JPH0459815B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field] The present invention relates to an optical communication system that transmits light pulses into the atmosphere and receives the transmitted light pulses.

[Prior art]

Small-sized optical communication devices that perform short-distance optical communication through the atmosphere are being considered. Since it is small and portable, it is convenient for simple data communication indoors or outdoors, but on the other hand, unlike stationary optical communication equipment, the optical path is not established, so
Each time a communication is attempted, a light path must be established.

〔the purpose〕

In view of this point, the present invention proposes a compact optical communication device that has a function to notify that an optical path has been established.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit block diagram of one embodiment of the present invention. PG is a pulse generator and a carrier wave generation circuit. TM is a transmission signal generation circuit, and RC is a reception circuit. G1 and G2 are AND gates, G3 is an OR gate, and INV is an inverter. TR1 and TR2 are transistors,
LED1 and LED2 are infrared light emitting elements, LED3 is a visible light emitting element, PD1 and PD2 are photodiodes,
L is an inductance, C is a capacitor, A is an amplifier, LPF is a low frequency pass filter, and SW is a switch that can be operated by the operator. FIG. 2 shows the operating waveforms of each part. Hereinafter, the operation of each part will be explained according to the timing chart shown in FIG.

When the switch SW is open, the AND gate G2 is open, and the AND gate G1 is closed because the switch signal is inverted through the inverter INV. AND GATE G
The output signal No. 2 drives the transistor TR1 through the OR gate G3 and the resistor R2, and causes the infrared light emitting element LED1 to emit light. That is, the signal output from the transmission signal generator TM modulates the signal from the carrier pulse generator PG, causing the infrared light emitting element LED1 to emit light, thereby transmitting an optical signal.
Here, when the operator closes the switch SW to find the path of the light, the signal b of the switch SW becomes "0".
Then, AND gate G2 is closed. Then, the AND gate G1, which receives a signal obtained by inverting the signal b from the switch SW through the inverter INV, is opened, and the signal from the carrier pulse generator PG, which is another input of the AND gate G1, is directly transmitted to the AND gate. This becomes the output of G1. OR gate G3 receives the output signal of AND gate G1
outputs the signal from the carrier pulse generator as it is, drives transistor TR1, and outputs the signal from the infrared light emitting element
Make LED1 emit light.

That is, by pressing the switch SW, only the carrier signal is always output as a light pulse. (See waveforms a, b, and c in Figure 2) Here, there is another small optical communication device with the same configuration, and this is called LC2. Now the carrier pulse is being sent from LC2, and the communication device LC1
Assume that you are searching for the path of light by moving the . The carrier pulse of infrared light sent from LC2 is received by photodiode PD1. The frequency of the resonant circuit composed of L and C is matched to the carrier pulse period. Therefore, since it resonates with a signal having the same period as the carrier pulse, it resonates upon receiving the carrier pulse signal from LC2, and a voltage is generated at both ends of L. The waveform is amplified through amplifier A, and then filtered through a low-pass filter.
When passed through the LPF, a constant voltage is output. (Second
(See e and f in the figure) The output of the low-pass filter LPF enters the receiver RC and at the same time drives the transistor TR2 through the resistor R4, causing the visible light emitting diode LED3 to emit light. That is, LC2
When receiving the carrier pulse from the visible light emitting diode LED3, the visible light emitting diode LED3 emits light. LED
Since the light path has been established based on the positional relationship where 3 emits light, the switch SW can be opened to perform transmission and reception operations. The same holds true when this relationship is reversed.

〔effect〕

As described above, by providing a means for notifying the operator that the optical path has been established, more reliable optical communication can be realized.

[Brief explanation of the drawing]

FIG. 1 is a circuit block diagram of an embodiment of the present invention.
FIG. 2 is a timing chart of signals in each part of FIG. 1. PG……Pulse generator, LED1, LED
2, LED3... light emitting element, PD1, PD2... light receiving element.

Claims (1)

[Scope of Claims] 1. In an optical communication system between terminals, at least one of which is movable, a first terminal includes a generation means for generating a carrier wave of a predetermined frequency, and a carrier wave generated by the generation means. a modulating means for modulating the carrier wave according to information to be transmitted; an instructing means for selectively instructing the transmission of a carrier wave modulated by the modulating means or a carrier wave generated by the generating means; a transmitting means for performing transmission based on an instruction from the means; a detecting means for detecting reception of a signal of the predetermined frequency; and a notification means for notifying the second terminal of detection of reception by the detecting means; An optical communication system characterized in that the optical communication system is characterized in that the communication is carried out using a communication path for which a notification has been received by the notification means.