RU2154906C1 - Method and device for data transmission and reception by means of optical signal - Google Patents

Abstract

FIELD: optical communications; control systems. SUBSTANCE: method includes counting time intervals between digital optical pulses by means of timer; novelty is that upon arrival of digital pulse at external interrupt input of processor unit or at parallel-port digit input of the latter, or at its clear input value is extracted from timer and constant is subtracted from this value to find time interval between present pulse and preceding one; then rendition table that includes command or data flag as well as data value or type of command for each time interval is used to determine data value obtained or type of command; when combination of data and commands is transmitted, digital start pulse is shaped across parallel-port digit lead of processor unit by setting logical one or logical zero level for time of chosen pulse width; then respective time interval is found for each data value and each command from rendition table and digital pulse is shaped across parallel-port digit lead of processor unit by setting logical one or logical zero level for time of chosen pulse width bearing in mind that its leading edge on time axis should be spaced apart from that of preceding pulse through distance equal to mentioned interval. Device implementing this method is given in description of invention. EFFECT: improved efficiency and reliability of data transmission. 2 cl, 6 dwg, 1 tbl

Description

 The invention relates to optical communication and control systems and is intended for use in any device, the core or part of which is a processor having a built-in timer (counter), parallel port discharge output, external interrupt input, or the ability to interrupt when the level at the parallel port discharge or input is interrupted reset. The invention can be used in optical data transmission systems, information collection systems, combination locks, security systems, electronic payment devices, data transmission and control systems using a common optical bus, data transmission devices located on moving parts, etc.

 Analogues of the patented method are as follows.

 1. The method described in [1] for transmitting a phase-shifted signal, which consists in generating a positionally modulated pulse at the moments of phase change of the phase-shifted signal in the transmitter and the inverse transformation into a phase-shifted signal in the receiver.

The disadvantages of the method are:
- the ability to work only with the phase-shifted signal;
- low noise immunity.

 2. The method described in [2] for synchronizing the clock frequency of a signal receiver with position-pulse modulation.

The disadvantages of the method are the following:
- the method requires special hardware;
- the method is not intended for use with differential positional pulse modulation.

 Analogues of a patented device are as follows.

 1. The transmitter and receiver devices described in [3], where the transmitter contains two optical elements And, two optical delay lines and two optical combiners. The receiver contains two or four optical delay lines, two optical elements And, and an optical combiner.

The disadvantages of the device are:
- the use of two pulses to transmit one bit of data;
- reduced transmission speed due to the modulation parameters used;
- the inability to change the type of modulation or its parameters.

 2. The device according to the invention [2], which describes a receiver containing a photomultiplier, a threshold discriminator, an amplifier, a limiter, a delay loop, and a data decoder.

The disadvantages of the device are:
- the high cost of the photomultiplier;
- the inability to work with differential positional-pulse modulation.

 The closest in technical essence are the device and method described in the invention [4], in which the transmitter contains a signal converter from pulse-code modulation to position-pulse, connected to a signal shaper of a dumper, which is connected to a dumper, to which a laser with modulation mode, and the output of the dumper is connected to a fiber optic cable. The receiver contains a detector, the input of which is connected to a fiber-optic communication line, and the output with a filter amplifier, the output of which is connected to the input of a synchronous threshold detector, the output of which is connected to a signal converter from position-pulse modulation to pulse-code modulation. In turn, to implement its functions, the signal converter from pulse-code modulation to position-pulse contains a five-digit counter, a bistable element, two shift registers, eight elements EXCLUSIVE OR, two elements AND-NOT, element NOT, element OR. The signal converter from position-pulse modulation to pulse-code modulation contains a five-digit counter, a bistable element, two multiplexers, and an OR element.

 The invention [4] proposes a method for transmitting binary data by generating signals using a counting signal with a period equal to the duration of the pulse position, counting these signals by the counter and issuing it at the moment when the counter value corresponds to the data bits being transmitted at the moment. A method for receiving positionally modulated pulses is also proposed, using the counter counting the time between pulses using a counting signal with a period equal to the duration of the pulse position, and outputting binary data corresponding to the value calculated in the counter.

The disadvantages of the prototype method include:
- the possibility of using only one type of position-pulse modulation;
- the inability to change the ratio of the time parameters of position-pulse modulation;
- a rigid dependence of the time parameters on the clock frequency;
- a rigidly specified number of data bits transmitted by one positionally modulated pulse;
- the inability to change the table of correspondence of the position number (slot) and the values of the transmitted data bits during system operation.

The disadvantages of the prototype device include:
- the need to use two shift registers, a bistable element, a counter, a whole set of logic gates in the transmitting circuit, the functions of which can be implemented using a microprocessor;
- the need to use in the receiving circuit of the counter two multiplexers with serial output, a bistable element and a valve, the functions of which can be realized using a microprocessor.

The aim of the invention are:
- reduction in the cost of the device;
- increasing the efficiency of information transfer;
- improving the reliability of information transfer;
- the ability to use two varieties of position-pulse modulation (differential and constant speed) and change the modulation parameters over a wide range.

 In accordance with the purpose of the invention, two types of positional pulse modulation (PIM) of an optical signal are used for transmitting information: differential PIM and PIM with a constant transmission rate, known in the literature as positional modulation. Most effectively, the objective of the invention is achieved using differential PIM. The device in question can use one of these varieties for transmission and (or) reception, or it can use both varieties, in the latter case an unambiguous procedure is required to switch the differential PIM and PIM modes at a constant speed. Such switching can be carried out by a command transmitted by optical pulses. The essence of the method of receiving and transmitting is to transmit information and commands, using a processor, modulating the time interval between the leading edges of discrete optical pulses and receiving information and commands, using a processor, measuring the time interval between the leading edges of discrete optical optical pulses and determining from it data value or command (hereinafter, it is assumed that the time interval between pulses is the time interval between the leading edges of the pulses). For transmission and reception, the device uses a timer (counter) built into the processor and a certain correspondence between the value of the time interval between the leading edges of adjacent optical pulses and the value of the data or command. This correspondence is present in table S.

 The essence of the method is as follows.

, где T_ST - время, необходимое процессору для остановки таймера, извлечению из него значения T и помещению в него округленного до целого значения

и запуска таймера, τ - время увеличения значения таймера на единицу, на которое настроен таймер, если же для извлечения значения T таймер не останавливается, то в него помещается округленное до целого значение

, где T_L - время, необходимое процессору для помещения в таймер значения округленного до целого

, или же таймер обнуляется. Если таймер обнуляется, то к T прибавляется округленное до целого

, где T_R - время, необходимое процессору для обнуления регистров таймера. При использовании позиционно-импульсной модуляции с постоянной скоростью передачи дополнительно из T вычитается округленное до целого значение

, где M - количество возможных позиций (слотов) позиционно-импульсной модуляции, T_поз - длительность во времени позиции (слота), T_пред - значение, оставшееся после обработки предыдущего позиционно-модулированного импульса (см. ниже). Если в результате

, где T_р - длительность разделяющего интервала позиционно-импульсной модуляции, то регистрируется сбой, если

, то регистрируется начало передачи, если ни то ни другое, то из T вычитается

и далее исходя из полученного T по таблице соответствия S определяется, чему соответствует T - команде или данным. Если T соответствует команде, то номер команды помещается в буфер команд произвольного размера или регистр команд, либо эта команда выполняется процессором сразу или с задержкой. Если T соответствует данным, то это значение данных помещается в буфер данных произвольного размера или регистр данных, либо обрабатывается процессором сразу или с задержкой. При использовании позиционно-импульсной модуляции с постоянной скоростью дополнительно T сохраняется как T_пред.When a positionally modulated pulse arrives at the processor interrupt input INT or the discharge port input of the parallel port of the processor P _i , or the reset input of the processor RESET, the value T is extracted from the timer (counter) integrated in the processor. Then, if the timer retrieves the value T, it stops placed rounded to integer value

, where T _ST is the time it takes the processor to stop the timer, extract the value of T from it, and place the value rounded to the nearest integer

and start the timer, τ is the time the timer value increases by the unit the timer is set to, if the timer does not stop to retrieve the value of T, then the value rounded to the nearest integer is placed

, where T _L is the time required for the processor to put the value rounded to the nearest integer in the timer

, or the timer is reset to zero. If the timer is reset to zero, then rounded to the nearest integer is added to T

where T _R is the time required by the processor to reset the timer registers. When using position-pulse modulation with a constant transmission speed, an additional value rounded to the nearest integer is subtracted from T

, where M is the number of possible positions (slots) of position-pulse modulation, T _pos is the time duration of a position (slot), T _pre is the value remaining after processing the previous position-modulated pulse (see below). If as a result

, where T _p is the duration of the dividing interval of position-pulse modulation, then a failure is detected if

, then the beginning of the transmission is recorded, if neither one nor the other, then subtracted from T

and further, based on the obtained T, according to the correspondence table S, it is determined what corresponds to the T - command or data. If T corresponds to a command, then the command number is placed in an arbitrary size instruction buffer or instruction register, or this command is executed by the processor immediately or with a delay. If T corresponds to the data, then this data value is placed in a data buffer of an arbitrary size or data register, or it is processed by the processor immediately or with a delay. When using position-pulse modulation with a constant speed, T is additionally stored as T _before .

 The transfer of data and commands is as follows.

First, the start pulse is transmitted by generating a logic signal “1” or logic “0” of duration T _imp at the discharge output of the parallel port P ₀ through the driver of the emitter 4, which leads to the appearance of an optical signal of duration T _imp on the emitters 5.5 ₁ ,. . ., 5 _m . Moreover, the time interval between the leading edges of this starting pulse and the last transmitted pulse from the previous sequence should be greater than T _p + M • T _pos , which will correspond to the beginning of transmission. Further, for each data or command value, based on the correspondence table S, the corresponding position (slot) number L is determined, the interval duration T _int corresponding to it is determined, and after time T _int after the formation of the previous pulse at the discharge output of the parallel port P ₀ , a logical signal is generated by the processor "or logical" 0 "of duration T _imp through the driver of the signal of the emitter 4, leading to the appearance of an optical signal of duration T _imp on the emitters 5.5 ₁ , ..., 5 _m emitting a discrete optical pulse into the optical path (atmosphere, vacuum, homogeneous or inhomogeneous optical medium), where T _int = T _p + (L-1) • T _pos + Δ when using differential positional-pulse modulation and T _int = T _p + (L- 1) • T _pos + (ML _pre ) • T _pos + Δ (T _{int. I} ) when using position-pulse modulation with constant speed, where L _pre is the position (slot) number corresponding to the previous impulse Δ ∈ [0, T _pos -T _imp ].

When using differential PIM, data (data values) and commands are transmitted by discrete optical pulses with a width of T _imp , the time interval between the leading edges of which T _int varies depending on the transmitted command or the transmitted data value. The sequence of data and commands is transmitted as a sequence of discrete optical pulses with a certain interval between the leading edges of adjacent pulses, a fragment of the pulse sequence is shown in FIG. 3. Differential positional-pulse modulation is characterized by the following parameters:
T _imp - the width of the discrete optical pulse;
T _p - the width of the separation interval, equal to the minimum possible interval between the leading edges of discrete optical pulses;
M is the number of discrete optical pulse positions (slots) used, equal to the sum of the number of possible data values and the number of commands;
T _pos - the length in time of the position (slot);
S - a table of correspondence of data values and command numbers to position numbers, in which each possible data value and each possible command corresponds to a position number, contains M sections, each of which corresponds to one position and contains a range of timer values, a command sign and data value or type of command .

Based on the definition of a differential PIM for transmitting the value of a data or command, it is necessary to determine the position (slot) number L from table S and form a discrete optical pulse of width T _imp with a time interval between its leading edge and front of the previous pulse equal to T _int , where T _int = T _p + (L _i -l) • T _pos + Δ, where Δ ∈ (0, T _pos ).

Based on the definition of a differential PIM for receiving a data value or a command, it is necessary to determine the time interval T _int between the leading edges of adjacent discrete optical pulses A and B, subtract from T _{int the} duration of the separation interval T _p and from the obtained value T _and determine the position number L, which corresponds to pulse, then proceeding from L from table S, determine the transmitted data value or command.

When using PIM with a constant transmission rate, data (data values) and commands are transmitted by discrete optical pulses with a width of T _imp , having a certain position on the time axis relative to the start pulse, depending on the value of the data or command.

Position-impulse modulation with a constant speed is characterized by the following parameters:
T _imp - the width of the discrete optical pulse;
T _p - the width of the separation interval;
M is the number of discrete optical pulse positions (slots) used, equal to the sum of the number of possible data values and the number of commands;
T _pos - the length in time of the position (slot);
T _PIM - the duration of the PIM period;
S is a table of correspondence of data values and command numbers to position numbers, in which each possible data value and each possible command corresponds to a position number, in which each possible data value and each possible command corresponds to a position number, contains M sections, each of which corresponds to one position and contains a range of timer values, a feature of the command, and a data value or type of command.

In a PIM with a constant speed, the position of the pulse is determined not relative to the previous pulse, as in the differential PIM, but relative to the start pulse A ₁ , from which the transmission of a sequence (packet) of data and commands begins.

Based on the definition of PIM with a constant speed for transmitting data or command values, it is necessary to determine the slot number L _i from table S and form a discrete optical pulse A _{i + 1 of} width T _imp with a time interval between its leading edge and the leading edge of the previous pulse A _i equal to T _int.i , where T _int.i = T _p + (L _i -1) • T _pos + (ML _i-1 +1) • T _pos + Δ, where Δ ∈ (0, T _pos ), and if impulse A _i starting (A ₁ ), then L _i-1 is taken equal to M + 1.

Based on the definition of PIM with a constant speed for receiving data or command values, it is necessary to determine the time interval T _int.i between the leading edges of adjacent discrete optical pulses A _i and A _{i + 1} , subtract from T _{int.i the} length of the separation interval T _p , add to value T _pos • (ML _i-1 + l) and from the received value T _i.i determine the position number L _i to which the impulse corresponds, then from L _i from table S the transmitted data value or command is determined.

The method of receiving and transmitting is intended to determine the value of the received data or command based on the value of the time interval T _int between the leading edges of adjacent discrete optical pulses A and B or A _i and A _i-1 measured using the built-in timer (counter) processor and for generating a sequence of discrete optical pulses with a time interval between the leading edges of adjacent pulses, depending on the value of the transmitted data or command. The interval is formed by the processor by counting the timer (counter) the time value and (or) using the time characteristics of the processor commands.

In accordance with the purpose of the invention, instead of a data converter from pulse-code modulation to position-pulse and a converter from position-pulse to pulse-code converter, a processor is introduced into the circuit; instead of a shaper and a dumper shaper, an optical emitter signal generating circuit is introduced, the input of which is connected to the parallel the port processor P _0, and the outputs are connected to the optical emitters and m additional optical emitters, in which role can act LEDs, laser diodes, lasers and other optical band radiating device. Instead of a detector, a filter amplifier, and a synchronous threshold detector, an amplifier is introduced into the circuit, the output of which is connected to the external interrupt input of the INT processor or to the discharge input of the parallel port of the processor P _i or connected to the input of a two-input OR logic element, the second input of which is connected to the output of the reset signal shaper processor, and the output is connected to the reset input of the RESET processor. And n + 1 inputs of the amplifier are connected to the output of the detector and n outputs of n additional detectors. The role of the detectors can be photodiodes or any other photodetectors that convert optical radiation into an electrical signal. The processor must have a built-in timer (counter), an external interrupt input, or the ability to interrupt when the level changes at the discharge of the parallel port or reset input.

A device for transmission can use one set of the above PIM parameters, and for reception it can be another, since the device under consideration provides a much higher data and command transmission rate than reception, mainly due to the fact that the interval T _p at reception has the minimum possible value , much larger than during transmission. It is possible to use one set of parameters for both transmission and reception.

 Since the method and device for transmitting information use position-impulse modulation, the essence of which is to modulate the time interval between discrete pulses, which means that for the device to work, it is necessary to correctly measure the time intervals between the leading edges of the incoming pulses and to form it correctly depending on the values transmitted data and commands time intervals between the leading edges of the issued pulses. The processor can measure the time between incoming pulses by extracting the value from the timer when the pulse arrives, increasing or decreasing the value at regular intervals, and use it to obtain the value of the time interval between only the incoming and previous pulses (the obtained interval value uniquely determines the transmitted data value or command ) For this it is necessary that the processor has the ability to interrupt when a pulse arrives at some of its inputs, it is possible to use an external interrupt input, a reset input, if the processor registers and the timer value are not reset during reset, it is possible to use some kind of discharge input of the parallel port of the processor, if the processor has the ability to interrupt from a level change at the discharge of the parallel port.

In FIG. 1 shows a diagram of a device for transmitting and receiving information by an optical signal, where:
a) is a variant of the circuit using the processor interrupt input;
b) - a variant of the circuit using the discharge input of the parallel port of the processor;
c) is a variant of the circuit using the processor reset input;
1,1 ₁ , ..., 1 _n - the main and n additional photodetectors;
2 - pulse amplifier;
3 - processor;
4 - shaper signal emitters;
5,5 ₁ , ..., 5 _m - main and m additional emitter;
6 - two-input logic gate OR;
7 is a diagram for generating a processor reset signal;
INT - processor interrupt input;
P _i - discharge input of the parallel port of the processor;
P ₀ - discharge output of the parallel port of the processor;
RESET - processor reset signal input.

In FIG. 2 is a diagram of the transmission of information using a variety of PIM differential positional-pulse modulation, where:
1 - position (slot) number 1;
2 - position (slot) number 2;
3 - position (slot) number 3;
L - position (slot) number L;
M-1 - position (slot) number M-1;
M - position (slot) number M;
A is the previous positionally modulated pulse;
B - subsequent positionally modulated pulse;
C is the zone of possible positions of a positionally modulated pulse;
T _imp - the width of the positionally modulated pulse;
T _p - the length of the separating interval of position-pulse modulation;
T _int - time interval between positionally modulated pulses;
T _and - the time interval equal to T _int -T _p ;
T _pos - the width of the position (slot);
M • T _pos - the length of the zone of possible positions of a positionally modulated pulse.

In FIG. 3 is a diagram - an example of information transmission using a variety of PIM differential positional-pulse modulation, where T _{int. 1} , T _{int. 2} , T _{int. 3} , T _{int. 4} , T _{int. 5} , T _{int. 6} indicate time intervals between the leading edges of the transmitted positionally modulated pulses.

In FIG. 4 is a diagram of the transmission of information using a variety of PIM positional-pulse modulation at a constant speed, where:
1 - position (slot) number 1 of the first positionally modulated pulse;
2 - position (slot) number 2 of the first positionally modulated pulse;
3 - position (slot) number 3 of the first positionally modulated pulse;
L ₁ - position (slot) number L _{1 of the} first positionally modulated pulse;
M-1 - position (slot) number M-1 of the first positionally modulated pulse;
M - position (slot) number M of the first positionally modulated pulse;
L ₂ - position (slot) number L _{2 of the} second positionally modulated pulse;
L ₃ - position (slot) number L _{3 of the} third positionally modulated pulse;
A ₁ - starting position-modulated pulse;
A ₁ , A ₃ , A ₄ - the first, second and third positionally modulated pulses, respectively;
C ₁ - zone of possible positions of the first positionally modulated pulse;
C ₂ - zone of possible positions of the second positionally modulated pulse;
C ₃ - zone of possible positions of the third positionally modulated pulse;
T _imp - the width of the positionally modulated pulse;
T _p - the length of the separating interval of position-pulse modulation;
T _{int. 1} , T _{int. 2} , T _{int. 3} - time intervals between positionally modulated pulses;
T and _.1 - time interval equal to T _{int. 1} -T _p ;
T _pos - the width of the position (slot);
M • T _pos - the length of the zone of possible positions of a positionally modulated pulse;
Z ₁ , Z ₂ , Z ₃ - zone of the first, second and third periods of transmission of positionally modulated pulses, respectively;
T _PIM - the value of the transmission period of positionally modulated pulses.

 The device operates as follows.

 Consider the process of receiving optical signals by a device that transmit data and commands from some external device to the device in question.

At the initial time, the processor 3 in the device in question performs some actions, and the timer (counter) built into the processor 3 during each time period τ increases the value by one. Discrete optical positionally modulated pulses transmitted by some external device after passing through the optical channel (atmosphere, vacuum, homogeneous or inhomogeneous optical medium) get into the photodetector (s) 1.1 ₁ , ..., 1 _m and cause the output (s) of the photodetector (s) of discrete electrical pulses that fall into amplifier 2 are amplified, normalized, and fall, depending on the version of the circuit used, to the external interrupt input of the processor INT or to the discharge input of the parallel port of the processor and P _i or, passing through the logic element OR 7, get to the reset input of the processor RESET. Each of these pulses initiates an interrupt in processor 3 - immediately upon receipt of a pulse or some of its edges, or after a short delay time. After initiating an interruption or after a reset, the processor stops performing the actions that it was previously occupied with and proceeds to receive data and commands in accordance with the described method. When transmitting the totality of data and commands to the discharge terminal of the parallel port P _{0, the} processor generates a discrete start pulse by setting the level of a logical unit or logical zero for the time of the selected pulse width T _imp and then determines the value of the corresponding interval for each data value and each command from the correspondence table time and generates a discrete pulse at the discharge terminal of the parallel port of the processor by setting the level of the logical unit or logical zero for the time of the selected irin of the pulse so that its leading edge on the time axis is at a distance equal to the value of this interval from the leading edge of the previous pulse. The signal generated at the discharge terminal of the parallel port P ₀ enters the signal generation circuit of the emitters 4 and leads to the appearance on the optical emitters 5.5 ₁ , ..., 5 _{m of an} optical signal that is emitted into the optical path and received by similar devices.

In the transmission diagram, when using a differential PIM (Fig. 2), the time interval T _{p is} plotted on the time axis to the right of the leading edge of the discrete optical pulse A, and then M segments are plotted one after the other with the length T _pos . These segments are the positions of the discrete optical pulse. All of them are M (in Fig. 2 they are designated 1,2,3, ... M-1, M). The appearance of a discrete optical pulse B after a discrete optical pulse A, the leading edge of which lies inside the position with the number L, will mean that a data value or command corresponding to the position number L in table S has been transmitted. The appearance of a discrete optical pulse with a leading edge outside zone C means start of transmission. The discrete optical pulse A is previous in the sequence of transmitted pulses, and the discrete optical pulse B is subsequent in the sequence of transmitted pulses. The time interval T _int between the leading edges of these pulses represents the transmitted data value or command; from it, at the time of reception, the position number L is uniquely determined, and then, according to table S, the data value or command. To determine the position of the leading edge of the discrete optical pulse following B, it is necessary to repeat the above procedure of laying off segments on the time axis from the leading edge of pulse B.

On the PIM transmission diagram with a constant speed (Fig. 4) on the time axis to the right of the leading edge of the discrete optical pulse A ₁ (start pulse), the time intervals Z ₁ , Z ₂ , Z ₃ , ... are the PIM periods of T _PIM duration each . Each period Z _i contains a dividing interval of duration T _p and a positional zone C _i containing M segments of duration T _pos - positions (slots) with numbers from 1 to M. The appearance of a discrete optical pulse A _i lying inside the position with number L _i will be mean that a data value or command corresponding to the position number L _i in table S is transmitted. The appearance of a discrete optical pulse outside any zone C _i and the segment T _p means the beginning of the transmission of a sequence (packet) of data and commands, and that this pulse will be the start for the last unsignedness. The leading edges of the transmitted discrete optical pulses will be separated from each other by the amount of time T _int.i , and, having determined the interval between the leading edges of adjacent pulses A _i and A _{i + 1} at reception and having at their disposal the interval value T _int.i-1 for the previous pair of pulses A _i-1 and A _i , you can uniquely determine the position number of the pulse L _i and then from L _i from table S determine the transmitted data value or command.

 A specific example of the method.

Let us consider an example in which two identical devices containing as an integral part the circuit shown in FIG. 1a, exchange data and commands. Differential PIM is used with the following parameters:
T _imp - 200 ns;
T _p - 16 μs;
M-26;
T _pos - 800 ns;
Δ = 400 ns.

 S has the form shown in the table.

 The timer in both devices is set to auto-increment by one each period τ = 200 ns. Let the first device transmit command N4, and a data packet of format 1 with a length of 4 four-digit data words: 3, 14, 7, 10. After this transmission, the first device goes into receive mode. The second device after receiving a command and a data packet transmits a packet acknowledgment.

Based on the definition of the differential PIM and table S, the first device transmits seven discrete optical pulses by generating a logic unit signal at the discharge terminal of the parallel port P _{0 of the} processor with six intervals between pulses T _int. 1 = 34.8 μs, T _int . ₂ = 29, 2 μs, T _int . ₃ = 18.8 μs, T _int . ₄ = 26.0 μs, T _int . ₅ = 18.0 μs, T _int . ₆ = 22.0 μs (Fig. 5), the interval between pulses is equal to the interval between the leading edges of the pulses, which through the driver of the emitters generate optical signals of the same duration, which they are then emitted into the optical path (atmosphere, vacuum, homogeneous or inhomogeneous optical medium) and reach the photodetectors of the second device, generating a signal of the same shape in them, which, after amplification, is fed to the external interrupt input of the INT processor of the second device.

 When the first pulse from this sequence arrives at the external interrupt input INT of the processor of the second device, the processor of the second device stops the timer, extracts the value from it, puts in the timer a constant equal to the time during which the timer is stopped to retrieve the value from it and enter a new one, expressed in units of the timer period, and starts the timer. The extracted value is large (greater than 183) and corresponds in Table S to the start transmission command. The processor of the second device sets the sign of the start of transmission.

When a second pulse from this sequence arrives at the external interrupt input INT of the processor of the second device, the processor of the second device stops the timer, extracts the value from it, puts in the timer a constant equal to the time during which the timer is stopped to retrieve the value from it and enter a new one, expressed in units of the timer period, and starts the timer. The extracted value = 173 (T _int. 1 = 34.8 μs) and corresponds to command N4 in table S. The processor of the second device executes command N4.

When a third pulse from this sequence arrives at the external interrupt input INT of the processor of the second device, the processor of the second device stops the timer, extracts the value from it, puts in the timer a constant equal to the time during which the timer is stopped to retrieve the value from it and enter a new one, expressed in units of the timer period, and starts the timer. The extracted value = 145 (T _int.2 = 29.2 μs) and corresponds in Table S to the command to start transmitting a packet of format 1. The processor of the second device is preparing to receive a packet of format 1.

When a fourth pulse from this sequence arrives at the external interrupt input INT of the processor of the second device, the processor of the second device stops the timer, extracts the value from it, puts in the timer a constant equal to the time during which the timer is stopped to retrieve the value from it and enter a new one, expressed in units of the timer period, and starts the timer. The extracted value = 93 (T _int . ₃ = 18.8 μs) and corresponds in table S to the value of the data word 3. The processor of the second device stores this value in the memory cell N1.

When a fifth pulse from this sequence arrives at the external interrupt input INT of the processor of the second device, the processor of the second device stops the timer, extracts the value from it, puts in the timer a constant equal to the time during which the timer is stopped to retrieve the value from it and enter a new one, expressed in units of the timer period, and starts the timer. The extracted value = 133 (T _int . ₄ = 26.0 μs) and corresponds in table S to the value of the data word 14. The processor of the second device stores this value in the memory cell N2.

When a sixth pulse from this sequence arrives at the external interrupt input INT of the processor of the second device, the processor of the second device stops the timer, extracts the value from it, puts in the timer a constant equal to the time during which the timer is stopped to retrieve the value from it and enter a new one, expressed in units of the timer period, and starts the timer. The extracted value = 89 (T _int . ₅ = 18.0 μs) and corresponds in table S to the value of the data word 7, The processor of the second device stores this value in the memory cell N3.

When a seventh pulse from this sequence arrives at the external interrupt input INT of the processor of the second device, the processor of the second device stops the timer, extracts the value from it, puts in the timer a constant equal to the time during which the timer is stopped to retrieve the value from it and enter a new one, expressed in units of the timer period, and starts the timer. The extracted value = 109 (T _int.6 = 22.0 μs) and corresponds in table S to the value of the data word 10. The processor of the second device stores this value in the memory cell N4. Since all four packet words are received, the end of the transmission of the data packet is recorded.

 Next, the first device goes into receive mode, and the second device goes into transmit mode. The processor of the second device transmits two discrete pulses with a width of 200 ns with a time interval between their leading edges of 30.8 μs, which corresponds to a command to confirm the receipt of a packet that generates optical signals of the same duration through the signal shaper that are emitted into the optical path and reach the photodetectors of the first devices, generating a signal of the same shape in them, which, after amplification, is fed to the external interrupt input of the INT processor of the first device.

 When the first pulse from this sequence arrives at the external interrupt input INT of the processor of the first device, the processor of the first device stops the timer, extracts the value from it, puts in the timer a constant equal to the time during which the timer is stopped to retrieve the value from it and enter a new one, expressed in units of the timer period, and starts the timer. The extracted value is large (greater than 183) and corresponds in Table S to the start transmission command. The processor of the first device sets the sign of the start of transmission.

When a second pulse arrives at the external interrupt input INT of the processor of the first device, the processor of the first device stops the timer, extracts a value from it, puts in the timer a constant equal to the time during which the timer is stopped to extract a value from it and enter a new one, expressed in units of the timer period , and starts the timer. The extracted value = 153 (T _int. 1 = 30.8 μs) and corresponds to the packet acknowledgment command in Table S. The processor of the first device registers the receipt of this acknowledgment and the end of the packet transmission.

 This ends the communication session.

 The introduction of the processor, which is a standard device with a low cost, allows you to achieve the goal of reducing the cost of the device by using relatively inexpensive types of processors. Additionally, the cost of the device is reduced due to the cheaper cost of its development, since the development and debugging of a processor program is usually cheaper than the development and debugging of a device consisting of logic circuits and programmable logic circuits.

 The introduction of the processor allows you to realize the possibility of using two varieties of positional-pulse modulation (differential and constant speed) and changing the modulation parameters over a wide range.

An increase in the transmission efficiency becomes possible here if the position values are assigned to the data values and commands based on the average probability of their occurrence, the higher the frequency of occurrence in the path, the lower the position number corresponds to this value or command and the lower the value of T _int . With this correspondence, with constant PIM parameters (except S), the average transmission rate increases.

By varying the parameters T _p , T _pos and T _imp it is possible to establish a compromise between the transmission speed and range. By increasing T _p , T _pos and decreasing T _imp , it is possible to increase the duty cycle of the transmitted optical pulses and, accordingly, increase the power emitted by the emitter and, accordingly, the transmission distance.

 Improving the reliability of transmission is achieved using the entered positions that correspond not to data values, but to commands. These commands can be used to control and manage the integrity of the transmitted data, the formation of data packets and commands.

 Additionally, the reliability of the transmission is increased due to simplification of the structure of the transmitted data packets, simplification of the algorithm for processing incoming data, since in the described device there is an unambiguous correspondence of signals with data and commands and commands appear that are not transmitted in the form of data, which increases the reliability of data transmission and teams.

Sources of information
1. US patent N 5214526 "Pulse modulated infrared data communications link". Appl. N 709749 Filed: June 4, 1991, Int. C1, H 04 B 10/04, US C1 359/184.

2. US patent N 4648133 "Synchronization tracking in pulse position modulation receiver". Appl. N 638586 Filed: Aug. 7, 1984, Int. C1, H 04 B9 / 00, US C1 455/608
3. US patent N 5408351. Apr. 18, 1995 "Optical communication system". Appl. N 961606 Filled: Oct. 15, 1992, Int. C1, H 04 B 10/00, US C1. 359/186.

 4. US patent N 4584720 "Optical communication system using pulse position modulation". Appl. N 527813. Filed: Aug. 30, 1983, Int. C1, H 04 B 9/00, US C1 455/608 - prototype.

Claims (2)

 1. A method of receiving and transmitting information by an optical signal, which includes counting by a timer the time intervals between discrete optical pulses, characterized in that when a discrete pulse arrives at the input of the external processor interrupt, or the discharge input of the parallel port of the processor, or the processor reset input from the built-in timer processor, a value is extracted from which a constant is subtracted to determine the time interval between the given and previous pulses, after which, based on the obtained value, a correspondence table containing for each value of the time interval the sign of a command or data and the data value or type of command, the obtained data value or type of command is determined, respectively, and when transmitting a set of data and commands at the discharge terminal of the parallel port of the processor, a start discrete pulse is generated by setting the logical level units or logical zero at the time of the selected pulse width and then for each data value and each command, the value is determined by the correspondence table at a corresponding time interval, a discrete pulse is formed at the discharge terminal of the parallel port of the processor by setting the level of a logical unit or logical zero for the time of the selected pulse width so that its leading edge on the time axis is at a distance equal to this interval from the leading edge of the previous pulse .  2. A device for receiving and transmitting information by an optical signal, comprising an optical emitter with a detector for converting optical radiation into an electrical signal, characterized in that an additional processor is introduced, comprising a built-in timer, an external interrupt input, or a parallel port discharge input with the ability to interrupt when the signal changes on it , the discharge output of the parallel port of which is the input of the shaper of optical emitters, the outputs of which are connected to the optical emitter and supplement optical emitters, and the input of the external processor interrupt or the discharge input of the parallel port of the processor is connected to the output of the amplifier, the inputs of which are connected to the output of the optical detector and the outputs of additional optical detectors, or the reset input of the processor is connected to the output of the two-input logic element OR, the inputs of which are connected to the output a circuit for generating a processor reset signal and an amplifier output, the inputs of which are connected to the output of the optical detector and the outputs of additional optical tectors.

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