JPS63268336A - Pulse modulation transmission circuit - Google Patents

Abstract

PURPOSE:To send a pulse with a shorter width by extending the pulse width of a transmission data by a time corresponding to the period from the start of an oscillation circuit to the steady-state oscillation while intermitting the oscillation circuit by the transmission data. CONSTITUTION:A pulse width extending means is provided to the pre-stage of a pulse modulation transmission circuit 1, and the means extends the pulse width of the transmission data D by a time TD from the just after state when the oscillation circuit is started by the transmission data till the steady-state oscillation. The said means consists of a one-shot multivibrator 2 and an OR circuit 3 and the output of the circuit 3 is used as an input data oscillating inter edge the oscillation circuit. The one-shot multivibrator 2 detects the trailing of the transmission data D to output a one-shot pulse P. The pulse width of the pulse P corresponds to the said period TD. Thus, an output signal having a pulse width being the sum of those of the data D and the pulse P is produced at the output of the OR circuit 3. The oscillation of the oscillation circuit is intermittent by the output signal to apply the pulse modulation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field 1] The present invention relates to a pulse modulation transmission circuit that performs pulse modulation by performing an oscillation operation of an oscillation circuit that generates a carrier signal based on transmission data.

[Background Art 1 A number of methods are used, one of which is a pulse modulation method. This transmits carrier waves intermittently depending on the input digital signal.

An example of a conventional transmitter circuit using this pulse modulation method is shown in FIG. This is done by energizing the oscillation circuit 4 that generates carrier No. 43 with a transistor Q and a crystal oscillator X, applying transmission data as a digital signal to the base of transistor Q, and using the voltage of this transmission data , transmitting circuit 4
By intermittent base bias current of transistor Q, oscillation operation is intermittent and pulse modulation operation is performed.

FIG. 4 shows a transmitting circuit using another pulse modulation method.

This is done by inserting a transistor Q2 in series with the oscillation circuit 4, applying transmission data to the base of the transistor Q2 to turn the transistor Q2 on and off, and intermittent power supplied to the oscillation circuit 4 according to the transmission data. , which performs pulse modulation operation by intermittent oscillation operation.

When a high-Q resonator is used, immediately after the oscillation circuit 4 is activated, a period of weaker amplitude than the steady-state amplitude continues for a certain period of time, although it depends on the circuit type and the device used. The time it takes for the output amplitude and frequency of the oscillation circuit 4 to reach a steady state is generally on the order of several hundred μsees to several +19ee. For example, in the circuit shown in FIG. 4, the time immediately after the transmission data rises from a low level to a high level corresponds to the activation time of the oscillation circuit 4, and the waveform at this time is as shown in the period TT shown in FIG. 5(b). is shown. On the other hand, the time it takes for the output amplitude to sufficiently attenuate after the oscillation circuit 4 stops operating is shorter than the time it takes for the oscillation circuit 4 to reach a steady state after starting. Therefore, when data as shown in FIG. 5(a) is transmitted, the detected waveform on the receiving side becomes distorted as shown in FIG. 5(c). Therefore, on the receiver side, this detected output is waveform-shaped as shown in ttS5 figure (d), but the received data after this waveform shaping is
The pulse width is shortened by approximately the period TD from the transmitted data,
Correct data transmission cannot be performed. For this reason, it usually takes time T until the oscillation circuit 4 reaches a steady state after starting up.
The above-mentioned transmission circuit that performs pulse modulation by intermittent oscillation operation could only be used when the data transmission speed is such that o is sufficiently short with respect to the pulse width to be transmitted. For example, if it takes 1 See to reach a steady state after the oscillation circuit 4 is activated, then if the allowable pulse width distortion is 10%, only a pulse with a minimum pulse width of 10 m5ec can be transmitted. In this case, if the NRZ code is used, there is a problem that the above-mentioned circuit can only be used when the transmission speed is 100 bps or less.

[Objective of the Invention 1 The present invention has been made in view of the above-mentioned points, and its purpose is to provide a transmission circuit that performs pulse modulation by intermittent oscillation operation of an oscillation circuit, to provide faster data transmission. The purpose is to enable transmission.

[Disclosure of the Invention 1 (Configuration) The present invention provides a pulse modulation transmitting circuit that performs pulse modulation by intermittent oscillation of an oscillation circuit that generates a slight transmission signal using transmission data that is a dinotal signal. This device is equipped with a pulse width extension means that lengthens the pulse width of the transmitted data by an amount equivalent to the time from immediately after starting the oscillation circuit with the transmitted data to the steady oscillation state when the circuit is interrupted. By lengthening the pulse width by the pulse width extension means by an amount corresponding to the time it takes for the oscillation circuit to reach a steady oscillation state, the pulse width of the transmission output can be corrected and shorter pulses can be sent. , which enables faster data transmission.

(Example) An example of the present invention is shown in ttLJllA. In this embodiment, in which stage of the pulse modulation transmitting circuit 1 explained in the conventional example section, the transmitted data D corresponds to the time T from immediately after starting the oscillation circuit 4 with the transmitted data until reaching the steady oscillation state.
A conventional transmitting circuit for pulse brightness that lengthens the pulse width is simply referred to as a transmitting circuit.

In this embodiment, the pulse width extension means includes a one-shot multipipe rake (hereinafter referred to as one-shot multi) 2 that detects the falling edge of the transmission data D and generates a pulse with a predetermined pulse width; It is composed of an OR circuit 3 that performs a logical sum with two one-shot multi-outputs. Note that the output of the off-circuit 3 is used as input data for causing the oscillation circuit 4 to oscillate intermittently.

The operation will be explained below with reference to FIG.

11t2 When the transmission data D shown in figure (a) is input to the one-shot multi 2, the one-shot multi 2 detects the falling edge of the transmission data D, and the one-shot multi 2 shown in figure (b) is input to the one-shot multi 2. Outputs pulse P. The pulse width of this pulse P corresponds to a period Tt from immediately after the oscillation circuit 4 is started until it reaches a steady oscillation state. Therefore, an output signal having a pulse width equal to the sum of the transmission data D and the pulse P, which is the one-shot multi-two output, is generated at the output of the off-circuit 3. As a result, pulse modulation is performed by intermittent oscillation of the oscillation circuit 4 in the same manner as explained in the conventional example section. The transmission output waveform transmitted from the transmission circuit 1 at this time is as shown in FIG. 2(d). The detection output of the receiver that received this transmission signal is as shown in Figure 2 (e), and the output obtained by shaping the waveform of this detection output (Figure 2 (f)) is as shown in Figure 2 (
The waveform is similar to that of the transmission data D in a). in this way,
Taking into consideration the response delay of the oscillation circuit 4, which is the period TD from the start of the oscillation circuit 4 until it reaches a steady state, the pulse width of the transmission data D is expanded in accordance with this period TD to correct the transmission output waveform. Therefore, on the receiver side, a waveform close to the transmission data D shown in FIG. 2(f) can be reproduced. Note that in this example, the one-shot multivibrator 2 and the OR circuit 3 were used to create a circuit-stretched pulse.
The expanded pulses may be created by software processing using a microcomputer or the like.

[Effect of the invention 1] As described above, the present invention reduces the pulse width of the transmission data by an amount corresponding to the time from immediately after starting the oscillation circuit with transmitter data to reaching the steady oscillation state when the oscillation circuit is intermittent with the transmission data. Since the transmitter is equipped with a pulse width extension means, the width of the transmission output is corrected by lengthening the pulse width of the transmission data by the pulse width extension means until the oscillation circuit reaches a steady oscillation state. Therefore, the receiving side can obtain an output similar to that of the transmitted data, and therefore it is possible to send out shorter pulses, which has the effect of enabling higher-speed data transmission.

[Brief explanation of drawings]

Fig. 11 is a circuit diagram of an embodiment of the present invention, Fig. 2 is an explanatory diagram of the same operation as above, Fig. 3 and fjIJ4 are circuit diagrams showing conventional transmitting circuits, and Fig. 5 is an explanatory diagram of the same as above. . 1 is a transmitting circuit, 2 is a one-shot multivibrator,
3 is an OR circuit, 4 is an oscillation circuit, and D is transmission data. Agent Patent Attorney Ishi 1) Ai Seven 2... One shot Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] (1) In a pulse modulation transmission circuit that performs pulse modulation by intermittent oscillation of an oscillation circuit that generates a carrier signal using transmission data, which is a digital signal, oscillation is performed using the transmission data when the oscillation circuit is intermittent with the transmission data. A pulse modulation transmission circuit comprising a pulse width extension means for lengthening the pulse width of transmission data by an amount corresponding to the time from immediately after the circuit is started until reaching a steady oscillation state.