Pulse coding method for erbium glass laser applied in wireless optical communication

Abstract

The application provides a pulse coding method for application of an erbium glass laser in wireless optical communication, comprising the following steps: dividing one laser communication process into M laser pulse coding sequences, each laser pulse coding sequence being composed of N laser pulses; each laser pulse coding sequence transmits the same information, and any one laser pulse coding sequence can successfully transmit information to realize communication success. The application is designed according to the characteristics of low modulation precision and low pulse repetition frequency of the erbium glass laser, and a pulse coding method capable of tolerating the modulation precision and pulse repetition frequency of the erbium glass laser is designed, so that wireless optical communication based on the erbium glass laser can be realized.

Description

Technical Field

[0001] This invention relates to the field of wireless optical communication technology, and more specifically, to a pulse coding method based on the application of erbium glass lasers in wireless optical communication. Background Technology

[0002] With the rapid development of modern communication technology, wireless optical communication technology, due to its advantages such as small size, low power consumption, and precise pointing, is gradually being applied in engineering. Currently, lasers widely used in wireless optical communication mainly include semiconductor lasers, optical fiber lasers, and solid-state lasers, each with its own advantages and disadvantages. Semiconductor lasers have high repetition rates, high modulation accuracy, and small size and weight, but lower emission power, and are generally suitable for communication projects with an operating distance of about 1 km. Optical fiber lasers also have the advantages of high repetition rates and high modulation accuracy, and their emission power is significantly increased compared to semiconductor lasers, but they are slightly larger and heavier, and can be used in communication projects with an operating distance of 3-5 km. Solid-state lasers have higher energy and higher modulation accuracy, but lower repetition rates and larger size and weight, and are less commonly used in communication engineering.

[0003] In recent years, a new type of laser, the erbium glass laser, has been widely used in the field of laser ranging. Due to its outstanding advantages such as small size, high power, low energy consumption, and long lifespan, it is favored by laser ranging users, which has increased the range of small handheld laser rangefinders to 10km. However, the erbium glass laser is difficult to apply to the field of wireless optical communication due to its low repetition frequency and low modulation accuracy. Overcoming its shortcomings and enabling its application in the communication field has become a hot topic of technical research. Summary of the Invention

[0004] The present invention aims to provide a pulse coding method for the application of erbium glass lasers in wireless optical communication. This pulse coding method can tolerate the deficiencies of erbium glass lasers in terms of modulation accuracy and pulse repetition rate, enabling them to be applied in the field of long-distance wireless optical communication.

[0005] This invention provides a pulse coding method for the application of erbium glass lasers in wireless optical communication, comprising:

[0006] One laser communication process is divided into M laser pulse coding sequences, and each laser pulse coding sequence consists of N laser pulses;

[0007] Each laser pulse coded sequence transmits the same information, and communication is successful if any laser pulse coded sequence successfully transmits the information.

[0008] Preferably, the N laser pulses in each laser pulse coding sequence are denoted as P0, P1, P2, ..., P... N-1 Then P1, P2, ..., PN-1 The delays relative to P0 are T1, T2, ..., T N-1 , where T1 is a fixed value that does not participate in the encoding.

[0009] Preferably, when N=5 in each laser pulse coding sequence:

[0010] T2 = 0.2x + 22ms;

[0011] T3 = 0.2y + 22ms;

[0012] T4 = 0.2z + 22ms;

[0013] Where x and y range from 0 to 31, and z ranges from 0 to 63, x, y, and z are combined into a 16-bit binary code, with a code size of 2. 16 That is, when using this pulse coding method for wireless optical communication, any 16-bit binary code can be transmitted in one operation.

[0014] Preferably, the value of T1 is different in each laser pulse coding sequence.

[0015] Preferably, when transmitting M laser pulse coded sequences, there is a fixed time interval T0 between each two laser pulse coded sequences.

[0016] As a preferred option, M=4.

[0017] Preferably, the fixed time interval T0 = 20ms is used between every two laser pulse coding sequences.

[0018] Preferably, the T1 values ​​for each laser pulse coding sequence are 20.4ms, 20.8ms, 21.2ms, and 21.6ms.

[0019] Preferably, the maximum duration of each laser pulse coding sequence is 111.4ms, 111.8ms, 112.2ms, and 112.6ms, respectively.

[0020] Preferably, when receiving and decoding a laser pulse coded sequence, the time interval T between two adjacent laser pulse coded sequences must first be determined, and the integer value obtained by rounding down according to the decoding formula: [(T / 200μs-11)+0.5] is the encoded data of that laser pulse coded sequence.

[0021] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0022] 1. This invention addresses the low modulation accuracy and low pulse repetition rate of erbium glass lasers by designing a pulse coding method that can tolerate their low modulation accuracy and low pulse repetition rate. This invention enables wireless optical communication based on erbium glass lasers.

[0023] 2. The pulse coding method designed in this invention divides a single laser communication into four laser pulse coding sequences (which can be increased or decreased as needed). The four laser pulse coding sequences transmit the same content to ensure the success rate of communication. A single laser pulse coding sequence contains 5 laser pulses (which can be increased or decreased as needed according to the coding length) and can transmit 16 bits (which can be increased or decreased as needed) of coded data. Its communication pulse coding method is original. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the pulse coding method based on erbium glass laser in wireless optical communication in an embodiment of the present invention.

[0026] Figure 2 This is a schematic diagram of the laser processing flow in an embodiment of the present invention.

[0027] Figure 3 This is a schematic diagram of the laser modulation control timing in an embodiment of the present invention. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0029] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0030] Example

[0031] This embodiment proposes a pulse coding method based on the single-pulse position modulation principle, combined with the modulation accuracy and pulse repetition frequency characteristics of erbium glass lasers, to enable erbium glass lasers to be applied in the field of long-distance wireless optical communication.

[0032] The basic parameters of the relatively mature eye-safe erbium glass laser currently available in China are as follows:

[0033] a) Operating wavelength: 1535nm;

[0034] b) Pulse repetition frequency: ≥20Hz;

[0035] c) Modulation accuracy: ≤50μs;

[0036] d) Maximum power: ≥20kW;

[0037] e) Single pulse width: 3-5 ns.

[0038] Based on the above operating parameters, if the erbium glass laser is to be applied in the field of wireless optical communication, a dedicated pulse coding method needs to be designed to tolerate a maximum modulation error of 50 μs and a minimum repetition rate of 20 Hz for the erbium glass laser. This embodiment proposes a pulse coding method for the application of erbium glass lasers in wireless optical communication, comprising:

[0039] One laser communication process is divided into M laser pulse coding sequences, and each laser pulse coding sequence consists of N laser pulses;

[0040] Each laser pulse encoding sequence transmits the same information. If any laser pulse encoding sequence successfully transmits the information, then communication is successful, thus ensuring the probability of successful communication.

[0041] The values ​​of M and N can be set as needed, such as... Figure 1 As shown, this embodiment is described in detail with M=4 and N=5. Therefore, the N=5 laser pulses in each laser pulse coding sequence are denoted as P0, P1, P2, ..., P4, and the delays of P1, P2, ..., P4 relative to P0 are T1, T2, ..., T4, respectively, where:

[0042] T1 is a fixed value that does not participate in the encoding. The value of T1 is different in each laser pulse encoding sequence, and is 20.4ms, 20.8ms, 21.2ms, and 21.6ms respectively.

[0043] T2 = 0.2x + 22ms;

[0044] T3 = 0.2y + 22ms;

[0045] T4 = 0.2z + 22ms;

[0046] Where x and y range from 0 to 31, and z ranges from 0 to 63, x, y, and z are combined into a 16-bit binary code, with a code size of 2. 16 That is, when using this pulse coding method for wireless optical communication, any 16-bit binary code can be transmitted in one operation.

[0047] A single identification process requires sending M=4 laser pulse coded sequences, with a fixed time interval T0=20ms between each two laser pulse coded sequences. For example... Figure 2 As shown, the maximum duration of each laser pulse coding sequence is 111.4ms, 111.8ms, 112.2ms, and 112.6ms, respectively, thus the laser processing time is ≤528ms.

[0048] Laser pulse coded sequence receiving and processing, such as Figure 3 As shown, after receiving the laser pulse code sequence, the receiver completes the laser pulse code sequence start determination at pulse position P1 and the laser pulse code sequence decoding at pulse position P4. The single-pulse modulation accuracy of laser emission should be better than 50μs, that is, the delay jitter between the actual light emission time and the selected emission time should be ≤50μs. During laser emission, there is a certain delay between the actual light emission time and the modulation control time. This delay can be divided into two parts, namely t0 and Δt. t0 is a fixed delay, which is related to the ambient temperature under certain hardware conditions. Within a set of laser pulse sequence time (approximately 120ms), the ambient temperature can be considered to remain unchanged, and the value of t0 is constant. Δt is the delay jitter, and its test value is required to be within the range of 0 to 50μs.

[0049] The laser emitter processor achieves timing control accuracy better than 1 μs, and the laser receiver processor achieves timing sampling accuracy better than 1 μs. Combined with a single-pulse modulation accuracy better than 50 μs, it can be estimated that the error between the sampling result of the time interval between two adjacent pulses and the ideal encoding time interval during laser receiver processing does not exceed 52 μs. The time interval judgment boundary for laser receiver processing is ±100 μs, which can effectively tolerate the maximum error. Furthermore, this pulse coding method is designed using single-pulse position modulation, which can transmit more information with fewer laser pulses. That is, a single laser pulse coding sequence containing 5 laser pulses can transmit 16 bits of information, reducing the requirement for the pulse repetition frequency of the erbium glass laser and achieving high coding efficiency.

[0050] When receiving and decoding a laser pulse coded sequence, the time interval T between two adjacent laser pulse coded sequences is determined. The floor function is then performed according to the encoding rules. The effective coded segment decoding formula is: [(T / 200μs-11)+0.5]. The resulting integer value is the encoded data of that laser pulse coded sequence.

[0051] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A pulse coding method for the application of erbium glass lasers in wireless optical communication, characterized in that, include: One laser communication process is divided into M laser pulse coding sequences, and each laser pulse coding sequence consists of N laser pulses; Each laser pulse coded sequence transmits the same information, and communication is successful if any laser pulse coded sequence successfully transmits the information. M=4, and the N laser pulses in each laser pulse coding sequence are denoted as P0, P1, P2, ..., P... N-1 Then P1, P2, ..., P N-1 The delays relative to P0 are T1, T2, ..., T N-1 Where T1 is a fixed value that does not participate in encoding; the value of T1 is different in each laser pulse encoding sequence; when N=5 in each laser pulse encoding sequence: T2 = 0.2x + 22ms; T3 = 0.2y + 22ms; T4 = 0.2z + 22ms; Where x and y range from 0 to 31, and z ranges from 0 to 63, x, y, and z are combined into a 16-bit binary code, with a code size of 2. 16 When using this pulse coding method for wireless optical communication, any 16-bit binary code can be transmitted in a single operation.

2. The pulse coding method for the application of erbium glass laser in wireless optical communication according to claim 1, characterized in that, When sending M laser pulse coded sequences, there is a fixed time interval T0 between each two laser pulse coded sequences.

3. The pulse coding method for the application of erbium glass laser in wireless optical communication according to claim 2, characterized in that, A fixed time interval T0 = 20ms is maintained between each two laser pulse coded sequences.

4. The pulse coding method for the application of erbium glass laser in wireless optical communication according to claim 2, characterized in that, The T1 values ​​for each laser pulse coding sequence are 20.4ms, 20.8ms, 21.2ms, and 21.6ms, respectively.

5. The pulse coding method for the application of an erbium glass laser in wireless optical communication according to claim 1, characterized in that, The maximum duration of each laser pulse coding sequence is 111.4ms, 111.8ms, 112.2ms, and 112.6ms, respectively.

6. A pulse coding method for the application of an erbium glass laser in wireless optical communication according to any one of claims 1-5, characterized in that, When receiving and decoding a laser pulse coded sequence, the time interval T between two adjacent laser pulse coded sequences must first be determined. Then, the integer value obtained by rounding down according to the decoding formula [(T / 200μs-11)+0.5] is the encoded data of that laser pulse coded sequence.

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