SU1483475A1 - Method and apparatus for data transmission - Google Patents

Abstract

The invention relates to telemetry and can be used in information transmission systems with pulse-width modulation. The method and apparatus implement the serial multiple transmission of one-way pulse-width modulated signals. At the same time, the durations of odd fixed transmission cycles and pulse-width modulated pulse signals in them are increased compared with the duration of even cycles, which increases the noise immunity and transmission accuracy. The device contains a pulse generator 1, counting triggers 2.3, elements AND 4.5 element OR 6, pulse counter 7 and a digital-analog converter 8. 2 Il.

Description

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The invention relates to telemetry and can be used in information transmission systems with pulse-width modulation.

The purpose of the invention is to improve the noise immunity and accuracy of transmission.

FIG. 1 shows a functional diagram of the proposed device} in FIG. 2 - timing diagrams explaining the operation of the device and the effect of the method.

The device contains the .generator 1 pulses, the first and second counting triggers 2 and 3, the first and second elements AND 4 and 5, the element OR 6, the counter 7 pulses, the digital-to-analog converter 8 and the null-gorgan 9..

The device works as follows.

The pulses from the generator 1 are fed to the counting input of trigger 2 and to the first input of element I 4. From the output of trigger 2, pulses whose frequency is two times lower than the frequency of generator 1 are sent to the first input of element I 5. The second inputs are element-. Commands and 5 receive the enable signals from the outputs of the trigger 3. Thus, the counting input of the binary counter 7 receives pulses through the element OR 6, the element I4, if the trigger 3 is in the zero state. If trigger 3 is in the single state, the input of the counter 7 receives pulses through the element OR 6, the element 5 and the trigger 2. The uniform binary code from the output of the counter 7 enters the input of the converter 8, at the output of which a step-increasing voltage is generated. Trigger 3 provides the duration of step-increasing voltage in even fixed time intervals two times shorter than odd ones (Fig. 2A). From the output of the converter 8, the step-increasing voltage goes to the first input of the zero-organ 9. The second voltage to the second input of the organ 9 receives the measured voltage U. As a result of comparing these two voltages, the width-modulated impulse signals from the device output (Fig. 2B) to the communication channel and to the counting input of trigger 3. The latter is transferred along the leading edge of the input pulses, and at its output signals are generated

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control elements of the operation And 4 and 5 and, accordingly, the duration of the steps of the stepped-ramp-saw voltage at the output of the converter 8.

The diagram of Fig. 2A shows the graphs of the output signal of the converter 8 and the measured voltage U. The diagram of Fig. 2B shows the pulses received at the output of the device and sent to the communication channel. The diagram of Fig. 2B shows the same pulses, but subjected to distortion in the communication channel, and the reference voltage Uor of the operation of the comparator on the receiving side. The following notation is used in the diagrams: T ,, T2 is the duration of the intervals between the leading edges of two adjacent pulses; T3 - the duration of the interval between the falling edges of the same pulses; f, 2 the duration of the pulses produced, respectively, in odd and even time intervals. The value of f is proportional to the measured voltage and can be determined on the receiving side by the formula

IT2- Ti L

As can be seen from the diagram of Fig. 2B, the distortion of the pulse fronts does not degrade the measurement accuracy of T, T3 values and, therefore, definition 1, because the front and rear edges are distorted equally and the distance between them does not depend on the level of the comparator on the receiving side .

Thus, the method of signal transmission protects against distortions of fronts in the communication channel, since repeated (in particular double) transmission of pulses makes it possible to accurately determine on the receiving side the duration of the initial pulse 1. In addition, the signal is retransmitted with sufficiently long pulses, which increases the noise immunity of the transmission, which is proportional to the duration of the transmitted pulses.

Claims (2)

1. The method of transmitting information, which consists in forming a pulse signal, duration € v which is an information parameter, and transmit the generated pulse signal to the communication channel in a transmission cycle, duration T. -7, the beginning of which coincides I 1 L OS K v with a leading edge of a pulse signal, characterized in that, in order to improve noise immunity and transmission accuracy, the generated pulse signal is transmitted N times, N 2, 3, ..., moreover, in even transmission cycles, the duration T g of transmission cycles and the duration of pulses increase in specified number of times. 2. A device for transmitting information containing a counter, the outputs of which are connected to the corresponding n inputs of the digital-analog conversion five A cell whose output is connected to the first input of a null organ, the second input of which is the device input, and a pulse generator, characterized in that, in order to improve the noise immunity and accuracy of information transmission by the device, triggers are introduced into it, the AND elements and the OR element, the output of the pulse generator is connected to the first input of the second element And, the first and second outputs of the second trigger are connected to the second inputs of the first and second elements, respectively, the outputs of which are connected respectively to the first and second inputs and the OR element, the output of which is connected to the input of the counter, the output of the null organ is connected to the input of the second trigger and is the output of the device. FIG. 2