JP2606756B2 - Digital signal transmission equipment - Google Patents

Description

The present invention relates to a digital signal transmission device.

<Prior Art> Conventionally, as a method of transmitting a sine wave analog signal by a signal transmission device, an analog signal transmission device that directly transmits a sine wave analog signal using an analog transmission (carrier) line is generally used. It is. However, the analog signal transmission device has a problem that it is easily affected by, for example, noise, signal attenuation, and the like, and there is a high possibility that a malfunction such as a malfunction occurs in the control system. In contrast, in recent years,
2. Description of the Related Art There is known a digital signal transmission device that converts an analog input signal into a digital signal, transmits the digital signal through an optical transmission line such as an optical cable, converts the transmitted digital signal back into an analog output signal, and transmits the signal. ing.

<Problems to be Solved by the Invention> In the conventional digital signal transmission device, various transmission delay times occur. That is, the transmission delay time is the time required to convert between parallel data normally processed by the microcomputer and serial data of serial transmission used to minimize the number of lines on the transmission path, This is the time obtained by adding the polling time for data linking with the receiving side, the transmission time for transmitting one bit at a time according to the transmission baud rate, and the like. Since it takes such a transmission delay time, when transmitting the digital signal by inputting an analog input signal as shown in a in FIG. 4, first, the transmission converts the analog input signal into a digital signal at time A ₁ . And, sequentially, time
Digital signals are transmitted to A ₂ , A _3, ..., And intermittent digital signals are transmitted every transmission cycle t. And when such intermittent digital signal is received,
The received signal has a step-like waveform as shown by b in FIG.
When such a stepped digital signal is converted into an analog output signal, there is a possibility that an analog input signal such as a in FIG. 4 cannot be accurately reproduced. If it is known in advance that the analog input signal to be transmitted is a sine wave signal, the sine wave analog input signal should be able to be accurately reproduced.

The present invention has been made in view of such a conventional problem, and has as its object to provide a digital signal transmission device that can reproduce an analog input signal that has been input almost accurately and output the signal.

<Means for Solving the Problems> For this reason, the present invention converts a sine wave analog input signal into a digital signal at a signal input unit, outputs the converted digital signal to a transmission line for each transmission cycle, and transmits the signal. In a digital signal transmission device that receives a digital signal transmitted through the transmission path at a signal output unit, reconverts the signal into a sine wave analog output signal, and outputs the sine wave analog output signal, a sine wave A data calculating means for calculating a phase angle based on the signal level value of the analog input signal and calculating an angular velocity based on the phase angle and the transmission cycle; and a digital data of the angular velocity and the phase angle calculated by the data calculating means. Data output means for outputting data to the transmission path, and a signal input unit for inputting digital data of angular velocity and phase angle output to the transmission path. Data input means, interpolation value calculation means for calculating an interpolation value using an interpolation formula for sine wave reconversion for each transmission cycle based on digital data of the angular velocity and the phase angle input by the data input means, An analog signal output unit that reconverts the signal into an analog output signal based on the interpolation value calculated by the interpolation value calculation unit and outputs the analog output signal.

<Operation> According to the above configuration, in the signal input unit, the data calculation unit converts digital data for each transmission cycle into digital data.
A phase angle is calculated based on the signal level value of the sine wave analog input signal, and an angular velocity is calculated based on the phase angle and the transmission cycle. The data output means outputs the digital data of the angular velocity and the phase angle to the transmission line for each transmission cycle. The transmitted digital data of the angular velocity and the phase angle are input by the data input means of the signal output unit, and the interpolation value calculating means uses an interpolation formula for sine wave reconversion based on the digital data of the angular velocity and the phase. An interpolation value for re-conversion to an analog output signal is calculated for each transmission cycle. A digital signal is formed based on the interpolated value, and the digital signal is converted into an analog output signal by analog signal output means and output.

Here, it is known in advance that the analog input signal is a sine wave, and since the data of the angular velocity and the phase angle do not greatly change during the transmission cycle, the difference between the angular velocity and the phase angle for each transmission cycle is obtained. The analog output signal formed based on the digital data is a signal that reproduces the analog input signal of the signal input section substantially accurately.

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

In FIG. 1 showing this embodiment, a digital signal transmission device inputs an analog signal such as a three-phase AC signal each of which is a sine wave signal, and converts digital data of angular velocity and phase angle based on the analog input signal. A signal input unit 1 for converting and further converting the optical signal into, for example, an optical signal;
An optical transmission line 3 which is a transmission line for transmitting an optical signal of digital data output from the optical input device, and digital data of the transmitted optical signal are input and converted from digital data of angular velocity and phase angle into a sine wave analog signal. And a signal output unit 2 for outputting the signal.

The signal input unit 1 is an A / D converter 1 for converting each of three-phase AC U, V, and W phase analog input signals into digital signals.
1, 12 and 13; a microcomputer (hereinafter referred to as a microcomputer) 14 which is a data calculating means for inputting the converted digital signal and calculating digital data of angular velocity and phase angle; An input / output interface (hereinafter referred to as DIO) 15
A display panel 16 for inputting digital data via the display 15 to display the operation state of the microcomputer 14, and an HDLC (High-leve
l An HDLC controller 17 that forms a transmission frame conforming to Data Link Control), and an optical modem 18 that converts the transmission frame, which is an electric signal, into an optical signal and outputs the optical signal to the optical transmission line 3. Is done. Note that the HDLC controller 17 and the optical modem 18 correspond to data output means.

The signal output unit 2 includes an optical modem 21 that inputs an optical signal from the optical transmission line 3 and converts the optical signal into an electric signal.
HDLC controller 22 that outputs digital data of angular velocity and phase angle to a microcomputer 23 from a transmission frame conforming to
And microcomputer 23 as interpolation value calculation means for inputting digital data of the angular velocity and the phase angle from the HDLC controller 22 and calculating an interpolation value using an interpolation formula for sine wave signal reconversion described later. A DIO 24 for inputting / outputting digital data, a display panel 25 for inputting digital data via the DIO 24 to display an operation state of the microcomputer 23, and a digital signal for each of the U, V, and W phases output from the microcomputer 23 D / A converter 2 for converting to analog signals
6, 27, 28 and U, V, W phase amplifiers 29, 30, 31 respectively
And Note that the optical modem 21 and the HDLC controller 22 correspond to data input means, and the D / A converter 2
6 to 28 and the amplifiers 29 to 31 correspond to analog signal output means.

Next, the operation will be described. In addition, U, V, W of three-phase AC signal
Since the signals of the phases are only shifted in phase, a description will be given of, for example, the U phase as an example.

As shown in FIG. 3A, the signal input unit 1 receives an analog input signal. This analog signal is a U-phase AC signal and a sine wave signal. A / D converter 1
1 converts the U-phase AC signal into a digital signal,
Output to the microcomputer 14. The microcomputer 14 calculates the angular velocity Δθ and the phase angle θ based on the input AC signal. In order to calculate the angular velocity Δθ and the phase angle θ from the input digital signal, since the analog input signal is a sine wave signal,
Detect the signal level value, calculate the phase angle θ from the signal level value, measure the phase angle advanced during the transmission cycle t, and calculate the angular velocity Δθ by dividing the advanced phase angle by the transmission cycle t I do. The data of the microcomputer 14 is displayed on the display panel 16 via the DIO 15 so that the operation state of the microcomputer 14 can be confirmed. Then, the data of the angular velocity Δθ and the phase angle θ calculated by the microcomputer 14 are formed into a HDLC-compliant transmission frame by, for example, the HDLC controller 17 as shown in FIG. Is converted into an optical signal and output to the optical transmission line 3.

The optical signal transmitted by the optical transmission line 3 is input to the optical modem 21 of the signal output unit 2 and is converted from the optical signal into an electric signal. Then, the HDLC controller 22 outputs to the microcomputer 23 the data of the angular velocity Δθ and the phase angle θ extracted from the transmission frame of FIG. The microcomputer 23 calculates an interpolation value for each interpolation output cycle T as shown in FIG. 3B from the input angular velocity Δθ and phase angle θ. Since it is known in advance that the transmitted optical signal is data based on a sine wave signal, to calculate an interpolation value from the angular velocity Δθ and the phase angle θ, the interpolation value = sin (θ + Δθ · T · n + Δθ · d ) Here, n is a multiple of the interpolation output cycle T, and d is a correction time for the transmission and processing delay time. Note that since the angular velocity Δθ and the phase angle θ do not change significantly during the transmission cycle t, even if the angular velocity Δθ and the phase angle θ are constant values during the transmission cycle t, the interpolation value is calculated. There is no big error. Further, each time the interpolated value is calculated, a digital signal for re-conversion to an analog output signal like b in FIG. 3 is formed, so that the signal during the transmission cycle t can be interpolated. The operation state of this microcomputer 23 is also DI
It can be confirmed on the display panel 25 via O24. The calculated interpolation value is reconverted by the U-phase D / A converter 26 into an analog output signal as shown by the broken line b in FIG. 3, and is amplified and output by the amplifier 29.

According to such a configuration, data of the angular velocity Δθ and the phase angle θ are calculated from the sine wave analog input signal input to the signal input unit 1, and the calculated data is output to the signal output unit 2 via the optical transmission line 3. And during the transmission period t in the signal output unit 2, based on the data of the angular velocity Δθ and the phase angle θ,
An analog input signal can be reproduced almost exactly by calculating an interpolation value using an interpolation formula for sine wave reconversion and forming a digital signal by interpolating the signal every interpolation output period T. The performance of the digital signal transmission device can be improved.

<Effects of the Invention> As described above, according to the present invention, the signal input unit calculates digital data of the angular velocity and the phase angle from the sine wave analog input signal, and transmits the calculated digital data every transmission cycle. Output signal, during a transmission period, a signal output unit calculates an interpolation value using an interpolation formula for sine wave reconversion based on the digital data based on the digital data to form a digital signal, and reconverts the signal to an analog output signal. Thus, the analog input signal can be reproduced almost exactly, and the performance of the digital signal transmission device can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment according to the present invention, FIG. 2 is a diagram showing a transmission frame transmitted and received in FIG. 1, FIG. 3 is a signal waveform diagram of FIG. FIG. 1 is a signal waveform diagram of a conventional signal transmission device. 1 ... Signal input unit, 2 ... Signal output unit, 3 ... Optical transmission line, 11-13 ... A / D converter, 14, 23 ... Microcomputer, 1
7, 22 ... HDLC controller, 18, 21 ... Optical modem, 26
~ 28 ... D / A converter, 29 ~ 31 ... Amplifier

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kimura Kuthiko 1-13-8 Kamikizaki, Urawa-shi, Saitama Nihon Signal Co., Ltd. Yono Office (72) Inventor Koji Inoue 1 Kamikizaki, Urawa-shi, Saitama No. 13-8, Nihon Signal Co., Ltd. Yono Office (56) References JP-A-1-221800 (JP, A)

Claims (1)

(57) [Claims] A sine wave analog input signal is converted into a digital signal at a signal input unit, and the converted digital signal is output to a transmission line for each transmission cycle and transmitted, and the digital signal transmitted via the transmission line is transmitted. In a digital signal transmission device that receives a signal at a signal output unit, reconverts the signal into a sine wave analog output signal, and outputs the digital signal, the digital data is transmitted every transmission cycle based on the signal level value of the sine wave analog input signal. Data calculating means for calculating a phase angle and calculating an angular velocity based on the phase angle and the transmission cycle; and a data output for outputting digital data of the angular velocity and the phase angle calculated by the data calculating means to the transmission path. Means for inputting digital data of angular velocity and phase angle output to the transmission path, comprising: Interpolation value calculation means for calculating an interpolation value using an interpolation formula for sine wave reconversion for each transmission cycle based on the digital data of the angular velocity and the phase angle input by the stage, and calculating by the interpolation value calculation means A digital signal transmission device comprising: a signal output unit that reconverts a sine wave analog output signal based on the interpolated value and outputs the sine wave analog output signal.