JPH02117233A - Signal transmission path monitoring circuit - Google Patents

Abstract

PURPOSE:To monitor the grounding and disconnection of a transmission path by transmitting to input a pilot signal consisting of 0 and 1 within the null time of a transmission signal, providing a selector and a pilot signal check circuit on a reception side, and checking the signal by the circuit. CONSTITUTION:A pilot signal generator 5 generates the pilot signal consisting of 0 and 1 within the null time in a signal transmission cycle. A switch generates signals y1-yn by inputting the pilot signal to transmission signals x1-xn, and transmits them to the transmission path via a line driver 2. On the reception side, the signal is received by a line receiver 3, and the pilot signal of each bit is taken out by the selector 7, and is sent to the check circuit 8. The check circuit 8 checks 0 and 1 of the pilot signal for each bit, and judges it as a normal signal when they are correct. When the grounding or the disconnection occurs in either transmission path, the pilot signal is received in combination of 0 and 0 or 1 and 1, therefore, a defective condition is judged for every bit.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a signal transmission line monitoring circuit that monitors the operation of a digital signal transmission line.

[Conventional technology]

FIG. 5 is a system diagram of a conventionally commonly used operation monitoring circuit for a digital signal transmission line.

In this figure, 1 is an n-bit signal Xl+xl+...
. . . A generator of parity bits X for x7, 2 is an (n+1) number of line driver, 3 is this line driver
(n+1) line receivers corresponding to driver 2; 4 is a parity error detector;

Next, the operation will be explained. Parity bit generator 1 generates n-bit signals x, x2 . . . . Generates parity bit X of odd parity or even parity for x7. This <n+1) bit signal including parity viat x2 is sent to each line driver 2.
is sent to the transmission path. On the receiving side, after these signals are received by (n+1) line receivers 3, a parity detector 4 determines whether there is a parity abnormality and monitors the transmission path.

[Problem to be solved by the invention]

Since the conventional signal transmission path monitoring circuit is constructed as described above, it has the disadvantage that it must transmit parity bits in addition to signals, and a transmission path must be provided for this purpose. Furthermore, with one parity bit, it is possible to detect an abnormality when an odd number of transmission lines occurs at the same time, but it cannot be detected when an abnormality occurs on an even number of transmission lines at the same time. There was a problem.

This invention was made to solve the above-mentioned problems, and it is possible to detect abnormalities due to grounding and disconnection of individual transmission lines without adding a transmission line using parity bits, etc., and to detect abnormalities at the same time. The present invention aims to provide a signal transmission line monitoring circuit that can detect abnormalities without any restrictions on the number of transmission lines.

[Means to solve the problem]

The signal transmission path monitoring circuit according to the present invention includes a pilot signal generator and a switching device on the transmitting side, injects a pilot signal consisting of O's and 1's for all bits of the transmitted signal during the signal idle time, and sends the pilot signal to the receiving side. A selector and a pilot signal check circuit are provided to check the pilot signal for each bit.

[Effect]

In this invention, grounding and disconnection can be detected for each transmission line by checking the pilot signal consisting of O's and 1's injected during signal idle time on the transmitting side on the receiving side, and parity bit etc. There is no need to provide a transmission line.

〔Example〕

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

In this embodiment, an n-bit digital signal X1+X2+...
. . . This is an example of a transmission path of xn. In FIG. 1, 5 is a biloft signal generator that generates a monitoring pilot signal consisting of O and 1 every transmission period, 6 is a transmission signal xl + X 2+...x, and a pilot signal generator. 5, n switchers that switch between the pilot signals generated at 5, 2, n line drivers that transmit n-bit signals, and 3, n corresponding to this line driver 2.
7 is a selector for extracting a biloft signal from each bit signal, and 8 is a biloft signal check circuit.

Next, the operation of the circuit according to this embodiment will be explained with reference to the system diagram shown in FIG. 1 and the timing chart shown in FIG. 2. n-bit transmission signal xl+Xz,...
... As shown in Fig. 2(a), x7 has the following values:
In addition to the signal transmission period Ts within the signal transmission cycle, there is also an idle time T
Assume that , exists. The pilot signal generator 5 is
During this idle time TD, a biloft signal consisting of O and 1 as shown in FIG. 2 (bl) is generated.
is the transmission signal XI+x! , ... Injecting this pilot signal into Xn, the signal shown in Fig. 2 (C))'l+
yz+...It is transmitted to the transmission line via the line driver 2 as y7. On the receiving side, this signal is received by a line receiver 3, and a selector 7 extracts a pilot signal of each bit. The pilot signal check circuit 8 checks O and 1 of this pilot signal for each bit, and determines that it is OK if it is correct. If any transmission line is grounded or disconnected, the pilot signal is received as a combination of O and O or 1 and 1, so it is possible to determine whether each bit is defective.

In addition, in the above embodiment, an example of a pattern of O and 1 was shown as a monitoring pilot signal, but this only requires at least one O and 1, and for example, a pattern of l and 0, 0, 1 and 0, etc. However, it goes without saying that the same effect as in the above embodiment can be obtained.

Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 3 is a system diagram showing the configuration of the circuit according to the second embodiment. In the figure, 9.10 is a generator of pilot signals each consisting of 0.1, and 11 is a generator for switching pilot signals of 0 and 1. switch; 6, n switchers for switching transmission signals and pilot signals; 2, n line drivers; 3;
are n line receivers, 7 is n selectors for extracting biloft signals from the transmitted signals, and 8 is a pilot signal check circuit.

The operation of the circuit according to this embodiment will be explained below using the system diagram shown in FIG. 3 and the timing chart shown in FIG. 4. This embodiment is an example in which O and 1 pilot signals are alternately injected every transmission period. The outputs of the pilot signal generator 9 consisting of 0 and the output of the pilot signal generator 10 consisting of 2 are alternately switched by a switch 11 every transmission period.

This pilot signal is transferred to the transmission signal idle time T by the switching device 6. The signal is injected into the line driver 2 and output to the transmission line. On the receiving side, this signal is received by a line receiver 3, a pilot signal is extracted by a selector 7, and a pilot signal check circuit 8 checks each bit for grounding and disconnection.

〔Effect of the invention〕

As described above, according to the signal transmission path monitoring circuit according to the present invention, a pilot signal generator and a switching device are provided on the transmitting side, a pilot signal consisting of O's and 1's is injected during the free time of the transmitted signal, and the Since a selector and a pilot signal check circuit are installed on the side and configured to check the pilot signal, grounding and disconnection of each transmission line can be monitored without adding transmission lines such as parity bits. The effect is that it can be done.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing a signal transmission line monitoring circuit according to a first embodiment of the present invention, FIG. 2 is a diagram showing a timing chart for explaining its operation, and FIG. FIG. 4 is a system diagram showing a signal transmission path monitoring circuit according to an embodiment, FIG. 4 is a diagram showing a timing chart for explaining its operation, and FIG. 5 is a system diagram showing a conventional signal transmission path monitoring circuit. l is a parity bit generator, 2 is a line driver, 3 is a line receiver, 4 is a parity error detector, 5 is a pilot signal generator consisting of O and 1, 6 is n
7 is a selector, 8 is a pilot signal check circuit, 9 is a pilot signal generator consisting of O, 1
0 is a pilot signal generator consisting of 1, and 11 is a switch. Note that the same reference numerals in the figures indicate the same or equivalent parts. Patent applicant: Ryozo Tsutsui, Director General, Technology Research Headquarters, Defense Agency, Figure 2, Figure 4

Claims (1)

[Claims] (1) In a signal transmission path monitoring circuit that monitors the operation of a circuit that transmits a 1-bit or multiple-bit digital signal, a pilot signal generator that generates a pilot signal for monitoring consisting of 0s and 1s is installed on the transmitting side. , a selector for injecting and transmitting the pilot signal during the idle time of the transmission signal, and a selector for extracting the pilot signal from the transmitted signal on the receiving side, and a selector for checking the pilot signal. 1. A signal transmission path monitoring circuit comprising a pilot signal check circuit.