JP3055219B2 - Signal transmission equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal transmission apparatus, and more particularly to a signal transmission apparatus for transmitting a main signal, a control signal, and the like using a modulator and a demodulator provided in a transmission unit and a reception unit, respectively.

[0002]

2. Description of the Related Art As shown in FIG. 2, a conventional signal transmission apparatus transmits a main signal S1 and a control signal S2 from a transmission unit 21 to a reception unit 22.
5 that generates a carrier signal of frequency f1 for use, modulator 2 that receives the carrier signal of f1 and modulates with main signal S1, and an oscillator that generates an antiphase signal of frequency f2 for a control signal 12, a switch 3 for inputting the f2 carrier signal and intermitting the f2 carrier signal at the drive cycle of the control signal S2, and the f1 carrier signal modulated by the main signal S1 and the f2 intermittent by the control signal S2. And a combining circuit 11 for combining the carrier signal. Receiver 22
Here, a band-pass filter 13 for extracting only the carrier signal of f1, a demodulator 9 for demodulating the main signal S1 from the carrier signal of f1, a band-pass filter 8 for extracting only the carrier signal of f2, and a carrier signal of f2 And the detector 10 for detecting the control signal S2 from the intermittent cycle of the above.

[0003]

The conventional signal transmission apparatus described above has a disadvantage that the circuit scale is increased since the transmission section has a combining circuit and two carrier oscillators. In addition, since carrier signals of different frequencies are combined, interference may occur and a malfunction may occur in information transfer of the main signal S1 and the control signal S2.

[0004]

According to the present invention, there is provided a signal transmission apparatus in which a transmitting unit generates a carrier signal having a frequency of f1 and a frequency divider which divides the frequency of the carrier signal of the frequency f1 to generate a frequency f2.
A frequency divider that outputs a carrier signal of frequency f1 and a switch that alternately selects and outputs a carrier wave of frequency f1 and a carrier wave of frequency f2 under the control of control signal S2, and frequency f1 and frequency f2 of the switch output by main signal S1. And a modulator that alternately modulates and outputs the carrier signals of the first and second carrier signals.
, A demodulator that outputs a main signal S1 from the two types of carrier signals, a second bandpass filter that passes only the carrier signal of frequency f2, and a control signal S2 that detects the carrier signal of frequency f2. And a detector for regenerating the data.

[0005]

Next, the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of one embodiment of the present invention. In the embodiment shown in FIG. 1, the main signal S1 and the control signal S
In the case of transmitting the carrier signal 2, the transmitter 1 alternates the frequency divider 4 for dividing the carrier signal of the frequency f1 into the frequency f2 and the carrier signal of the f1 and the carrier signal of the f2 in the cycle of the control signal S2. It comprises a switch 3 for switching and outputting, and a modulator 2 which receives a carrier signal of a frequency f1 or f2, which is alternately switched, and modulates it with a main signal S1. The receiving unit 6 includes a band-pass filter 7 for passing two types of carrier signals of frequencies f1 and f2, a demodulator 9 for demodulating the main signal S1 from the alternately input carrier signals of f1 and f2, and a frequency f2. And a converter 10 for detecting the intermittent period of the carrier signal of frequency f2 extracted by the band-pass filter 8 and extracting the control signal S2.
Next, the operation of this embodiment will be described. The carrier signal modulated by the main signal S1 alternately outputs either the frequency f1 or f2 under the control of the switch 3. Therefore, the receiving unit 6
Demodulator 9 demodulates main signal s1 from the carrier signal of frequency f1 or f2 in a time-division manner, so that the problem of interference can be avoided. On the other hand, the detector 10 detects the presence / absence of the f2 carrier signal in the cycle of the control signal S2, but the main signal is not mixed with the f1 carrier signal as in the conventional example. The interference problem can be avoided in the same manner as described above. Since the frequencies f1 and f2 of the carrier signal do not always exist in more than one type, the requirements for the attenuation characteristics of the band-pass filters 7 and 8 covering other frequencies are not strict.

[0006]

As described above, according to the present invention, the main signal S
By alternately selecting and transmitting the carrier signals of the frequencies f1 and f2 to be modulated by 1, there is an effect that there is always only one kind of carrier wave and interference when transmitting using two kinds of carrier waves can be avoided. . In addition, since one oscillator can be constituted by the frequency divider and there is no combining circuit, there is an effect that the circuit scale is simplified.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a configuration diagram of a conventional signal transmission device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transmitting part 2 Modulator 3 Switch 4 Divider 5, 12 Oscillator 6 Receiving part 7, 8, 13 Bandpass filter 9 Demodulator 10 Detector 11 Synthesis circuit

Claims (1)

(57) [Claims] An oscillator for generating a carrier signal having a frequency of f1; a frequency divider for dividing the frequency of the carrier signal having a frequency of f1 to output a carrier signal having a frequency of f2; a switch for alternately selecting and outputting a carrier of frequency f1 and a carrier of frequency f2;
A first band-pass filter having a modulator that alternately modulates and outputs a carrier signal having a frequency f1 and a frequency f2 of the switch output, and a receiving unit that passes two types of carrier signals having the frequencies f1 and f2; A demodulator that outputs a main signal S1 from the two types of carrier signals, a second band-pass filter that passes only the carrier signal of frequency f2, and a detection that detects the carrier signal of frequency f2 and reproduces the control signal S2. A signal transmission device characterized by having a device.