JP4393000B2 - ASK modulation signal demodulator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ASK modulation signal demodulating apparatus for demodulating an ASK (Amplitude Shift Keying) modulation signal for turning on / off a carrier pulse, which is an oscillation signal, according to a data signal, which is digital information.
[0002]
[Prior art]
For example, as shown in FIG. 7, the modulation device 51 amplitude-modulates the data signal (digital information) shown in FIG. 8 (a) with a carrier having a carrier pulse (oscillation signal) of a predetermined width. The data communication system that transmits the ASK modulation signal shown in Fig. 2 through the two signal lines 53 and 54 and receives the ASK modulation signal by the demodulator 55 is a tool for machine tools, parts and products in the factory. As shown in FIG. 9, the conventional ASK modulation signal demodulator 55 used in such a communication system has a received ASK modulation signal (FIG. ), The voltage waveform at the point A shown in FIG. 11A is shaped by the comparator 57 (the voltage waveform at the point B shown in FIG. 10B and FIG. 11B), and then slightly more than the carrier pulse width. With a long time constant 10 is input to the monostable multivibrator 57 to operate the monostable multivibrator 57, and the output of the monostable multivibrator 57 generates a demodulated waveform having a period in which there is oscillation due to the carrier pulse of the ASK modulated signal as a data signal (FIG. 10). (C) and FIG. 11 (C)).
[0003]
[Problems to be solved by the invention]
However, conventionally, when the signal lines 53 and 54 are short, the voltage at the point A, the voltage at the point B, and the voltage at the point C have voltage waveforms as shown in FIGS. However, when the signal lines 53 and 54 are long, an oscillating voltage due to LC is generated, so that an oscillating waveform a is generated in the ASK modulation signal as shown in FIG. As shown in FIG. 10 (b) and FIG. 10 (c), erroneous pulses also occur in the voltage waveform at point B and the voltage waveform at point C, and the data signal may not be accurately demodulated.
[0004]
In view of the above problems, the present invention enables a data signal to be accurately demodulated from an ABS modulated signal with a simple circuit configuration.
[0005]
[Means for Solving the Problems]
Technical means of the present invention to solve this technical problem, the ASK modulated signal of the data signal at the carrier and amplitude-modulated with a carrier pulse of Tokoro constant width, received by the data signal from the received ASK modulated signal In the demodulating apparatus of the ASK modulation signal to be extracted,
After the received ASK modulated signal is waveform-shaped, it is input to the monostable multivibrator 3 having a time constant slightly longer than the carrier pulse width, and the output signal of the monostable multivibrator 3 and the ASK modulated signal are waveform-shaped. A signal that is not more than twice the carrier pulse width of the ASK modulated signal is removed from the signal, and a period in which the oscillation of the carrier pulse of the ASK modulated signal continues more than twice the carrier pulse width is extracted as a data signal. It is in the point.
[0006]
Another technical means of the present invention is to receive an ASK modulation signal obtained by amplitude-modulating a data signal with a carrier wave having a carrier pulse having a predetermined width, and to extract the data signal from the received ASK modulation signal. In a signal demodulator,
The received ASK modulated signal is waveform-shaped and then input to the monostable multivibrator 3 having a time constant slightly longer than the carrier pulse width, and the output signal of the monostable multivibrator 3 and the received ASK modulated signal are waveformd. A D flip-flop circuit 4 is provided to extract an output signal that is shifted from the shaped signal by the next carrier pulse of the ASK modulation signal from the output signal of the monostable multivibrator 3, and the output of the monostable multivibrator 3 is provided. The signal less than twice the carrier pulse width of the ASK modulation signal is removed from the logical condition of the signal and the output signal of the D flip-flop circuit 4, and the oscillation of the carrier pulse of the ASK modulation signal is more than twice the carrier pulse width. The subsequent period is extracted as a data signal.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In FIG. 1, reference numeral 1 denotes a comparator which inputs a received ABS modulation signal and shapes the waveform so that the carrier pulse becomes a rectangular wave having a constant voltage. The ABS modulation signal input by the comparator 1 is obtained by amplitude-modulating a data signal (digital information) with a carrier having a carrier pulse (oscillation signal) having a predetermined width by a modulation device (not shown). (B) or the voltage waveform shown in FIG. 10 (a), the carrier pulse, which is an oscillation signal, is turned on / off according to the data signal, which is digital information. It is transmitted over a long distance from the modulation device.
[0008]
3 is a monostable multivibrator having a time constant slightly longer than the pulse width of the carrier pulse of the ABS modulation signal, and the voltage at the falling edge of the output signal of the comparator 1 (voltage waveform at point B shown in FIG. 2B). Falls and holds the L voltage (zero or low voltage) until a period slightly longer than the pulse width of the carrier pulse. Therefore, the monostable multivibrator 3 holds the L voltage during the period in which the carrier pulse continues as shown in FIG. 2B when the carrier pulse oscillation of the ABS modulation signal input from the comparator 1 is continuous. One on signal or off signal is output.
[0009]
Reference numeral 4 denotes a D flip-flop circuit, which inputs the output signal of the monostable multivibrator 3 (voltage waveform at point C shown in FIG. 2B) to the D input terminal and outputs the output signal of the comparator 1 to the clock input terminal (see FIG. 2). 2 (A) is input, and an output signal that changes from the Q output terminal to the voltage waveform at point C at the falling edge of the voltage waveform at point B (shown in FIG. 2 (C)). Voltage waveform at point D) is output.
[0010]
Reference numeral 6 denotes a NOR circuit which inputs the output signal of the monostable multivibrator 3 and the output signal of the D flip-flop circuit 4. Reference numeral 7 denotes a NOT circuit for inputting the output signal of the NOR circuit 6 (voltage waveform at point E shown in FIG. 2D). The NOR circuit 6 and the NOT circuit 7 constitute an OR circuit 8, and the output signal of the OR circuit 8 (voltage waveform at point F shown in FIG. 2 (e)) is taken out as a data signal obtained by demodulating the ABS modulation signal. It has become.
[0011]
According to the above embodiment, as shown in FIG. 2 (a), the received ABS modulated signal is waveform-shaped by the comparator 1 so that the carrier pulse becomes a rectangular wave having a constant voltage, and this waveform-shaped ABS is obtained. The monostable multivibrator 3 inputs the modulation signal, and the monostable multivibrator 3 has the voltage falling at the falling edge of the output signal of the comparator 1 (the voltage waveform at point B shown in FIG. 2A). Then, an output signal (voltage waveform at point C shown in FIG. 2B) is output that holds the L voltage until a period slightly longer than the pulse width of the carrier pulse.
[0012]
Then, the D flip-flop circuit 4 inputs the output signal of the monostable multivibrator 3 (voltage waveform at point C shown in FIG. 2B) to the D input terminal, and outputs the output signal of the comparator 1 to the clock input terminal ( 2), the D flip-flop circuit 4 outputs an output signal that switches from the Q output terminal to the voltage waveform at point C at the falling edge of the voltage waveform at point B. (Voltage waveform at point D shown in FIG. 2 (c)) is output, and the OR circuit 8 inputs the output signal of the monostable multivibrator 3 and the output signal of the D flip-flop circuit 4, and both signals are When both are at the L voltage, a signal (voltage waveform at point F shown in FIG. 2E) that is at the L voltage is output, and the output signal of this OR circuit 8 is taken out as a data signal obtained by demodulating the ABS modulation signal.
[0013]
Therefore, the D flip-flop circuit 4 latches the output signal of the monostable multivibrator 3 at the falling edge of the voltage waveform at the point B and synthesizes the waveform, and the output signal of the D flip-flop circuit 4 The voltage waveform deviates from the output signal of the vibrator 3 by the next carrier pulse of the ASK modulation signal, and the logical condition between the output signal of the monostable multivibrator 3 and the output signal of the D flip-flop circuit 4 is obtained by the OR circuit 8. Then, a signal that is not more than twice the carrier pulse width of the ASK modulated signal is removed, and a period in which the oscillation of the carrier pulse of the ASK modulated signal continues more than twice the carrier pulse width is taken out as a data signal. As a result, even if an oscillating voltage due to LC is generated, and an erroneous pulse due to an oscillating waveform in the ASK modulation signal is generated in the voltage waveform at point B and the voltage waveform at point C, the erroneous pulse is ignored. A signal due to malfunction does not appear in the voltage waveform and the voltage waveform at the point F, and the data signal can be accurately demodulated from the ABS modulation signal by reliably removing the one-pulse error signal caused by the long signal line.
[0014]
FIG. 3 shows another embodiment showing a specific configuration of the present invention. The demodulator receives an ABS modulated signal via the pulse transformer 11 and shapes the waveform of the received ABS modulated signal by the comparator 1. I have to. Further, the output signal of the comparator 1 is input to the clock input terminal of the D flip-flop circuit 4, and the output signal from the Q output terminal of the monostable multivibrator 3 is output from the comparator 1 by the resistor 12 and the capacitor 13. The data is input to the D input terminal of the D flip-flop circuit 4 with a slight delay. The OR circuit 8 includes a pair of diodes 15 and 16 in place of the NOR circuit 6 and the NOT circuit 7.
[0015]
The other points are the same as those in the above embodiment, and according to the experimental data, the point B has a voltage waveform as shown in FIG. 4 (a), and the point E is shown in FIG. 4 (b). As in the case of the above-described embodiment, a signal having a width less than twice the carrier pulse width of the ASK modulation signal is removed, and the oscillation of the carrier pulse of the ASK modulation signal is twice the carrier pulse width. The period that continues is extracted as a data signal, and the data signal can be accurately demodulated from the ABS modulated signal with a simple circuit configuration.
[0016]
In the above-described embodiment, the OR circuit 8 is constituted by a series circuit of the NOR circuit 6 and the NOT circuit 7 or a pair of diodes 15 and 16, but instead of this, the OR circuit 8 is shown in FIG. As shown in the figure, it may be constituted by a series circuit of a NOR circuit 18 and a NOT circuit 19, or may be constituted by one OR circuit as shown in FIG.
[0017]
In the above embodiment, the monostable multivibrator 3 is configured such that the monostable multi is an L voltage (zero) until the voltage falls at the fall of the output signal of the comparator 1 and is slightly longer than the pulse width of the carrier pulse. Alternatively, a monostable multivibr may be configured to operate at the rising edge of the output signal of the comparator 1.
[0018]
In the above embodiment, the D flip-flop circuit 4 is configured to switch to the voltage waveform of the output signal of the monostable multivibrator 3 at the falling edge of the output signal of the comparator 1. Instead, the D flip-flop circuit 4 may be configured to switch to the voltage waveform of the output signal of the monostable multivibrator 3 at the rising edge of the output signal of the comparator 1.
[0019]
【The invention's effect】
According to the present invention, it is possible to accurately demodulate a data signal from an ABS-modulated signal by removing an erroneous signal of one pulse generated due to a long signal line or the like with a simple circuit configuration.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing an embodiment of the present invention.
FIG. 2 is a voltage waveform diagram for explaining operation;
FIG. 3 is a circuit diagram showing another embodiment.
FIG. 4 is a voltage waveform diagram for explaining operation;
FIG. 5 is a diagram showing another configuration of the OR circuit.
FIG. 6 is a diagram showing another configuration of the OR circuit.
FIG. 7 is a circuit diagram showing a conventional example.
FIG. 8 is a waveform diagram showing a data signal and an ABS modulated signal.
FIG. 9 is a circuit diagram showing a conventional example.
FIG. 10 is a waveform diagram for explaining operation.
FIG. 11 is a waveform diagram for explaining operation.
[Explanation of symbols]
1 Comparator 3 Monostable Multivibrator 4 D Flip-Flop Circuit 6 OR Circuit

Claims (2)

In an ASK modulation signal demodulator that receives an ASK modulation signal obtained by amplitude-modulating a data signal with a carrier wave having a carrier pulse having a predetermined width, and extracts the data signal from the received ASK modulation signal.
After the received ASK modulated signal is waveform-shaped, it is input to the monostable multivibrator (3) having a time constant slightly longer than the carrier pulse width, the output signal of the monostable multivibrator (3), and the ASK modulated signal Is removed from the waveform-shaped signal, and a signal that is less than twice the carrier pulse width of the ASK modulated signal is removed, and the period in which the oscillation of the carrier pulse of the ASK modulated signal continues at least twice the carrier pulse width A demodulator for an ASK modulated signal, characterized in that it is extracted as In an ASK modulation signal demodulator that receives an ASK modulation signal obtained by amplitude-modulating a data signal with a carrier wave having a carrier pulse having a predetermined width, and extracts the data signal from the received ASK modulation signal.
The received ASK modulated signal is waveform-shaped and then input to the monostable multivibrator (3) having a time constant slightly longer than the carrier pulse width. The output signal of the monostable multivibrator (3) and the received ASK A D flip-flop circuit 4 is provided for taking out an output signal shifted from the output signal of the monostable multivibrator (3) by the next carrier pulse of the monostable multivibrator (3) from the waveform-shaped signal of the modulation signal. From the logic condition of the output signal of the stable multivibrator (3) and the output signal of the D flip-flop circuit (4), a signal not more than twice the carrier pulse width of the ASK modulated signal is removed, and the carrier pulse of the ASK modulated signal demodulation vibration, the period in which lasted over twice the carrier pulse width, the ASK modulation signal, characterized in that they were taken out as a data signal Location.

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