Automatic gain control method and device for photon counting communication

Abstract

The invention provides an automatic gain control method and device for photon counting communication. The device comprises an average photon counting rate counting module, a threshold comparator, a pulse interval detection module and a pulse density attenuation module. The average photon counting rate counting module counts photon counting rates within a certain range to obtain an average photon counting rate, the threshold comparator compares the average photon counting rate with a set threshold, if the average photon counting rate is smaller than or equal to the threshold, the average photon counting rate is normal and can be directly output, and if the average photon counting rate is larger than the threshold, the average photon counting rate is abnormal. The pulse interval detection module detects the pulse interval extreme value, the pulse density attenuation module conducts pulse density attenuation on the pulse, then the average photon counting rate is counted again, if the average photon counting rate is normal compared with a threshold value, output is conducted, and if the average photon counting rate is abnormal, cyclic density attenuation is conducted again till normal output is achieved. The output pulse density tends to be stable, the threshold does not need to be dynamically adjusted, and therefore the problems that threshold adjustment is poor in accuracy, time-consuming in the process and not easy to achieve are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of photon counting wireless optical communication, and in particular to an automatic gain method and device for photon counting communication. Background Art

[0002] Photon counting wireless optical communication technology is a technology that uses the principle of photon counting for wireless communication. It is based on photon counting technology, which is a weak light signal detection technology that realizes digital detection of signals by recording each photoelectron pulse. The typical method of photon counting technology is to use a photomultiplier tube as a receiver to convert the light signal into a photoelectron form for detection. Among them, the receiver mediation and restoration of the original signal is the key part. In the process of restoring the original signal, it is necessary to compare with the pre-set threshold to filter out the noise or unnecessary parts in the signal, thereby retaining or enhancing useful information. However, according to the patent with publication number CN104677511A, since the dark noise state of the system will change with the change of environmental conditions, this means that the comparison threshold also needs to be adjusted in real time according to different noise states. Therefore, the fixed threshold method is obviously unable to meet this requirement.

[0003] According to the patent with publication number CN112284554A, most of the existing technologies use some external adjustment methods such as buttons to control the threshold change. This adjustment method has objective technical defects such as poor accuracy and time-consuming process. In addition, in many working environments, the adjustment buttons are in places that are not easy to access and cannot be manually adjusted.

[0004] Therefore, it is urgent to provide a solution to improve the above problems. Summary of the invention

[0005] The purpose of the present invention is to apply automatic gain control so that the photon pulse density output by the receiving end tends to be stable, so that there is no need to dynamically adjust the threshold, and then correctly restore the original signal after comparing it with the preset fixed threshold. This improves the problems of poor accuracy, time-consuming process and difficulty in implementation of the threshold adjustment described in the background technology.

[0006] In a first aspect, the present invention provides an automatic gain control method for photon counting communication, comprising the following steps:

[0007] Segmenting a single-photon pulse signal that conforms to the Poisson distribution to obtain single-photon pulse segments;

[0008] Calculate the photon counting rate of the single-photon pulse segment and calculate the average photon counting rate of the single-photon pulse signal;

[0009] When the average photon count rate is less than or equal to a preset threshold, the single photon pulse signal is output; otherwise, the difference between the average photon count rate and the preset threshold is calculated as the front difference, and the sum of the average photon count rate and the preset threshold is calculated as the back difference;

[0010] Selecting a single-photon pulse segment based on the front difference and calculating the maximum pulse interval, and selecting a single-photon pulse segment based on the back difference and calculating the minimum pulse interval;

[0011] After eliminating pulses whose pulse interval is less than the minimum pulse interval or greater than the maximum pulse interval in the single-photon pulse signal, an attenuation signal is obtained and the attenuation signal is subjected to the above-mentioned segmented cyclic calculation until the attenuation signal is output.

[0012] The automatic gain control method provided by the invention has the technical effects of automatic control, simple operation and easy implementation.

[0013] Optionally, when a single-photon pulse signal obeying a Poisson distribution is segmented into single-photon pulse segments, the number of pulses in the multiple single-photon pulse segments is any value within a range of 100-500.

[0014] Optionally, the preset threshold is (0, 1] times the average photon count rate of a single-photon pulse signal whose pulse interval obeys an exponential distribution characteristic, there are no two consecutive pulses, each pulse is one clock cycle and obeys a Poisson distribution characteristic.

[0015] Optionally, when a single-photon pulse segment is selected based on the previous difference and the maximum pulse interval is calculated, the difference between the photon count rate in each single-photon pulse segment and the previous difference is calculated, the pulse interval of adjacent pulses in the single-photon pulse segment corresponding to the minimum difference is calculated and the maximum value is selected as the maximum pulse interval.

[0016] Optionally, when a single-photon pulse segment is selected based on the post-difference value and the minimum pulse interval is calculated, the difference between the photon count rate in each single-photon pulse segment and the post-difference value is calculated, the pulse interval of adjacent pulses in the single-photon pulse segment corresponding to the minimum difference is calculated and the minimum value is selected as the minimum pulse interval.

[0017] Optionally, the method for eliminating pulses in a single-photon pulse signal whose pulse interval is less than the minimum pulse interval or greater than the maximum pulse interval is, starting from the second pulse of the single-photon pulse signal, comparing the interval between the pulse and the previous pulse with the minimum pulse interval and the maximum pulse interval; if it is less than the minimum pulse interval or greater than the maximum pulse interval, the pulse is eliminated; otherwise, it is retained.

[0018] In a second aspect, the present invention further provides an automatic gain device for photon counting communication, comprising:

[0019] An average photon counting rate counting module is used to calculate the photon counting rate of a single-photon pulse segment and calculate the average photon counting rate of a single-photon pulse signal;

[0020] A threshold comparator, used to compare the average photon count rate with a preset threshold and calculate a front difference value and a rear difference value;

[0021] A pulse interval detection module, used to select a single-photon pulse segment based on the front difference and calculate the maximum pulse interval, and to select a single-photon pulse segment based on the back difference and calculate the minimum pulse interval;

[0022] A pulse density attenuation module is used to remove pulses whose pulse interval is less than the minimum pulse interval or greater than the maximum pulse interval in the single-photon pulse signal to obtain an attenuation signal;

[0023] The average photon counting rate counting module, the threshold comparator, the pulse interval detection module and the pulse density attenuation module are loop-connected in sequence.

[0024] The automatic gain control device provided by the present invention has the technical effects of precise control, simplicity and rapidity.

[0025] Optionally, the average photon count rate counting module includes: a counter M1, a counter M2, a photon count rate statistics module and a two-input OR gate, the counter M1 is connected to the two-input OR gate, the two-input OR gate is connected to the counter M2, and the counter M2 is connected to the photon count rate statistics module.

[0026] Optionally, the pulse interval detection module includes: a corresponding single-photon pulse module, a counter and an interval detection module, the corresponding single-photon pulse module is connected to the counter, and the counter is connected to the interval detection module.

[0027] Optionally, the pulse density attenuation module includes: a single-photon pulse buffer and a pulse density attenuator, and the single-photon pulse buffer is connected to the pulse density attenuator. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the implementation of the device of the present invention;

[0029] Figure 2 It is a structural schematic diagram of the device of the present invention;

[0030] Figure 3 This is a structural diagram of an average photon counting rate module of the device of the present invention;

[0031] Figure 4 It is a timing diagram of the average photon counting rate module of the device of the present invention;

[0032] Figure 5A structural diagram of a threshold comparator of the device of the present invention;

[0033] Figure 6 is a timing diagram of a threshold comparator of the device of the present invention;

[0034] Figure 7 It is a structural diagram of a pulse interval detection module of the device of the present invention;

[0035] Figure 8 It is a timing diagram of the pulse interval detection module of the device of the present invention;

[0036] Fig. 9 It is a structure diagram of the pulse density attenuation module of the device of the present invention;

[0037] Fig.10 This is a timing diagram of the pulse density attenuation module of the device of the present invention. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be understood by people with general skills in the field to which the present invention belongs. "Including" and similar words used in this article mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects.

[0039] The present invention provides an automatic gain control method for photon counting communication, comprising the following steps:

[0040] S1. Segmenting a single photon pulse signal conforming to Poisson distribution to obtain single photon pulse segments;

[0041] S2, calculating the photon counting rate of the single-photon pulse segment and calculating the average photon counting rate of the single-photon pulse signal;

[0042] S3, when the average photon count rate is less than or equal to the preset threshold, output the single photon pulse signal, otherwise the difference between the average photon count rate and the preset threshold is calculated as the front difference, and the sum of the average photon count rate and the preset threshold is calculated as the back difference;

[0043] S4, selecting a single-photon pulse segment based on the front difference and calculating the maximum pulse interval, and selecting a single-photon pulse segment based on the back difference and calculating the minimum pulse interval;

[0044] S5. After eliminating pulses whose pulse interval is less than the minimum pulse interval or greater than the maximum pulse interval in the single-photon pulse signal, an attenuation signal is obtained and the above-mentioned segmented cyclic calculation is performed on the attenuation signal until the attenuation signal is output.

[0045] When executing step S1, the single-photon pulse signal that obeys the Poisson distribution is segmented into single-photon pulse segments. The number of pulses in multiple single-photon pulse segments is any value within the range of 100-500. If it is too small, the single-photon pulse characteristics are not obvious. If it is too large, it affects the transmission speed of the system.

[0046] When executing step S2, the photon counting rate of each single-photon pulse segment is recorded, and the average photon counting rate of the photon pulse signal is obtained by statistics.

[0047] When executing step S3, if Figure 1 As shown, when the average photon count rate is less than or equal to the preset threshold, the single-photon pulse signal is output normally, and subsequent clock synchronization is performed. After the time slot synchronization clock is restored, the modulated signal is demodulated to restore the original data and transmitted to the receiving terminal through the network port. Otherwise, automatic gain control is performed, and the difference between the average photon count rate and the preset threshold is calculated as the front difference, and the sum of the average photon count rate and the preset threshold is calculated as the back difference. The above preset threshold should be (0, 1] times the average photon count rate of a single-photon pulse signal whose pulse interval obeys the exponential distribution characteristics, there are no two consecutive pulses, each pulse is one clock cycle and obeys the Poisson distribution characteristics.

[0048] When executing step S4, when selecting a single-photon pulse segment based on the front difference and calculating the maximum pulse interval, the specific steps include: calculating the difference between the photon count rate in each single-photon pulse segment and the front difference, outputting the single-photon pulse segment corresponding to the minimum difference, and calculating the pulse interval of adjacent pulses, and selecting the maximum value as the maximum pulse interval. When selecting a single-photon pulse segment based on the rear difference and calculating the minimum pulse interval, the specific steps include: calculating the difference between the photon count rate in each single-photon pulse segment and the rear difference, outputting the single-photon pulse segment corresponding to the minimum calculated difference, and calculating the pulse interval of adjacent pulses, and selecting the minimum value as the minimum pulse interval.

[0049] When executing step S5, the method for eliminating pulses whose pulse interval in the single-photon pulse signal is less than the minimum pulse interval or greater than the maximum pulse interval is to compare the interval between the pulse and the previous pulse with the minimum pulse interval and the maximum pulse interval, and if it is less than the minimum pulse interval or greater than the maximum pulse interval, the pulse is eliminated, otherwise it is retained. The pulse signal after density decay is used as the output signal, looped back to the average photon count rate module, and the next cycle is performed. If it is still greater than the threshold, the output is abnormal and the density decay is less than or equal to the threshold according to the above process again. Output normally.

[0050] The present invention also provides an automatic gain control device for photon counting communication, comprising:

[0051] An average photon counting rate counting module is used to calculate the photon counting rate of a single-photon pulse segment and calculate the average photon counting rate of a single-photon pulse signal;

[0052] A threshold comparator, used to compare the average photon count rate with a preset threshold and calculate a front difference value and a rear difference value;

[0053] A pulse interval detection module, used to select a single-photon pulse segment based on the front difference and calculate the maximum pulse interval, and to select a single-photon pulse segment based on the back difference and calculate the minimum pulse interval;

[0054] A pulse density attenuation module is used to remove pulses whose pulse interval is less than the minimum pulse interval or greater than the maximum pulse interval in the single-photon pulse signal to obtain an attenuation signal;

[0055] like Figure 2 As shown, the average photon counting rate counting module, the threshold comparator, the pulse interval detection module and the pulse density attenuation module are loop-connected in sequence.

[0056] The structure diagram of the average photon counting rate counting module is as follows: Figure 3As shown, it includes a counter M1, a counter M2, a photon counting rate statistics module and a two-input OR gate U1, the output terminal td and the system reset Rst of the counter M1 are respectively connected to the input terminal of the two-input OR gate U1, the output terminal of the two-input OR gate U1 is connected to the reset terminal rst of the counter M2, and is used to control the counter M2 to reset and clear after each counting within the counting range Rg is completed, and to count within the next counting range Rg, the output terminal counting range Rg of the counter M1 is connected to the enable terminal of the counter M2, and is used to control the counter M2 to count the single photon pulse RXD and the pulse txd after density attenuation within the counting range Rg. , the input end data1 of the counter M2 is a single photon pulse RXD having a Poisson distribution characteristic after passing through a single photon detector, the input end data2 of the counter M2 is a pulse txd after density attenuation, the system clock Clk is connected to the input end clock clk of the counter M1 and the counter M2, the output ends C1, C2...Cn of the counter M2 are connected to the input end of the photon counting rate statistics module, which is used to perform statistics on the photon counting rate obtained by counting to obtain an average photon counting rate, the output end signal of the photon counting rate statistics module is the output signal of the average photon counting rate counting module, and the average photon counting rate Avg is output;

[0057] The timing diagram of the average photon counting rate counting module is as follows Figure 4 As shown, the modulation signal Send is the input signal of the single-photon detector, which is transmitted from the transmitting end. The single-photon pulse RXD is the output signal of the single-photon detector. When the counting range Rg is at a high level, it is the counting range of the selected statistical photon counting rate. After reaching the maximum value of the counting range, it will become a low level for a cycle, and then continue to maintain a high level to perform photon counting rate statistics in the next process. The count value Cnt counts the single-photon pulse under the high level of the counting range Rg of the counter M2. Each time the counting range Rg reaches the maximum value, the count value Cnt is the photon counting rate Cn within the range (where n is 1, 2, 3...). The photon counting rate statistics module exports the received photon counting rate data statistics, uses Matlab to analyze the data, and obtains the average photon counting rate Avg;

[0058] The structure diagram of the threshold comparator is as follows: Figure 5 As shown, the input of the threshold comparator is the average photon count rate Avg, the threshold value θ, the system clock Clk, the system reset Rst and the enable signal en, the output of the threshold comparator is out when it is normal, start when it is abnormal, the front difference d1, and the rear difference d2;

[0059] The threshold comparator timing diagram is as follows: Figure 6As shown, the average photon count rate Avg is imported under the system clock clk, the preset threshold value θ is selected as 18, and the average photon count rate Avg is compared with the set threshold value θ. When Avg≤θ, the normal output out signal is valid. When Avg>θ, the start is enabled to be high level when it is abnormal, indicating that there is no normal output out signal at this time. At the same time, the front difference d1=Avg-θ, and the rear difference d2=Avg+θ;

[0060] The structure diagram of the pulse interval detection module is as follows: Figure 7 As shown, it includes a corresponding single-photon pulse module, a counter M3, and an interval detection module. The input of the corresponding single-photon pulse module is the input of the pulse interval detection module, and the front difference d1 and the rear difference d2 are input, so that the corresponding single-photon pulse module selects the single-photon pulse outputs q1 and q2 within the corresponding range according to the difference. The output ends q1 and q2 of the corresponding single-photon pulse module are respectively connected to data1 and data2 of the counter M3. The counter M3 counts the pulse intervals of the single-photon pulses within the corresponding range of the two input differences, and counts the intervals between each two pulse times as outputs O1, O2...On. The counter M3 counts the pulse intervals of the single-photon pulses within the corresponding range of the two input differences, and counts the intervals between each two pulse times as outputs O1, O2...On. The output terminals O1, O2···On of M3 are connected to the input terminals i1, i2···in of the interval detection module. The interval detection module selects the maximum interval count value pie1 and the minimum interval count value pie2 respectively according to the input interval count value. The system clock Clk, the system reset Rst and the abnormal enable start are respectively connected to the corresponding single-photon pulse module, the counter M3, the input terminal clock clk, the reset rst and the enable en of the interval detection module. The output of the interval detection module is the output of the pulse interval detection module, and the output pulse interval count value pie1 and the pulse interval count value pie2 are output;

[0061] The timing diagram of the pulse interval detection module is as follows: Figure 8 As shown, under the system clock clk, the interval between each two input single photon pulses is counted, and the count value On (where n is 1, 2, 3...) is stored in the register each time, and then cleared to count the next pulse interval. The pulse interval pie compares the interval count value stored in the register, and when the single photon pulse within the range is input, the maximum value is selected as the selected pulse interval value pie;

[0062] The structure diagram of the pulse density attenuation module is as follows: Fig. 9As shown, it includes a single-photon pulse buffer and a pulse density attenuator. The single-photon pulse buffer output s1 is connected to the input terminal i3 of the pulse density attenuator A1, and the single-photon pulse output abnormally is density-attenuated. The pulse interval count value pie1 and the pulse interval count value pie2 are connected to the input terminals i1 and i2 of the pulse density attenuator. These two pulse interval count values ​​are used as density attenuation rules, and the pulses with an interval between the pulse interval pie1 and the pulse interval pie2 are retained to density-attenuate the input pulses. The system reset Rst and the system clock Clk are connected to the input reset signal rst and the clock signal clk of the pulse density attenuator. The output of the pulse density attenuator is the output of the pulse density attenuation module, and the pulse txd after output density attenuation is output.

[0063] The pulse density decay module timing diagram is as follows: Fig.10 As shown, under the system clock clk, a single photon pulse s1 is input, and a pulse interval count value pie1 and a pulse interval count value pie2 are input. According to the two pulse interval count values, the density of the pulses whose pulse intervals are not between pie1 and pie2 is attenuated. The pulse txd after density attenuation is used as the output signal and looped back to the average photon counting rate module for the next cycle. If it is still greater than the threshold, the output is abnormal, that is, the density is decayed according to the above process to be less than or equal to the threshold and then the output is normal.

[0064] Although the embodiments of the present invention are described in detail above, it is obvious to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations are within the scope and spirit of the present invention as described in the claims. Moreover, the present invention described herein may have other embodiments and may be implemented or realized in a variety of ways.

Claims

1. An automatic gain control method for photon counting communication, characterized in that: The following steps are involved: Segmenting a single-photon pulse signal that conforms to the Poisson distribution to obtain single-photon pulse segments; Calculate the photon counting rate of the single-photon pulse segment and calculate the average photon counting rate of the single-photon pulse signal; When the average photon count rate is less than or equal to a preset threshold, the single photon pulse signal is output; otherwise, the difference between the average photon count rate and the preset threshold is calculated as the front difference, and the sum of the average photon count rate and the preset threshold is calculated as the back difference; Selecting a single-photon pulse segment based on the front difference and calculating the maximum pulse interval, and selecting a single-photon pulse segment based on the back difference and calculating the minimum pulse interval; After eliminating pulses whose pulse interval is less than the minimum pulse interval or greater than the maximum pulse interval in the single-photon pulse signal, an attenuation signal is obtained and the attenuation signal is subjected to the above-mentioned segmented cyclic calculation until the attenuation signal is output.

2. The automatic gain method according to claim 1, characterized in that: When a single-photon pulse signal obeying a Poisson distribution is segmented into single-photon pulse segments, the number of pulses in the multiple single-photon pulse segments is any value within a range of 100-500.

3. The automatic gain method according to claim 1, characterized in that: The preset threshold is (0, 1] times the average photon count rate of a single-photon pulse signal whose pulse interval obeys exponential distribution characteristics, there are no two consecutive pulses, each pulse is one clock cycle and obeys Poisson distribution characteristics.

4. The automatic gain method according to claim 1, characterized in that: When selecting a single-photon pulse segment based on the previous difference and calculating the maximum pulse interval, it includes: calculating the difference between the photon count rate in each single-photon pulse segment and the previous difference, calculating the pulse interval of adjacent pulses in the single-photon pulse segment corresponding to the minimum difference and selecting the maximum value as the maximum pulse interval.

5. The automatic gain method according to claim 1, characterized in that: When selecting a single-photon pulse segment based on the latter difference and calculating the minimum pulse interval, it includes: calculating the difference between the photon count rate in each single-photon pulse segment and the latter difference, calculating the pulse interval of adjacent pulses in the single-photon pulse segment corresponding to the minimum difference and selecting the minimum value as the minimum pulse interval.

6. The automatic gain method according to claim 1, characterized in that: The method for eliminating pulses in single-photon pulse signals whose pulse interval is less than the minimum pulse interval or greater than the maximum pulse interval is, starting from the second pulse of the single-photon pulse signal, comparing the interval between this pulse and the previous pulse with the minimum pulse interval and the maximum pulse interval. If it is less than the minimum pulse interval or greater than the maximum pulse interval, the pulse is eliminated, otherwise it is retained.

7. An automatic gain device for photon counting communication, characterized in that: include: An average photon counting rate counting module is used to calculate the photon counting rate of a single-photon pulse segment and calculate the average photon counting rate of a single-photon pulse signal; A threshold comparator, used to compare the average photon count rate with a preset threshold and calculate a front difference value and a rear difference value; A pulse interval detection module, used to select a single-photon pulse segment based on the front difference and calculate the maximum pulse interval, and to select a single-photon pulse segment based on the back difference and calculate the minimum pulse interval; A pulse density attenuation module is used to remove pulses whose pulse interval is less than the minimum pulse interval or greater than the maximum pulse interval in the single-photon pulse signal to obtain an attenuation signal; The average photon counting rate counting module, the threshold comparator, the pulse interval detection module and the pulse density attenuation module are loop-connected in sequence.

8. The device for implementing the automatic gain method according to claim 7, characterized in that: The average photon counting rate counting module includes: a counter M1, a counter M2, a photon counting rate statistics module and a two-input OR gate, the counter M1 is connected to the two-input OR gate, the two-input OR gate is connected to the counter M2, and the counter M2 is connected to the photon counting rate statistics module.

9. The device for implementing the automatic gain method according to claim 7, characterized in that: The pulse interval detection module includes: a corresponding single-photon pulse module, a counter and an interval detection module. The corresponding single-photon pulse module is connected to the counter, and the counter is connected to the interval detection module.

10. The device for implementing the automatic gain method according to claim 7, characterized in that: The pulse density attenuation module comprises: a single-photon pulse buffer and a pulse density attenuator, and the single-photon pulse buffer is connected to the pulse density attenuator.

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