JPH113485A - Data transmission system for telecon and telemeter - Google Patents

Abstract

(57) [Summary] [PROBLEMS] In general, a value to be transmitted is an analog value, which is represented by a digital code and transmitted with an error control code added to this information code. Drops. If it is attempted to transmit data of a large number of channels with only one transmission system, the data transmission rate must be increased, and the transmission error increases as the data transmission rate increases. SOLUTION: A value expected to be taken by a next sample is predicted by using an immediately preceding sample value and two sample values immediately before another, and a difference between the predicted value and an actual value is transmitted. On the receiving side, a predicted value at the present time is obtained from the immediately preceding first and second sample values which have already been reproduced in the same manner as the transmitting side, and the received difference is added to this predicted value to obtain the current value. Regenerate the sample values of. In the following, all the sample values are reproduced by successively executing this method for the subsequent sample values.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data transmission technique for compressing and transmitting data to be transmitted in telecontrol and telemeter of various analog data and restoring the original data on a receiving side.

[0002]

2. Description of the Related Art Telemeters for transmitting data such as voltage, current and power consumption of various devices, temperature and humidity, various weather data, etc. to remote points, and temperature, pressure, and temperature of objects at remote points. In telecontrol for controlling the flow rate, the number of rotations, the position, and the like, generally, an object to be transmitted is an analog value, which is converted into a digital code, and this data is transmitted by a normal data transmission method. In data transmission, usually, to correct a code error occurring on a transmission line,
Although error control is performed, a redundant code for error control is added to the data code in order to perform the error control, so that a reduction in transmission efficiency due to this is inevitable. Therefore, when attempting to transmit data of many channels by only one transmission system, the data transmission speed must be increased, and the transmission error increases as the data transmission speed increases. Therefore, in order to prevent this, compensating measures such as limiting the amount of transmission data or increasing the transmission signal power are required, but increasing the signal power is generally difficult.

[0003]

As described above, in the prior art, if error control of a data code is performed, the transmission efficiency necessarily decreases. In general data transmission (for example, transmission of character codes), the redundancy between codes sent one after another is small, but in data for transmission of analog values such as telemeters and telecontrols, redundancy between adjacent codes (between analog values). The degree is extremely large. Therefore, if this large redundancy can be efficiently reduced, the amount of transmission data can be compressed, so that error control technology can be easily introduced. Therefore, an object of the present invention is to find an efficient data compression method for analog data and a data restoration method on the receiving side.

[0004]

In the transmission of analog data, generally, an analog signal of an information source is periodically sampled, converted into a digital code, and transmitted. As described above, analog data sample values generally have a large degree of redundancy between adjacent data, so the first method of data compression is to calculate the difference from the immediately preceding sample value and calculate this. This is a method in which the data is transmitted and the receiving side restores the original data value by accumulating the difference value.

[0005] A considerable compression effect can be obtained in this way.
In this method, only one immediately preceding sample value is used. However, if the immediately preceding sample value and the two previous sample values are used, the next sample can be taken from these two sample values. Since a possible value can be predicted, if the difference between the predicted value and the actual value is transmitted, a greater compression effect can be expected than when the difference from the immediately preceding sample value is obtained.

According to the data transmission system for telecon and telemeter of the present invention, in a telecon and telemeter for periodically sampling analog data, encoding the analog data and transmitting the encoded analog data, the first and second sample values are connected. The predicted value at the present time is obtained from the straight line, the difference between the predicted value and the present sample value is obtained and transmitted, and the receiving side has already reproduced the immediately preceding first and second sample values. , The predicted value at the current time is obtained in the same manner as the transmitting side, and the sample value at the current time is reproduced by adding the received difference code to the predicted value. In the following, by successively performing this method for the subsequent sample values,
It is characterized in that all sample values are reproduced.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A data transmission system for a teleconverter and a telemeter according to the present invention is a teleconverter and a telemeter which periodically samples analog data, encodes the analog data, and transmits the encoded data. From the straight line connecting the sample values of the current value, the difference between this predicted value and the current sample value is calculated and transmitted. From the second sample value, a current predicted value is obtained in the same manner as the transmitting side, and the current sample value is reproduced by adding the received difference code to the predicted value. In the following, all the sample values are reproduced by successively executing this method for the subsequent sample values. According to the present invention, by compressing transmission data, even if redundant bits for error control are added, voltage data can be transmitted without reducing the information transmission speed. Can be performed by a microprocessor, so that a circuit for transmitting analog data can be configured simply and compactly.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the principle and embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a circuit diagram of the transmission section. In FIG. 1, 1 is a signal input terminal, 2 is a doubler (details will be described later), 3 is a register REG1, 4 is a subtractor, 5 is a RE
G2 is a register, 6 is a subtractor, and 7 is a signal output terminal.

An analog value to be transmitted, for example, voltage, current,..., Output from a sensor such as temperature, wind speed, pressure, etc., is sampled at a signal input terminal 1 in FIG.
The digitally converted code signal is added. Less than,
The operation of this circuit will be described with reference to the waveform diagram of FIG.

A curve shown by a solid line in FIG. 2 shows a change state of the analog voltage from the sensor. This signal is t ₁ ,
.. are periodically sampled as t ₂ , t _3, ... and A / D converted into digital codes representing E ₁ , E ₂ , E ₃ ,.
This digital code is input from the signal input terminal 1. Hereinafter, all the operations are performed by digital code calculations, but the analog representation is easier to understand, so the description will be made as an analog operation.

The predicted value that will be obtained at t ₁ from the two sample values E ₁ and E _{2 in} FIG. is 2E ₂ -E ₁ as shown in FIG. Therefore, the difference from the actual sample value E ₃ is E ₃ −2E ₂ + E ₁ .

The circuit shown in FIG. 1 is configured to perform the above-described operation. Both registers 3 and 5 delay their input signal by one time slot. A doubler of 2 means outputting a value twice the value of the input signal. In the case of a commonly used binary digital code, it is only necessary to shift the code upward by one bit. .

The input sample value signal is doubled by a doubler 2 and 3
Is delayed by one time slot in the register REG1 of
Since the difference is obtained by the subtracter 4, respectively, here 2E ₂
Predicted value of -E ₁ is obtained. Since the predicted value is added to the subtractor 6 is an additional 5 registers REG2 delay one time slot, where E ₃ -2E ₂ + E ₁ is determined by the output signal which is the difference between the current sample value E ₂ Becomes

An error control code is added to the difference signal from the predicted value and transmitted, and the reception side removes the error control code and restores the original data signal. Since this part deviates from the subject of the present case, its description is omitted here.

The operation for obtaining the difference signal E ₃ -2E ₂ + E ₁ from the predicted value can also be realized by the circuit configuration shown in FIG. Since this circuit is configured in the form of the arithmetic expression, its operation description will not be necessary. In the figure, those having the same numbers as those in FIG. 1 are the same circuits as those in FIG. In this circuit configuration, the contents of the three registers REG1 are shifted to the next-stage register REG2 in the next time slot.

Further, the circuit configuration shown in FIG. 4 operates similarly. As in the case of FIG. 3, blocks having the same numbers as those in FIG. 1 are the same circuits as those in FIG. 1, and 9 is an adder.

In FIG. 4, register REG1 indicated by 3
And the adder 9 constitute an accumulator in which sample values in the immediately preceding time slot are stored. Since the immediately preceding sample value is subtracted from the current sample value by the subtractor 4, a difference from the immediately preceding sample value is obtained here. This difference at time t ₂ is E ₂ −E _1, and this value is recorded in the register REG2 indicated by 5. At time t ₃ the difference output of the subtracter 4 are the subtracter 6 because they become _{E 3 -E 2 (E 3 -E} 2) - (E 2 -E 1) i.e. E ₃ -2E
₂ + E ₁ is required.

Next, the restoration circuit on the receiving side will be described. FIG. 5 is a circuit diagram for explaining this. In FIG. 5, those having the same numbers as those in FIG. 1 are the same as those in FIG.
10 is an input terminal for a received signal (difference signal from the predicted value), 11
Is an output terminal of the restored sample value signal.

Since this circuit has two feedback loops, its operation may seem complicated at first glance, but is very simple, as will be apparent from the following description. That is,
Sampled values are reproduced in the register REG2 of 5 E ₁ is 3
The registers REG1 and sample values E ₂ reproduced are notes, predicted from the signal input terminal 10 signals the error E ₃
When −2E ₂ + E ₁ is added, + 2E ₂ and −E ₁ are added to the adder / subtracter 8 from the two registers with respect to this signal, so that a sample value of E ₃ is output.
The E ₃ and at the same time are notes in the register REG1 in Katsuki time slot, the sampling value E ₂ had note is the register REG1 far is shifted to register REG2. By performing such an operation in the next time slot, the next sample value is reproduced and shifted to the register.

In FIG. 5, an adder / subtracter is used. In an analog circuit, addition and subtraction of a plurality of inputs can be performed at once, but in a digital circuit, it is usually difficult. Therefore, it would be appropriate to divide the circuit into an adder and a subtractor as shown in FIG. This is the same in the case of FIG.

Thus, in the steady state, the transmitted data is considerably compressed. The degree of compression depends on how the analog value of the information source changes, and although it is not absolutely certain, it can be expected that the compression will be considerable as can be inferred from FIG. Therefore, in the steady state, the number of code bits for representing the prediction error is considerably small.

However, since the prediction operation cannot be performed at the moment when the system starts up, the sample value appears as it is at this time, and the second output is not a correct prediction error output. However, a correct prediction error is obtained after the third time (that is, after the time when the correct sample value is stored in the register). Therefore, since the first and second data when the system starts up are not compressed, only these two data need to be transmitted using the number of bits that can transmit the sample value itself with high accuracy. Since the subsequent data is compressed, it is only necessary to switch to a code with a smaller number of bits and transmit it.

Referring to FIG. 1, the operation of each part when the above-mentioned initial state is shifted to the steady state will be described with reference to Table 1.

[0025]

[Table 1] The left end of Table 1 is a sampling time slot.
Numerals 1 to 6 in the upper row indicate that the output is the same numbered circuit in FIG. .., 0, E ₁ , E ₂ ... Indicate sample values in each time slot, and the numbers in parentheses indicate an example of sample values. Since given suddenly enter t ₁ In this example, the value is directly appear in the output. However, t ₃ after it is found that the correct prediction error is obtained.

Table 2 shows the operation of each part of the circuit of FIG. 5 when the prediction error of Table 1 is input.

[0027]

[Table 2] The way to read the figure is the same as that in Table 1. From this figure, it can be seen that a correct output is obtained.

[0028]

As described above in detail, according to the present invention, even if redundant bits for error control are added by compressing transmission data, voltage data can be stored without reducing the information transmission speed. Can be transmitted. In addition, since all of the sign arithmetic operations can be performed by a microprocessor, a circuit for transmitting analog data can be simplified,
It can be made compact.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram showing a configuration example of a transmission section for describing the principle and embodiments of the present invention.

FIG. 2 is a waveform chart for explaining the operation of a transmission unit.

FIG. 3 is a circuit configuration diagram showing another configuration example of a transmission unit.

FIG. 4 is a circuit configuration diagram showing another configuration example of a transmission unit.

FIG. 5 is a circuit configuration diagram illustrating a configuration example of a receiving unit.

FIG. 6 is a circuit configuration diagram showing another configuration example of the receiving unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transmission signal input terminal 2 Doubler 3 Register 4 Subtractor 5 Register 6 Subtractor 7 Transmission signal output terminal 8 Adder / subtractor 9 Adder 10 Received signal input terminal 11 Received signal output terminal

Claims (5)

[Claims] 1. A teleconverter or telemeter which periodically samples analog data, encodes and transmits the analog data, and doubles an input data code (in a binary code, simply shifts up by one bit) and one sampling. In addition to register 1 which accumulates and delays by the period, the outputs of both are applied to subtractor 1 and the output code of register 1 is subtracted from the output code of the doubler, so that the input which will occur in the next sampling time slot A predicted value of a code is obtained, added to a register 2 for accumulating and delaying the predicted value by one sampling period, an output of the register 2 and an input code are applied to a subtractor 2, and an output code of the register 2 is subtracted from an input code. Thereby detecting an error of a predicted value with respect to an actual input code, and transmitting the error code.
Data transmission method for telemeters. 2. A teleconverter and a telemeter which periodically sample analog data and encode and transmit the analog data, add an input data code to a two-stage shift register which shifts the input data code at a sampling period, , A code obtained by doubling the output code of the register second stage and the output of the register first stage by a doubler (in the case of binary code, simply shifting up by one bit) is added to the adder / subtractor. A teleconverter characterized in that an error of a predicted value with respect to an actual input code is detected by subtracting an output code of a doubler from a sum with an output code of a second stage, and the error code is transmitted. , Telemeter data transmission system. 3. A teleconverter or telemeter which periodically samples analog data, encodes the analog data, and transmits the encoded data, adds an input data code to a subtractor 1, adds an output of the subtracter to an adder, and outputs an output of the adder. Is added to the register 1 for accumulating and delaying by one time slot of the sampling cycle,
An accumulator is formed by adding the output code of the register 1 to the adder.
In addition to the above, by subtracting the output code of the register 1 from the input data code, a code corresponding to the difference between the current sample value and the immediately preceding sample value is obtained at the output of the subtractor 1, and this difference code is added to the subtractor 2. In addition, in addition to the register 2 for accumulating and delaying by one time slot of the sampling period, the output of the register 2 is applied to the subtractor 2, and the subtracter 2 subtracts the output code of the register 2 from the difference code. A data transmission system for telecon and telemeters, wherein an error of a predicted value with respect to an actual input code is detected and the error code is transmitted. 4. A method used in a teleconverter and a telemeter for periodically sampling analog data, encoding the analog data, and transmitting the encoded analog data, wherein the analog data is obtained from an extension line of two sample values immediately before and one before the analog data. In a restoration method for transmitting an error of a predicted value to an actual value, that is, a prediction error code, and restoring the prediction error code to an original sample value, a prediction error code of a received input is added to an adder / subtractor, and the output of the adder / subtractor is output by 2 In addition to the shift register that shifts at the sampling period in a stage configuration, the output of the first stage register is doubled (in the case of a binary code, only 1
(A shift to the upper bit) and the output of the second-stage register are added to the adder / subtractor, and the output code of the second-stage register is calculated from the sum of the input prediction error code and the output code of the doubler. A data transmission method for a teleconverter or telemeter, wherein the data is restored to a code corresponding to an original sample value by subtraction. 5. A method used in a teleconverter and a telemeter which periodically samples analog data, encodes the data, and transmits the encoded data, and is obtained from an extension of two sample values immediately before and one immediately before the teleconverter. In a restoration method for transmitting an error of a predicted value to an actual value, that is, a prediction error code, and restoring the prediction error code to an original sample value, a prediction error code of a received input is added to an adder, and the output of the adder is added to 2. In addition to the shift register that shifts at the sampling period in a stage configuration,
A code obtained by doubling the output of the first-stage register by a doubler (in a binary code, simply shifting up by one bit) and the output of the second-stage register are added to a subtractor. A prediction code is obtained by subtracting the output code of the second-stage register, and this prediction code is added to the adder and added here to the prediction error code of the received input, thereby restoring the code to the original sample value. A data transmission system for a teleconverter and a telemeter, characterized by being constituted.