JP2578843B2 - Communication device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a communication device using an underground pipe such as a gas pipe buried underground as a transmission line.

[Problems to be Solved by the Invention] Underground buried pipes laid over a wide area, such as gas pipes buried underground, are not set as signal transmission paths. Communication is possible. When an underground pipe is used as a transmission line for communication, there is no need to install a new transmission line, which is very advantageous in terms of cost.

However, since such an underground pipe is not originally installed as a transmission line, there is a problem that noise is easily mixed. For example, a frequency component of a commercial power supply or a harmonic component thereof is mixed with considerable intensity.

In addition, signal attenuation in the transmission path is large, and this also causes noise.

[Technical problem] In view of the above points, the present invention is intended to enable communication with extremely high reliability without being affected by noise in a communication device using an underground pipe as a transmission line. Things.

[Means for Solving the Problems] A communication device according to the present invention has been made to solve the above problems. In a communication device using an underground buried pipe as a transmission line, a commercial power supply is provided on the transmission side of the transmission line. A transmitter for transmitting a signal having a frequency and a harmonic frequency thereof is provided, and a receiver for receiving a signal transmitted from the transmitter is provided on a receiving side of the transmission line.

Further, the signals transmitted from the transmitter are a plurality of signals having different frequencies from each other, and are transmitted in combination in accordance with predetermined information to be transmitted, and the receiver determines the combination of the signals. It is characterized by extracting and determining whether the information transmitted from the transmitter is correct or not.

[Operation] In the above configuration, the transmitter sends a signal avoiding the frequency of the commercial power source and its harmonic frequency to the transmitting side of the transmission path. Then, the receiver receives a signal transmitted from the transmitter from the receiving side of the transmission path.

Further, when a plurality of signals having different frequencies are transmitted from the transmitter and are transmitted in combination in accordance with predetermined information, the receiver extracts the combination of the signals and outputs the combination of the signals. Analyze the information sent from.

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a block diagram of this embodiment. This communication device comprises a transmitter 1, a receiver 2, and a transmission line 3 by a gas pipe.
It is constituted by. That is, from the transmitter 1,
Commercial power frequency (for example, 50 Hz) and its harmonic frequency (for example, 100 Hz, 150 Hz, 200 Hz ... 600 Hz, 650 Hz, 700 Hz, 750)
Hz, 800Hz ...) (for example, 625Hz, 675Hz, 72
5Hz, 775Hz ...) signal is supplied to the transmission side of the transmission path 3,
The signal is received by the receiver 2 provided on the receiving side of the transmission path 3.

In the receiver 2, after the received signal is amplified by the amplifier circuit 21, it is detected by the detection circuit 22 and the signal transmitted from the transmitter 1 is extracted.

Therefore, the signal from the transmitter 1 is received by the receiver 2 with the extracted signal. Here, in order to improve the quality of communication and increase the amount of information to be transmitted, the transmitter 1 Sends a signal to the transmission line 3 based on the nCr communication system, and the receiver receives the signal via the transmission line 3.

Transmitter 1, using the four kinds of signals having different frequencies here, a predetermined number from among these signals, for example, by combining the two signals to generate a combined signal 4C ₂ representing predetermined information, this Send. The transmitter 1 uses, as the four types of signals, signals having frequencies that are less than the frequency of the commercial power supply and its harmonics. These signals are transmitted to the transmission line 3 as burst waves by superimposing two signals having different frequencies on each other.

By combining any two of these four types of signals having different frequencies, six types of information can be transmitted as shown in Table 1.

In the table, S _{1 to} S ₄ represent the above four types of signals having different frequencies, and information 1 to information 6 represent information expressed by a combination of these signals. In addition, ○ indicates that the signal of the column is used, and × indicates that the signal of the column is not used. For example, information 1 It is represented by a combination of signals S ₁ and the signal S _2, information 2 is represented by a combination of signals S ₁ and the signal S _3.

The receiver 2 has an amplification circuit 21 and a detection circuit 22, and the combined signal from the transmission line 3 is amplified to a predetermined level by the amplification circuit 21 and input to the detection circuit 22. The detection circuit 22 converts the combination signal from the amplification circuit 21 into four signals having different frequencies before superposition.
The signals are separated into different types of signals, and then envelope detection is performed. FIG. 2 shows an example of the combination signal and the separated signal. The detection circuit 22 further provides a predetermined threshold,
The signal after detection is binarized. Of the resulting four signals, typically only two of them are at logic level "1" and the remaining two signals are at logic level "0". These binary signals are input to a test circuit including a signal determination circuit 23, a combination number determination circuit 24, a time width determination circuit 25, and a time difference determination circuit 26.

Signal judgment circuit 23 of the four binary signals from the detection circuit 22, which signal is checked whether the logical level "1", and outputs the signal j ₁ to j ₆ corresponding to the information 1 to information 6 . For example, when the signals S ₁ and S ₂ are transmitted from the transmitter ₁ , the output of the detection circuit 22 corresponding to these signals becomes a logical level “1”, and the signal determination circuit 23 outputs the signal j ₁ corresponding to the information ₁ Is output. Similarly, when the signals are S ₁ and S ₃ , the signal j ₂ is output.

The number-of-combinations determination circuit 24 checks how many of the four binary signals from the detection circuit 22 have the logical level “1”. Then, only when the two signals have the logic level "1", it is determined that these signals are correct signals.

As shown in FIG. 3, the time width determination circuit 25 measures the time width T of the signal of the logic level "1" included in the four binary signals from the detection circuit 22, and determines that the width is within a predetermined range. internal T ₁ ~T ₂
Only when the signal is included, it is determined that the signal is a correct signal.

As shown in FIG. 4, the time difference determination circuit 26 compares the time widths of the signals of the logic level “1” included in the four binary signals from the detection circuit 22, for example, the binary signals a and b, Only when the difference ΔT in the time width falls within a predetermined range, these signals are determined to be correct signals.

Signal sorting circuit 27, the combination number decision circuit 24, when it is determined that the signal that all is input duration determining circuit 25 and the time difference determining circuit 26, the correct signal, the signal j ₁ ~ from the signal judging circuit 23 Output j ₆ .

 Next, the operation will be described.

If the transmitter 1 transmits, for example, information 1,
The transmitter 1 superimposes _two signals S ₁ and S ₂ having different frequencies and transmits the superimposed signals to the transmission line 3.

The combination signal representing the information 1 is input from the transmission path 3 to the receiver 2, first amplified to a predetermined level by the amplification circuit 21, and then input to the detection circuit 22.
The detection circuit 22 separates the combination signal from the amplification circuit 21 into four types of signals having different frequencies before superposition, and then performs envelope detection. The detection circuit 22 further binarizes the signal after detection by a predetermined threshold. Assuming that the four signals obtained as a result have no influence of noise or the like, only the binary signals corresponding to the signals S ₁ and S ₂ are at the logic level “1”, and the other two signals are at the logic level “1”. 0 ".

These binary signals are then input to the signal determination circuit 23, the combination number determination circuit 24, the time width determination circuit 25, and the time difference determination circuit 26.

The signal determination circuit 23 checks which of the four binary signals from the detection circuit 22 is at the logical level “1”.
And outputs the signal j ₁ to j ₆ corresponding to the information 1 to information 6. In this case, the outputs corresponding to the signals S ₁ and S ₂ are at the logic level “1”.
Therefore, the signal determination circuit 23 outputs the signal j ₁ corresponding to the information 1.

On the other hand, the number-of-combinations determination circuit 24 checks how many of the four binary signals from the detection circuit 22 have the logical level “1”. In this case, since the two signals are at the logical level “1”, the number of signals at the logical level “1” is two. Therefore, the combination number determination circuit 24 determines that these signals are correct signals. If the number is other than 2 due to noise or the like, it is determined that the signal is not correct.

At the same time, the time width determination circuit 25
The time width of two logic level “1” signals corresponding to S ₁ and S ₂ is measured. If there is no influence of noise or the like and the width is within a predetermined range, this determination circuit determines that these signals are correct signals.

The time difference determination circuit 26 also compares the time widths of the two signals of logic level “1” from the detection circuit 22. Assuming that the difference between the time widths falls within a predetermined range, the time difference determination circuit 26 determines that these signals are correct signals.

The signal selection circuit 27, the combination number determination circuit 24, the time width determination circuit 25, and all of the time difference determination circuit 26, as described above, determined that the input signal is a correct signal, from the signal determination circuit 23 The signal of is output. And
In this case, since the signal determination circuit 23 outputs j ₁ , the signal selection circuit 27 outputs the signal j ₁ representing the information 1.

As described above, the case where all of the three determination circuits determine that the signals are correct has been described. However, if the influence of noise is large and even one of the three determination circuits determines that the signal is not correct, the signal selection circuit is determined. No signal is output from 27.

[Effect of the present invention] As described above, the communication device of the present invention is provided with a transmitter for transmitting a signal avoiding the frequency of the commercial power supply and its harmonic frequency on the transmission side of the transmission path, On the receiving side,
Since the receiver for receiving the signal transmitted from the transmitter is provided, communication can be performed using the transmission path of the underground pipe while removing noise caused by the commercial power supply.

The signals transmitted from the transmitter are a plurality of signals having different frequencies from each other, and are transmitted in combination in accordance with predetermined information to be transmitted. The receiver extracts the combination of the signals. When the information sent from the transmitter is analyzed, the communication quality can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.
FIG. 3 and FIG. 4 are waveform diagrams showing signals of respective parts of the embodiment. DESCRIPTION OF SYMBOLS 1 ... Transmitter, 2 ... Receiver, 3 ... Transmitter, 21 ... Amplification circuit,
22… Detector circuit, 23… Signal judgment circuit, 24-26… Test circuit,
24: combination number judgment circuit, 25: time width judgment circuit, 26: time difference judgment circuit, 27: signal selection circuit.

Claims (2)

(57) [Claims] 1. A communication device in which an underground pipe is used as a transmission line 3. A transmitter 1 for transmitting a signal avoiding a frequency of a commercial power supply and a harmonic frequency thereof is provided on a transmission side of the transmission line 3, A communication device, comprising: a receiver 2 for receiving a signal transmitted from the transmitter 1 on a receiving side of a transmission path 3. 2. A signal transmitted from a transmitter 1 is a plurality of signals having different frequencies from each other and is transmitted in combination in accordance with predetermined information to be transmitted. 2. The communication apparatus according to claim 1, wherein the combination is extracted to determine whether the information transmitted from the transmitter 1 is correct.