RU2778546C1 - Device and method for receiving optical signal reflected from sounding object - Google Patents

Abstract

FIELD: communication technology.

SUBSTANCE: invention relates to communication technology and can be used in optical communication systems. To achieve the effect, pseudonoise optical signals are used in communication devices. The optical receiver operates in a non-linear mode and allows you to create scanners (lidars) for remote detection of metal objects in a crowd of people, in thickets, remotely detect and determine the concentration of gases in the air, create lidars operating in conditions of limited visibility for the human eye and includes an adjustment unit quantum efficiency in terms of the frequency of sensor responses and a gating adaptation signal generation unit.

EFFECT: increasing the selectivity of the resolution of the probed objects with a limited power of the probe signal and/or the duration of the probe signal.

2 cl, 16 dwg, 6 tbl

Description

The field of technology to which the invention belongs

This invention relates to the field of receiving optical modulated signals, including signals used in measuring the time it takes a signal to travel a distance from a signal emitting source to an optical signal receiving device, in communication devices using pseudonoise optical signals, including a clock signal generator, an optical receiver a device operating in a non-linear mode, a matched filtering unit, a threshold signal detection module, and can be used, for example, in navigation, in laser ranging, reflectometry, locating complex extended objects that have many constituent elements and moving relative to the signal receiver, for time synchronization of optical lines with synchronous detection of an optical signal.

In this description, the following terms are used.

LIDAR (transliteration LIDAR English Light Identification Detection and Ranging - light detection and ranging) is a technology for obtaining and processing information about distant objects using active optical systems that use the phenomena of light reflection and its scattering in transparent and translucent media. Lidar, as a device, is at least an active optical range finder. Usually in Russia, such devices are called laser rangefinders and laser radars.

Optical radiation - electromagnetic waves, the lengths of which are in the range with conditional boundaries from 3000 µm to 0.25 µm.

PWB , Pseudo-random (pseudo-noise) sequences are completely deterministic digital sequences that appear random to an external observer.

M-sequences . An M-sequence is a recurrent sequence of order n modulo p, where p is a prime generated by the equation:

принимает значения из интервала от 0 до p-1, имеет максимально возможный минимальный период равный

. Recurrent sequence of order n modulo p for any prime p and some combinations

takes values from the interval from 0 to p-1, has the maximum possible minimum period equal to

.

An example of an M-sequence .

порождается уравнением M-sequence of the first order modulo 37, period

generated by the equation

где,

where,

получена из первых 37 членов этой М-последовательности. Subsequence

obtained from the first 37 members of this M-sequence.

β= {8; 3; fifteen; one; 5; 25; fourteen; 33; 17; eleven; eighteen; 16; 6; thirty; 2; ten; 13; 28; 29; 34; 22; 36; 32; 12; 23; four; twenty; 26; 19; 21; 31; 7; 35; 27; 24; 9; eight}.

Binary, position modulated (PM) sequences. In foreign literature, such sequences are called - nonuniform trains, position modulated trains, non-uniformly spaced trains.

длины L в которой члены последовательности принимают значения 0 и 1 и только N членов последовательности принимают значение равное 1.Sequences

length L in which the members of the sequence take the values 0 and 1 and only N members of the sequence take the value equal to 1.

), где

равны 1, а остальные члены последовательности α равны 0. Такие последовательности относятся к двоичным нерегулярным последовательностям. Последовательность

длины N, назовем последовательностью модулирующих сдвигов, а последовательность

- двоичной позиционно-модулированной последовательностью (ПМ). Примером последовательности

может служить последовательность, приведенная выше, в качестве примера М-последовательности.Members of the sequence α with numbers

), where

are equal to 1, and the remaining members of the sequence α are equal to 0. Such sequences are binary irregular sequences. Subsequence

of length N, we will call the sequence of modulating shifts, and the sequence

- binary position-modulated sequence (PM). Sequence example

the sequence above may serve as an example of an M-sequence.

так, что при

и

, тогда ненормированная АКФ последовательности α Rα(i)

принимает значение, равное N при

, и не более K при

. Такая последовательность называется последовательность со свойством «не более K совпадений».Let's extend the sequence

so that at

and

, then the non-normalized ACF of the sequence α Rα( i )

takes on a value equal to N when

, and no more than K at

. Such a sequence is called a sequence with the property "no more than K matches".

Binary sequences that have K=1 are called sequences with the "no more than one match" property.

For the examples discussed in the patent, the following is accepted:

• The numbering of members of a binary sequence starts from the zero member.

называются членами с четными номерами.• Members of the binary sequence with numbers j, for which the equality is true

are called even-numbered terms.

называются членами с не четными номерами.• Members of the binary sequence with numbers j, for which the equality is true

are called terms with odd numbers.

If a sequence γ of length L with the property "no more than K matches" contains terms equal to "1", both with even and odd numbers, divide into two sequences:

, состоящую из членов последовательности γ с четными номерами и последовательность

, consisting of even-numbered members of the sequence γ and the sequence

, состоящую из членов последовательности γ с нечетными номерами, то будет верно, что для последовательностей

и

так же выполняется свойство «не более K совпадений», т. е. уровень боковых лепестков ненормированной АКФ последовательностей

и

не будет принимать значения более K.

, consisting of members of the sequence γ with odd numbers, then it will be true that for the sequences

and

the property “no more than K matches” is also satisfied, i.e. the level of side lobes of the unnormalized ACF of sequences

and

will not take values greater than K.

An example of the formation and matched filtering of a binary PM sequence with the property of no more than one match.

, длины

, приведенной в примере (М-последовательности), сформируем последовательность

длины

.From the modulating sequence

, length

, given in the example ( M-sequence) , we form the sequence

length

.

,

,

,

,

с номерами

, где

равны 1, а остальные члены равны 0. Последовательность

обладает свойством «не более одного совпадения». Members

with numbers

, where

are equal to 1, and the remaining terms are equal to 0. The sequence

has the "no more than one match" property.

длины

. Блок 1 содержит тридцать шесть последовательно включенных каскадов 1.1. In FIG. 1 shows the scheme of formation and subsequent matched filtering of the PM sequence. The scheme consists of block 1 for the formation of the PM sequence

length

. Block 1 contains thirty-six cascades connected in series 1.1.

The first input of cascade 1.1 is the input of block 1.

The second output of stage 1.1 of block 1 is the output of block 1.

The first input of each next stage is connected to the first output of the previous stage, that is, the input of block 1.2 is connected to the first output of block 1.1, etc.

The second output of each cascade is connected to the second input of the previous cascade, that is, the second output of side 1.2 is connected to the second input of block 1.1, and so on.

The first output of the last thirty-sixth cascade 1.36 is connected to the second input of the same cascade 1.36.

и ее последующей согласованной фильтрации на вход блока 1 подается последовательность, нулевой (в принятой нумерации) член которой равен 1, а остальные члены последовательности равны 0. Начиная с нулевого по

такт работы устройства в точке соединения блоков 1 и 2 при помощи блока записи и отображения Т1 фиг. 1 зафиксируем последовательность

. Двоичная последовательность

поступает на вход блока 2 (блок согласованной фильтрации). Each stage consists of a discrete delay line (marked on the diagram as positions 1.1.2, 1.2.2, 1.3.2), etc., and one element that performs the disjunction operation (or), marked on the diagram as positions 1.1.1, 1.2.1, 1.3.1, connected as shown in block diagram 1 in Fig. 1. To form the PM sequence

and its subsequent matched filtering, the input of block 1 is fed with a sequence whose zero (in the accepted numbering) member is equal to 1, and the remaining members of the sequence are equal to 0. Starting from zero to

the operation cycle of the device at the connection point of blocks 1 and 2 using the recording and display unit T1 of FIG. 1 fix the sequence

. binary sequence

is fed to the input of block 2 (matched filtering block).

Figure 1 shows:

длины

1 - block for the formation of the PM sequence

length

2 - matched filtering unit

1.1, 1.2, 1.3 ... 1.36 - cascades of block 1.

2.1, 2.2, 2.3, ... 2.36 - cascades of block 2.

Block 2 (matched filtering unit) consists of thirty-six cascades connected in series 2.1, 2.2, ... 2.36, connected in the same way as in block 1. Each cascade of block 2 consists of a discrete delay line (marked in the diagram of Fig. 1 as 2.1.2, 2.2.2, 2.3.3, ...2.36.2) and one addition element connected as shown in fig. 1 (marked in the diagram of Fig. 1 as 2.1.1, 2.2.1, 2.3.1, ... 2.36.1)

Table 1. Formulas for determining the delays in the delay line of the cascades of blocks 1 and 2 in FIG. one.

The name of the block in the diagram of Fig. one. The formula for calculating the number of delay cycles in the delay line of the cascade from the cascade number (i) (cascade numbering from 1 to 36, from left to right in Fig.1) Block 1 of the formation of the PM sequence

Block 2 of the matched filtering of the PM sequence

зафиксированной блоком Т1 фиг. 1. (нижний график). Figure 2 (upper graph) shows a fragment of the response at the output of the matched filter of block 2, fixed by the registration and display unit T2 of Fig. 1 when fed to its input sequence

fixed by block T1 of FIG. 1. (bottom graph).

с номером

не равного нулю в последовательности на входе согласованного фильтра (вх. Блока 2) совпадает с (главным) пиком отклика на выходе согласованно фильтра, зафиксированного блоком Т2. Отсчеты, соседствующие с пиком отклика, будем называть боковыми лепестками (пика) отклика (в литературе встречается название боковые пики), а отношение их максимальной амплитуды к амплитуде пика отклика будем называть УБЛ уровнем боковых лепестков (отклика). В литературе так же используют термин уровень боковых пиков. As can be seen, the position of the reference

with number

not equal to zero in sequence at the input of the matched filter (input of block 2) coincides with the (main) peak of the response at the output of the matched filter fixed by block T2. The readings adjacent to the response peak will be called the response side lobes (peak) (there is a name in the literature side peaks), and the ratio of their maximum amplitude to the response peak amplitude will be called the UBL level of the side lobes (response). In the literature, the term side peak level is also used.

Modulating discrete sequence is a sequence of finite length, the numbers of members of which are confined to the numbers of time positions at which the lidar emits an optical pulse, if the member of the modulating sequence is different from zero.

– длительность временной позиции ПИМ сигнала

– duration of the time position of the PIM signal

- частота модуляции испускаемого оптического сигнала.

is the modulation frequency of the emitted optical signal.

A member of the modulating sequence can be not only a binary value (0 - no emission, 1 - emission), but an array of data characterizing the shape, frequency, amplitude and phase of the emitted pulse, i.e., the specified characteristics of the optical pulse.

Position-pulse modulation (PIM). If the modulating sequence is a binary PM sequence, then the sequence of emitted optical pulses modulated by it is called a position-modulated sequence of (optical) pulses or a position-pulse modulated ( PIM ) sequence of (optical) pulses ( PIMPOI ).

In foreign literature, such sequences of emitted pulses are called " PPM sequence". US Pat. No. 8,072,582 describes a closely related type of pulse train modulation called "pulse timing sequence, with pseudo-random timing".

The probing signal is a modulated sequence of optical pulses emitted by the lidar.

Quantum efficiency ξ is the probability of generation by a single photon of a free carrier hitting the optical sensor, which will reach the region of a high field sufficient for impact ionization or the probability of triggering the sensor when a single photon hits the sensor surface.

при условии увеличения числа фотонов η попадающих на поверхность сенсора на интервале времени

, на величину ∆η, к величине ∆η при ∆η/η менее 0,1. Dynamic quantum efficiency - the ratio of the increase in the probability of sensor operation over a time interval

subject to an increase in the number of photons η falling on the sensor surface in the time interval

, by the value of ∆η, to the value of ∆η at ∆η/η less than 0.1.

Dynamic conversion factor (dynamic sensitivity) photocurrent/power. For optical sensors operating in the power-to-photocurrent conversion mode, the dynamic conversion factor.

, где

фототок,

мощность излучения, попадающая на сенсор.

, where

photocurrent,

radiation power reaching the sensor.

An example of such an optical sensor is a matrix silicon photomultiplier, referred to in foreign literature as SiPM.

The dynamic photocurrent/power conversion ratio also decreases with an increase in the radiation power coming to the sensor surface.

The mode of detecting an optical signal by a quantum optical sensor, in which the “dynamic quantum efficiency” index is reduced by two or more or times, or the detection mode by an optical sensor operating in the power-to-photocurrent conversion mode, in which the dynamic photocurrent/power conversion coefficient is reduced by two or more more times, we will call the mode of operation of the sensor in the mode of saturation or limitation.

Saturation threshold - the minimum radiation power or the average number of photons for a given time interval arriving at the sensor at which the sensor operates in saturation (limitation) mode.

A resolvable object is an object or element/segment of an object that enters the beam target, in which the optical radiation emitted by the lidar transmitter is concentrated and into the beam target, in which the reflected radiation is concentrated, falling on the surface of the optical sensor of the lidar receiver.

ESR (Effective Scattering Surface) is a quantitative measure of the property of a resolvable object to scatter part of the optical radiation towards the receiving sensor. The energy of the reflected probing signal arriving at the optical sensor is proportional to the RCS of the resolved object.

The received signal is a superposition of the reflected probing signals from the object/s, the distance to which/s is measured, and the reflected probing signals from other (objects) arriving at the surface of the optical sensor or sensors, if the optical sensor contains several receiving elements and noise emission.

In this superposition, the reflected optical signals arriving at the sensor surface can differ in intensity, including signals whose intensity is insufficient to resolve the object by the method with which the comparison is made, we will call "weak", the intensity signals of which on the sensor surface exceed the saturation threshold, we will call "strong" ( i.e. strong signals include those signals in which single optical pulses arriving at the sensor surface lead to its operation with a probability close to 1.0), and signals whose intensities on the sensor surface do not exceed the saturation threshold of the sensor, and at the same time are resolved using the method with which the comparison is made will be called "ordinary".

Similarly, we will call the EPR of objects, and the objects themselves, generating reflected signals, as "weak", "strong", "ordinary".

Selectivity - the ability of a lidar to resolve (reliably determine the range to a probed object using a threshold detector) a probed object or a segment of an extended probed object falling into the beam target if there are other nearby objects (elements of a composite object) with large RCS and noise radiation in the beam target, hitting the surface of the receiving sensor. It can be said that if the peak of the response or peaks of the responses from the probed object/objects, or the element/elements of the object/objects are clearly distinguished on the reflectogram above the noise level, side lobes of the responses, then a lidar using a method or device that leads to obtaining a real trace uses a method that selectively resolves objects (elements of objects) and generates resolvable response peaks on the secondary trace.

Optical sensors operating in Geiger counter mode

Known sensors (optical receiving elements) for detecting optical radiation SSPD (Superconducting Single-Photon Detector) or superconducting single-photon detectors operating at temperatures close to absolute zero and used to detect single photons and operating in the Geiger counter mode in the wavelength range from 250 to 3000 nm. An example of such a sensor is the sensor described in patent RU 2346357, published in 2009, based on thin-film superconducting structures. Such sensors are characterized by quantum efficiency up to 80-90%, time resolution up to 25 ps. On the basis of such receivers, integrated registration systems are created with dozens of channels (pixels). The disadvantage of using SSPD sensors is the need to cool the sensor to temperatures close to absolute zero.

Known sensors for detecting optical radiation InGaAs / InP SPAD (Indium Gallium Arsenide / Indium Phosphide Single-Photon Avalanche Diode) or Arsenide Gaallium-Indium single-photon avalanche diodes based on, used to detect single photons operating in the Geiger counter mode in the wavelength range from 900 up to 1700 nm. Compared to superconducting single photon detectors, they do not require expensive cryogenic coolers. The main disadvantage of SPAD sensors is the high probability of repeated triggering of the sensor after receiving an optical pulse in a time interval of up to 100 ns; to compensate for this disadvantage, a special SPAD operating mode is used, called fast gating.

Fast gating (Ultra-short gating, extremely short gating) is an optical sensor operating mode in which the sensor is switched to the Geiger counter mode for very short time intervals of 100-200 ps. Fast gating allows to reduce the time during which the sensor is not ready for operation due to the transient processes occurring in it that occur as a result of receiving optical radiation in the Geiger counter mode and to reduce the probability of the sensor re-triggering (afterpulsing probability) during subsequent fast pulses after receiving optical radiation. gating of the optical sensor.

Fast gating can be done in a variety of ways. US Pat. No. 7,705,284 proposes a gating method and apparatus in which the sum of the bias voltage of the gating sinusoidal signal is applied to the anode of the diode. During each period of the strobe signal, a photon can be detected at the time interval in which the voltage at the anode of the diode exceeds the breakdown voltage and the diode is in an active state (ready to receive a photon). A signal representing a superposition of an avalanche signal and a sinusoidal signal is taken from the resistance in the diode cathode circuit. The avalanche signal is separated from the sinusoidal signal by a notch filter that suppresses the first harmonic of the sampling frequency. The disadvantages of this method include the fact that the instantaneous efficiency of photon reception in the time interval in which the voltage at the anode exceeds the breakdown voltage is not constant and is determined by the shape of the voltage at the anode, which changes according to a sinusoidal law. The gate time interval depends on the gate frequency and amplitudes of the bias voltage of the sinusoidal signal and the sinusoidal signal itself.

US Pat. No. 9,012,860 describes a method and apparatus for single photon reception in fast gating mode. The device contains two identical LTD diodes, to which, through a signal divider, a strobe signal in the form of a meander and a positive bias voltage are supplied to the cathodes of the diodes. The first APD diode is adopted as a radiation receiver, and the second one is idle and is used as a source, identical in the first capacitive transient, which occurs on the first APD when a strobe signal in the form of a meander is applied to it. The avalanche signal from the first LTD is extracted by subtracting from it the transient process formed on the second LTD. Due to the use of a square wave as a gating signal, the quantum efficiency in the time interval when the diode voltage exceeds the breakdown voltage is approximately constant. The time interval in which the diode is in the state of receiving a photon is almost independent of the meander amplitude and bias voltage. This method of reception is the most suitable for use in the described invention, but does not limit it.

Fast gating allows the sensor to receive optical radiation that enters the sensor only at gating intervals.

Optical sensor. By optical sensor we mean a single optical sensor operating in the fast gating mode or a group of sensors operating in the fast gating mode.

Received optical signal, reflectograms. Under the received signal we mean the final discrete sequence formed in the process of receiving the optical signal. Each member of this sequence is formed based on the results of the operation of a sensor (or a group of optical sensors) in the corresponding time interval

In our case, such a signal is also called the primary reflectogram or binary detection signal (sequence).

The secondary reflectogram is understood as the primary reflectogram processed by the matched filtering method. The secondary reflectogram is used to calculate the time delays of the optical signal reflected or generated by the probed object.

PC - a computer with software and interface modules designed to control the bench that simulates the operation of the lidar and to process the primary reflectograms generated by the bench to form auxiliary sequences of the bench blocks loaded into the memory.

Objectives of the invention

An obvious way to increase the resolution efficiency of target elements with "weak" EPR is to increase the energy of the probing optical pulses, which makes it possible to increase the signal-to-noise ratio on the surface of the optical sensor. But often an increase in energy requires significant material costs or technically, at this level of technology, is not feasible. At the same time, relatively accessible methods for generating optical radiation are known, which have limitations in terms of peak power, and sources, such as laser diodes, optical-terahertz converters, for example, using the Dember effect [DOI: 10.1364/OL.428599].

The use of such sources of pulsed terahertz radiation in conjunction with terahertz radiation receivers (see, for example, SSPD) in fast gating mode using the technical solutions described in this patent makes it possible to create scanners (lidars) for remote detection of metal objects and determining their shape, for example , in a crowd of people, in thickets in the presence of fog, for remote determination of low concentrations of gases in the atmosphere, etc.

The purpose of this invention is to ensure the detection of all elements of the probed object in the case when the energy of the emitted optical pulses is insufficient to provide reliable resolution of the probed objects and there are time limits for resolving these objects. Preferably, the time required for resolution does not exceed one probing cycle.

Or, in other words, the task is to improve the selectivity of the resolution of probed objects with limited probing signal power and/or probing signal duration.

Disclosure of invention

Based on this original observation, the present invention mainly aims to provide an apparatus for receiving an optical signal, including a clock signal generator connected to an optical receiver operating in a non-linear mode, a matched filtering unit, a signal threshold detection module, allowing, by at least smooth out at least one of the above disadvantages, namely, to ensure the detection of all elements of the probed object in the case when the energy of the emitted optical pulses is insufficient to ensure reliable resolution of the probed objects by known methods and there are restrictions on the probing time , which is the technical problem of the present invention.

To achieve this goal, the device includes a node for adjusting the quantum efficiency by the average frequency of sensor responses and a block for generating a gating adaptation signal.

Due to these advantageous characteristics, it becomes possible to reduce the time of probing, to carry out probing of all elements of the probed object that fall into the target of the probing beam at the same time.

The invention also relates to methods for receiving an optical signal, in which a clock signal is generated, a signal reflected from a resolvable object is received by an optical receiver operating in a nonlinear mode, having a matched filtering unit and a signal threshold detection module.

In order to ensure the detection of all elements of the probed object in the case when the energy of the emitted optical pulses is insufficient to ensure reliable resolution of the probed objects and there are restrictions on the probing time, it is proposed, according to the invention, to add a step in which the strobe signal is adapted, regulate the quantum efficiency by the frequency of sensor activations.

Due to these advantageous characteristics, it becomes possible to reduce the time of probing, to carry out probing of all elements of the probed object that fall into the target of the probing beam at the same time.

There is a variant of the invention in which the formation of the gating adaptation signal is carried out in the process of probing based on the results of matched filtering of a fragment of the probing PIM sequence or a separate probing pilot signal, which makes it possible to estimate the time delays of the reflected signal from the elements of the probed object with “strong” RCS.

Thanks to these advantageous characteristics, it becomes possible to refuse the use of an additional optical path necessary for the formation of the gating adaptation signal.

Brief description of the drawings

Other features and advantages of the present invention will clearly appear from the description below, by way of illustration and without being restrictive, with reference to the accompanying figures, in which:

и ее согласованной фильтрации. Figure 1 shows the block diagram of the PIM sequencer

and its matched filtering.

Figure 2 depicts fragments of discrete sequences captured and displayed by blocks T2 (upper graph) and T1 (lower graph). The abscissa indicates the operation cycles of the device of FIG. one.

Figure 3 is a graph explaining a method for generating a gate pulse signal.

Figure 4 shows options for the possible timing of the strobes (strobe pulses) relative to the received PIM sequence of (optical) pulses.

- graph A - schematically depicts two fragments of the received PIM signal, containing four signal time positions, even time positions are marked with a "0" sign, odd ones with a "1" sign.

- plots B, C, D, E schematically display periodic gating signals, differing only in their position in time relative to the beginning of even signal time positions.

Figure 5 shows a graph, where the abscissa of graphs B, C, D, E plotted the numbers of samples of the binary sequence obtained by the method considered in the example. On the ordinates of the graphs B, C, D, E, the amplitudes of the samples are plotted, the binary sequence obtained by the method considered in the example, differing in the position of the gating signals, the variants of which are shown in the graphs B, C, D, E in figure 4.

Figure 6 shows a diagram of the generation and subsequent matched filtering of the PIM sequence.

Figure 7 depicts a fragment of the filter response (from clock 74000 to clock 76750) at the output matched at point T2 of Figure 6 (on the recording device and display T2) and at the output of the notch filter at point T3 of Figure 6 (on the recording device and display T3).

Figure 8 depicts a functional diagram of the stand for imitation of the receiving and transmitting paths of the lidar, without the functional blocks for processing reflectograms implemented programmatically in a PC.

Figure 9 depicts the robot of the block for the formation of the modulating binary PM sequence.

Figure 10 depicts the operation of the gating signal adaptation signal conditioning unit.

Figure 11 schematically depicts the device of the block for simulating a complex probed object (CISO).

Figure 12 schematically depicts the relationship of samples in the binary detection sequence (plot E in Fig. 13) with gate time intervals (plot D) and clock timing (plot B).

Figure 13 shows a functional diagram of signal processing and generation implemented in software on a PC.

Figures 14 and 15 show fragments of the Z trace obtained after processing the primary traces by matched filtering and the corresponding fragments of the 5*Y auxiliary sequence.

In FIG. 16 shows a possible diagram of the optical path of the gating adaptation signal generator.

Implementation of the invention.

от числа фотонов с пуассоновским распределение по времени по материалам [DOI: 10.1049/el:19840411] можно представить в виде простого уравнения (1) Let us show how the quantum efficiency ξ of the sensor is controlled in the fast gating mode. Optical sensor triggering probability for

on the number of photons with a Poisson time distribution over materials [DOI: 10.1049/el:19840411] can be represented as a simple equation (1)

, где (one)

, where

– вероятность срабатывания сенсора при отсутствии излучения на пов. сенсора за интервал времени

(dark count probability),

is the probability of triggering the sensor in the absence of radiation on the surface. sensor per time interval

(dark count probability),

- среднее число фотонов, попадающее на сенсор за интервал времени

.ξ - quantum efficiency,

is the average number of photons that hit the sensor over a time interval

.

Equation (1) can be conveniently represented as (2)

, где

(2)

, where

, попадающее на поверхность сенсора за время стробирования

состоит из фотонов шумовой составляющей (нижний индекс _N) и собственно сигнальной (нижний индекс _S)In the practical application of this equation, the number of photons

falling on the sensor surface during the gating time

consists of photons of the noise component (subscript _N ) and the actual signal component (subscript _S )

(3)

можно рассматривать, как элемент шумовой составляющей в детектируемом сигнале несмотря на то, что он связан с внутренней природой сенсора. From a practical point of view, the spontaneous operation of the sensor, expressed by the variable

can be considered as an element of the noise component in the detected signal, despite the fact that it is associated with the internal nature of the sensor.

и соответственно

в режиме скоростного стробирования увеличивается при уличении показателя

путем увеличения напряжения смещения на ЛПД, работающем в режиме счетчика Гейгера, увеличения рабочей температуры сенсора и сокращения времени прошедшего от момента предшествующего срабатывания сенсора до момента начала нового стробирования. It is known that

and correspondingly

in high-speed gating mode increases when the indicator is detected

by increasing the bias voltage on the LPD operating in the Geiger counter mode, increasing the operating temperature of the sensor and reducing the time elapsed from the moment of the previous sensor operation until the start of a new strobing.

понимают собственно сумму среднего числа шумовых фотонов, попадающих на поверхность сенсора за время стробирования обозначаемую здесь как

и величины

, характеризующей собственный шум сенсора.

- эквивалентное число шумовых фотонов. In practice, under the noise component

understand the actual sum of the average number of noise photons that hit the sensor surface during the gating time, denoted here as

and quantities

, which characterizes the intrinsic noise of the sensor.

is the equivalent number of noise photons.

(four)

The probability of sensor operation during the gating time in the absence of a signal optical pulse hitting the sensor surface can be expressed by the equation:

(5)

The probability of sensor operation during the gating time when a signal optical pulse hits the sensor surface can be expressed by the equation:

, где

=

/

.

, where

=

/

.

The increase in the probability of sensor operation when an optical signal hits the sensor surface can be defined as

The presence of the gain allows you to extract from the detected optical signal by matched filtering, information about the time of the start of arrival at the optical sensor of the PIMPOI, for example, reflected from the element of the probed object.

в отсчете – пике отклика на выходе дискретного согласованного фильтра будет увеличено по сравнению с соотношением при условиях детектирования. With matched filtering of one PIM sequence, the relation

in the sample-peak response at the output of the discrete matched filter will be increased compared to the ratio under the detection conditions.

при условиях детектирования, как

Denote the ratio

under detection conditions as

, где M число оптических импульсов принимаемых в режиме стробирования и вносящих вклад в формирование пика отклика согласованной фильтрации, а шумовую, как среднеквадратическое отклонение

выходных отсчетов согласованного фильтра при подаче на его вход последовательности, получаемой при детектировании только шумовой составляющей .The signal component of the response at the output of the matched PIM sequence filter can be estimated as the mathematical expectation of the response peak count value at the output of the matched filter equal to M

, where M is the number of optical pulses received in the gating mode and contributing to the formation of the matched filtering response peak, and the noise pulse, as the standard deviation

output samples of the matched filter when applying to its input the sequence obtained by detecting only the noise component .

.(7)

.

на для пика отклика на выходе согласованно фильтра можно записать как,

for the peak response at the output of the matched filter can be written as,

(eight)

достигается если выполняется условие Maximum per

is achieved if the condition is met

, при

и(9)

, at

and

при

. (ten)

at

.

и заданном

при оптимальной квантовой эффективности квантовой эффективности, при которой показатель

максимален, вероятность срабатывания сенсора от шумовой составляющей на интервале времени

составит

≈ 0,63 ≈

, а с увеличением соотношения

должна убывать обратно пропорционально

и при

≈

.From equation (10) it follows that at

and given

at the optimal quantum efficiency quantum efficiency, at which the exponent

maximum, the probability of the sensor triggering from the noise component in the time interval

will be

≈ 0.63

, and with an increase in the ratio

must decrease inversely

and at

≈

.

An example of estimating the average frequency of sensor activations

, где

– частота стробирования сенсора. Среднее число фотонов в каждом оптическом импульсе, поступающем на поверхность сенсора равно 1.

1, Соотношение сингал/шум определяемое, как отношение среднего числа фотонов в оптическом импульсе, поступающем на интервале стробирования на поверхность сенсора к эквивалентному среднему числу шумовых фотонов, поступающих на интервале стробирования на поверхность сенсора

= 1,0. PIMPOI contains N ≈ 500 optical pulses of these pulses, only a part in the amount of M=200 in time to reach the sensor surface coincides with the time intervals of high-speed gating of the sensor. PIMPOI duration is 20000/

, where

– sensor strobe frequency. The average number of photons in each optical pulse arriving at the sensor surface is 1.

1, Singal/noise ratio defined as the ratio of the average number of photons in the optical pulse arriving at the sensor surface during the gating interval to the equivalent average number of noise photons arriving at the sensor surface during the gating interval

= 1.0.

сенсора равный или не выше 0,69/1 = 69%, устанавливаем

= 25% , как максимально достижимый для данного типа сенсоров.Then, according to equation (9), it is necessary to establish

sensor equal to or not higher than 0.69 / 1 = 69%, set

= 25%, as the maximum achievable for this type of sensors.

= 25% получим, что For

= 25% we get that

= 0,42

= 0.42

= 0,17/0,42

= 0,42 •14,14 = 5,87

= 0.17/0.42

= 0.42 •14.14 = 5.87

составит while the average frequency of sensor activations

will be

= (

(20000-M)/20000 +

M/20000)

=(

(20000-M)/20000+

M/20000)

≈ 0,22*

= (0.22*(20000-M)/20000 +0.39*M/20000)

≈ 0.22*

, определяемой шумовой составляющей, а она в свою очередь определяется по уравнению (5) произведением

.   С повышением соотношения

, величина

снижается, что требует большего времени для оценки средней частоты срабатываний сенсора  

, поэтому применение метода целесообразно использовать при

не более 5, предпочтительно не более 3. As can be seen from the above example, the average frequency of sensor responses is determined mainly by the value

determined by the noise component, and it, in turn, is determined by equation (5) by the product

. With increasing ratio

, value

decreases, which requires more time to evaluate the average frequency of sensor triggers

, therefore, it is advisable to use the method when

no more than 5, preferably no more than 3.

на сенсоре и минимальном рабочем соотношении

для оптимизации

на выходе согласованного фильтра необходимо поддерживать фиксированную среднюю за время

частоту срабатываний сенсора, путем регулирования квантовой эффективности сенсора. Такое регулирование можно реализовать, например, при помощи контура регулирования амплитуды напряжения смещения

, подаваемого в сумме с прямоугольным сигналом стробирования на ЛПД диод, эксплуатируемый в режиме счетчика Гейгера или непосредственно регулируя напряжение стробирования. Поясняющая способ формирования сигнала стробирования фигура приведена на фиг. 3.Thus, for given: noise level

on sensor and minimum working ratio

for optimization

at the output of the matched filter, it is necessary to maintain a fixed average over time

the frequency of sensor activations, by adjusting the quantum efficiency of the sensor. Such regulation can be implemented, for example, using a bias voltage amplitude regulation loop

, supplied in total with a rectangular gating signal to the LPD diode, operated in the Geiger counter mode or directly regulating the gating voltage. A figure explaining the method of generating the strobe signal is shown in FIG. 3.

Table 2 3

one

Bias voltage 2

The minimum voltage amplitude at which an avalanche breakdown is possible. 3

=

Gating voltage amplitude that determines ξ at gating intervals. four

=

The amplitude of the sensor switch-off voltage from the Geiger counter mode. 5

and

Amplitudes of the positive and negative half-wave of the bipolar gating signal, which is a square wave with a frequency

and a strobing half-wave interval equal to

In Fig.3

=

6

The duration of the gating interval. In FIG. 3

where

7

Gating period.

в установившемся режиме регулирования в пределах ±5 % от среднего установившегося значения, не оказывает существенно влияния на технические характеристики приемного тракта лидара или иного устройства, использующего рассматриваемый метод. The time τ is defined as the time sufficient to determine the average relative frequency of sensor responses with an acceptable error. Since the average relative frequency of sensor triggering is determined by the quantum efficiency of the sensor, as the time τ increases, the fluctuations in the quantum efficiency of the sensor will also decrease. In fact, the control loop maintains the average frequency of sensor responses close to the control setpoint through the control action on the quantum efficiency of the sensor, but the changes in the control action must be smooth and provide a minimum relative fluctuation of the quantum efficiency during the control process. Relative fluctuations

in the steady-state control mode within ±5% of the average steady-state value, does not significantly affect the technical characteristics of the receiving path of the lidar or other device using the method under consideration.

This control loop can be used for high speed gating of an optical sensor, for example, as described in US Pat. No. 9,012,860.

Sensor gating adaptation.

Adaptive gating can be used to reduce sensor false alarms associated with an effect known as "after-pulsing probability" (APP) described for example in [DOI: 10.1155/2018/9585931].

Indeed, there is a problem that an increase in sensor ξ by increasing the voltage amplitude at the moments of sensor operation in the Geiger counter mode leads to an increase in the so-called. false positives of the sensor, both permanently and additionally at the time interval necessary for the complete restoration of the sensor parameters.

The number of false alarms induced by the reception of optical pulses from "strong" and "ordinary" or "strong" signals can be reduced by turning off the sensor from the Geiger counter mode at the moments when optical pulses, reflected from objects with strong and ordinary EPR, are expected to hit the sensor surface ( strong and ordinary signals).

The strobe signal applied to the sensor can be adapted based on a priori information about the moments when optical "strong" and "ordinary" optical pulses arrive at the sensor surface.

An obvious application of adaptive gating is to turn off the receiving sensor at time intervals delayed from the optical pulse emission time intervals by the time required for the optical pulse to travel from the optical pulse transmitter to the sensor surface. For example, this is required in cases where the sensor and the transmitter of optical pulses use a common transmit-receive optical path. In this case, adaptive gating can be implemented by adapting the signal by performing a conjunction operation on the gating signal (“1” - there is a sensor gating, “0” - there is no sensor gating) and the inverted signal emitting optical pulses (“1” - there is no emission of an optical pulse on gating interval, "0" - is the emission of an optical pulse at the gating interval).

Example #1

Imagine PIM signal that is modulated by the PM sequence α from the example: "An example of the formation and matched filtering of a binary PM sequence with the property of no more than one match." The number of non-zero terms with even-numbered terms in the sequence α is close to the number of odd-numbered terms.

.Pulse duration in PIM signal

.

PIM modulation frequency

PIM modulation period

. (частота сигнала стробирования

=

). Длительность импульсов стробирования (стробов)

, что соответствует ½ периода стробирования увеличенного ½ длительности импульсов в детектируемом ПИМ сигнале. This PIM signal is fed to the synchronous detection device, which is also supplied with a periodic signal of strobe pulses with a period

. (gate signal frequency

=

). The duration of the strobing pulses (strobes)

, which corresponds to ½ of the gate period of the increased ½ pulse duration in the detected PIM signal.

The synchronous detection device works according to the following principle:

- if at least one pulse of the PIM sequence or its fragment with a duration of at least ½ of the duration of the optical pulse and the strobe (strobe) pulse coincides in time, a logical unit with a duration of 200 ps is formed along the trailing edge of the strobe, followed by a logical "zero", with a duration of 200 ps;

- otherwise (if there is no coincidence or the coincidence in time of the strobe and the optical pulse is less than ½ of the duration of the PIM signal pulse), two logical zeros with a duration of 200 ps are formed on the trailing edge of the strobe. Thus, a binary sequence is formed, with a clock transition time of 200 ps.

Let's call this method of receiving binary signal detection.

The sequence formed in the described way is fed in cycles to the matched filter - block 2, which is shown in Fig. one.

It is obvious to the specialist that since every second sample in the processed sequence is a “0” signal, then when processing the signal, the number of addition operations can be halved and the frequency of performing streaming operations necessary to implement matched filtering can be halved. However, since the purpose of this patent is not to reduce the addition operations in matched filtering, a simplified description of the filtering devices is used in the description.

In FIG. 4 schematically shows how the time position of the gates relative to the start of the even time positions of the PIM signal pulses affects the shape of the output binary sequence (binary detection signal). By even time positions we mean time positions that are confined to even members of the sequence α, by odd ones, which are confined to odd members of the sequence α.

In FIG. 4 (graph A) schematically shows a fragment of the received PIM signal containing four time positions of the pulses (zero (even), first (odd), second (even) and j-th (odd)). The received pulses are displayed in place of the zero (even) and j-th (odd) time positions of the pulses, and the absence of the received pulse is displayed in the place of the first (odd) and second (even) positions.

In FIG. 4 (plots B, C, D, E) are schematic representations of periodic gating signals, differing only in their position in time relative to the start of the even time positions of the pulses. Thus, the gate signal "B" ensures the gate of only even time positions of the pulses, and the gate signal "E" - only the odd positions of the pulses. Signal "C" provides gating of even positions and partially odd ones. The "D" signal provides gating for odd positions and partially even ones.

, полученные при подаче на его вход дискретных последовательностей, полученных при двоичном детектировании ПИМ сигнала, рассматриваемого в настоящем примере, при вариантах положения стробов относительно временных позиций кода (B, C, D, E), приведенных на фиг. 4.In FIG. 5. shows the signals (fragments of discrete sequences - reflectograms) at the output of the matched filter considered in the example - block 2, which is shown in FIG. 1 with pulse x-coy

, obtained by applying to its input discrete sequences obtained during binary detection of the PIM signal considered in this example, with options for the position of the strobes relative to the time positions of the code (B, C, D, E) shown in Fig. four.

Designations of variants of the relative position of the gates in Fig. (B, C, D, E) correspond to the notation obtained at the output of the matched filter fragments of discrete sequences.

As can be seen from FIG. 5 - traces B and E allow determining the time position of the PIM sequence (the position of the trailing edge of the last pulse in the received PIM sequence) with an accuracy of ±100 ps, and traces C and D allow determining the position with an accuracy of ±200 ps.

Thus, for use in range measurements, the accuracy of determining the distance to the probed object will not exceed ±30 nm.

The practice of using PIM signals

It is known that when probing objects, PIM pulse sequences are used, including those obtained by position-pulse modulation using a binary, PM sequence with the property "no more than one match" as a modulating sequence. [“High resolution waveforms suitable for a multiple target environment”/ Resnick, Joel B/ Thesis (M.S.) --MIT, Dept. of Electrical Engineering, 1962. URI: http://hdl.handle.net/1721.1/11436].

The use of modulated probing signals in this way makes it possible to improve the selectivity of the resolution of the probed objects after matched filtering of the detected signal due to the low level of side lobes of the normalized ACF (no more than 1/N), where N is the number of positions in the modulating binary sequence different from 0 and simultaneously with This minimizes the loss in the signal-to-noise ratio for “ordinary” signals extracted by matched filtering, if a signal receiver operating in the limiting receiver is used to receive them, and a superposition of the received detected signals from various resolvable objects is fed to the input of this receiver. [Proc. IEEE vol. 54, p. 438-439 (1966) / DOI: 10.1109/PROC.1966.4745].

квадратично зависит от N - число ненулевых позиций в двоичной модулирующей последовательности. Согласно сведениям, приведенным в монографии [“Оптимальные дискретные сигналы”/ М.Б.Свердик / “Сов. Радио” 1975]. Длительность зондируемого сигнала

, где L – число членов в двоичной модулирующей последовательности,

длительность временной позиции ПИМ сигнала.The disadvantages of using probing signals with the property of the modulating sequence "no more than one match" is that the duration of the probing signal

depends quadratically on N - the number of non-zero positions in the binary modulating sequence. According to the information given in the monograph [“Optimal discrete signals”/ M.B. Sverdik / “Sov. Radio” 1975]. Probe signal duration

, where L is the number of terms in the binary modulating sequence,

the duration of the time position of the PIM signal.

где, C - скорость света, L– число членов в двоичной модулирующей последовательности,

- скорость модуля радиус-вектора цели. К примеру, если

= 6000 m/c, то

. Этот недостаток можно преодолеть. Так, например, пусть групповая цель движется по направлению к приемнику (сенсору), при этом отраженные сигналы от элементов цели поступающие на сенсор от элементов цели «сжимается». Для компенсации этого «сжатия»/ «растяжения» необходимо всего лишь увеличить/уменьшить частоту синхроимпусов стробирования сенсоров. Новая частота синхроимпульсов стробирования будет определяться следующим образом:

где

частота стробирования без поправки на радиальную скорость.This shortcoming will lead to an increase in the probing time and the duration of the probing signal and does not solve the problem of reducing the probing time, provided that the maximum radiated power (pulse energy) of the pulsed emitter is limited. Additionally, in the case of probing a high-speed target, there is also a limitation on the duration of the probing signal associated with its Doppler “stretching” or “compression”, depending on whether the probed object is moving away or approaching the sensor. The conditions limiting the scope of the application of the "Doppler" model are as follows:

where, C is the speed of light, L is the number of terms in the binary modulating sequence,

- velocity of the radius-vector modulus of the target. For example, if

= 6000 m/s, then

. This shortcoming can be overcome. So, for example, let a group target move towards the receiver (sensor), while the reflected signals from the target elements arriving at the sensor from the target elements are “compressed”. To compensate for this "squeezing" / "stretching", it is only necessary to increase / decrease the frequency of the strobe clock of the sensors. The new gate clock frequency will be determined as follows:

where

gating frequency without radial velocity correction.

(блок формирования синхроимпульсов приема). To compensate for the Doppler effect, the block diagram of the lidar or other receiving device must include a block for generating sync pulses with a frequency

(block for generating clock reception).

It is possible to reduce the duration of the probed signal if we refuse to use PIM sequences with the property “no more than one match”, we will replace them with sequences with the property no more than “K matches”. This will reduce the duration of the probed signal by about K times, but at the same time, the level of side lobes of the ACF of the function of the probed signals will increase by K times; lobes, from responses from objects with "strong" EPR and will not be allowed.

Example #2

In FIG. 6 shows a diagram of the formation and subsequent matched filtering of the PIM sequence.

Block 3 for generating PIM sequences of length L=L ₁ +L ₂ -1=2017+74629-1=76645 consists of two serially connected blocks for generating PIM sequences, 3.1 and 3.2, where

, а block 3.1 generates a length sequence

, a

. block 3.2 generates a length sequence

.

,

,

,

,

,

,

,

,

Unit 4 matched filtering PIM sequence of length L consists of sequentially connected blocks 4.1 and 4.2 matched filtering,

, block 4.1 - for sequence length

,

. block 4.2 - for sequence length

.

When connected in series, a matched filter is obtained for a PIM sequence of length L=L ₁ +L ₂ -1=2017+74629-1=76645.

Each of the blocks for the formation of PIM sequences 3.1 and 3.2 and blocks of matched filtering 4.1 and 4.2 consist of thirty-six stages, similar to those shown in figure 1.

The formulas for calculating the number of DL delay cycles for each stage are given in Table 3.

Table 3 Formulas for calculating the number of delay cycles in the DL of the first and second blocks for the formation of PIM sequences and the third and fourth blocks

The name of the block in the diagram of Fig. 6. The formula for calculating the number of delay cycles in the LZ of the cascade from the cascade number (i) (the numbering of the cascades from 1 to 36, from left to right Fig.6) PIM sequence generation unit 3.1

PIM sequence generation unit 3.2

Consistent filtering block PIM sequence 4.1

Consistent filtering PIM sequence block 4.2

Additionally, a discrete notch filter 5 is introduced into the circuit in figure 6, consisting of

- amplitude limiter 5.1,

- LPF (low-pass filter) 5.2 of the first order with a gain in the constant component of the signal equal to 1,

- amplifier 5.3 with a gain of 10–50,

- element 5.4, subtracting the signal from the output of the amplifier pos. 5.3 from the signal (sequence, response) input to the notch filter 5 and

- an additional element 5.5, which subtracts from the signal from the output of the element 5.4 the signal from the output of the LPF 5.2.

Further in the examples, a similar notch filter 5 is used.

, где

в которой член с номером 0, равен 1, а остальные члены равны 0. Let us apply to the input of the circuit of Fig. 6 length sequence

, where

in which term 0 is 1 and the other terms are 0.

At point T1, a sequence of the same length will be fixed, the first L members of which are a PIM sequence matched with the PIM sequence filter 4 of Fig. 6.

At point T2, the response of the matched filter to the input to its input (input of block 3) of the matched PIM sequence will be fixed. At the 76644th cycle (the numbering of cycles starts from the zero cycle), at the point T2, a response peak with an amplitude of K= N2 =1369 will be recorded. The same cycle corresponds to the last member of the PIM sequence, equal to 1, supplied to the input of the matched filter 4 of Fig. 6, consisting of blocks 4.1 and 4.2 connected in series. fig 6.

The amplitude of the other response members (side lobes) at the output of the matched filter (output of block 4.1) will not exceed 60. To reduce the level of side lobes adjacent to the response peak, a notch filter 5 Fig. 6 is used. Due to this, the amplitude of the side lobes is reduced from to 30 , which can be observed from a fragment of the reflectogram fixed at point T3.

When using a similar (with the addition of a notch filter 5 to blocks 4.1 and 4.2) matched filter when processing signals obtained by binary detection of an optical signal, it is important to note that the notch filter 5 also suppresses the DC component caused by the so-called. background illumination, “background light”, which is fed to the sensor along with the optical signal. Nonlinear element 5.1 amplitude limiter received on the band pass filter samples reduces the amplitude of transients when received at the input of the notch filter 5 peak response. Notch filter 5 with a non-linear element must be placed after the matched filter.

The response recorded at point T2, in this example, provides information about the energy loss of the first signal (more precisely, the number of missed pulses of the first signal) when received jointly with the second signal, which is a replica of the first signal, delayed or ahead of the first signal by the number of cycles W, if the resulting the signal is obtained by disjunction of the first and second signals (disjunction is analogous to the joint reception of two singals by a threshold device). To estimate the number of missed pulses, it is necessary to plot the number of delay/advance cycles W along the X axis (clock/time axis) from the response peak, while the sidelobe amplitude corresponding to the distance W from the response peak determines the number of impulses in the first signal that will not be received since the sensor will be triggered by the pulses of the second signal. Thus, the NBL indicator calculated from the reflectogram recorded at point T2 gives an idea of the proportion of lost samples by signal 1 if it is received by binary detection with signal 2, which is a replica of signal 1 delayed by W cycles.

. Сформированная на выходе блока 3 ПИМ последовательность не является минимаксной в смысле минимальности уровня боковых лепестков АКФ двоичной ПИМ последовательности при заданных L и N, но описание способа ее получения и согласованной фильтрации наиболее просто и позволяет сократить описание настоящего патента. In FIG. 7 is a fragment of the filter response (from cycle 74000 to cycle 76750) at the output matched at point T2 (at the recording and display device T2) and at point T3 (at the output of notch filter 5). Along the abscissa of Fig. 7 postponed the number of cycles multiplied by

. The PIM sequence generated at the output of block 3 is not minimax in the sense of the minimum level of the side lobes of the ACF of the binary PIM sequence for given L and N, but the description of the method for obtaining it and matched filtering is the simplest and allows us to shorten the description of this patent.

=76645 против ожидаемой

, т.е. длительность последовательности, а следовательно, и время испускания зондирующего сигнала сократилось в 17÷20 раз, но при этом в 60 раз увеличился уровень боковых лепестков АКФ ПИМ сигнала, используемого при зондировании. В данном примере сигнал не оптимизирован по уровню боковых лепестков АКФ и используется в примере для упрощения и сокращения описания, т. к. целью настоящего изобретения не является сокращения уровня боковых лепестков АКФ ПИМ сигнала.In this example, we deviated from the “no more than one match” rule, which led to a reduction in the duration of successively

=76645 vs expected

, i.e. the duration of the sequence, and hence the time of emission of the probing signal, decreased by 17–20 times, but at the same time, the level of side lobes of the ACF of the PIM signal used in probing increased by a factor of 60. In this example, the signal is not optimized for the level of ACF sidelobes and is used in the example to simplify and shorten the description, since the purpose of the present invention is not to reduce the sidelobe level of the PIM ACF signal.

Stand for imitation of lidar operation

In FIG. Fig. 8 shows a functional diagram of the stand for imitation of the receiving and transmitting paths of the lidar, without the functional blocks for processing reflectograms implemented on a PC. Primary reflectograms, which are binary sequences, are recorded by the T4 block, see Fig.8 and then read out and transferred to a PC to form secondary reflectograms.

101- Block for the formation of a sync pulse at the beginning of the probing cycle.

102 - Clock signal generation unit.

103 - Block for the formation of the modulating binary PIM sequence (seq. µ).

103–1 - Block 103 entrance.

103–2 - Input for transmission to block 103 of the modulating sequence from the PC.

105 - Signal conditioning unit for adapting the gating signal.

105–1 - Entrance to block 105.

105-2 - Input for transmission from PC to 105 gate adaptation sequencer

106 - Strobe signal adaptation block.

106–3 - entrance to block 106 and block 106–1

106–5 - entrance to block 106,

106–4 - input (inverted) to block 106–1

106-1- An element that performs the conjunction operation on the operand from input 106-3 and the inverse value of the operand from input 106-4.

"0" - Logic zero setter block 106

106–2 - A two-position key that switches input 106–4 of element 106–1 either to the output of the logical zero generator “0” (the first position of the key is “no gating adaptation”), or to the output 105-3 of block 105 (second position key - "adaptation gating"). The key is controlled from a PC.

107 - Block of imitation of a complex probed object (BISO).

108 - Optical reception unit with control loop.

108–4 - Optical input of block 108.

108–5 - Gate logic input.

108–1 - Sensor gating implementation block. The block generates a signal that determines the current state of the sensor (operation mode) and its quantum efficiency. The block has two entrances. The first input is a gate logic signal from block 106.

108-1-1 is the (second) input of block 108-1 through which a signal is supplied from block 108-2 that determines the quantum efficiency of the sensor of block 108-3.

108–2 - Control circuit of the signal controlling the quantum efficiency of the sensor.

108–3 - Optical sensor and binary detection signal generation circuit. The optical signal is fed to block 108-3 through input 108-4 (first), the second input (108-3-1) of block 108-3 is supplied with a sensor control signal from block 108-1

108-3-1 is the second input of block 108-3, through which the signal controlling the sensor is supplied.

SP1 - Setpoint of the a priori amplitude of the sensor bias voltage of block 108–3 or setter of the a priori quantum efficiency of the sensor of block 108–3, since the quantum efficiency of the sensor is determined by the bias voltage. The setpoint is transferred to the setter from the PC (the port for transferring the setpoint to the setter is not indicated in Fig. 8).

SP2 - Setpoint adjuster for the average normalized frequency of operation of the sensor block 108–3. The setpoint is transferred to the master from the PC (the port for transferring the setpoint to the master is not specified).

, определяющего квантовую эффективность сенсора блока 108–3 или задатчик квантовой эффективности сенсора блока 108–3. Уставка передается в задатчик с ПК (порт для передачи уставки в задатчик фиг.8 не указан). SP3 - Fixed bias voltage generator (setpoints) with amplitude

, which determines the quantum efficiency of the sensor of block 108–3 or the quantum efficiency setter of the sensor of block 108–3. The setpoint is transferred to the setter from the PC (the port for transferring the setpoint to the setter is not specified in Fig. 8).

108-2-1 - Differential signal generator. (The element that performs the operation of subtracting the signal of binary detection from block 108-3 from the regulation setpoint of the normalized frequency of the sensor actuations of block 108–3)

108-2-2 - Difference signal integrator.

108-2-3 - An element that performs the operation of adding to the signal at the output of the integrator 108-2-2 the initial (a priori) bias voltage (or another signal that determines the a priori quantum efficiency of the sensor).

108-2-4 - A two-position switch that switches the input of block 108-2-5 either to the output of the master SP3 (the first position of the key is “given quantum efficiency of the sensor”), or to the output of the adder 108-2-3 (the second position of the key - "regulation (tuning) of the quantum efficiency of the sensor" block 108-3). Key position is controlled by PC.

÷

] (или иного сигнала, регулирующего квантовую эффективностью сенсора). 108-2-5 - Bias voltage limiter limiting the range of the control signal from block 108-2 range [

÷

] (or another signal that regulates the quantum efficiency of the sensor).

T4 - Block of registration and reading of the primary reflectogram.

The stand consists of a block 101 for generating a clock pulse at the beginning of the probing cycle, connected to a block 102 for generating a clock signal, connected to the inputs of blocks 106 (Gating signal adaptation block), 105 (Gating signal adaptation signal generating block) and 103 (Binary modulating PIM sequence generation block)

The output of block 105 is connected through the second input 106-5 of block 106 with the input 108-5 of block 108 (Optical signal reception unit in fast strobing mode).

The output of block 103 is connected to the input of block 107 (BISO), the optical output of which is connected to the optical input 108–4 of block 108.

To the output of block 108 is connected to the block of registration and reading of the primary reflectogram pos. T4.

Block 103 Generates a PIM pulse train.

Block 105 generates a gating adaptation signal that initiates the sensor to turn off at the time intervals when "strong" and "ordinary" or "strong" optical pulses arrive at the sensor.

Block 107 simulates the reflected optical signal from a complex target.

Block 106 adapts the gate logic signal, which is essentially the clock signal of block 108, so that when "strong" and "ordinary" or "strong" optical pulses arrive at the optical sensor, the sensor of block 108-3 is not in Geiger counter mode.

Block 108 performs binary reception of optical pulses arriving at the surface of the receiving sensor at the moments of its strobing (being in the Geiger counter mode) and generates a binary detection logic signal.

Description of the principles of operation and purpose of the stand blocks

Block 101. Generates a pulse to start the probing cycle.

By the pulse of the beginning of the probing cycle, the counting of the clock pulses of the probing cycle begins, according to which:

;1) recording of signals by the block of registration and reading (transmission) of the primary reflectogram (T4). The recording cycle is 400

;

2) the formation of the PIM sequence block 103;

3) generation by block 105 of the gating adaptation signal.

Block 102. The block generates a binary sequence of periodically changing logical zeros and ones. The frequency of transition from one to zero is 2.5 GHz. Clock transition frequency 5 GHz.

Logical unit signal at the output of block 102 on the rising edge -

1) at input 106-3 of block 106-1, provided that the signal at input 106-4 of block 106-1 is a logical zero, initiates the transfer of the sensor in block 108 to the Geiger counter mode;

2) at input 105–1 of block 105, initiates reading from block 105 of one bit of the gating adaptation signal to input 106–5 of block 106.

3) at the input 103–1 of block 103, it initiates the reading of two members of the PIM sequence from the serial memory of block 103 for the subsequent formation by the PIM block of a sequence of pulses supplied to the BISO block 107.

на следующем тактовом переходе (от нуля к единице) от происходит формирование нечетного импульса ПИМ последовательности импульсов, при условии, если второй бит кода равен «1». Если биты кода равны «0» формирование импульсов не осуществляется. Таким образом формируется ПИМ последовательность импульсов с частотой модуляции 5 ГГц, равной частоте тактовых импульсов. Интервал тактовых импульсов равен 200

и обозначается символом

. Block 103 . Generates a PIM pulse sequence supplied to block 107 (BISO). The block is a device for sequential reading of a two-bit code, which represents the modulating sequence. The reading is performed on the leading edge of the logical one pulse from block 102. The even members of the PM sequence are represented by the first bit of the code, and the odd ones by the second bit of the code. After reading the two-bit code by the clock transition (the clock generator is not indicated on the functional diagram) to logical zero, an even pulse of the PIM sequence is formed if the first bit of the code is "1", and with a delay of 200

at the next clock transition (from zero to one) from, an odd PIM pulse of the pulse sequence is formed, provided that the second bit of the code is "1". If the code bits are equal to "0", the formation of pulses is not carried out. Thus, a PIM pulse sequence is formed with a modulation frequency of 5 GHz, equal to the frequency of the clock pulses. The clock interval is 200

and is denoted by the symbol

.

Figure 9 depicts the operation of block 103

9A - Schematic representation of the last. clock pulses and their numbering

9B - Schematic representation of the log sequence. ones and zeros generated by block 102 of Fig. 8 of the stand, and their numbering.

в двоичном коде и ее формальное представление в виде индексированной последовательности

длины

9C - Values of the binary modulating discrete sequence

in binary code and its formal representation as an indexed sequence

length

9D - Formed PIM pulse sequence its formal representation as a binary indexed sequence

длины

. Временные позиции, соответствующие отсчетам равным нулю отмечены точками, временные позиции отсчетов равных единице отмечены вертикальными чертами.

length

. Time positions corresponding to counts equal to zero are marked with dots, time positions of counts equal to one are marked with vertical lines.

Block 105 generates a gate signal adaptation logic signal.

The signal is a binary logic signal generated based on the binary sequence read from the serial memory unit 105.

«сильного» или «ординарного» оптического импульса. Если ключ на два положения 106–2 находится в положении «адаптация стробирования», то сигнал логической единицы с блока 105 отменяет стробирование сенсора в блоке 108. The reading is performed on a clock transition from a logical one to a logical zero in a binary signal from block 102. If a logical one is read, then at the next transition from logical zero to one, a logical one is formed at the output of block 105, which exists before the clock transition in the binary signal from block 102 from zero to one. And otherwise, if a logical zero is read, then a logical zero is formed that exists until the next formation of a logical unit when it is read. The logical unit in the signal, as a rule, is timed to the event of arrival at the sensor surface in block 108 on the time interval of the duration gating

"strong" or "ordinary" optical pulse. If the 2-position switch 106-2 is in the "gating adaptation" position, then the logic-one signal from block 105 cancels the sensor gating at block 108.

Figure 10 depicts the operation of block 105 and block 106, and program module 307

15A - Schematic representation of the last. clock pulses and their numbering

15B - Schematic representation of the log sequence. units and zeros generated by the block 102 of the stand, and their numbering.

15C - Values of the binary sequence read from the memory of block 105 δ and its formal representation as an indexed sequence {δ (0), δ (1), δ (2) ......} of length N.

15D - Gating adaptation signal generated by block 105,

15E - gate signal adapted by block 106.

15G is the binary sequence generated by the program module 307 when simulating adaptive gating in order to calculate the auxiliary Y sequence.

Block 106 - adapts the logical gate signal supplied to the input 106-3 of block 106 from block 102 by excluding from the sequence of logical zeros and ones, logical ones, the time positions of which are timed to the time positions of logical ones in the sequence of the gating adaptation signal coming from block 105 to the input 106-5 of the block 106. Functionally, the block performs the operation of the conjunction of the gating signal and the inversion (in which logical units are replaced by zeros and vice versa) gating adaptation signal. The block is supplemented with a two-position key, position 106–2 in Fig. 8 (key positions “gating adaptation” and “no gating adaptation”), the position of which is controlled by the program installed on the PC. When the key is set to “no gating adaptation”, the gating signal is not adapted; the input 106–4 of block 106-1 receives a logical zero from the logical zero generator indicated in Fig. 8 icon "0".

Block 107. Block for simulating a signal from a probed object (BISO).

Block diagram 107 is shown in FIG. eleven

Figure 11 shows:

201 - shaper of the optical probing signal and signal delay.

202 - optical signal splitter (splitter), dividing the signal into nine equal streams.

2031 -2039 - optical signal delay lines,

204 - optical adder,

2051–2053 - signal attenuators,

207 - signal generation lines simulating an interference signal.

, оптического аттенюатора (2013) и линию задержки в виде оптоволоконного волновода (2014) имитирующей задержку отраженного сигнала от сложного объекта. Block 201 consists of a block for the formation of a pulsed power supply of a laser diode (2011), a laser diode (2012) that generates short pulses with a duration of up to 100

, an optical attenuator (2013) and a delay line in the form of a fiber optic waveguide (2014) simulating the delay of the reflected signal from a complex object.

и имитирующих задержку отраженных сигналов от отражающих элементов сложного зондируемого объекта.Nine optical signal delay lines (2031, 2032, ... 2039), which are fiber optic waveguides that delay the optical signal by the appropriate number of shares

and simulating the delay of reflected signals from the reflecting elements of a complex probed object.

Table 4. Specification for optical delay lines (DL)

No. Pos. on the diagram

Delay,

Type of delayed PIMPOI one 2031 0.5 "strong" 2 2032 0.5+ 3*0.2 "strong" 3 2033 0.5+9*0.2 "strong" four 2034 0.5+10*0.2 "strong" 5 2035 0.5+11*0.2 "strong" 6 2036 0.5+101*0.2 "strong" 7 2037 0.5+88*0.2 "ordinary" eight 2038 0.5+21*0.2 "weak" 9 2039 0.5*23*0.2 "weak"

Delay lines are connected to the first six inputs of adder 204, in the order listed in Table 4.

The signals from the delay lines 2037 and 2038, and 2039 are connected to the seventh, eighth and ninth inputs of the adder 204 through attenuators 2051, 2052, 2053.

The signal generation line simulating an interference signal 207 connected to the tenth input of the adder 204 consists of a laser diode power supply voltage driver 2071, a laser diode 2072, a signal attenuator 2073, and a connecting optical waveguide 2074.

. Лазерный диод 2012 по сигналу с блока 103 формирует короткие импульсы длительностью до 100

. Последовательность оптических импульсов с лазерного диода 2012, имитирующая зондирующий сигнал, через аттенюатор 2013 и оптический волновод 2014 подается на вход оптического делителя сигнала 202. Через линии задержки и аттенюаторы суммируется на сумматоре 204 и смешивается на сумматоре 204 с шумовой составляющей с 207 и через дополнительный аттенюатор и оптический волновод (не указаны на фиг. 12) через вход 108-4 (фиг.8) поступают на сенсор оптического сигнала в блоке 108. Laser diodes (2012 and 2072) and sensor block 108 are adapted to work at a wavelength of 1550

. The laser diode 2012 generates short pulses with a duration of up to 100

. A sequence of optical pulses from a laser diode 2012, simulating a probing signal, is fed through an attenuator 2013 and an optical waveguide 2014 to the input of the optical signal divider 202. It is summed through the delay lines and attenuators at the adder 204 and mixed at the adder 204 with the noise component from 207 and through an additional attenuator and an optical waveguide (not shown in Fig. 12) through the input 108-4 (Fig. 8) are fed to the optical signal sensor in block 108.

Signals from delay lines 2031–2036 imitate “strong” reflected signals from the elements of the probed object.

Signals from delay lines 2038–2039 imitate “weak” reflected signals from the elements of the probed object.

Signals from the delay line 2037 simulates the "ordinary" reflected signal from the elements of the probed object.

Block 108. Block for receiving an optical signal in the fast strobing mode, including the sensor. The diagram of the receiving block 108 with the control loop is shown in FIG. eight.

Block 108–1. Sensor strobing block.

и прямоугольного сигнала стробирования с периодом

и длительностью импульсов стробирования

и амплитудами положительной и отрицательной полуволны соответственно

и

. Суммарная амплитуда

=

определяет квантовую эффективность сенсора на интервале стробирования длительности

. При этом для осуществления стробирования должно выполняться условие

=

(см. фиг. 3 и таблицу 2). Сигнал стробирования - прямоугольный сигнал с заданными амплитудами

и

и длительностью импульсов стробирования

формируется в этом же блоке на основании сигнала, поступающего на вход 108–5 блока 108. Времéнное положение переднего фронта импульсов стробирования совпадает с положением переднего фронта логических единиц в логическом сигнале стробирования на входе 108–5 блока 108.The signal that controls the gating of the sensor of block 108-3 is fed to the input 108-3-1 of block 108-3 is formed by block 108-1, based on the logical gate signal applied to input 108-5 and the signal that specifies the quantum efficiency of the sensor of block 108-3 and supplied to input 108-1-1 and is a superposition of DC bias voltage with amplitude

and a rectangular gate signal with a period

and the duration of the strobing pulses

and the amplitudes of the positive and negative half-waves, respectively

and

. Total amplitude

=

determines the quantum efficiency of the sensor on the gating interval of the duration

. In this case, for the implementation of gating, the condition

=

(see Fig. 3 and table 2). Gating signal - a rectangular signal with specified amplitudes

and

and the duration of the strobing pulses

is formed in the same block based on the signal input 108–5 of block 108. The time position of the leading edge of the gate pulses coincides with the position of the leading edge of logic ones in the gate logic signal at input 108–5 of block 108.

Block 108–2. Control loop for the signal controlling the quantum efficiency of the sensor.

The regulation of the average frequency of the sensor response is carried out by the control loop 108-2, which

(частота неадаптированного сигнала стробирования) частоты срабатываний сенсора

(здесь и далее нормированные частоты обозначаются заглавной буквой

) ниже уставки средней частоты срабатываний сенсора

или диапазона регулирования нормированных частот [

÷

] увеличивает амплитуду напряжения стробирования

на интервалах стробирования (сигнала стробирования формируемого блоком 108-1 и подаваемого на сенсор блока 108-3 через вход 108-3-1 ) , так чтобы текущая средняя нормированная частота срабатываний сенсора находилась в заданном диапазоне уставок регулирования [

÷

] или была по крайней мере максимально приближена к заданному диапазону или уставке регулирования

, но таким образом чтобы

не превышало максимально допустимого рабочим диапазоном напряжений стробирования

, 1) with a decrease in the average, normalized to

(frequency of non-adapted gating signal) sensor actuation rates

(hereinafter, the normalized frequencies are denoted by a capital letter

) below the sensor average frequency setting

or regulation range of normalized frequencies [

÷

] increases the gate voltage amplitude

at the strobing intervals (strobe signal generated by block 108-1 and supplied to the sensor of block 108-3 through input 108-3-1), so that the current average normalized sensor actuation frequency is within the specified range of control settings [

÷

] or was at least as close as possible to the specified range or control setpoint

, but in such a way that

did not exceed the maximum allowable gating voltage operating range

,

, ниже уставки

или границы диапазона регулирования [

÷

], снижает амплитуду напряжения стробирования

на интервалах стробирования, 2) with an increase in the average normalized frequency of sensor responses

, below the setpoint

or control range limits [

÷

], reduces the amplitude of the gating voltage

at gating intervals,

÷

] или была по крайней мере максимально приближена к заданному диапазону или уставке регулирования

, но таким образом, чтобы

не опускалось ниже

. so that the current average normalized frequency of sensor operation is within the specified range of control settings [

÷

] or was at least as close as possible to the specified range or control setpoint

, but in such a way that

did not fall below

.

и двоичного сигнал с выхода блока 8-3. Постоянная составляющая сигнала на выходе блока 8–3 пропорциональна нормированной частоте срабатываний сенсора. Уставка регулирования нормированной средней частоты срабатываний сенсора (

) формируется задатчиком SP2, по значению записываемому в него (в задатчик) из ПК. Such a control loop can be implemented, for example, in the form of a standard control loop, consisting of an integrating controller (I-controller), the output signal of which can vary in the range of acceptable values that determine the range of change in the gating voltage or bias voltage or the quantum efficiency of the sensor, and the input is signal representing the difference of the control setpoint

and a binary signal from the output of block 8-3. The constant component of the signal at the output of block 8–3 is proportional to the normalized frequency of sensor responses. Adjustment setting for the normalized average sensor actuation frequency (

) is formed by the SP2 master, according to the value written to it (to the master) from the PC.

лежит в диапазоне [0,2 ÷ 0,6]. Разница уставки регулирования нормированной средней частоты срабатываний сенсора

и сигнала с выхода блока 108-3 (сигнал можно представить, как сумму постоянной составляющей сигнала и переменной) с элемента 108-2-1 подается на интегратор 108-2-2, который увеличивает сигнал на своем выходе, только если разница между уставкой и постоянной составляющей сигнала положительна и, наоборот, уменьшает, если разница отрицательна и ничего не изменяет если разница нулевая. Переменная же, составляющая сигнала, максимально подавляется интегратором 108-2-2 и не влияет на процесс регулирования. Весовой коэффициент интегрирования, выполняемого интегратором 108-2-2 обратно пропорционален постоянной τ контура регулирования. Весовой коэффициент интегрирования подбирается так, чтобы обеспечить, достаточную относительную погрешность регулирования средней нормированной частоты срабатываний сенсора и относительные колебания ξ в установившемся режиме регулирования. Для ускорения регулирования возможно динамическое изменение весового коэффициент интегрирования, так если амплитуда разностного сигнала на выходе блока 8-2-1 достаточно велика, то весовой коэффициент можно увеличить в 2–3 раза, но по мере снижения амплитуды разностного сигнала его необходимо уменьшать до начального значения. Preferred control setpoint

lies in the range [0.2 ÷ 0.6]. Adjustment setpoint difference of the normalized average sensor actuation frequency

and the signal from the output of block 108-3 (the signal can be represented as the sum of the constant component of the signal and the variable) from element 108-2-1 is fed to the integrator 108-2-2, which increases the signal at its output only if the difference between the setpoint and the constant component of the signal is positive and, conversely, reduces if the difference is negative and does not change anything if the difference is zero. The variable component of the signal is maximally suppressed by the integrator 108-2-2 and does not affect the regulation process. The weighting factor for the integration performed by the integrator 108-2-2 is inversely proportional to the control loop constant τ. The weighting coefficient of integration is selected so as to provide a sufficient relative error in the regulation of the average normalized frequency of sensor responses and relative fluctuations ξ in the steady state control mode. To speed up the regulation, it is possible to dynamically change the weighting coefficient of integration, so if the amplitude of the difference signal at the output of block 8-2-1 is large enough, then the weighting factor can be increased by 2–3 times, but as the amplitude of the difference signal decreases, it must be reduced to the initial value .

To speed up the regulation process (tuning the quantum efficiency of the sensor), in addition to the signal at the output of the integrator (108-2-2 of Fig. 8), block 108-2-3 adds a setpoint generated by the SP1 generator. This setting sets the value of the a priori (expected) quantum efficiency at the gating intervals of the block 108–3 sensor.

сенсора блока 108-3. Блок 108-2-5 это ограничитель регулирующего сигнала определяющий диапазон изменения напряжения смещения и/или напряжения стробирования и/или квантовой эффективности сенсора блока 108-3 In comparative examples, block 108-2 can also operate in the mode of issuing a fixed signal to input 108-1-1 of block 108-1, the amplitude of which determines the fixed quantum efficiency at the gating intervals of the block 108-3 sensor. This mode is used to compare the reception with the regulation (adjustment) of the average frequency of operations with the reception of a signal with a constant quantum efficiency of the sensor. To switch to this mode, a two-position switch 108-2-4 is used; in the mode of fixing the quantum efficiency, a setpoint signal is supplied to the input 108-1-1 of block 108–1 from the signal generator SP3, the amplitude of which determines the specified quantum efficiency

block 108-3 sensor. Block 108-2-5 is a control signal limiter that determines the range of change in the bias voltage and / or gate voltage and / or quantum efficiency of the sensor of block 108-3

Block 108–3. Optical sensor and binary detection signal (sequence) generation circuit.

из блока 108–3 поступает на блок регистрации и считывания поз. Т4. At the output of block 108-3, a binary detection signal is generated, which is a sequence of logical zeros and ones. The logical unit corresponds to the event of the sensor operation at the gating interval, logical zero, the absence of sensor operation at the gating interval. Logic signal with baud rate 2.5

from block 108–3 enters the block of registration and reading pos. T4.

, второй в ячейку с номером

и так далее. Последний член последовательности двоичного детектирования заносится в ячейку

, где

число членов последовательности двоичного детектирования. Так формируется последовательность двоичного детектирования By block T4, the first member of the binary detection diskette sequence is entered in the cell with the number

, the second to the cell with the number

and so on. The last member of the binary detection sequence is entered in the cell

, where

the number of members of the binary detection sequence. This is how the binary detection sequence is formed

=40000,

– номер члена последовательности двоичного детектирования.µ(i) lengths

=40000,

– number of the member of the binary detection sequence.

In FIG. 12 schematically shows the relationship of samples in the binary detection sequence (plot E in FIG. 13) with gate time intervals (plot D) and clock timing (plot B).

Fig 12:

13A - numbering of clock pulses,

13B - schematic representation of the sequence of clock pulses),

13C is a schematic representation of the optical pulses arriving at the sensor,

13D is a schematic representation of the gate signal,

13E - binary detection logic generated by block 108,

13F - numbering of samples of the logical signal.

13J – binary detection sequence μ

суть оценка вероятности срабатывания сенсора на интервале

.Average normalized sensor actuation frequency

the essence of the evaluation of the probability of sensor operation on the interval

.

сигнала может быть измерена путем измерения амплитуды постоянной составляющей сигнала на выходе блока 108–3. Приведем поясняющий пример. Пусть амплитуда логической единицы на выходе блока 108–3 равна 1,0

, а амплитуда логического нуля 0,0

, а средняя частота срабатываний сенсора нормированная на частоту стробирования составляет 0,4 тогда амплитуда постоянной составляющей сигнала на выходе блока 108-3 составит 0,4*1 = 0,4

. Для поддержания на постоянном уровне частоты срабатываний сенсора нужно подать с задатчика уставки SP2 уставку равную 0,4

. Value

signal can be measured by measuring the amplitude of the DC component of the signal at the output of block 108-3. Let's give an explanatory example. Let the amplitude of the logical unit at the output of block 108–3 be equal to 1.0

, and the amplitude of the logical zero is 0.0

, and the average frequency of sensor responses normalized to the gating frequency is 0.4 then the amplitude of the constant component of the signal at the output of block 108-3 will be 0.4 * 1 = 0.4

. To maintain the frequency of sensor operation at a constant level, it is necessary to apply a setpoint equal to 0.4 from the setpoint adjuster SP2

.

Functional diagrams for simulation of binary detection signal processing units, gating adaptation signal generation units, modulating PIM sequence generation units.

Some of the blocks implemented in a practical lidar were implemented on a bench installation by their software simulation. Software simulation is carried out:

1) On simulation cycle 1: Formation of the modulating PIM sequence in a format convenient for writing to the memory array of block 103 of the stand.

2) On simulation cycle 2: processing of the primary reflectogram read from the T4 block of the stand or the accumulated primary reflectogram to obtain a secondary reflectogram in the form of an array of readings Z.

3) On simulation loop 3:

3.1) formation of a strobing adaptation sequence δ in the form of an array of binary samples in a format convenient for writing to block 105 of the stand.

равен числу интервалов стробирования, на которых происходил прием сигнала в режиме стробирования, вносящих вклад в формирование соответствующего отсчета вторичной рефлектограммы

. Т. е. если

= 1500, то, следовательно, отсчет вторичной рефлектограммы

с номером 100, получен путем обработки 1500 информационных (см. определение далее по тексту) отсчетов первичной рефлектограммы. 3.2) formation of an auxiliary sequence of readings Y. Member of the sequence

is equal to the number of gating intervals at which the signal was received in the gating mode, contributing to the formation of the corresponding reading of the secondary reflectogram

. i.e. if

= 1500, then, consequently, the reading of the secondary reflectogram

number 100 was obtained by processing 1500 information (see the definition below) readings of the primary reflectogram.

Additionally, the program implements interface modules that read / write binary sequences from / to the simulation stand and visualization units of the data obtained during the work of the stand.

The functional scheme for processing the primary reflectogram with obtaining a secondary reflectogram and generating a gating adaptation signal) implemented in software imitates (with the exception of interface blocks responsible for reading / writing test bench signals) a block diagram for processing the primary reflectogram in real time, i.e. allows you to calculate the readings of secondary reflectograms as they arrive at the input of the circuit for processing the readings of the primary reflectogram.

In FIG. 13 shows a functional diagram of signal processing and generation. In the diagram, the software modules that imitate the functional blocks of the lidar and work during the simulation in a single cycle are circled with rectangles drawn by a dotted line.

Specification for the diagram of Fig. 13

IM1 (Interface module1) - designed to read the primary reflectogram from the stand on a PC into the memory area pos. P-1.

P-1 - an array of memory cells for recording, storing, accumulating and reading the primary reflectogram.

301 - Module for generating a primary reflectogram to a form adapted for processing by matched filtering.

302 - The matched filtering module is designed to calculate the secondary reflectogram.

P-2 - an array of memory cells for recording, storing and reading the secondary reflectogram.

303 - Module for generating a secondary reflectogram in a form adapted for further processing.

304 - Threshold detection module.

305 - Strobe adaptation sequencing module.

306 - Module for making the strobing adaptation sequence convenient for writing to the memory module of the stand block 105.

P-3 - an array of memory cells for writing, storing and reading the strobing adaptation sequence.

IM2 - (Interface module 2) - is designed to transfer the strobing adaptation sequence for its subsequent recording to the memory module of block 105 of the stand.

307 - A module for generating a sequence that is analogous to an adapted gate logic signal.

.308 - Module for the formation of an auxiliary sequence of readings

.

.P-4 - an array of memory cells for writing, storing and reading to visualize the auxiliary sequence

.

309 - Input sequencing module for module 310.

310 - Module for the formation of the modulating PIM sequence.

311 - Module for bringing the modulating sequence to a form convenient for writing to the memory module of block 103.

P-5 - Memory area for recording, storing, reading the modulating PIM sequence.

IM3 - (Interface module 3) - designed to transmit the modulating sequence, for subsequent recording in the memory module of block 103 of the stand.

Interface module IM1

The IM1 module is designed to read the primary reflectogram into the array of memory cells P-1 in a PC.

.

. On command from the control unit, the operating cycle of the stand (probing simulation cycle) is activated, in which the emission and reception of an optical signal is simulated in the form of a binary sequence (primary reflectogram) recorded in the memory block of the T4 block of the stand. Upon completion of the working cycle of the stand, the interface block IM1 (on command from the control unit) reads the primary reflectogram from the block of the stand T4

.

.

и почленно записывает результат прибавления в ячейки памяти П-1. Нумерация ячеек памяти П-1 соответствует порядку нумерации отсчетов первичной рефлектограммы. Указанная выше последовательность операций (рабочий цикл стенда – считывание – сложение - запись) осуществляется необходимое число раз от 1 до K. Next, the IM1 interface unit reads from the P-1 memory cells in the PC the previously recorded reflectogram (or zero values entered into the P-1 memory cells before the first probing cycle) and adds the read primary reflectogram to it term by term

and writes the result of the addition to the memory cells P-1 term by term. The numbering of memory cells P-1 corresponds to the order of numbering of readings of the primary reflectogram. The sequence of operations indicated above (working cycle of the stand - reading - addition - writing) is carried out the required number of times from 1 to K.

, где индекс K обозначает число просуммированных первичных рефлектограмм.

. As a result of the operations performed in the array of memory cells P-1, a knee-length primary reflectogram is formed

, where index K denotes the number of summed primary reflectograms.

.

The need to accumulate the primary reflectogram is due to the limited memory for recording the primary reflectogram in the stand. Therefore, one long cycle of sounding simulation is replaced by K cycles with the accumulation of the primary reflectogram. In the examples under consideration, K = 5, with a decrease in the power of the optical noise signal simulated on the bench by the 2072 laser diode, one cycle of the bench would be enough, but the essence of the examples is to show how the lidar works under conditions of strong interference, which requires PIM sequences of longer duration ( magnified by K times), which is simulated by the accumulation of reflectograms.

Interface module IM2

. The module is designed to read from the array of memory cells P-3 and transfer to the stand for writing to the memory cells of block 105, the strobing adaptation sequence

.

Interface module IM3

,

. The module is designed to read from the array of memory cells P-5 and transfer to the stand for writing to the memory cells of block 103 of the modulating sequence in a two-bit format

,

.

Formation of the modulating PIM sequence (Operations in cycle 1)

- счетчик цикла,

если

четное и иначе

если

нечетное.

– число членов модулирующей ПИМ последовательности.The formation of the modulating PIM sequence is carried out in cycle 1. Variable

- cycle counter,

if

even and otherwise

if

odd.

is the number of members of the modulating PIM sequence.

= 76645.As a modulating PIM sequence, a sequence of length is used

= 76645.

. Если переменная - счетчик цикла

= 0, то переменная A=1, во всех остальных случаях переменная A = 0. Operation 309 – formation of a member of the input sequence for module 310. The generated value is assigned to variable A. The number of the member of the input sequence for module 310 is determined by the value of the variable

. If the variable is a loop counter

= 0, then the variable A=1, in all other cases the variable A = 0.

Номер такта работы имитатора блока 3 (программный модуль 310) соответствует значению переменной

. На каждом цикле на вход модуля 310 подается переменная A и переменная

. Если

, то значение вычислений, имитирующих один такт работы блока 3, присваивается переменной C, а если

, то значение отсчета, полученное в результате вычислений, присваивается переменной B, Operation 310 is carried out by the program module 310. Each time it is accessed, the module simulates one cycle of operation of block 3 of Fig. 6 for generating a PIM sequence of length

The number of the cycle of operation of the block simulator 3 (program module 310) corresponds to the value of the variable

. At each cycle, the input of module 310 is supplied with the variable A and the variable

. If a

, then the value of calculations simulating one cycle of block 3 is assigned to variable C, and if

, then the reference value obtained as a result of calculations is assigned to the variable B,

выполняется условие

, то в массив ячеек памяти П-5 в ячейку с номером

заносится двухбитный код, первый бит которого принимает значение равное значению переменной С, а второй бит принимает значение равное значению переменной B. Таким образом, в массиве ячеек памяти П-5 формируется двоичная модулирующая дискретная последовательность ύ в формате удобном для записи в блок 103 стенда. Operation 311 - bringing the modulating sequence to a format convenient for writing to the block of the stand 103 is carried out by the program module 311. The essence of the operation: if for a variable

the condition

, then into the array of memory cells P-5 into the cell with the number

a two-bit code is entered, the first bit of which takes the value equal to the value of the variable C, and the second bit takes the value equal to the value of the variable B. Thus, in the array of memory cells P-5, a binary modulating discrete sequence ύ is formed in a format convenient for writing to block 103 of the stand.

Formation of a secondary reflectogram. (Operations in cycle 2)

[0; N-1].Before starting the formation of a secondary reflectogram, the primary accumulated reflectogram must be transferred from the test bench and accumulated in memory cells P-1

[0; N-1].

,

.Simulation of the operation of the matched filtering unit is carried out in a loop. Variable - loop counter denoted

,

.

, если

четное, соответствует временной интервал [

;

] т.е. это интервал на котором происходит стробирование сенсора, если оно не отменено сигналом адаптации стробирования (примечание: отсчет времени на стенде ведется от переднего фронта нулевого тактового импульса, формируемого на стендовой установки при имитации цикла зондирования). Each simulation cycle is timed to a certain time interval of the stand operation in the probing simulation cycle, so the variable is the cycle counter

, if

even, corresponds to the time interval [

;

] i.e. this is the interval at which the sensor gating occurs, if it is not canceled by the gating adaptation signal (note: the time on the bench is counted from the rising edge of the zero clock pulse generated on the bench when simulating a probing cycle).

нечетное, то временной интервал [(

+

; (

] это интервал времени, на котором сенсор всегда выключен. If a

odd, then the time interval [(

+

; (

] is the time interval in which the sensor is always off.

Thus, the number of the cycle variable i is timed to the number of the clock pulse i (plot A in Fig. 10) synchronizing the operation of the sensor operating in the Geiger counter mode with fast gating.

и

примерно равны. Будем считать, что каждому циклу имитационного моделирования, соответствует в реальном времени интервал равный 200

. For simplicity of presentation, since the intervals

and

approximately equal. We assume that each simulation cycle corresponds to a real-time interval equal to 200

.

Operation 301 (formation of primary reflectogram reading)

длины

,

∈ [0;

].Operation 301 is performed by module 301 which generates a binary detection sequence in a process-friendly (matched filtering) form.

length

,

∈ [0;

].

The formation of the sequence μ ^m , like all processing, occurs in the signal processing cycle, where the variable i - the counter of the processing cycle of the binary detection sequence (processing simulation cycle) is timed to the number of the sequence member μ ^m

которые соответствуют интервалам времени, на которых сенсор был включен, назовем «информационными» они могут быть равны либо нулю, либо единице, а остальные отсчеты всегда равны нулю. countdowns

which correspond to the time intervals at which the sensor was turned on, let's call them "informational", they can be equal to either zero or one, and the remaining readings are always equal to zero.

With matched filtering, only information samples form a response on the secondary reflectogram.

The formation of the sequence μ ^m is carried out as follows:

принимает четное значение, то на выходе модуля формируется отсчет

путем считывания из ячейки памяти П-1 с номером

отсчета

;if variable

takes an even value, then a count is formed at the output of the module

by reading from the memory cell P-1 with the number

reference

;

принимает нечетное значение, то на выходе модуля формируется нулевой отсчет, т. е.

if variable

takes an odd value, then a zero count is formed at the output of the module, i.e.

(

∈ [ 0;

] ) модулем 301 формируется член последовательности

и подается на выполнение операции 302 выполняемой модулем 302 симуляции согласованной фильтрации ПИМ последовательности длины

. On the cycle with number

(

∈ [ 0;

] ) module 301 generates a member of the sequence

and is submitted to the execution of operation 302 performed by the simulation module 302 matched PIM filtering simulation of the length sequence

.

Operation 302 (formation of secondary reflectogram reading)

- счетчик цикла изменяется от 0 до 2N-1 ) на вход модуля 302 подается сформированный в модуле 301 отсчет

и в том же цикле, начиная с цикла с номером

отсчеты вычисленные в модуле 302 заносятся в ячейки памяти П-2, так что в ячейке памяти с номером

будет отсчет вычисленный на

цикле, а в ячейке памяти

будет отсчет? вычисленный на

цикле и так далее. Таким образом, в ячейках памяти П-2 будет записан массив

длины 2N-L рассматриваемый нами, как вторичная рефлектограмма

.Operation 302 is performed by module 302 (consistent filtering module 302). Module 302 simulates the operation of a matched filter with a notch filter (blocks 4 and 5 connected in series in FIG. 6). At each processing cycle with a number (variable

- the cycle counter changes from 0 to 2N-1) to the input of the module 302 the count generated in the module 301 is fed

and in the same cycle, starting from the cycle with the number

the readings calculated in module 302 are entered into memory cells P-2, so that in the memory cell with the number

there will be a count calculated on

cycle, but in a memory cell

will there be a countdown? calculated on

cycle and so on. Thus, in the memory cells of P-2, an array will be written

length 2N-L considered by us as a secondary reflectogram

.

, соответствующий временному интервалу [0;

], в ячейке с номером 1 отсчет

соответствующий временному интервалу [

; 2

] и так далее.So, in the memory cell with number 0, the reflectogram reading will be placed

, corresponding to the time interval [0;

], in the cell with the number 1 count

corresponding to the time interval [

; 2

] and so on.

Here we are talking about intervals along the delay axis of the optical signal reflected from the resolvable object.

может отображаться на экране ПК в виде рефлектограммы при помощи функционального модуля визуализации (модуль не отображен на фигурах). The sequence thus obtained

can be displayed on the PC screen as a reflectogram using the visualization functional module (the module is not shown in the figures).

Generating the Gating Adaptation Sequence (Operations in Cycle 3)

Formation of the sequence δ for gating adaptation (simulation modeling) and calculation of the Y function, which makes it possible to estimate the signal loss when receiving in the adaptive gating mode for each sample on the secondary reflectogram.

The formation of a binary sequence δ used as a gating adaptation signal from the block of the stand 105 is carried out in the third processing cycle. The sequence δ is formed in a format convenient for writing its stand block 105,

вторичной рефлектограммы. Поскольку в примерах используется накопленная первичная рефлектограмма Additionally, the sequence Y is also calculated in the third processing cycle. Its essence is as follows: the member of the sequence with index k gives the sum of the number of gating intervals, the signal reception at which contributed to the formation of the sample

secondary reflectogram. Since the examples use the accumulated primary trace

и

осуществляется в третьем цикле обработки после выполнения операций второго цикла на основании вторичной рефлектограммы

записанной в массиве ячеек памяти П-2 Formation of both sequences

and

carried out in the third processing cycle after performing the operations of the second cycle based on the secondary reflectogram

recorded in the array of memory cells P-2

выполняются следующие операции. (На каждом цикле вычисления k – переменная счетчик цикла изменяется от 0 до 2N-1).When forming a sequence

the following operations are performed. (On each cycle of calculation k - the variable cycle counter changes from 0 to 2N-1).

Operation 303 (module 303 for generating a secondary trace in a form adapted for post-processing ):

, то отсчет, формируемый в результате выполнения операции 303 равен содержимому ячейки памяти с номером k из массива ячеек памяти П-2. If the loop counter variable

, then the count generated as a result of operation 303 is equal to the contents of the memory cell with the number k from the array of memory cells P-2.

Operation 304 (threshold detection module 304):

результат операции 303 сравнивается с уровнем порога обнаружения - если отсчет, полученный в результате операции 3 превышает или равен уровню порогового обнаружения то формируется логический отсчет «1» и «0» если иначе. On cycle

the result of operation 303 is compared with the detection threshold level - if the count obtained as a result of operation 3 is greater than or equal to the threshold detection level, then a logical count of "1" and "0" is formed if otherwise.

Step 305 (Gating Adaptation Sequencing Unit 305)

на каждом такте его работы. Т. е. такт работы эквивалентен одному циклу вычисления. Module 305 on each cycle performs the same calculations as the block (pos. 3 in Fig. 6) for generating a PIM sequence of length

at every step of its operation. That is, a cycle of work is equivalent to one calculation cycle.

Operation 306. (decimation module 306)

The report generated at operation 305 on the calculation cycle k is written to the memory cell pos. P -3 with number k/2 if k is even, and vice versa, if k is odd, then no entry is made.

Thus, in the memory cells with numbers from 0 to N–1 (note: N is an even number), a sequence δ of length N will be written, transmitted (written) to block 105.

The rejection of every second sample in the generated sequence is performed because the numbers of discarded readings are timed to the numbers of clock pulses (odd), on which the gating signal of the sensor operating in the fast gating mode is not generated.

Operation 307 (module 307 generation of the sequence, which is analogous to the adapted signal of the gating signal formation)

Operation 307, like operation 306, is performed after operation 305

The essence of operation 307 is the formation of a sequence (plot 15G. See Fig. 10) which is an analogue of the adapted gating signal (plot 15E. See Fig. 10).

The sequence is formed as follows: if the value of the variable k loop counter is even and the count calculated by module 305 (operation 305) is 0, then the result of the operation will be "1", in all other cases the result of the operation is "0".

Operation 308. (Module 308 generation of auxiliary sample sequence Y)

The module allows you to estimate the energy loss of the received signals (PIM of optical pulse sequences, due to the fact that the sensor receives an optical signal, it turns on only at gating intervals, due to which a part of the optical pulses arriving at the sensor surface will not be accepted.

позволяющую оценить потери энергии для каждого отсчета

вызванные тем, что прием оптического сигнала ведется только на интервалах стробирования сенсора. Так отсчет

будет равен числу информационных отсчетов первичной рефлектограммы

суммирование которых с весовыми коэффициентами отличными от нуля в процессе в отсчете

было использовано. Поскольку обработке подвергается первичная накопленная рефлектограмма, то значения

увеличиваются в K раз, где K - число циклов формирования накопленной рефлектограммы. В примерах K=5 и поэтому фиг 14 и 15 по ординате отложены значения

.The module calculates a sequence of readings

allowing to estimate the energy loss for each reading

caused by the fact that the reception of the optical signal is carried out only at the sampling intervals of the sensor. So countdown

will be equal to the number of information samples of the primary reflectogram

summation of which with non-zero weight coefficients in the process in the reference

has been used. Since the primary accumulated reflectogram is processed, the values

increase by K times, where K is the number of cycles of formation of the accumulated reflectogram. In the examples K=5 and therefore Figs 14 and 15 the values are plotted along the ordinate

.

(

счетчик цикла изменяется от 0 до

) на вход модуля 308 подается сформированный в модуле 307 (график 15G. фиг. 10) отсчет и в том же цикле, начиная с цикла с номером

отсчеты вычисленные в модуле 308 заносятся в массив ячеек памяти П-4, так что в ячейке памяти с номером

будет отсчет вычисленный на

цикле, а в ячейке памяти

будет отсчет вычисленный на

цикле и так далее. Таким образом, в массиве ячеек памяти П-4 будет записана последовательность

длины

рассматриваемая нами, как вспомогательная последовательность позволяющая оценить потери энергии для каждого отсчета

вызванные особенностями приема оптического сигнала сенсором, а именно его стробированием. Для каждого отсчета

величина

, где

число циклов формирования накопленной рефлектограммы определяет общее число интервалов стробирования, на которых осуществлялся прием оптического сигнала внесших вклад в формирование отсчета

Module 308 simulates the operation of the matched filter block 4 of FIG. 6. At each processing cycle with a number

(

loop counter changes from 0 to

) the input of the module 308 is supplied with the sample generated in the module 307 (graph 15G. Fig. 10) and in the same cycle, starting from the cycle with the number

the readings calculated in module 308 are entered into the array of memory cells P-4, so that in the memory cell with the number

there will be a count calculated on

cycle, but in a memory cell

there will be a count calculated on

cycle and so on. Thus, in the array of memory cells P-4, the sequence will be written

length

considered by us as an auxiliary sequence that allows us to estimate the energy loss for each sample

caused by the features of the reception of the optical signal by the sensor, namely its strobing. For every count

magnitude

, where

the number of cycles of formation of the accumulated reflectogram determines the total number of gating intervals at which the optical signal was received, which contributed to the formation of the reading

Example 3

Practical Gating Adaptation Signal Generation Options

Using an optional sensor

The gating adaptation signal can also be obtained using an additional sensor located in an adjacent optical path, and the adjacent optical path is designed so that the moment of arrival of the front of the optical pulse wave on the surface of the additional optical sensor is ahead of the time of its arrival at the surface of the sensor, the gating of which is being adapted.

In FIG. 16 shows a possible diagram of such an optical device. The device consists of two optical systems: a lens 404 that focuses optical radiation on the surface of the sensor (or sensors) 401 and a fragment of a parabolic mirror 403 that focuses optical radiation on the surface of the sensor (or sensors) 402. Both sensors are located in the focus of the parabolic sensor side by side, as shown in Fig.16.

The optical pulse reflected from the probed object is divided into two, the first of which reaches the surface of the sensor 401 before it reaches the surface of the sensor 402 with reflection from the parabolic mirror. The time delay is determined by the time of passage of the path segments of the beam A1+B1 or A2+B2. The travel time of these segments is the same and determines the time delay of the second optical pulse that hits the surface of the sensor 402 with respect to the first one that hits the surface of the sensor 401.

, то задержка между временем достижения оптическим импульсом поверхности сенсора 402 и оптическим импульсом поверхности сенсора 401, составит 0,66

, что является приемлемым временем для обработки принятого первого оптического импульса и формирования сигнала на выключение оптического сенсора 402. So, if the sum of the lengths of segments A1 and B1 is 20

, then the delay between the time the optical pulse reaches the sensor surface 402 and the optical pulse of the sensor surface 401 will be 0.66

, which is an acceptable time to process the received first optical pulse and generate a signal to turn off the optical sensor 402.

A sensor 401 that receives only high-energy optical pulses (corresponding to "strong" or "strong" and "ordinary" optical pulses) striking the surface of the combined optical system of the type of FIG. 16), generates a signal to turn off the sensor 402. As a result, the frequency of the sensor 402 responses at a given quantum efficiency of the sensor 402 is reduced, which allows the sensor 402 to receive optical pulses at a higher quantum efficiency of the sensor 402, which is more preferable for receiving “weak” optical pulses. . It also allows you to simultaneously eliminate the influence on the detection of “weak” response peaks on the secondary reflectogram obtained by signal processing from the 402 sensor, side lobes (side peaks) of responses from receiving “strong” or “strong” and “ordinary” optical pulses received only by the sensor 401 and increase the security of the path for receiving and processing the signal of the sensor 402 from impulse noise.

The optical sensor 401 and the optical sensor 402 may comprise multiple optical sensors to which appropriate gating signals are applied.

Using a trial (pilot) probing signal

Another variant of adaptive gating is based on the use of information about the time intervals of arrival of "strong" and "ordinary" optical pulses on the surface of the receiving sensor, obtained during the reception and processing of the test signal.

The essence of the solution is that to determine the signal transit time from the transmitter to an object with a "strong" and/or "ordinary" ESR and back to the receiving sensor, further than the transit time, it is sufficient to use probing sequences with a smaller number of optical pulses, the so-called . test signals.

The probe signal is emitted by the lidar before the main optical signal is sent. After receiving the secondary reflectogram and determining the time delays of the probing test signal, a gating adaptation signal is formed. The main probing signal is received already with the adaptation of the strobing signal. Emission and reception of test and main signals can be carried out in one probing cycle.

, и задержка в его обработке в реальном времени

, время начала испускания основного сигнала должно быть задержано относительно момента начала испускания пробного сигнала не менее, чем на 2

+

.So, if the duration of the test signal is equal to

, and the delay in its processing in real time

, the start time of the emission of the main signal must be delayed relative to the start of the emission of the test signal by at least 2

+

.

Table 5 General information on examples 4-7

Name of parameter/indicator Unit rev. Value Operating wavelength of the sensor

1550 The duration of optical pulses in sequences applied to the sensor, no more than

100 Sensor type InGaAs/InP Sensor cooling temperature

-fifty Maximum sensor quantum efficiency % 25

Example 4

The main parameters of the stand in example 4

The number of probing cycles K = 5.

Information about the allowed delays arriving at the surface of the PIMPOI sensor is given in Table 4.

) поступающая на поверхность сенсора составляет 20 , одна ПИМПОИ ординарная относительная энергия поступающая на поверхность сенсора составляет 5 и две ПИМПОИ слабые относительная энергия поступающая на поверхность сенсора составляет 1,2 . In total, 8 PIMPOIs arrive at the sensor surface, of which 5 are strong, in which the relative energy (normalized to the energy of one photon with a wavelength of 1550

) arriving at the sensor surface is 20 , one PIMPOI ordinary relative energy arriving at the sensor surface is 5 and two PIMPOI weak relative energy arriving at the sensor surface is 1.2 .

PIMPOs are modulated with the sequence from example 2.

The number of optical pulses in each PIMPOI -1369

.Equivalent power of the noise component of the signal detected by the sensor - 1.28

.

- 0,3Setpoint for the regulation loop of the rated sensor frequency

- 0.3

In FIG. 14 (example 4)

Top Graph

The X-axis shows the time in the clock pulses of the stand multiplied by 10 ^-4 .

помноженное на 5, где 5 — это число циклов накопления в первичной рефлектограмме. The value of the auxiliary function is plotted on the Y-axis

multiplied by 5, where 5 is the number of accumulation cycles in the primary trace.

Bottom chart

On the X-axis is the time in the clock pulses of the stand, multiplied by 10 ^-4 .

On the Y-axis, the values taken by the secondary Z trace obtained after processing the primary accumulated trace.

16A - peaks of responses on the secondary reflectogram from sequences of "strong" optical pulses,

16B - peak of responses on the secondary reflectogram from a sequence of "ordinary" optical pulses.

16C - peaks of responses on the secondary reflectogram from sequences of "weak" optical pulses.

As a result of accumulation of five primary reflectors and processing of the accumulated reflectogram, a secondary reflectogram was obtained, a fragment of which is shown in Fig. 14 (bottom graph).

The reflectogram clearly shows positive peaks of responses from weak and ordinary PIMPOIs with different delays and negative peaks of responses obtained as an effect of adaptive gating from strong PIMPOIs.

, суть которой – значение числа отсчетов первичной рефлектограммы, вносящих вклад в формирование отсчета вторичной рефлектограммы

. Такие отсчеты в первичной рефлектограмме мы определили, ранее в описании, как информационные. Поскольку при получении вторичной рефлектограммы

была использована первичная накопленная из 5 рефлектограмм, значения функции

были умножены на 5.To evaluate the effect of gating on signal energy loss, an auxiliary sequence is calculated

, the essence of which is the value of the number of readings of the primary reflectogram, contributing to the formation of the reading of the secondary reflectogram

. We defined such readings in the primary reflectogram, earlier in the description, as informational. Since when obtaining a secondary reflectogram

the primary accumulated of 5 reflectograms was used, the values of the function

were multiplied by 5.

были бы константой равной 1369*5 = 6845. Таким образом, за счет стробирования попадает в интервалы стробирования от 42 до 50% оптических импульсов в ПИМПОИ. It can be seen from the upper graph that in the formation of each report of the secondary reflectogram, from 2900 to 3450 information samples from the primary reflectograms were used, which is associated with the gating of the sensor. Assuming no gating value 5

would be a constant equal to 1369 * 5 = 6845. Thus, due to gating, it falls into the gating intervals from 42 to 50% of the optical pulses in the PIMPOI.

The results for example 4 are shown in table 6

Example 5

Example 5 differs from Example 4 in that adaptive gating has been disabled.

In FIG. 15 (example 5)

Top Graph

The X-axis shows the time in the clock pulses of the stand multiplied by 10 ^-4 .

помноженное на 5, где 5 — это число циклов накопления в первичной рефлектограмме. The value of the auxiliary function is plotted on the Y-axis

multiplied by 5, where 5 is the number of accumulation cycles in the primary trace.

Bottom chart

On the X-axis is the time in the clock pulses of the stand, multiplied by 10 ^-4 .

, полученной после обработки первичной накопленной рефлектограммы.On the Y axis, the values taken by the secondary reflectogram

obtained after processing the primary accumulated reflectogram.

17A - peaks of responses on the secondary reflectogram from sequences of "strong" optical pulses

17B - peak of responses on the secondary reflectogram from a sequence of ordinary optical pulses.

As can be seen from the example, when the gating adaptation function is turned off, it is not possible to determine the delays of weak PIMPOIs.

The results of example 5 are shown in table 6

Example 6

и увеличена относительная энергия импульсов (нормированная на энергию одного фотона с длинной волны 1550 nm) в слабых ПИМПОИ до 2. Example 6 differs from example 4 only in that the equivalent power of the noise component of the signal detected by the sensor is increased to 3.2

and the relative energy of pulses (normalized to the energy of one photon with a wavelength of 1550 nm) in weak PIMPOIs was increased up to 2.

The results of example 6 are shown in table 6

Example 7

Example 7 differs from example 6 only in that the adaptive gating is disabled and the bias voltage is set to provide the maximum quantum efficiency of the sensor equal to ≈25%.

The results of example 7 are shown in table 6

Table 6 below summarizes examples 4-7.

Cells with a negative result are highlighted in bold with underlining (no resolution on the secondary trace) - the response does not stand out above the background level of the trace.

Table 6. Summary of examples

Example Unit rev. four 5 6 7 The power of the noise component of the signal detected by the sensor

1.28 1.28 3.21 3.21 Adaptive gating Yes Not Yes Not Automatic adjustment of the quantum efficiency of the sensor. Yes Yes Yes Not Information about the signals arriving at the sensor surface at the same time. Probing sequences from "strong" optical pulses number of simulated permitted objects* PCS. 6 6 6 6 Average number of photons in an optical pulse** PCS. twenty twenty twenty twenty Probing sequences from "ordinary" optical pulses number of simulated resolvable objects PCS. one one one one Average number of photons in an optical pulse PCS. 5 5 5 5

*** for "ordinary" J/J 2.5 2.5 one one

**** for "ordinary" Ampl./ampl. 7.4 3.7 6.3 1.3 Probing sequences from "weak" optical pulses number of allowed objects PCS. 2 2 2 2 Average number of photons per pulse PCS. 1.2 1.2 2 2

for the "weak" J/J 0.6 0.6 0.4 0.4

for the "weak" Ampl./ampl. 3.25 0.74 2.41 1.33

GHz/GHz 0.3 0.3 0.3 0.72

% 19.3 12.5 eight 25

* the number of simulated resolved objects is the number of objects delayed relative to the start time of emission of the probing optical sequence PIMPOI with the same energy in each optical pulse.

** the average number of photons in an optical pulse is the average energy of an optical pulse in PIMPOI, normalized to the energy of one optical radiation quantum with a frequency of 1550 nm.

– определяется, как отношение энергии одного оптического импульса ПИМПОИ, попадающего на поверхность сенсора на интервалах стробирования к сумме энергии шумового излучения поступающего на поверхность сенсора на интервалах стробирования и энергии эквивалентного шумового излучения, характеризующей проявление собственного шума сенсора на интервалах стробирования, но без учета эквивалентного шумового излучения вызванного эффектом APP . ***

– is defined as the ratio of the energy of one optical pulse of the PIMPOI, which hits the sensor surface at the strobing intervals, to the sum of the noise radiation energy arriving at the sensor surface at the strobing intervals and the energy of the equivalent noise radiation, which characterizes the manifestation of the sensor’s own noise at the strobing intervals, but without taking into account the equivalent noise radiation caused by the APP effect.

- по вторичной рефлектограмме определяется, как минимальное отношение амплитуд пиков соответствующих откликов («ординарных» или «слабых») к максимальной амплитуде боковых лепестков рефлектограммы по выборке из 10 однотипных рефлектограмм, на фиг. 14 и 15 приведены одни из этих рефлектограмм. ****

- according to the secondary reflectogram, it is determined as the minimum ratio of the amplitudes of the peaks of the corresponding responses ("ordinary" or "weak") to the maximum amplitude of the side lobes of the reflectogram for a sample of 10 similar reflectograms, in Fig. Figures 14 and 15 show some of these reflectograms.

– измеренная на интервале приема оптического сигнала нормированная на частоту стробирования средняя частота срабатываний сенсора, установившаяся при регулировании ее по уставке

(примеры 3,4,5) или при фиксированной квантовой эффективности сенсора

(пример 7).

– measured at the interval of receiving the optical signal, normalized to the gating frequency, the average frequency of sensor responses, which was established when it was adjusted according to the setpoint

(examples 3,4,5) or at a fixed quantum efficiency of the sensor

(example 7).

(примеры 3,4,5) по уставке

или заданная уставкой

(пример 7).ξ is the average quantum efficiency of the sensor at the gating intervals established as a result of regulation

(examples 3,4,5) by setting

or preset

(example 7).

Industrial applicability.

The proposed device for receiving an optical signal makes it possible to use relatively inexpensive, low power devices as sources of pulsed radiation.

Additional benefits:

1) noise immunity,

2) range resolution - from 3–5 cm.

3) the possibility of resolving all objects in the beam alignment in one probing cycle.

. за счет стробирования и наличия в принимаемом сигнале сильных импульсных помех или «сильных» ПИМПОИ, затрудняющих обработку принимаемого сигнала, путем вычисления вспомогательной функции Y. 4) the ability to control losses in the ratio

. due to gating and the presence in the received signal of strong impulse noise or “strong” PIMPOI, which make it difficult to process the received signal, by calculating the auxiliary function Y.

для пиков откликов на рефлектограмме «слабых» сигналов и регулирование средней частоты срабатываний сенсора позволяет установить оптимальную квантовую эффективностью сенсора при которой достигается максимальное соотношение

. An additional technical result is that the gating adaptation increases

for response peaks on the reflectogram of “weak” signals and adjusting the average frequency of sensor triggering allows you to set the optimal quantum efficiency of the sensor, at which the maximum ratio is achieved

.

Claims (2)

1. A method for receiving an optical signal, in which a clock signal is generated, the signal reflected from the probed object is received by a sensor of an optical detector operating in a nonlinear mode, having a matched filtering unit and a threshold signal detection module, characterized in that the strobe signal is adapted and the quantum efficiency is adjusted according to sensor response rate. 2. The method according to claim 1, characterized in that the adaptation of the gating signal is carried out by generating a gating adaptation signal in the probing process based on the results of matched filtering of a fragment of the reflected probing signal in the form of a PIM sequence or a separate probing pilot signal, which makes it possible to estimate the time delays of the reflected probing signal from the elements of the probed object with signals at which single optical pulses arriving at the sensor surface of the optical detector lead to its operation with a probability close to unity.

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