JPH04196644A - Isolation system for transmission line - Google Patents

Abstract

PURPOSE:To attain transmission in bit-free by using a pulse transformer to isolate a transmission line and a transmitter, modulating a transmission data at a sender side with an optimum pulse and sending the result and demodulating the modulated signal at a receiver side. CONSTITUTION:A transmission line 13 is isolated from a sender side and a receiver side transmitter respectively by using pulse transformers T1, T2. Then a modulation circuit 11 modulates a transmission data A by a modulation pulse P and outputs a resulting signal Vout and the signal Vout is subject to current amplification by a transistor(TR) 12 and inputted to the pulse transformer T1. The signal Vout sent through the transmission line 13 is rectified by a diode D1 via the pulse transformer T2 and becomes a rectified wave signal Vin by an integration circuit 14. Moreover, a hysteresis comparator 15 converts the signal Vin into a reception data V0 and the signal Vout is demodulated into a reception data signal V0. Thus, the transmission is attained in bit-free regardless of the transformer system independently of the modulation form of a serial data especially.

Description

Detailed Description of the Invention A. Industrial Field of Application The present invention is an insulation method for a transmission line for transmitting and receiving data. On the transmitting side, the transmitted data is modulated with the optimal pulse to drive the pulse transformer, and then transmitted.On the receiving side, the signal from the pulse transformer is shaped into a waveform using an integrating circuit, and then converted into a digital waveform using a hysteresis comparator. The signal is demodulated and transmitted bit-free while being isolated using a pulse transformer.

C3 Conventional technology As shown in FIGS. 3 and 4, as a conventional method of insulating a transmission line, the transmitting and receiving sides of the transmission line 13 are connected to a pulse transformer Tl.
, transformer type insulating with T2 and photocoupler F5.
There is one type of photocoupler that insulates with 26.

In the case of the transformer method, since the pulse transformers Tl and T2 are directly connected to the transmission line 13, an isolated power supply such as a DC/DC converter for the driver 23 and receiver 24 connected to the transmission line as in the photocoupler type is required. 27 and 28 are unnecessary and high-speed operation is possible.

On the other hand, in the case of a single photocoupler type, since the photocoupler passes direct current, there is no restriction on the modulation method.

D0 Problems to be Solved by the Invention However, the transformer system cannot pass direct current, and also has the disadvantage that the shape of the transformer becomes large at low speeds.

Further, in the case of the one-type photocoupler, an insulated power source is required as described above, and high-speed operation is difficult due to the switching speed of the photocoupler.

The present invention has been made in view of the above-mentioned problems of the conventional technology, and its purpose is to provide a transmission line that can transmit bit-free data using a transformer method, particularly regardless of the modulation format of serial data. The purpose of this invention is to provide an insulation method.

E1 Means for Solving Problems In order to achieve the above object, the transmission line insulation method in the present invention is to insulate the transmission line from the transmitting side and receiving side transmission devices with pulse transformers respectively, and then transmit. In this system, the transmitted data is modulated into a pulse optimal for driving a pulse transformer by a modulation circuit, and on the receiving side, the signal from the pulse transformer is waveform-shaped by an integrating circuit, and then demodulated into a digital waveform by a hysteresis comparator. .

20 Effects On the transmitting side, the transmitting data is modulated into a signal that is optimal for driving the pulse transformer by a modulation circuit, so this modulated signal is transmitted to a transmission line insulated by a pulse transformer on the transmitting and receiving sides, respectively. be able to.

On the receiving side, when the modulated signal from the pulse transformer is shaped by an integrating circuit, a shaped waveform that looks like the waveform of the transmitted data is distorted is obtained. When this shaped waveform is input to a hysteresis comparator, it can be demodulated into a digital waveform determined by the two threshold values of the hysteresis comparator.

Therefore, transmission data having a DC component can be transmitted using a transmission line insulated by a pulse transformer.

G. Embodiments Examples of the present invention will be described with reference to the drawings. Components that are the same as those conventionally shown in FIGS. 3 and 4 are designated by the same reference numerals, and redundant explanation thereof will be omitted.

In FIG. 1, 11 is a modulation circuit using an AND circuit into which transmission data and modulation pulses are input, 12 is a transistor that current amplifies the output signal of the modulation circuit 11 connected in series with the transmission side pulse transformer T1, and Dl is A diode that rectifies the output signal of the receiving pulse transformer T2, and 14 resistors R1 and R2 that integrate the signal rectified by the diode.
, an integrating circuit consisting of a capacitor C1, 15 is an integrating circuit 1
This is a hysteresis comparator that demodulates the output waveform of No. 4 into a digital waveform.

Next, the operation of this circuit will be explained with reference to waveforms of various parts in FIG.

The modulation circuit 11 modulates the transmission data A with the modulation pulse P and outputs a signal V out. This signal V out is current-amplified by the transistor 12 and input to the pulse transformer T1. However, since the pulse of the signal V out has a small voltage-time product, the pulse transformer T1. Transmission is possible without saturation of T2.

The transmitted signal V out is rectified by a diode D1 via a pulse transformer T2, and is converted into a rectified wave signal Vin by an integrating circuit 14. Hysteresis comparator 1
5, this signal Vin is the threshold voltage VT) IHI G
The signal Vin is converted to received data vo and the signal v out is demodulated to received data signal Vo. Therefore, data having a DC component, such as transmission data A, can be transmitted using a transformer method.

The integration circuit 14 also functions as a filter to improve the noise margin.

H9 Effects of the Invention Since the present invention is configured as described above, it produces the following effects.

(1) When transmitting serial data with a DC component such as NRZ, and when high speed is not particularly required, conventionally a photocoupler type was used as the insulation method for the transmission line, but since the present invention uses a transformer type, Compared to conventional photocoupler single-type systems, expensive insulated power sources such as DC/DC converters are not required.

(2) Although the present invention is a transformer method, bit-free transmission is possible regardless of the modulation format of serial data.

(3) The integrating circuit also functions as a filter to improve noise margin.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram showing the circuit of the transmission line insulation method according to the embodiment of the present invention, FIG. 2 is a waveform diagram showing waveforms of each part of the circuit diagram, and FIGS. 3 and 4 are respectively for conventional transmission. FIG. 2 is a block circuit diagram showing a circuit of a path insulation type. 11... Modulation circuit, 12... Transistor, Tl. T2...Pulse transformer, 13...Transmission line, 14.
...Integrator circuit, 15...Hysteresis comparator,
21゜23...Driver, 22.24...Receiver-125,26...Hotokabu-127,28...
isolated power supply. 1 other person

Claims (1)

[Claims] (1) The transmission path is isolated from the transmitting side and receiving side transmission devices by pulse transformers, and on the transmitting side, the transmitting data is modulated by a modulation circuit into a pulse that is optimal for driving the pulse transformer, and is then transmitted and received. On the other hand, the transmission line insulation method is characterized by shaping the waveform of the pulse transformer signal using an integrating circuit and then demodulating it into a digital waveform using a hysteresis comparator.