RU2121229C1 - Optical communication system - Google Patents

Abstract

FIELD: automatic control and computer engineering; wireless data exchange, for example, between two movable computers or those separated by stationary obstacles interfering with establishing wire communications. SUBSTANCE: system has on sending end controlled reference-frequency generator 1, combined counter 2, pulse current amplifier 3, and light emitter 4. On receiving end, it has photodetector 5, limiting pulse voltage amplifier 6, low-frequency filter 7, one-shot multivibrator 8, and signal reception indicator 9. Sending part of communication system functions as converter of signal waveform of input digital information into short light pulses to reduce active state time of optical system and to provide for increasing light pulse power. EFFECT: improved operating reliability and increased communication distance. 2 dwg

Description

 The invention relates to automation and computer technology and can be used for wireless information exchange, for example, between two computers that are in a mobile state relative to each other or separated by an obstacle for wired communication means.

 Known devices for an optical information transmission system (see German patents N 3930067, 3930069 MKI H 04 B 10/00, 1991). These devices contain an electro-optical converter on the transmitting side and an optoelectronic converter in the receiver. A carrier frequency oscillation is generated in the transmitter, which is modulated by the transmitted signal, and the modulated signal is fed to the electro-optical converter. The presence of a voltage-controlled generator and phase detectors complicates the circuit, which affects its reliability.

 An optical system is also known (see Japanese Patent No. 4-59815 MKI H 04 B 10/24, 10/40, 1992), adopted by the author as a prototype. This system communicates between devices, among which at least one is mobile. The device comprises a generating circuit that generates a carrier signal of a given frequency, a modulator that modulates the received carrier using the transmitted information, a control device that carries out selective carrier transmission, an indicator informing about the signal reception. The system communicates using a communication channel, the presence of which is confirmed by the indicator.

 The constant presence of the carrier frequency leads to the fact that the light emitter is in the working position all the time, i.e. 100% loaded. This circumstance, as well as the bulkiness of the circuit, leads to a decrease in its reliability.

 The technical result achieved by the invention is to increase the reliability of the communication system and increase the communication range. This technical result is achieved in that the optical communication system, consisting of a transmitting part, which includes a light emitter, and a receiving part, including a photodetector and a signal reception indicator, the transmitting part is made in the form of a signal form converter of input discrete information into shortened light pulses, including a serially connected controlled reference frequency generator, a combined counter, a pulse current amplifier and a light emitter, in addition, the mode selection input is combined of the counter is connected to the input of the controlled reference frequency generator and is the information input of the transmitting part, the information inputs of the combined counter are the input of the number code, and the receiving part is made in the form of a unit for restoring the original waveform, which includes a series-connected photodetector, a pulse amplifier-voltage limiter, a low-pass filter, a single-shot and a signal reception indicator, and the output of a single-shot is an information output of the receiving part.

 Comparison of the proposed solution with the prototype shows that the transmitting part of the communication system is made in the form of a signal form converter of input discrete information into shortened light pulses, thereby reducing the time of the active state of the optical system and creating conditions for increasing the power of light pulses, and hence the communication distance.

 Comparison of the proposed solution not only with the prototype, but also with other technical solutions in the art did not allow to reveal in them a given set of features. And the above combination allows you to achieve the necessary technical result - improving the reliability of the communication system and increasing the communication range.

 In FIG. 1 is a functional diagram of an optical communication system; FIG. 2 is a signal diagram explaining its operation.

 The optical communication system contains in the transmitting part: a controlled reference frequency generator 1 (hereinafter “generator”), a combined counter 2 (hereinafter “counter”), a pulse current amplifier 3 and a light emitter 4.

 In the receiving part there is a photodetector 5, a pulse amplifier-voltage limiter 6, a low-pass filter 7, a single-shot 8 and a signal reception indicator 9.

The speed scale for the exchange of information over serial channels between two computers is standard and depending on the selected speed V _BIT and on the division coefficient K _{cc of} counter 2, the reference frequency f _{g of} generator 1 is selected.

f _g = K _sc • V _BIT .

The duration of the restored output pulse t _imp single-vibrator 8 is selected approximately
t _imp ≈ 1 / V _BIT ≈ t _BIT ,
Where
t _BIT - duration of one bit of information
The optical communication system operates as follows.

In the initial state, when there is no information at the input of the transmitting part of the system, a generator inhibit signal is received at the control input of generator 1, at the same time, at the input of the mode selection, counter 2 - allows parallel writing to the counter 2 of the number corresponding to the number code on its information inputs and equal to half the coefficient dividing the counter K _sc / 2. In this case, the outputs of the transfer of the counter 2 and the pulse current amplifier 3, the light emitter 4, the outputs of the photodetector 5, the amplifier-voltage limiter 6, the low-pass filter 7 and the one-shot 8 are set to zero, corresponding to the mode of lack of information.

Information at the input of the system begins with a start bit that gives permission for the operation of generator 1 (see Fig. 2 (1)) and sets the counter 2 to the mode of dividing the frequency of the signal from the output of generator 1 to the counting input of counter 2 (Fig. 2 ( 2)). Counter 2, having a preset code number K _cq / 2, counts the number of pulses K _MF / 2 and the overflow outputs a carry output pulse is equal to one period of the output signal of the generator 1 (FIG. 2 (3)). This pulse is transmitted by a pulsed current amplifier 3 to a light emitter 4, sensed by a photodetector 5, amplified, and when the signal amplitude increases with a decrease in the length of the optical communication channel, it is formed by a voltage-limiting pulse amplifier-amplifier 6, and then, after processing the pulse shape with a low-pass filter 7, the leading edge starts one-shot 8, the output of which takes a single state for a time t _imp , and thus the start bit of information is restored (Fig. 2 (4)). The recovered bit of information differs from the original by a phase shift of 90 e. degrees and duration t _imp ≈ t _bits , which is insignificant for the reliability of receiving the start bit by the computer receiver according to the characteristics of the asynchronous mode of exchanging information over the serial channel.

If the logical level of the next bit of information does not change after the start bit, then generator 1 continues to work, and counter 2 counts the pulses from the output of generator 1. At the next overflow of counter 2 through K _sc counts, a short pulse will again appear at the transfer output, shifted by 90 el. relative to the start of the current bit. And then the system responds to this impulse in the same way as described with the start bit. If the logic level of the next data bit after the starting or the like by the level of this bit is changed, then the control input of oscillator 1 enters inhibiting signal generation, a counter 2 for entry mode selection - allowing code parallel recording number K _cq / 2 similarly to the initial state of the system, and at the output of the one-shot 8 at the end of the formation of the previous bit with a unit level, a zero level is set.

 Thus, due to the presented schematic solution of the optical communication system, the time of the active state of the system is reduced and conditions are created to increase the reliability of its operation while increasing the power of light pulses and, consequently, the communication range.

Claims (1)

 An optical communication system, consisting of a transmitting part, which includes a light emitter, and a receiving part, including a photodetector and a signal reception indicator, characterized in that the transmitting part is made in the form of a waveform converter of the input discrete information into shortened light pulses, including in series connected by a controlled reference frequency generator, a combined counter, a pulsed current amplifier and a light emitter, in addition, the combined counter mode selection input is connected to the input ohm of the controlled reference frequency generator and is the information input of the transmitting part, the information inputs of the combined counter are the input of the number code, and the receiving part is made in the form of a unit for restoring the original waveform, which includes a series-connected photodetector, a pulse voltage limiting amplifier, a low-pass filter, a single vibrator and a signal reception indicator, wherein the output of the single vibrator is the information output of the receiving part.

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