JPH01202933A - Distribution line carrier signal transmission system using differential phase modulation - Google Patents

Abstract

PURPOSE:To attain high speed and sure transmission by sending a signal with differential phase modulation, and allowing a reception side to apply differential demodulation. CONSTITUTION:A 60Hz synchronizing pulse synchronized with a commercial frequency is generated from a commercial frequency synchronizing pulse generator 3. A data pulse synchronously with a synchronizing pulse is generated with the information code to be space from a serial data generator 4 according to the inputted information code (60bps). A commercial frequency zero cross phase correction device 6 generates a signal (g) of a waveform being the inversion of the latter half phase of each one bit period of the output (f) of a phase modulation generator 5 based on an output (b) of the commercial frequency synchronizing pulse generator 3. The signal (g) controls the energization of a switching transistor 7. Then a load current (h) flows to a load resistor 8 via a rectifier 9 in response to the control and the current is injected to a distribution line via a pole transformer.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention uses power distribution lines (power lines) as a signal transmission medium to transmit control signals in supervisory control systems such as load control and switch control, as well as automatic meter reading. This field relates to a signal transmission method using differential phase modulation that can be used for data transmission in systems, etc.

(Prior art) Conventionally, in information transmission using power distribution lines, there are many harmonics of the commercial frequency when extracting signals from the power distribution lines, so it is necessary to increase the signal-to-noise ratio, so narrowband filters are used. The method used was to extract and receive the signal. However, passing the signal through a narrowband filter increases the rise time of the signal.
Moreover, since distortion occurs in the waveform, the signal transmission speed is extremely slow, on the order of several bits/second.

(Problems to be Solved by the Invention) It is an object of the present invention to provide a distribution line carrier signal transmission system that solves the problems of the prior art described above and dramatically increases signal transmission speed.

(Means for Solving the Problems) The distribution line carrier signal transmission system of the present invention has a transmitting side transmitting a transmission signal using 1/n (n is a positive integer) of the commercial frequency f of the power transmitted over the distribution line. When the serial data to be transmitted is the first binary bit, the previous bit is A phase modulation means that inverts the modulation phase to the opposite modulation phase and does not invert the modulation phase when the serial data to be transmitted is a second binary bit, and a distribution line for transmitting the modulated carrier wave modulated by the phase modulation means. A transmitting device is provided having an injection means for injecting.

On the receiving side, there is an extraction means that extracts the modulated carrier wave from the current flowing in the distribution line, and a differential carrier that delays the modulated carrier wave for one bit period and calculates the difference between the delayed modulated carrier wave and the undelayed modulated carrier wave. A receiving device is provided which has differential demodulation means for outputting a demodulated carrier signal and Fourier demodulation means for Fourier demodulating data from the differentially demodulated carrier signal.

Specifically, when m is set to an even number, the first binary bit can be made to correspond to a "mark" and the second binary bit can be made to correspond to a "space".

In that case, a subtraction circuit is used to calculate the difference between the delayed modulated carrier wave and the non-delayed modulated carrier wave on the receiving side.

Furthermore, when m is set to an odd number, the first binary bit can be made to correspond to a "space" and the second binary bit can be made to correspond to a "mark". In that case as well, the calculation of the difference between the delayed modulated carrier wave and the non-delayed modulated carrier wave on the receiving side is configured by a subtraction circuit.

Furthermore, in the case where m is set to an odd number, the first 2
The hexadecimal bit can also correspond to a "mark" and the second binary bit can correspond to a "space". and,
In that case, the calculation of the difference between the delayed modulated carrier wave and the non-delayed modulated carrier wave on the receiving side is configured by an adder circuit.

(Function) As described above, the present invention is configured to transmit using differential phase modulation on the transmitting side and perform differential demodulation on the receiving side, thereby eliminating harmonic noise in the transmission path and transmitting the signal using differential phase modulation. The carrier wave is converted into an amplitude modulated signal with twice the amplitude, and since the signal is reproduced by applying Fourier demodulation to this amplitude modulated signal, high-speed and reliable transmission can be achieved.

(Embodiment) FIG. 1 shows an embodiment of a transmitting device in a distribution line carrier signal transmission device of the present invention, and FIG. 2 shows waveforms of each part thereof. In this example, the commercial frequency f is 60Hz, n=
1 and m=17 (that is, an odd number) to perform differential phase modulation.

The transformer 2 lowers the low voltage 220■ of the pole transformer 1 to a further low voltage 6■, and the commercial frequency waveform (second
6 synchronized with the commercial frequency by shaping based on the voltage at point a in the figure
A commercial frequency synchronization pulse generator 3 that generates a 011z square wave synchronization pulse (Fig. 2 shows a focal voltage), and a 60 bps serial generator that generates a pulse that rises when the information code is a space by its output and information code input C. data (second
The serial data generator 4 generates a carrier wave (voltage at point d in Figure 2), and the serial data to be transmitted based on the output of the serial data generator 4 (Figure 2 e) is the first binary bit (
When the serial data to be transmitted is the second binary bit ("mark" in this example), the modulation phase is reversed to the modulation phase of the previous bit (in this example, "space"). A phase-modulated wave generator 5 generates a phase-modulated wave (FIG. 2 f) that is phase-modulated so that the modulation phase remains as it is without inverting, and a phase-modulated wave generator 5 generates a phase-modulated wave (FIG. 2 f) that does not invert the modulation phase, and uses the zero cross of the synchronizing pulse b to A commercial frequency zero cross phase corrector 6 corrects the waveform with the phase reversed (Fig. 2g), a switching transistor 7 whose conduction and non-conduction are controlled by its output, and the voltage is passed through a load resistor 8. It consists of a rectifier 9 which is opened and closed by a switching transistor 7 to flow a load current (h in FIG. 2).

Next, the operation of the transmitter using differential phase modulation according to the present embodiment configured as described above will be explained.

The low voltage side (220v) of the pole transformer 1 is further stepped down to 6v by the transformer 2 (Fig. 2a), and the commercial frequency synchronous pulse generator 3 takes the zero cross of the output of the transformer to convert the voltage to 6v. Generates a 60Hz synchronization pulse synchronized with the frequency. The serial data generator 4 generates data pulses di and d2 (FIG. 2 d) synchronized with the synchronization pulse when the information code is a space in accordance with the input information code (60 bps, FIG. 2 C).

As shown in FIG. 3, the phase modulated wave generator 5 includes a voltage follower 51 that passes the carrier wave with the same phase, an inverter 52 that inverts the phase of the carrier wave, and these voltage followers 5.
The switch circuit 53 includes a switch circuit 53 that selects and outputs one of the outputs of the inverter 1 and the output of the inverter 52, and a D flip-flop 54 connected to a control terminal of the switch circuit 53.

A data pulse d is input to the clock terminal K of the D flip-flop 54, and the data pulse d is applied to the clock terminal K of the D flip-flop 54.
4 is reversed (FIG. 2 FF). Based on the Q output, the switch circuit 53 alternately switches and selects the output of the voltage follower 51 and the output of the inverter 52, and outputs the modulation signal f.

The commercial frequency zero cross phase corrector 6 generates a signal g having a waveform in which the phase of the second half of each 1-bit period of the output f of the phase modulated wave generator 5 is reversed based on the output of the commercial frequency synchronous pulse generator 3. do. The output signal g controls the conduction and non-conduction of the switching transistor 7, and in accordance with the control, a load current flows through the load resistor 8 through the rectifier 9, and this current is passed through the pole transformer 1 to the distribution line. injected into.

In this embodiment, the load current is controlled by the switching transistor 7 for signal injection, which is a very simple and useful configuration, but since the signal current is directly switched on and off during switching, electromagnetic waves are not generated. The injected signal may be modulated at the commercial frequency. In order to avoid such problems, it is preferable to use an injection device in which a resonant circuit is formed by a coupling transformer and a resonant capacitor.

FIG. 4 shows a block configuration diagram of a receiving device installed in a substation (receiving side) in this embodiment.

A signal current that arrives through a certain high-voltage distribution line as a transmission path flows into the high-voltage bus, but a main current transformer 11 is inserted in the middle of the signal current, and an auxiliary current transformer 12 is further inserted in the secondary circuit of the main current transformer 11. The voltage generated by the load resistor 13 of the secondary winding circuit of the current transformer 12 is input to the reception filter 14 . In the reception filter 14.

The commercial frequency and its harmonic noise components are removed, and the signal carrier wave is extracted and amplified to an amplitude of about 1V.

The output of the reception filter 14 is input to a differential demodulator 15.

As shown in FIG. 5, the differential demodulator 15 includes a baud rate time delay delay element 151 that delays the signal by one bit period, and a subtractor that subtracts the baud rate time delay signal of the delay element 151 from the input signal u (t). It consists of a circuit 152. As shown in FIG.
When (t) is subtracted, when the data is a mark, the amplitudes of both signals are added, resulting in a signal with a large amplitude, but when the data is a space, the amplitudes of both signals are subtracted, and the amplitude becomes O. Such differential demodulation increases the S/N ratio. The differential demodulated output signal y (t) shown in FIG. 6 has been converted into an amplitude modulated signal, and this amplitude modulated wave A
sinωt is the reference sine wave signal Bs1n (ωt+φ) and the reference cosine wave signal Be in the Fourier demodulator 16 of FIG.
A cross-correlation is taken for both os(ωt+φ) and Fourier demodulation is performed.

FIG. 7 shows the configuration of the Fourier demodulator. The output signal A sinωt of the differential demodulator 15 is sent to the two multipliers 2
Entered on 6.27. The multiplier 26 multiplies the input signal frequency generated by the reference cosine wave generator 28 by a reference cosine wave Bcos(ωt+φ) of the truncation frequency, and outputs a sinφ component of the signal amplitude.

On the other hand, the multiplier 27 multiplies the reference sine wave Bs1n (ωt+φ) generated by the reference sine wave generator 29, and outputs the CO8φ component of the signal amplitude.

The output of the multiplier 26 is a composite wave of double-frequency AC and DC components, which passes through analog switches 32 and 33 that alternately open and close for every 1 bit of the signal, and is alternately integrated for 1 bit time by the integrators 36 and 37 to generate a DC signal. Output only the components. The outputs of the two integrators 36, 37 are summed to output a series of sinφ components of the pulse code signal wave amplitude.

Similarly, the output of the multiplier 27 is passed through an analog switch 34.35 which alternately opens and closes for each bit to an integrator 38.39.
The cosφ component of the signal amplitude is outputted alternately for 1 bit time, and the adder 41 adds the cosφ component of the signal wave amplitude.

sinφ component output from adder 40 and adder 4
The eO3φ components outputted from 1 are squared by squarers 42 and 43, respectively, and added by an adder 44 to output a square value of the absolute value of the signal amplitude. That is, when it is a mark of the information pulse code, the square value of the signal frequency amplitude is output, and when it is a space, since there is no signal frequency, OV is output.

The code regenerator 17 shapes the signal demodulated by the Fourier demodulator 16 and regenerates the encoded code.

Figure 8 shows an example of waveforms as a result of an actual transmission test performed on the receiving device, and is a waveform diagram showing the reception filter output, differential demodulator output, and Fourier demodulator output in Figure 4. It is. It can be seen that good error-free demodulation results are obtained by combining differential demodulation and Fourier demodulation.

FIG. 9 shows the switching transistor 7 in FIG.
, shows an example of a signal injection device using an LC resonant circuit that can be used in place of the signal injection device consisting of a load resistor 8 and a rectifier 9. An LC resonant circuit consisting of a loosely coupled transformer T and resonant capacitors CI and C2, a power source consisting of a rectifier and a rectifying capacitor for charging the resonant capacitor C1, and a power source from the above power source under the control of a differential phase modulation signal. It consists of a switch circuit having an electronic switch SWI for charging the resonant capacitor C1 and an electronic switch SW2 for discharging the charge from the resonant capacitor CI. The LC resonant circuit is tuned to have a resonant frequency centered on the carrier frequency of the differential phase modulation signal. The opening and closing of the two electronic switches in the switch circuit are controlled by differential phase modulation signals (signal f in Figure 2), but control signals with mutually opposite phases are supplied to the control terminals of the surface electronic switch. Therefore, the capacitor C1 operates alternately according to the signal f, and the capacitor C1 alternately repeats charging and discharging, so that the components of the differential phase modulation signal are injected into the high voltage distribution line. This example has a resonant circuit using a loosely coupled transformer, so efficient signal injection can be achieved.

(Effect of the invention) Conventionally, in this type of distribution line carrier signal transmission system, in order to avoid the influence of harmonic noise of the commercial frequency, which accounts for most of the transmission line noise, the receiving device extracts the signal using a narrow band filter. was. However, using a narrowband filter increases the rise time of the filter and causes distortion in the waveform, which limits the signal speed and necessitates a low speed of several bits per second.

According to the present invention, all of these conventional problems can be solved. That is, in the present invention, by transmitting with differential phase modulation and performing differential demodulation on the receiving side, harmonic noise in the transmission path is removed, a narrow band filter is not required, and the signal carrier wave is twice as large. S in the form converted into an amplitude modulated signal of amplitude
Since the signal is reproduced by performing Fourier demodulation on this amplitude modulated signal, high-speed and reliable transmission can be achieved.

[Brief explanation of the drawing]

Fig. 1 shows an embodiment of the transmitting device in the distribution line carrier signal transmission device of the present invention, and Fig. 2 shows the waveforms of each part thereof. An example of a mark is shown in FIG. 3(b), where the information code is space, space, mark. This is an example of a mark. FIG. 3 is a diagram showing an example of the configuration of a one-phase modulated wave generator. FIG. 4 is a diagram showing a block configuration of a receiving device installed in a substation (receiving side) in this embodiment. FIG. 5 is a diagram showing an example of a differential demodulator, and FIG. 6 is a diagram showing waveforms of each part thereof. FIG. 7 is a diagram showing the configuration of a Fourier demodulator. FIG. 8 is a diagram showing waveforms of each part of the receiving device of FIG. 4. FIG. 9 is a diagram showing an example of a signal injection device using an LC resonant circuit. 1... Pole transformer, 2... Transformer, 3... Commercial frequency synchronous pulse generator, 4... Serial data generator,
5... Phase modulated wave generator, 6... Commercial frequency zero cross phase corrector, 7... Switching transistor, 8...
... Load resistance, 9... Rectifier, 11... Main current transformer, 12... Auxiliary current transformer, 13... Load resistance,
14... Reception filter, 15... Differential demodulator, 16.
...Fourier demodulator, 17... code regenerator. Patent applicant: Kyushu Denki Seizo Co., Ltd. Figure 3 Figure 4 Figure 5 Ft) Figure 8

Claims (3)

[Claims] (1) On the transmitting side, set the transmission speed of the transmission signal to 1/n (n is a positive integer) of the commercial frequency f of the power transmitted over the distribution line, and set the transmission speed to m/2 times the transmission speed (m is a positive integer). When the serial data to be transmitted is the first binary bit, the modulation phase is inverted to the opposite of the modulation phase of the previous bit, and the serial data to be transmitted is A transmitter is provided on the receiving side, which has a phase modulation means that does not invert the modulation phase when is the second binary bit, and an injection means that injects the modulated carrier wave modulated by the phase modulation means into the distribution line, an extraction means for extracting the carrier wave from the current flowing in the distribution line; and a means for extracting the carrier wave from the current flowing in the distribution line;
It has differential demodulation means that calculates the difference between a delayed modulated carrier wave and a non-delayed modulated carrier wave and outputs a differentially demodulated carrier signal, and a demodulation means that performs Fourier demodulation of data from the differentially demodulated carrier wave signal. A distribution line carrier signal transmission system using differential phase modulation characterized by the provision of a receiving device. (2) The injection device comprises a rectifier connected to the low voltage side of the pole transformer, a load resistor connected to the rectifier, and a switch means for opening and closing the current flowing through the load resistor using a differential phase modulation signal. Characteristic Claim No. 1
) Distribution line carrier signal transmission system using differential phase modulation as described in section 2. (3) The injection device includes an LC resonant circuit including a loosely coupled transformer and a resonant capacitor, a power supply circuit for applying a DC voltage to the LC resonant circuit, and an application of DC voltage from the power supply circuit to the LC resonant circuit. A distribution line carrier signal transmission system using differential phase modulation according to claim 1, further comprising a switch circuit controlled by a differential phase modulation signal.