaneously with the same code, the amount of information to be transmitted does not decrease by transmitting one synchronized word, and is a synchronizing signal for systems where frames are generated from information from independent devices. As a method, the present invention has extremely great effects.

[Brief explanation of the drawing]

Each of the figures is a detailed explanation of the present invention, and the first
2 is a diagram showing a code format, FIG. 2 is a diagram showing an example of an information frame structure, FIG. 3 is a diagram showing the correspondence between binary codes and signal formats, and FIG. 4 is a block diagram of the system. Figures 5 to 7
The figure is a photograph showing the signal waveform seen with an oscilloscope. (Main symbols) M...Bus termination K Tt~Tn...Terminal B
...Nox FS...Frame synchronization bit MS...Multi-frame synchronization bit. Figure 1 2 Shinsei now 10 Figure 2 Figure 7 Procedural amendment July 1920//I:I Showa Care in hand Permission No. 7321-+4 2, Date of issue 11-2 Relationship with 41 Application Personal Address 330 Marunouchi Yaesu Building, 2-6-2 Marunouchi, Chiyoguchi 1-ku, Tokyo Amendments The following matters in the specification of the present application have been amended. In the third line from the bottom of page 1 and 2, the phrase ``code for information transmission Bi-φ-L code'' is corrected to ``code for information transmission and Bi-φ-L code.''

Claims (1)

[Claims] 1. In a time division multiplex signal transmission system, a Bi-φ-L code is used as an information transmission code, and the bits at the frame synchronization signal transmission position are changed depending on the information contained in the bits. A synchronization signal method that transmits information and frame synchronization signals simultaneously by adding different violations. 2. The synchronization signal system according to claim 1, wherein the violation is added by inserting an NRZ code. 3. The synchronization signal system according to claim 1, wherein the violation is added by shifting the phase of the bit cell. 4. In a time division multiplex signal transmission system in which transmitted information has a multi-frame structure, Bi-
By using the φ-L code, different violations are added to the bits at the frame synchronization signal transmission position and the bits at the multiframe synchronization signal transmission position, depending on the information contained in each bit. A synchronization signal method in which synchronization signals and information and multiframe synchronization signals are transmitted simultaneously. 5. The synchronization signal system according to claim 4, wherein the violation is added by inserting an NRZ code. 6. The synchronization signal system according to claim 4, wherein the violation is added by shifting the phase of the bit cell.