Distributed passive Internet of Things optical cable identification system

Abstract

The invention relates to a distributed passive Internet of Things optical cable identification system, which relates to the technical field of optical cable identification and comprises a plurality of passive tags, at least one exciter and a receiver. The passive tags are respectively arranged on different optical cables, the optical cables are arranged in grooves under the ground, and an optical cable cover is arranged on one side, close to the ground, of each groove and is used for storing optical cable information of the coded optical cables, responding to excitation signals and sending back scattering signals; the exciter is in communication connection with the passive tags and sends excitation signals to the passive tags; the receiver comprises a plurality of antennas, each antenna is arranged on one side, far away from the groove, of the optical cable cover, and is used for receiving self-interference signals corresponding to the backscattering signals and the excitation signals, filtering the self-interference signals by adopting a cross-link interference elimination algorithm to obtain the backscattering signals, demodulating and decoding the backscattering signals in sequence, and outputting the backscattering signals. And obtaining optical cable information of the optical cable, and sending the optical cable information to a background server. The system can improve the communication distance.

Description

Technical Field

[0001] The present application relates to the field of optical cable identification technology, and in particular to a distributed passive Internet of Things optical cable identification system. Background Art

[0002] Fiber optic communication in power systems is the foundation of power communications, offering advantages such as large bandwidth, strong anti-interference capabilities, and high security. However, power communication optical cables are numerous and the laying environment is complex. For overhead and shallowly buried optical cables, optical cable identification is difficult and inefficient, severely restricting the operation, maintenance, and emergency repair efficiency of power optical cables. Traditional optical cable identification and maintenance relies on on-site personnel to collect optical fiber resources, using paper labels and documentation for management. Overhead optical cables require personnel to climb poles for inspection, a method that presents challenges such as difficulty in finding and identifying, a high workload, and high risks. Related technologies use radio frequency identification (RFID) technology to identify optical cables. However, as the scope of application expands, the passive RFID systems in related technologies suffer from limited communication distances. Summary of the Invention

[0003] Based on this, it is necessary to provide a distributed passive Internet of Things optical cable identification system that can improve the communication distance of passive radio frequency identification to address the above technical problems.

[0004] In a first aspect, the present application provides a distributed passive IoT optical cable identification system, comprising:

[0005] A plurality of passive tags, each of the passive tags being disposed on a different optical cable, the optical cable being disposed in a trench beneath the ground, a cable cover being disposed on a side of the trench close to the ground, the passive tags being configured to store encoded optical cable information of the optical cable and to emit a backscattered signal in response to an excitation signal; the optical cable information including at least one of an optical cable identifier, a tag node location, and an optical cable starting point;

[0006] At least one exciter, communicatively connected to each of the passive tags, and configured to send an excitation signal to the passive tags disposed on at least one optical cable;

[0007] A receiver comprising a plurality of antennas, each of which is arranged on a side of the optical cable cover away from the groove, the receiver being used to receive the backscattered signal and the self-interference signal corresponding to the excitation signal, and to filter the self-interference signal using a cross-link interference elimination algorithm to obtain the backscattered signal, and to successively demodulate and decode the backscattered signal to obtain optical cable information of the optical cable, and to send the optical cable information to a background server.

[0008] In one embodiment, filtering the self-interference signal using a cross-link interference cancellation algorithm includes:

[0009] The receiver is further configured to construct a reverse constant-amplitude signal of the self-interference signal using a cross-link interference cancellation algorithm according to a signal model of the self-interference signal, and send the reverse constant-amplitude signal to the exciter.

[0010] In one embodiment, the receiver is further used to determine the baseband signal of the communication link of the receiver based on the signal model of the self-interference signal, and to use a cross-link interference cancellation algorithm based on the baseband signal to obtain the amplitude and phase of the signal of the communication link of the self-interference signal, and to construct a reverse equal-amplitude signal based on the amplitude and phase of the signal of the communication link of the self-interference signal, and to send the reverse equal-amplitude signal to the exciter.

[0011] In one embodiment, the step of obtaining the amplitude and phase of the communication link signal of the self-interference signal by using a cross-link interference cancellation algorithm based on the baseband signal includes:

[0012] The receiver is further configured to compensate for the carrier frequency offset of the baseband signal by adopting a cross-link interference cancellation algorithm to obtain the amplitude and phase of the signal of the communication link of the self-interference signal.

[0013] In one embodiment, the signal model corresponding to sending the excitation signal to the passive tag disposed on at least one optical cable includes:

[0014]

[0015] in, represents the path attenuation from the exciter to the passive tag, represents the random initial phase of the exciter, represents the phase delay of the excitation signal sent to the passive tag, f represents the frequency of the excitation signal, represents the excitation signal.

[0016] In one embodiment, the passive tag is further used to modulate the impedance of the passive tag to perform state switching, and the state includes a reflective state and a non-reflective state;

[0017] The expressions corresponding to the states include:

[0018]

[0019] in, represents the state of the passive tag, , respectively represent the non-reflective and reflective states of the passive tag, represents the phase shift caused by the passive tag.

[0020] In one embodiment, the passive tag is configured to emit a signal model corresponding to a backscattered signal in response to an excitation signal, including:

[0021]

[0022] in, represents the path attenuation of the backscattered signal from the passive tag to the receiver, represents the path delay from the passive tag to the receiver, represents the backscattered signal.

[0023] In one embodiment, the signal model corresponding to the self-interference signal corresponding to the excitation signal includes:

[0024]

[0025] in, represents the attenuation coefficient from the exciter to the receiver, represents the phase delay from the exciter to the receiver, represents the self-interference signal.

[0026] In one embodiment, the receiver is further used to demodulate the backscattered signal to obtain the FM0 code, decode the FM0 code to obtain the decoded optical cable information, and perform CRC check on the decoded optical cable information. When the end bit of the FM0 code is checked, the optical cable information is sent to the background server.

[0027] In one embodiment, the receiver is also used to receive the optical cable information sent by the background server when no information is written to the passive tag, and to encode the optical cable information using the FM0 encoding algorithm to obtain the encoded optical cable information, and write the encoded optical cable information into the passive tag.

[0028] The above-mentioned distributed passive Internet of Things optical cable identification system includes multiple passive tags, at least one exciter and a receiver; wherein each of the passive tags is respectively set on a different optical cable, the optical cable is set in a trench under the ground, and an optical cable cover is set on the side of the trench close to the ground, and the passive tag is used to store the encoded optical cable information of the optical cable and emit a backscattered signal in response to an excitation signal; the optical cable information includes at least one of the optical cable identification, the tag node position and the optical cable starting point; the exciter is communicatively connected to each of the passive tags and sends an excitation signal to the passive tag set on at least one optical cable, thereby improving the coverage range of the passive tag for radio frequency communication; The receiver includes multiple antennas, each of which is arranged on a side of the optical cable cover away from the groove. The receiver is used to receive the backscattered signal and the self-interference signal corresponding to the excitation signal, and use a cross-link interference elimination algorithm to filter the self-interference signal to improve the accuracy and reliability of the received backscattered signal, obtain the backscattered signal, and successively demodulate and decode the backscattered signal to obtain the optical cable information of the optical cable, and send the optical cable information to the background server. The system separates the reader / writer in the traditional radio frequency communication technology into a receiver and an exciter, improves the performance and coverage of the system, and thus increases the communication distance of radio frequency communication. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the conventional technology, the following briefly introduces the drawings required for use in the embodiments or the conventional technology descriptions. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 Schematic diagram of the structure of a distributed passive Internet of Things optical cable identification system in one embodiment;

[0031] Figure 2 A schematic structural diagram of a passive Internet of Things optical cable identification system in another embodiment;

[0032] Figure 3 1 is a flow chart of the steps of decoding optical cable information in one embodiment;

[0033] Figure 4 Schematic diagram of FMO encoding in one embodiment;

[0034] Figure 5 A schematic diagram of a preamble in one embodiment;

[0035] Figure 6A schematic diagram showing an optical cable identification result page in one embodiment;

[0036] Figure 7 A schematic diagram of opening and closing the optical cable cover in one embodiment;

[0037] Figure 8 is a schematic diagram of optical cables at different depths according to one embodiment;

[0038] Figure 9 Schematic diagram of a passive tag with different orientations in one embodiment. DETAILED DESCRIPTION

[0039] To facilitate understanding of the present application, the present application will be described more fully below with reference to the accompanying drawings. The accompanying drawings provide embodiments of the present application. However, the present application may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to make the disclosure of the present application more thorough and comprehensive.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0041] It will be understood that the terms "first," "second," etc. used herein may be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish a first element from another element.

[0042] Spatially relative terms such as "under," "beneath," "beneath," "under," "above," "above," etc., may be used herein to describe the relationship of an element or feature shown in the figures to other elements or features. It should be understood that in addition to the orientations shown in the figures, spatially relative terms also include different orientations of the device in use and operation. For example, if the device in the drawings is turned over, the element or feature described as "under" or "beneath" or "beneath" the other elements will be oriented as "above" the other elements or features. Thus, the exemplary terms "under" and "under" can include both upper and lower orientations. In addition, the device can also include alternative orientations (e.g., rotated 90 degrees or other orientations), and the spatial descriptors used herein are interpreted accordingly.

[0043] It should be noted that when an element is considered to be "connected" to another element, it can be directly connected to the other element or connected to the other element through an intervening element. In addition, the "connection" in the following embodiments should be understood as "electrical connection", "communication connection", etc., if there is transmission of electrical signals or data between the connected objects.

[0044] When used herein, the singular forms "a", "an", and "the" may also include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" and the like specify the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof.

[0045] As mentioned in the background, existing optical cable identification technologies suffer from limited communication distance. The inventors' research has discovered that this problem stems from the fact that optical fiber communication in power systems is fundamental to power communications and offers advantages such as high bandwidth, strong anti-interference capabilities, and high security. However, the sheer number of power communication cables and the complex installation environment make identification of overhead and shallowly buried cables difficult and inefficient, severely hindering the operation, maintenance, and repair of power cables. Traditional optical cable identification and maintenance relies on on-site personnel collecting fiber resources and using paper labels and documentation. Overhead cables require personnel to inspect them on poles, a method that presents challenges such as difficult search and identification, high workload, and high risk. Therefore, developing an automated optical cable identification system that enables real-time monitoring is crucial for improving the efficiency of power cable operation, maintenance, and repair. Radio Frequency Identification (RFID) technology has been widely used in the Internet of Things (IoT) due to its advantages such as low cost, low power consumption, automation, and large capacity. However, as its application expands, challenges such as limited communication distance and low tag access capacity of traditional passive RFID systems have become increasingly apparent, limiting their further application.

[0046] Based on the above reasons, the present invention provides a distributed passive Internet of Things optical cable identification system, which aims to improve the communication distance of passive radio frequency identification.

[0047] In one embodiment, Figure 1 As shown, a distributed passive Internet of Things optical cable identification system 1 is provided, including: multiple passive tags 11, at least one exciter 12 and a receiver 13.

[0048] Among them, each passive tag 11 is respectively set on a different optical cable 14, and the optical cable 14 is set in a groove 15 under the ground. An optical cable cover 16 is set on the side of the groove 15 close to the ground. The passive tag 11 is used to store the encoded optical cable 14 information of the optical cable 14, and to send a backscattered signal in response to an excitation signal; the optical cable 14 information includes at least one of the optical cable 14 identification, the tag node position and the starting point of the optical cable 14; the exciter 12 is communicatively connected with each passive tag 11, and sends an excitation signal to the passive tag 11 set on at least one optical cable 14; the receiver 13 includes multiple antennas 131, and each antenna 131 is set on the side of the optical cable cover 16 away from the groove 15. The receiver 13 is used to receive the backscattered signal and the self-interference signal corresponding to the excitation signal, and use a cross-link interference elimination algorithm to filter the self-interference signal to obtain the backscattered signal, and successively demodulate and decode the backscattered signal to obtain the optical cable 14 information of the optical cable 14, and send the optical cable 14 information to the background server 17.

[0049] The optical cable 14 information may further include the optical cable 14 identification (such as serial number), label node location (such as GPS coordinates), optical cable 14 starting point, optical cable 14 type (feeder cable, distribution cable, etc.), maintenance records (such as installation date, last inspection time), and other metadata (such as manufacturer, length).

[0050] It is understood that the position of the exciter 12 does not affect the recognition of the passive tag 11 on the optical cable 14. Therefore, the position of the exciter 12 can be flexibly arranged and can be set according to the excitation effect of the exciter 12 on each passive tag 11. The multiple antennas 131 of the receiver 13 form an antenna 131 array, which can more accurately receive the backscattered signals sent by the passive tags 11. In addition, the specifications of the antennas 131 can be the same or customized according to actual needs. Configuration parameters such as module model, frequency band support range, interface type, and antenna 131 configuration are set based on actual communication requirements.

[0051] It should be noted that a passive tag 11 is provided for each optical cable 14, which is a one-to-one correspondence. The exciter 12 and the passive tag 11 can be a one-to-many correspondence. The exciter 12 that has the best excitation effect on the passive tag 11 of the optical cable 14 to be identified is preferably used to send the excitation signal. In addition, the passive tag 11 is fixed to the surface of the optical cable 14, and the fixing method can be pasting or the like. The orientation and position of the passive tag 11 on the surface of the optical cable 14 can be flexibly set, and there is no specific limitation on this. Due to the presence of multi-path communication and other scatterers in the system, regardless of whether the passive tag 11 is in a reflective state, the receiver 13 will always receive the continuous wave of the excitation signal emitted by the exciter 12. This link is called cross-link interference in the distributed passive Internet of Things optical cable 14 identification system. The continuous wave of the excitation signal received by the receiver 13 is called a self-interference signal. The receiver 13 uses a cross-link interference elimination algorithm to eliminate the self-interference signal, thereby making the received backscattered signal more accurate.

[0052] The above-mentioned distributed passive Internet of Things optical cable 14 identification system includes a plurality of passive tags 11, at least one exciter 12 and a receiver 13; wherein each passive tag 11 is respectively arranged on a different optical cable 14, and the optical cable 14 is arranged in a trench 15 under the ground, and an optical cable cover 16 is arranged on the side of the trench 15 close to the ground, and the passive tag 11 is used to store the encoded optical cable 14 information of the optical cable 14, and to send a backscattered signal in response to the excitation signal; the optical cable 14 information includes at least one of the optical cable 14 identification, the tag node position and the starting point of the optical cable 14; the exciter 12 is in communication connection with each passive tag 11, and sends an excitation signal to the passive tag 11 arranged on at least one optical cable 14, thereby improving the passive tag 11 The coverage range of radio frequency communication is increased; the receiver 13 includes multiple antennas 131, and each antenna 131 is arranged on the side of the optical cable cover 16 away from the groove 15. The receiver 13 is used to receive the backscattered signal and the self-interference signal corresponding to the excitation signal, and use the cross-link interference elimination algorithm to filter the self-interference signal to improve the accuracy and reliability of the received backscattered signal, obtain the backscattered signal, and demodulate and decode the backscattered signal in succession to obtain the optical cable 14 information of the optical cable 14, and send the optical cable 14 information to the background server 17. The system separates the reader / writer in the traditional radio frequency communication technology into the receiver 13 and the exciter 12, improves the performance and coverage of the system, and thus increases the communication distance of the radio frequency communication.

[0053] In one embodiment, the passive tag 11 is further used to modulate the impedance of the passive tag 11 to perform state switching, where the states include a reflective state and a non-reflective state;

[0054] The expressions corresponding to the status include:

[0055]

[0056] in, Indicates the state of the passive tag 11, , respectively represent the non-reflective and reflective states of the passive tag 11, represents the phase shift caused by the passive tag 11, Represents the excitation signal.

[0057] Passive tag 11 modulates its own impedance to switch states. A specific implementation involves integrating a variable load circuit (such as a switch-controlled resistor, capacitor, or inductor) within the tag 11. This load modulates the tag's impedance by switching the load. The load then causes the tag's internal impedance to match, maximizing backscatter and translating into a reflective state. The load also causes the tag's internal antenna 131 to mismatch, suppressing reflection and translating into a non-reflective state. This modulation process requires no external power supply and relies on the energy of an excitation signal to drive the switch (e.g., via a diode or microelectromechanical switch).

[0058] It is understandable that the passive tag 11 is also used to modulate the impedance of the passive tag 11 to switch between the reflective state and the non-reflective state, so that the passive tag 11 does not need to actively transmit signals and can transmit data only through backscattering, which significantly reduces energy consumption. In addition, the passive tag 11 relies on the excitation signal for power supply, and can reduce energy consumption in the non-reflective state (such as entering a low-power mode), thereby extending the life of the passive tag 11.

[0059] In one embodiment, a cross-link interference cancellation algorithm is used to filter the self-interference signal, including:

[0060] The receiver 13 is further configured to construct a reverse constant-amplitude signal of the self-interference signal according to a signal model of the self-interference signal and adopt a cross-link interference cancellation algorithm, and send the reverse constant-amplitude signal to the exciter 12 .

[0061] Among them, the signal model of the self-interference signal is a method of describing the signal characteristics and behaviors in mathematical or other forms.

[0062] It should be noted that if Figure 2 As shown, the distributed passive IoT optical cable 14 identification system includes: a downlink from the exciter 12 to the passive tag 11, an uplink from the passive tag 11 to the receiver 13, and a self-interference link from the exciter 12 to the receiver 13. A corresponding signal model is constructed for each communication link. The signal model corresponding to the excitation signal sent by at least one passive tag 11 on the optical cable 14, i.e., the downlink signal model, includes:

[0063]

[0064] in, represents the path attenuation from the exciter 12 to the passive tag 11, represents the random initial phase of the exciter 12, represents the phase delay of the excitation signal sent to the passive tag 11, f represents the frequency of the excitation signal, Represents the excitation signal.

[0065] The passive tag 11 is used to respond to the excitation signal and emit a signal model corresponding to the backscattered signal, that is, the uplink signal model, including:

[0066]

[0067] in, represents the path attenuation of the backscattered signal from the passive tag 11 to the receiver 13, represents the path delay from the passive tag 11 to the receiver 13, represents the backscattered signal, Indicates the state of the passive tag 11.

[0068] The signal model corresponding to the total communication link from the exciter 12 to the receiver 13 through the passive tag 11 is:

[0069]

[0070] in, represents the path attenuation from the actuator 12 to the tag, represents the random initial phase of the exciter 12, represents the phase delay of the signal from the actuator 12 to the tag, , respectively represent the non-reflective and reflective states of the tag, is the phase shift caused by the tag, represents the path attenuation from the tag to the antenna 131, represents the path delay from the tag to the antenna 131.

[0071] It is understandable that when the passive excitation tag is in a non-reflective state, the signal received by the receiver 13 is the received self-interference signal. The signal model corresponding to the self-interference signal corresponding to the excitation signal, that is, the signal model of the self-interference link, includes:

[0072]

[0073] in, represents the attenuation coefficient from the exciter 12 to the receiver 13, represents the phase delay from the exciter 12 to the receiver 13, represents the self-interference signal.

[0074] It can be understood that the receiver 13 is also used to construct a reverse equal-amplitude signal of the self-interference signal based on the signal model of the self-interference signal and adopt a cross-link interference elimination algorithm, and send the reverse equal-amplitude signal to the exciter 12. By sending a reverse equal-amplitude signal with the same amplitude and phase as the self-interference signal but opposite amplitude to the exciter 12, the self-interference signal generated by the excitation signal to the receiver 13 is offset, so that the backscattered signal sent by the passive tag 11 obtained by the receiver 13 is more accurate.

[0075] In one embodiment, the receiver 13 is also used to determine the baseband signal of the communication link of the receiver 13 based on the signal model of the self-interference signal, and to obtain the amplitude and phase of the signal of the communication link of the self-interference signal by adopting the cross-link interference elimination algorithm based on the baseband signal, and to construct a reverse equal-amplitude signal based on the amplitude and phase of the signal of the communication link of the self-interference signal, and to send the reverse equal-amplitude signal to the exciter 12.

[0076] It can be understood that, referring to the description of the above embodiment, the signal received by the receiver 13 is a mixture of the backscattered signal and the self-interference signal. The signal model of the signal received by the receiver 13 can be expressed as:

[0077]

[0078] in, The receiver 13 receives the signal, is the self-interference signal, is the backscattered signal, The state of the passive tag 11. The receiver 13 determines the baseband signal of the communication link of the self-interference signal according to the signal model of the self-interference signal. In addition, since the distributed passive IoT optical cable 14 identification system separates the reader into the exciter 12 and the receiver 13, the excitation and reception no longer use the same clock, resulting in a carrier frequency deviation in the down-converted baseband signal. , therefore, the baseband signal can be expressed as:

[0079]

[0080] in, is the total uplink attenuation coefficient of the excitation signal after it is backscattered by the passive tag 11. is the self-interference link amplitude coefficient, is the total phase shift of the excitation signal propagating through the passive tag 11, The receiver 13 receives the baseband signal of the communication link.

[0081] In this embodiment, the baseband signal of the communication link of receiver 13 is determined. The baseband signal is a low-frequency signal with the carrier frequency removed, and directly carries the amplitude, phase, and modulation information of the self-interference signal. By extracting the baseband signal, receiver 13 can accurately analyze the characteristics of the self-interference signal (such as delay, frequency offset, channel response, etc.), thereby more accurately filtering the self-interference signal and extracting the backscattered signal.

[0082] In one embodiment, the cross-link interference cancellation algorithm is used according to the baseband signal to obtain the amplitude and phase of the communication link signal of the self-interference signal, including:

[0083] The receiver 13 is further configured to use a cross-link interference cancellation algorithm to compensate for the carrier frequency offset of the baseband signal, and obtain the amplitude and phase of the communication link signal of the self-interference signal.

[0084] It can be understood that, referring to the description of the above embodiment, after determining the baseband signal of the communication link of the receiver 13, because there is a carrier frequency offset, the receiver 13 is also used to use a cross-link interference cancellation algorithm to compensate for the carrier frequency offset of the baseband signal and obtain the amplitude and phase of the signal of the communication link of the self-interference signal. First, based on the baseband signal of the communication link of the receiver 13, the carrier frequency offset is estimated. , and then multiply the baseband signal by The carrier frequency offset is compensated, thereby effectively eliminating the carrier frequency offset. The signal model of the baseband signal of the communication link of the receiver 13 after eliminating the carrier frequency offset is:

[0085]

[0086] when , that is, when the passive tag 11 is in a non-reflective state, the received signal only has a self-interference link, and by estimating the amplitude of the self-interference signal and phase ,Constructing a reverse equal-amplitude signal can eliminate cross-link interference in the digital domain, thus enabling ,more accurate extraction of the backscattered signal.

[0087] In one embodiment, the receiver 13 is also used to demodulate the backscattered signal to obtain the FM0 code, decode the FM0 code to obtain the decoded optical cable 14 information, and perform CRC check on the decoded optical cable 14 information. When the end bit of the FM0 code is checked, the optical cable 14 information is sent to the background server 17.

[0088] Among them, FM0 code is a bi-phase interval code, which uses level changes in a bit window to represent logical data.

[0089] The specific implementation method for receiver 13 to perform decoding is as follows: when identifying optical cable 14, exciter 12 first modulates the signal through the RF module and issues a series of read commands for passive tag 11. When passive tag 11 enters the response area of exciter 12, it receives RF energy and begins to demodulate the reader's instructions. Only after correctly receiving the read command will passive tag 11 send its ID information and other data back to receiver 13 via backscatter. Receiver 13 demodulates the received backscatter signal into a baseband signal and then sends it to the processor for decoding. The specific decoding steps are as follows: Time interval classification: Through the reader command setting, the passive tag 11 can return data at a rate of 160Kb / s. The interval between two adjacent edges of the FM0 code can only have three possible situations: 0.5T, T, and 1.5T. Under a 12 MHz external clock, the upper and lower half-widths of "0" are 3.125μs, and the captured timer count value is about 0x25, recorded as 0.5T; the bit width of a received "0" or "1" is 6.25μs, and the captured timer count value is about 0x4B, recorded as T; in the preamble, the bit width of "V" is 9.375μs, and the captured timer count value is about 0x70, recorded as 1.5T. The decoding flow chart is attached. Figure 3 As shown. Preamble synchronization: When decoding the received FM0 code, since there is no synchronization signal, data synchronization must be performed first. This means decoding 12 consecutive zeros and the subsequent 1010 V1 preamble data before the required data can be decoded. When decoding the preamble, the first 12 zeros are arranged according to the principle that two 0.5Ts form one zero. Decoding must continue until 24 consecutive 0.5Ts have occurred; otherwise, the system will return to counting 12 zeros again. When decoding 1010 V1, pay attention to a special bit, "V." It is only recorded when a 1.5T width of data is captured. During this period, if a single bit is decoded incorrectly, the system will return to counting 12 zeros again. Only when the entire preamble is decoded correctly can the required data be decoded. The width of the captured data, whether 0.5T or 1T, determines whether it is a half-zero or a full 1. Data decoding rules: Based on the characteristics of FM0 code, when an "H" or "L" is captured, the operator must determine whether the 0.5T represents the first or last half of a "0." If it represents the first half, the operator must wait for the next 0.5T to combine with the remaining half of the previous half to form a "0." If it represents the last half, the operator must combine it with the remaining half of the previous half to form a "0." Capturing data with a width of one T is recorded as a "1."

[0090] The verification process is implemented as follows: the FM0 code returned by passive tag 11 may contain either CRC5, CRC16, or no checksum. Codes with CRC must undergo CRC verification after decoding. If the CRC is correct when the stop bit is detected, communication is normal and the next step can proceed. The receive circuit may contain a lot of noise signals and glitches leaking from the transmit circuit. Multiple consecutive "0"s may appear on the receive circuit, forming 24 consecutive 0.5T intervals. This may be mistakenly identified as the start of a preamble. However, the subsequent preamble decoding process will fail when a 1.5T wide "V" appears. Errors may also occur during verification or stop bit detection, requiring a new preamble search.

[0091] In this embodiment, receiver 13 performs FM0 demodulation on the backscattered signal (to extract the level transition timing), then converts it into binary data (such as the identification and location information of optical cable 14) according to encoding rules, ensuring efficient restoration of the original information. Furthermore, a CRC check is performed to ensure the integrity of the optical cable 14 information sent to backend server 17.

[0092] In one embodiment, the receiver 13 is also used to receive the optical cable 14 information sent by the background server 17 when no information is written to the passive tag 11, and to encode the optical cable 14 information using the FM0 encoding algorithm to obtain the encoded optical cable 14 information, and to write the encoded optical cable 14 information into the passive tag 11.

[0093] It is understood that the specific implementation method of using the FM0 encoding algorithm to encode the optical cable 14 information is to use level changes within a bit window to represent logic. If the level flips from the beginning of the bit window, it represents a logical "1"; if the level flips not only at the beginning of the bit window but also in the middle of the bit window, it represents a logical "0"; according to the rules of FM0 encoding, it can be found that no matter whether the transmitted data is 0 or 1, a jump must occur at the beginning of the bit window, as shown in the attached figure. Figure 4 As shown. According to the EPCGen2 protocol, the data received from the tag is in FM0 encoding format and starts with a preamble. The preamble consists of two parts: the first 12 leading zeros and the following 6 specific bits. It should be noted that there is a 1-bit offset in the preamble (that is, the phase inversion should occur but it actually does not), which is represented by "V". It is used to distinguish the preamble from the data code. The preamble is followed by the received data, as shown in the attached figure. Figure 5 shown.

[0094] In this embodiment, when no information is written to the passive tag 11, such as the optical cable 14 information during the production, deployment or maintenance process of the optical cable 14, the receiver 13 background server 17 sends the optical cable 14 information, and uses the FM0 encoding algorithm to encode the optical cable 14 information to obtain the encoded optical cable 14 information, and write the encoded optical cable 14 information into the passive tag 11, paving the way for subsequent identification of the optical cable 14.

[0095] In one embodiment, a distributed passive IoT optical cable 14 identification method is provided, which is applied to the distributed passive IoT optical cable 14 identification system of any of the above embodiments. The method includes:

[0096] Step 1: The passive tag 11 stores the encoded optical cable 14 information of the optical cable 14 and emits a backscattered signal in response to an excitation signal; the optical cable 14 information includes at least one of the optical cable 14 identification, the tag node location, and the starting point of the optical cable 14;

[0097] Step 2: at least one exciter 12 sends an excitation signal to a passive tag 11 disposed on at least one optical cable 14;

[0098] In step 3, the receiver 13 receives the backscatter signal and the self-interference signal corresponding to the excitation signal, and uses a cross-link interference elimination algorithm to filter the self-interference signal to obtain the backscatter signal, and successively demodulates and decodes the backscatter signal to obtain the optical cable 14 information of the optical cable 14, and sends the optical cable 14 information to the background server 17.

[0099] For example, Figure 6 As shown in the figure, the passive IoT optical cable identification system display interface is provided, from which it can be seen that three tags have been successfully identified. According to the EPC (Electronic Product Code), it can be determined which tag is associated with the optical cable, and the information contained in it, such as the optical cable name, starting point, and location, can be interpreted to successfully achieve optical cable identification.

[0100] In one embodiment, the inventor provides test verification results for the reliability of the above embodiment, including three groups of tests, wherein:

[0101] The first set of tests studied the effect of concrete cable covers on signal attenuation. Except for opening and closing the covers, the other conditions remained the same as before, as shown in the attached figure. Figure 7 The signal strength and bit error rate were recorded in the open (cable cover) and closed scenes, and the recognition results are shown in Table 1:

[0102] Table 1

[0103]

[0104] When the fiber optic cable is buried at a depth of 0.4m, all passive tags can be read normally with the cover open. However, when the cover is closed and the original settings are maintained, the tags cannot be read correctly. Replacing the high-power excitation antenna (exciter) (12dBi) and changing the exciter tilt angle, or using a low-power antenna (9dBi) and increasing the transmitter power to 30dB, all tags can be read correctly. The results show that the concrete fiber optic cable cover attenuates the tag signal, but increasing the transmitter power or the excitation antenna gain can still correctly read all tags.

[0105] The second set of tests studied the effect of cable burial depth on identification results. The tests were conducted at the measured depths of 0.4m, 0.4m with a concrete cable cover, 1.2m, and 1.2m with a plastic cable cover. The other conditions remained the same as before, as shown in the attached figure. Figure 8 The strength and accuracy of the recognition signal were tested. The test results are shown in Table 2:

[0106] Table 2

[0107]

[0108] The results show that all tags can be successfully identified at measured depths of 0.4m, 0.4m with a concrete cable cover, 1.2m, and 1.2m with a plastic cable cover. The experimental conclusion is: all tags can be easily identified at a depth of 0.4m with a cover; at a depth of 1.2m with a cover, a high-excitation antenna and the appropriate excitation direction are required to successfully identify all tags.

[0109] The third set of tests studied the effect of the tag's orientation on the recognition effect, changed the tag's rotation direction, tested the changes in the recognition signal, and analyzed the impact of different directions on signal recognition. The experiment set up tags with different orientations in the 0.4m optical cable trench and the 1.2m optical cable trench, including the upward, tilted downward, and downward directions. In the scenario where the optical cable trench depth is 1.2m, a total of 5 tags were deployed, including 4 on the surface and 1 on the back. Tags including those on the back of the optical cable can also be successfully identified, but a high-power exciter is required to adjust the angle and orientation, and the receiving antenna needs to cover multiple directions to capture the weak signal of the tag. The experimental setup is shown in the attached figure. Figure 9 The test results are shown in Table 3:

[0110] Table 3

[0111]

[0112] The test concluded that the method can correctly identify tags in various rotational orientations, even when attached to the front, side, or directly below the optical cable. In deep cable trenches, a high-gain excitation antenna, along with appropriate receiving orientation and excitation direction, is required to correctly read all tags. These results demonstrate the effectiveness and stability of the proposed method.

[0113] It should be understood that, although the various steps in the flowcharts involved in the various embodiments described above are displayed in sequence according to the instructions of the arrows, these steps are not necessarily executed in sequence in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and these steps can be executed in other orders. Moreover, at least a portion of the steps in the flowcharts involved in the various embodiments described above can include multiple steps or multiple stages, and these steps or stages are not necessarily executed and completed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a portion of steps or stages in other steps.

[0114] Those skilled in the art will appreciate that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the above-mentioned embodiments. In particular, any reference to memory, database, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The databases involved in the various embodiments provided herein may include at least one of a relational database and a non-relational database. Non-relational databases may include, but are not limited to, distributed databases based on blockchains. The processors involved in the various embodiments provided herein may be, but are not limited to, general-purpose processors, central processing units (CPUs), graphics processing units (GPUs), digital signal processors (DSPs), programmable logic devices (PLDs), data processing logic devices based on quantum computing, and the like.

[0115] Throughout this specification, references to terms such as "some embodiments," "other embodiments," and "desired embodiments" indicate that a particular feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. Although these terms are used interchangeably throughout this specification, they do not necessarily refer to the same embodiment or example.

[0116] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0117] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A distributed passive Internet of Things optical cable identification system, characterized in that: The system comprises: A plurality of passive tags, each of the passive tags being disposed on a different optical cable, the optical cable being disposed in a trench beneath the ground, a cable cover being disposed on a side of the trench close to the ground, the passive tags being configured to store encoded optical cable information of the optical cable and to emit a backscattered signal in response to an excitation signal; the optical cable information including at least one of an optical cable identifier, a tag node location, and an optical cable starting point; At least one exciter, communicatively connected to each of the passive tags, and configured to send an excitation signal to the passive tags disposed on at least one optical cable; A receiver comprising a plurality of antennas, each of which is arranged on a side of the optical cable cover away from the groove, the receiver being used to receive the backscattered signal and the self-interference signal corresponding to the excitation signal, and to filter the self-interference signal using a cross-link interference elimination algorithm to obtain the backscattered signal, and to successively demodulate and decode the backscattered signal to obtain optical cable information of the optical cable, and to send the optical cable information to a background server.

2. The distributed passive Internet of Things optical cable identification system according to claim 1, characterized in that: The adopting a cross-link interference cancellation algorithm to filter the self-interference signal includes: The receiver is further configured to construct a reverse constant-amplitude signal of the self-interference signal using a cross-link interference cancellation algorithm according to a signal model of the self-interference signal, and send the reverse constant-amplitude signal to the exciter.

3. The distributed passive Internet of Things optical cable identification system according to claim 2, characterized in that: The receiver is further configured to determine a baseband signal of a communication link of the receiver based on a signal model of the self-interference signal, and to obtain an amplitude and phase of a signal of the communication link of the self-interference signal using a cross-link interference cancellation algorithm based on the baseband signal, and to construct a reverse constant-amplitude signal based on the amplitude and phase of the signal of the communication link of the self-interference signal, and to send the reverse constant-amplitude signal to the exciter.

4. The distributed passive Internet of Things optical cable identification system according to claim 3, characterized in that: The step of obtaining the amplitude and phase of the communication link signal of the self-interference signal by adopting a cross-link interference cancellation algorithm according to the baseband signal comprises: The receiver is further configured to compensate for the carrier frequency offset of the baseband signal by adopting a cross-link interference cancellation algorithm to obtain the amplitude and phase of the signal of the communication link of the self-interference signal.

5. The distributed passive Internet of Things optical cable identification system according to claim 1, characterized in that: The signal model corresponding to sending an excitation signal to a passive tag disposed on at least one optical cable includes: in, represents the path attenuation from the exciter to the passive tag, represents the random initial phase of the exciter, represents the phase delay of the excitation signal sent to the passive tag, f represents the frequency of the excitation signal, represents the excitation signal.

6. The distributed passive Internet of Things optical cable identification system according to claim 5, characterized in that: The passive tag is further used to modulate the impedance of the passive tag to perform state switching, wherein the states include a reflective state and a non-reflective state; The expressions corresponding to the states include: in, represents the state of the passive tag, , respectively represent the non-reflective and reflective states of the passive tag, represents the phase shift caused by the passive tag.

7. The distributed passive Internet of Things optical cable identification system according to claim 6, characterized in that: The passive tag is used to respond to the excitation signal and emit a signal model corresponding to the backscattered signal, including: in, represents the path attenuation of the backscattered signal from the passive tag to the receiver, represents the path delay from the passive tag to the receiver, represents the backscattered signal.

8. The distributed passive Internet of Things optical cable identification system according to claim 7, characterized in that: The signal model corresponding to the self-interference signal corresponding to the excitation signal includes: in, represents the attenuation coefficient from the exciter to the receiver, represents the phase delay from the exciter to the receiver, represents the self-interference signal.

9. The distributed passive Internet of Things optical cable identification system according to claim 1, characterized in that: The receiver is also used to demodulate the backscattered signal to obtain the FM0 code, decode the FM0 code to obtain the decoded optical cable information, and perform CRC check on the decoded optical cable information. When the end bit of the FM0 code is checked, the optical cable information is sent to the background server.

10. The distributed passive Internet of Things optical cable identification system according to any one of claims 1 to 9, characterized in that: The receiver is also used to receive the optical cable information sent by the background server when no information is written to the passive tag, and to encode the optical cable information using the FM0 encoding algorithm to obtain the encoded optical cable information, and to write the encoded optical cable information into the passive tag.

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