JP2001119354A - Noise removal-type signal transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a noise removal-type signal transmission system removing periodical noise and other noise, which occur in a transmission cable while the digital signal of a clock pulse transmitted through a transmission cable is transmitted. SOLUTION: When transmitting a digital signal from one of transmission devices 10 and 20 connected to each end of a transmission cable 30 to the other device through the transmission cable 30, signal generation parts 11 and 21, signal comparison parts 12 and 22, noise removal parts 13 and 23, signal reception detection parts 14 and 24 and reception signal recognition parts 15 and 25 are installed in the transmission devices 10 and 20 respectively, a reception signal comprising noise is fed back and noise information is extracted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a noise-elimination signal transmission system, and more particularly, to transmitting a high-frequency clock signal through a cable affected by noise, the transmitted signal and the signal returned from the receiving side. The feedback type noise that obtains the noise information by comparing with and sends it to the receiving side as a low frequency signal that is not affected by the noise, so that the noise component is almost completely removed at the receiving side The present invention relates to a signal transmission method by removal.

[0002]

2. Description of the Related Art In a conventional noise elimination type signal transmission system,
As shown in FIG. 9, the first transmission device 100 and the second transmission device 200 are connected by a transmission cable 150. The first transmission device 100 includes a signal generation unit 110, a noise removal unit 120, and a signal reception detection unit 130. Further, the second transmission device 200 includes the noise removing unit 21.
0, a signal generation unit 220 and a signal reception detection unit 230.

The first transmission device 100 and the second transmission device 2
Signals such as clocks generated by the signal generation units 110 and 210 in 00 have waveforms like the signal 111 on the time chart shown in FIG. 10 and are affected by noise and the like when passing through the transmission cable 150. And the signal 221
Or a waveform including noise such as 121 is transmitted to the receiving unit of the second transmission device 200 (or the first transmission device 100). To eliminate the influence of this noise, the second transmission device 2
The effect of noise is removed by a noise removing unit 210 (or 120) including a filter or the like in the 00 (or the first transmission device 100). After the noise removal, the signal 2 in FIG.
31 (or 131) and the signal reception detection unit 230 (or 13) of the second transmission device 200 (or the first transmission device 100).
0).

[0004]

The problem of the prior art is that a filter is constituted by a single type of resistor, capacitor, etc. without specifying the type of noise. Is effective, but has no effect on other types of noise. The reason is that there is an infinite number of ways of generating noise due to a combination of line noise of the transmission cable 150 and the like, and there are various differences in the degree of the noise. I can't decide. Therefore, it is not possible to suppress various types of noise generated in the transmission cable 150 with only a filter including a single type of resistor, capacitor, and the like.

[0005]

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to completely remove a noise component added to a signal waveform irrespective of the type of noise added to the signal waveform in a transmission cable connecting a transmitting device and a receiving device. It is another object of the present invention to provide a noise-eliminated signal transmission system with improved transmission efficiency and reliability by reproducing the signal waveform from which noise has been eliminated on the receiving device side.

[0006]

Means for Solving the Problems In order to solve the above-mentioned problems, the noise eliminating type signal transmission system according to the present invention employs the following characteristic configuration.

(1) 1 cable connected to both ends of the transmission cable
In a noise elimination type signal transmission method for transmitting a digital signal between a pair of transmission devices, each of the transmission devices receives a signal transmitted from the partner transmission device via the transmission cable and returns the signal to the transmission device on the transmission side. A received signal recognition unit to perform
A signal comparing unit that compares the transmission signal and a feedback signal from the received signal recognizing unit; and a noise removing unit that removes noise of the received signal based on a comparison result by a signal comparing unit of the transmission device on the other end. Noise removal type signal transmission method.

(2) The noise removal type signal transmission method according to the above (1), wherein the reception signal recognition section latches the reception signal with a high-speed clock and detects detailed information of noise added by the transmission cable.

(3) The received signal recognizing section generates a plurality of delayed frame pulses sequentially delayed using a high frequency clock, latches the received signal added with noise, and performs high-frequency to low-frequency conversion. Or the noise removal type signal transmission system of (2).

[0010] (4) The received signal recognizing unit is a signal combining unit that combines the received signal with the noise added thereto, the division information from the counter circuit that receives and counts, and the signal obtained by converting the latched signal into a binary number. (1) and (2) above having
Or (3) a noise removal type signal transmission system.

(5) The noise elimination type signal transmission method according to the above (1), wherein the noise elimination section subtracts a low-frequency conversion result signal of the received signal and noise information from the signal comparison section by a subtraction processing circuit.

(6) The noise removal type signal transmission method according to the above (5), wherein the noise information is inputted to the subtraction processing circuit via a protection circuit including a three consecutive coincidence detecting section.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the structure and operation of a preferred embodiment of a noise elimination type signal transmission system according to the present invention will be described in detail with reference to the accompanying drawings.

First, FIG. 1 is a block diagram showing a preferred embodiment of a noise elimination type signal transmission system according to the present invention. This noise removal type signal transmission system includes a first transmission device 10 and a second transmission device 20 interconnected via a transmission cable 30. The first transmission device 10 includes a signal generation unit 1
1, includes a signal comparing unit 12, a noise removing unit 13, a signal receiving detecting unit 12, and a received signal recognizing unit 15. Similarly, the second transmission device 20 includes a signal generation unit 21, a signal comparison unit 22, a noise removal unit 23, a signal reception detection unit 24, and a reception signal recognition unit 25.

In the noise removal type signal transmission system having such a configuration, the clock signal generated by the signal generation unit 11 (or 21) in the first transmission device 10 (or the second transmission device 20) transmits the clock signal through the transmission cable 30. The data is transmitted to the second transmission device 20 (or the first transmission device 10) via the second transmission device 20. Further, in the first transmission device 10 (or the second transmission device 20), the signal comparing unit 12 (or the signal comparing unit 12 (or the second signal transmitting unit 20) that compares the original signal with the signal that has passed through the transmission cable 30 and returned under the influence of noise. 22). On the other hand, in the receiving device 20 (or 10), a signal reception detecting unit 24 (or 14) for receiving and detecting a clock signal and a noise for removing noise of a clock signal transmitted based on detailed noise information from the transmitting side are included. It has a removing unit 23 (or 13).

The configuration of the noise elimination type signal transmission system shown in FIG. 1 will be described in more detail with reference to FIGS. 4 to 6 and FIG. FIG. 4 is a diagram illustrating the reception signal recognition unit 15 (or 2) in FIG.
It is a block diagram which shows the detailed structure of 5). FIG.
It is a block diagram which shows the detailed structure of the signal comparison part 12 (or 22) inside. FIG. 6 is a block diagram showing a detailed configuration of the noise removing unit 13 (or 23) in FIG. FIG. 8 is a block diagram showing a detailed configuration of the protection circuit 53 or 64 in FIGS. 5 and 6.

The received signal recognition unit 15 (or 25) shown in FIG.
Is a counter circuit 41, a high frequency-low frequency conversion circuit 42,
It comprises a binary number converter 43, a frame pulse generator 44 and a signal synthesizer 45. A high frequency clock for signal division is input to the frame pulse generator 44.
The signal comparison unit 12 (or 22) in FIG. 5 includes the same circuit 51, a subtraction processing circuit 52, and a protection circuit 53 as the reception signal recognition unit 15 (or 25) in FIG. Further, FIG.
The noise removal unit 13 (or 23) shown in FIG.
1, a signal correction processing unit 62, a decoding conversion unit 63, and a protection circuit 64. Further, the protection circuits 53 and 64 in FIGS. 5 and 6 are constituted by binary value detectors 81, 82 and 83 and three consecutive coincidence detectors 84 as shown in FIG.

The noise elimination type signal transmission system shown in FIGS. 1, 4 to 6 and 8 will be described in detail with reference to the timing charts of FIGS. Now, it is assumed that the digital (clock) signal 11A generated by the signal generation unit 11 in the first transmission device 10 of FIG. 1 has a signal waveform as shown in (a) of the timing chart of FIG. Consider the moment when this clock signal 11A arrives at the second transmission device 20 in FIG. 1 under the influence of noise such as line noise while passing through the transmission cable 30. When this signal is returned to the first transmission device 10 immediately after arriving at the second transmission device 20, the signal is returned to the first transmission device 10 under the influence of noise such as line noise while passing through the transmission cable 30 again. When
For example, it has a waveform like the signal 11B in FIG.

As described above, the signal waveform 11B of FIG. 2B affected by noise through the transmission cable 30 and the signal 11A at the time of signal transmission (see FIG. 2A) are included in the first transmission device 10. The signals are input to the signal comparing unit 12 shown in FIGS. 4 and 5 and compared. That is, the counter circuit 41 to which the noise-added signal 11B is input calculates how many pieces of information to divide by counting by the signal dividing high-frequency clock CK4. The high-frequency / low-frequency conversion circuit 42 converts the high-frequency information into the frame pulse
At 4, voltage values are latched by frame pulses (FP) generated by sequentially delaying each of the minute times t 1, t 2, t 3,...
, And the information of the number of divisions is combined with the signal combining unit 45 and output.

Further description will be made with reference to the timing charts of FIGS. Figure 2 (c) through
(e) is shown enlarged. That is, as shown in FIG. 2 (c), the feedback signal 11B including noise from the transmission device 20 is latched by a plurality of frame pulses t1 to tg shifted every minute by the high frequency clock CL4. FIG. 2D shows the frame pulse FP. As a result, FIG.
As shown in FIG. 3, the signal is converted into a high-frequency digital signal L (tn), and is converted into binary information as shown in FIG. 3 based on the latched voltage value. Regarding the conversion method to a binary number, it is assumed that noise becomes H level or higher. For example, a voltage twice as high as the H level is expressed as (8/8) × V, and is expressed in the form of (n / 8) × V. For example, the time t in FIG.
The voltage value at 1 is n = 4 (100 in binary),
The voltage value at time tc is n = 1 (00 in binary number).
1).

The signal 11B shown in FIG. 1, which is expressed by the low-frequency information of about 1 Hz and includes information on the number of divisions and information on the details of the noise level, is returned to the signal transmitting side. The signal is returned to the transmitting side almost without being affected by the above-mentioned periodic noise. Even if there is an influence of noise, the signal is input to the signal comparison unit 12 in the first transmission device 10 without being affected by the noise by the protection circuit 53 described later. The operation in the signal comparison unit 12 is as follows.
As shown in FIG. 5, the original signal 11A is converted into low-frequency binary information in the received signal recognizing section 51, and this is compared with the above-mentioned signal passing result of the protection circuit 53. In the digital binary state, the subtraction is performed by the subtraction processing circuit 52, so that only the noise information becomes the comparison result 12A.
Will be output. That is, FIG.
As shown in (c), the waveform after noise addition has a different binary value at time tc as compared with the original waveform, and the signal 12A is obtained by comparing and subtracting this value. Note that the same applies to the case of transmission from the second transmission device 20 to the first transmission device 10 via the transmission cable 30.

The output signal 12A from the signal comparing section 12 (or 22) is again transmitted to the signal receiving side, that is, the transmission device 20.
(Or 10), but is a low-frequency signal that is hardly affected by noise. Even if it is affected by noise, it passes through the transmission cable 30 without being affected by noise by the protection circuit 53. Is the noise detail amount information added to the transmission device 20 (or 10).
3 (or 13). These noise removing units 23
(Or 13) has the configuration shown in FIG. 6 described above, and the subtraction processing circuit 61 subtracts the feedback signal 11B containing noise from the noise information passed through the protection circuit 64.

Here, an example of the subtraction processing operation in the subtraction processing circuit 61 of the noise removing unit 13 (or 23) is shown in the timing chart of FIG. FIGS. 7A to 7D show waveforms, respectively.
71 which is the result (AB) of subtracting the waveform (B) from (A)
To 74 are shown. Since the waveforms 71 and 74 are the same, the confusion does not occur by adding the positive / negative discrimination to the subtraction result. By making this determination in the signal correction / correction processing section 62, noise added to the digital signal can be removed. Further, by passing the signal through the decoding conversion unit 63, the value represented by the low-frequency digital binary number is restored to the analog display voltage value. As a result, the digital signal is restored to the original digital signal, and is input to the signal reception detectors 14 and 24. As shown in FIG. 8, the protection circuit 64 is implemented by a three-continuation matching circuit 84 having the same value.

The configuration and operation of the preferred embodiment of the noise elimination type signal transmission system according to the present invention have been described above in detail. However, it should be understood by those skilled in the art that the present invention should not be limited to only the specific embodiment, and various modifications can be made without departing from the gist of the present invention.

[0025]

As will be understood from the above description, according to the noise elimination type signal transmission system of the present invention, when a high frequency clock signal is transmitted between transmission apparatuses via a transmission cable, noise is generated during transmission of the transmission cable. , The receiving apparatus can reproduce and receive the clock signal from which the influence of the noise has been removed. The reason is that even if the high-frequency clock is affected by noise during transmission through the transmission cable, this clock signal is turned back from the receiving side to the transmitting side and compared with the original clock signal. Then, the information on the magnitude of the noise level and the detailed time of noise addition is obtained, and this information is sent to the receiving side, so that the receiving side can remove the noise.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a preferred embodiment of a noise elimination type signal transmission system according to the present invention.

FIG. 2 is a timing chart for explaining a noise detection operation of the noise elimination type signal transmission system of FIG. 1;

FIG. 3 is a timing chart illustrating the operation of the noise elimination type signal transmission system of FIG. 1;

FIG. 4 is a block diagram illustrating a detailed configuration of a received signal recognition unit in FIG. 1;

FIG. 5 is a block diagram illustrating a detailed configuration of a signal comparing unit in FIG. 1;

FIG. 6 is a block diagram illustrating a detailed configuration of a noise removing unit in FIG. 1;

FIG. 7 is a diagram illustrating the operation of the noise removing unit in FIG. 6;

FIG. 8 is a block diagram showing a detailed configuration example of the protection circuit of FIGS. 5 and 6;

FIG. 9 is a block diagram of a conventional noise removal type signal removal method.

FIG. 10 is a timing chart for explaining the operation of FIG. 9;

[Explanation of symbols]

 Reference Signs List 10, 20 Transmission device 11, 21, Signal generation unit 12, 22, Signal comparison unit 13, 23 Noise removal unit 14, 24 Signal reception detection unit 15, 25 Received signal recognition unit 30 Transmission cable 41 Counter circuit 42 High frequency-low frequency conversion circuit 43 Binary number converter 44 Frame pulse generator 45 Signal synthesizer 53, 64 Protection circuit

Claims (6)

[Claims] 1. A noise elimination type signal transmission system for transmitting a digital signal between a pair of transmission devices connected to both ends of a transmission cable, wherein each of the transmission devices transmits from a partner transmission device via the transmission cable. A reception signal recognition unit that receives the received signal and returns to the transmission device on the transmission side, a signal comparison unit that compares the transmission signal and a feedback signal from the reception signal recognition unit, and a signal of the transmission device on the other side. A noise removing unit that removes noise of the received signal based on a comparison result by the comparing unit. 2. The noise elimination type according to claim 1, wherein the received signal recognition unit latches the received signal with a high-speed clock and detects detailed information of noise added by the transmission cable. Signal transmission method. 3. The received signal recognizing section generates a plurality of delayed frame pulses sequentially delayed using a high frequency clock, latches the received signal added with noise, and performs high frequency to low frequency conversion. The signal transmission method according to claim 1. 4. The received signal recognizing unit includes a signal combining unit that combines the received signal with the noise added thereto, division information from a counter circuit that receives and counts, and a signal obtained by converting the latched signal into a binary number. The signal transmission system according to claim 1, 2 or 3, wherein 5. The noise elimination unit according to claim 1, wherein the noise elimination unit subtracts a low-frequency conversion result signal of the received signal and noise information from the signal comparison unit by a subtraction processing circuit. Type signal transmission system. 6. The noise elimination type signal transmission system according to claim 5, wherein said noise information is inputted to said subtraction processing circuit via a protection circuit including a three consecutive coincidence detecting section.