High-precision synchronous fire emergency broadcasting system and method with state feedback

Abstract

The invention provides a high-precision synchronous fire-fighting emergency broadcasting system and method with state feedback, relates to the field of fire-fighting emergency broadcasting, and solves the technical problems that a traditional fire-fighting emergency broadcasting system is low in time synchronization precision, unknowable in playing state and unverifiable in integrity. The method comprises the following steps: acquiring a plurality of timestamps of a time synchronization message, and analyzing a clock delay amount; analyzing the current temperature compensation clock drift amount of each broadcast terminal; analyzing the clock correction amount of each broadcast terminal based on the clock delay amount and the temperature compensation clock drift amount, and correcting the clock of each broadcast terminal based on the clock correction amount; and constructing an original audio fingerprint sequence and a return audio fingerprint sequence, and analyzing the playing integrity of each broadcast terminal. The application is used in a fire-fighting emergency broadcast process.

Description

Technical Field

[0001] This application relates to the field of fire broadcasting, and in particular to a high-precision synchronous fire emergency broadcasting system and method with status feedback. Background Technology

[0002] In modern fire emergency systems, emergency broadcasting serves as a crucial means of information transmission in emergencies, and its reliability and real-time performance directly impact personnel evacuation efficiency and life safety. Traditional fire emergency broadcasting systems often employ a centralized control center for unified playback and passive terminal response, resulting in problems such as low time synchronization accuracy, unknowable playback status, and inability to verify integrity. Therefore, this invention provides a high-precision synchronous fire emergency broadcasting system and method with status feedback. Summary of the Invention

[0003] This application provides a high-precision synchronous fire emergency broadcasting system and method with status feedback, which solves the technical problems of low time synchronization accuracy, unknown playback status, and inability to verify integrity in traditional fire emergency broadcasting systems.

[0004] To achieve the above objectives, this application adopts the following technical solution: Firstly, a high-precision synchronous fire emergency broadcasting method with status feedback is provided, including: The fire control center sends time synchronization messages to multiple broadcast terminals and obtains several timestamps from the time synchronization messages to analyze the clock delay; wherein, the timestamps are the times when the fire control center and broadcast terminals receive or send the time synchronization messages; In addition, the temperature-compensated clock drift of each broadcast terminal is analyzed; wherein the clock drift is the clock error caused by changes in ambient temperature of the broadcast terminal. Based on the clock delay and temperature-compensated clock drift, the clock correction of each broadcast terminal is analyzed, and the clock of each broadcast terminal is corrected based on the clock correction. After clock calibration of each broadcast terminal, the fire control center sends a playback instruction with a preset playback time to multiple broadcast terminals; upon receiving the playback instruction, each broadcast terminal returns a receipt confirmation receipt to the fire control center. When the local clock of each broadcast terminal reaches the preset playback time, the broadcast audio signal is played synchronously, and the played audio signal is collected and marked as the return audio signal; the audio characteristics of the return audio signal are extracted and sent to the fire control center. The fire control center analyzes the playback integrity of each broadcast terminal based on the audio characteristics of the returned audio signals.

[0005] Based on the above technical solution, this application provides a high-precision synchronous fire emergency broadcasting method with status feedback. By combining high-precision time synchronization and temperature compensation technologies, all broadcasting terminals achieve millisecond-level time alignment, ensuring highly consistent playback timing. The fire control center sends playback instructions with precise timestamps, and each terminal immediately sends back a confirmation signal upon receipt, ensuring reliable instruction transmission. At a specified time, all terminals synchronously play audio and locally collect the playback content in real time, extracting characteristic data such as MFCC (Melbourne Frequency Cepstral Coefficient) and audio energy, which are then uploaded to the center. The fire control center analyzes and judges whether each terminal has accurately and completely executed the playback task through multi-dimensional feature comparison. This mechanism constructs a complete closed loop of "instruction issuance—execution response—status feedback—result verification," comprehensively covering the entire process from instruction reception to playback execution. The system can not only promptly detect playback omissions, delays, or audio quality distortion, but also trigger real-time alarms and link emergency response, significantly improving the collaborative efficiency, operational reliability, and centralized control capabilities of the fire broadcasting system.

[0006] In conjunction with the first aspect above, in one possible implementation, obtaining several timestamps of the time synchronization message includes: The time synchronization messages include Sync messages, Delay_Req messages, and Delay_Resp messages; The time when the fire control center sends the Sync message is marked as a timestamp. and will the first timestamp Encapsulated in a Sync message and sent to the broadcast terminal; The moment when the broadcast terminal receives the Sync message is marked as the second timestamp. ; The moment when the broadcast terminal sends the Delay_Req message to the fire control center is marked as a third timestamp. ; The moment when the fire control center receives the Delay_Req message is marked as the fourth timestamp. It is then encapsulated in a Delay_Resp message and returned to the broadcast terminal.

[0007] In conjunction with the first aspect above, in one possible implementation, the analysis of the temperature-compensated clock drift of each broadcast terminal includes: Obtain some crystal oscillator frequency and temperature data for broadcast terminal i from historical data, and establish a mapping model between the crystal oscillator frequency and temperature of broadcast terminal i: ; Where i is the sequence number of the broadcast terminal, and is a positive integer. For the frequency deviation of broadcast terminal i, The ambient temperature of the current broadcast terminal i. For the target temperature, All are temperature drift coefficients, and all have values ​​of (0,1]. Based on the frequency deviation of the current broadcast terminal i Through formula The clock drift of the current broadcast terminal i is calculated. :in, Nominal frequency, The time interval for sending Sync messages to the fire control center.

[0008] In conjunction with the first aspect above, in one possible implementation, the analysis of the clock correction amount of each broadcast terminal includes: Based on the first timestamp Second timestamp Third timestamp and the fourth timestamp Through formula The clock delay of the broadcast terminal was calculated. ; Based on temperature-compensated clock drift and clock delay Through formula + The clock correction amount of broadcast terminal i is calculated. ;in, For correction factor, .

[0009] In conjunction with the first aspect above, in one possible implementation, when the fire control center does not receive a reception confirmation from broadcast terminal i, it marks broadcast terminal i as having a communication anomaly and triggers an offline alarm for the device.

[0010] In conjunction with the first aspect above, in one possible implementation, the method for acquiring the returned audio signal includes: Before starting to play the broadcast audio signal, the broadcast terminal presets an audio acquisition time window and acquires the playback return audio signal through a microphone within the preset audio acquisition time window; wherein, the length of the audio acquisition time window is greater than the duration of the broadcast audio signal, and a first protection time is reserved before the start of playback and a second protection time is reserved after the end of playback; each broadcast terminal is equipped with a microphone device.

[0011] In conjunction with the first aspect above, in one possible implementation, the analysis of the playback integrity of each broadcast terminal includes: Extract audio features from broadcast audio signals to construct the original audio fingerprint sequence. The original audio fingerprint sequence is a set of audio features of the broadcast audio signal; Extract audio features from the returned audio signal to construct the returned audio fingerprint sequence. The returned audio fingerprint sequence is a set of audio features of the returned audio signal. Calculate the original audio fingerprint sequence With the returned audio fingerprint sequence similarity distance between ; Based on similarity distance Through formula The playback integrity index value of broadcast terminal i is calculated. ; Determine the playback integrity index value Does it exceed a preset threshold? If yes, broadcast terminal i plays the entire message; otherwise, broadcast terminal i plays the message incompletely, and broadcast terminal i is inspected. This is the preset maximum distance.

[0012] In conjunction with the first aspect above, in one possible implementation, the original audio fingerprint sequence The construction process includes: The broadcast audio signal is divided into frames, and the first N order Mel-frequency cepstral coefficients of each frame are extracted. and energy value ;in, The sequence number of the frame. , For frame number, For the first The energy value of a frame. , For the first The first frame of the audio signal The amplitude value of each sampling point; The sampling point number, , is the total number of sampling points; N is the dimension of the Mel frequency cepstral coefficients extracted from each frame of audio, N>0 and is a positive integer. For the first The N-dimensional Mel frequency cepstral coefficient vector of the frame; The original audio fingerprint sequence was constructed. ; The returned audio fingerprint sequence The construction process includes: Using the same framing parameters and feature extraction algorithm as the broadcast audio signal, audio features of the returned audio signal are extracted to construct the returned audio fingerprint sequence. .

[0013] In conjunction with the first aspect above, in one possible implementation, the calculation of the original audio fingerprint sequence... With the returned audio fingerprint sequence similarity distance between ,include: ; in, For broadcast audio signals Frames The audio signal returned to broadcast terminal i Frames The Euclidean distance between them For broadcast audio signals Frames The audio signal returned to broadcast terminal i Frames The absolute value of the difference between them , , Let y be the path of the y-th frame pair, where y is the number of frame pair paths and is a positive integer. For the y-th path The Middle Frame and the Frame alignment, Σ represents the alignment of the y-th path All frame pairs Summation of the Euclidean distances between them , This is the proportionality coefficient, and its value is (0,1).

[0014] Secondly, this application provides a high-precision synchronous fire emergency broadcasting system with status feedback, including: an acquisition module, a correction module, and an integrity verification module; the acquisition module is used to acquire several timestamps of the time synchronization message; the correction module is used to analyze the clock delay and the temperature-compensated clock drift of each broadcast terminal; based on the clock delay and the temperature-compensated clock drift, the clock correction of each broadcast terminal is analyzed, and the clock of each broadcast terminal is corrected based on the clock correction; the integrity verification module is used to construct the original audio fingerprint sequence and the returned audio fingerprint sequence, and analyze the playback integrity of each broadcast terminal.

[0015] This application provides a high-precision synchronous fire emergency broadcasting system and method with status feedback. By combining a time synchronization mechanism with temperature compensation, it achieves millisecond-level ultra-high precision clock alignment between broadcasting terminals, ensuring that all terminals start and stop playback synchronously under a unified absolute time reference, completely eliminating voice misalignment or overlap problems caused by clock deviations. Combined with preset playback time commands and a receiving confirmation receipt mechanism, a closed-loop control process of "issuance—confirmation—execution—feedback" is constructed to ensure the manageability and controllability of playback tasks. By collecting and transmitting the acoustic characteristics of the playback audio signals locally at the terminals, the fire control center can... Multidimensional fingerprinting (MCC + energy) and dynamic time warping algorithm are used for integrity comparison, realizing automated and quantitative verification of whether audio content is complete and played accurately. The overall architecture introduces a full-process status feedback mechanism, covering the entire lifecycle from command reception, clock correction, playback execution to result auditing. It can not only monitor the operating status of each terminal in real time, but also promptly alarm and trigger maintenance when playback is abnormal or equipment fails. This significantly improves the reliability, coordination and traceability of the fire emergency broadcast system, truly achieving the high-security communication goal of "commands must be delivered, playback must be accurate, process is visible, and anomalies can be judged". Attached Figure Description

[0016] Figure 1 A system architecture diagram of a high-precision synchronous fire emergency broadcast system with status feedback provided in this application embodiment; Figure 2 A flowchart illustrating a high-precision synchronous fire emergency broadcasting method with status feedback provided in an embodiment of this application; Figure 3 This is a flowchart illustrating a fire emergency broadcasting method provided in an embodiment of this application. Detailed Implementation

[0017] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] The high-precision synchronous fire emergency broadcasting method with status feedback provided in this application embodiment can be applied to a high-precision synchronous fire emergency broadcasting device with status feedback, such as... Figure 1 As shown, the communication device includes: fire control center 101 and broadcast terminals (including 102, 103...).

[0019] The fire control center 101 sends time synchronization messages to multiple broadcast terminals and obtains several timestamps of the time synchronization messages. It analyzes the clock delay and the current temperature-compensated clock drift of each broadcast terminal. Based on the clock delay and temperature-compensated clock drift, it analyzes the clock correction of each broadcast terminal and corrects the clock of each broadcast terminal based on the clock correction. After the clocks of each broadcast terminal are calibrated, the fire control center 101 sends a playback instruction with a preset playback time to multiple broadcast terminals; after receiving the playback instruction, each broadcast terminal returns a receipt confirmation receipt to the fire control center 101. When the local clock of each broadcast terminal reaches the preset playback time, the broadcast audio signal is played synchronously, and the played audio signal is collected and marked as the return audio signal; the audio characteristics of the return audio signal are extracted and sent to the fire control center 101. The fire control center 101 determines the playback integrity of each broadcast terminal based on the audio characteristics of the returned audio signal.

[0020] To address the technical problems of low time synchronization accuracy, unknown playback status, and inability to verify integrity in traditional fire emergency broadcast systems, this application provides a high-precision synchronized fire emergency broadcast method with status feedback. The method includes: the fire control center sending time synchronization messages to multiple broadcast terminals, obtaining several timestamps from the time synchronization messages, and analyzing clock delay; analyzing the temperature-compensated clock drift of each broadcast terminal; analyzing the clock correction of each broadcast terminal based on the clock delay and temperature-compensated clock drift, and correcting the clock of each broadcast terminal based on the clock correction; after clock correction of each broadcast terminal, the fire control center... The fire control center sends playback instructions with preset playback times to multiple broadcast terminals. Upon receiving the playback instructions, each broadcast terminal sends a confirmation receipt back to the fire control center. When the local clock of each broadcast terminal reaches the preset playback time, it synchronously plays the broadcast audio signal and collects the played audio signal, marking it as a return audio signal. The audio features of the return audio signal are extracted and sent to the fire control center. The fire control center determines the playback integrity of each broadcast terminal based on the audio features of the return audio signal. Based on this, by integrating high-precision time synchronization and temperature compensation mechanisms, it ensures that each broadcast terminal achieves clock alignment within milliseconds, unifying the playback sequence. The fire control center issues playback instructions with time tags, and the terminals receive and send back confirmation, ensuring reliable delivery of the instructions. At the preset time, all terminals synchronously play and locally collect audio, extracting MFCC and energy features for return. The fire control center determines whether the audio content is complete and accurately broadcast through multi-dimensional feature comparison. The entire process constructs a closed-loop monitoring system of "command-execution-feedback-verification", covering the entire lifecycle of the terminal from receiving, responding to playing. It can not only effectively identify problems such as missing playback, delay or distortion, but also provide real-time alarms and initiate handling measures, comprehensively improving the coordination, reliability and manageability of the fire broadcast system.

[0021] like Figure 2 As shown in the figure, an embodiment of this application provides a high-precision synchronous fire emergency broadcasting method with status feedback, comprising: S201. The fire control center sends time synchronization messages to multiple broadcast terminals, obtains several timestamps of the time synchronization messages, and analyzes the clock delay. The timestamp represents the moment when the fire control center or broadcast terminal receives or sends a time synchronization message.

[0022] Time synchronization messages include Sync messages, Delay_Req messages, and Delay_Resp messages; The time when the fire control center sends the Sync message is marked as a timestamp. and will the first timestamp Encapsulated in a Sync message and sent to the broadcast terminal; The moment when the broadcast terminal receives the Sync message is marked as the second timestamp. ; The time when the broadcast terminal sends the Delay_Req message to the fire control center is marked as a third timestamp. ; The moment the fire control center receives the Delay_Req message is marked as the fourth timestamp. It is then encapsulated in a Delay_Resp message and returned to the broadcast terminal.

[0023] Based on the above technical solution, this time synchronization method is based on the core mechanism of IEEE 1588 PTP. By exchanging Sync, Delay_Req and Delay_Resp messages between the fire control center and multiple broadcast terminals and recording four key timestamps, it can calculate the bidirectional transmission delay and clock deviation of the network with high precision, thereby achieving microsecond-level time synchronization.

[0024] S202. Analyze the current temperature compensation clock drift of each broadcast terminal; Among them, clock drift is the clock error caused by changes in ambient temperature at the broadcast terminal.

[0025] It should be noted that the clock offset is mainly due to the fact that the local crystal oscillator frequency of the broadcast terminal is not completely consistent with the standard clock frequency of the fire control center. Ideally, all equipment uses crystal oscillators of the same frequency, but due to the influence of ambient temperature changes, the actual output frequency of the crystal oscillator will have a slight deviation, i.e., "clock drift". For example, a crystal oscillator nominally rated at 24MHz may actually operate at 24.0001MHz or 23.9998MHz. This frequency deviation will cause the terminal clock to run slightly faster or slower. As time goes by, the difference between the local time and the main control time will continue to accumulate, thus forming the clock offset, which is the absolute time difference between the two at a certain moment.

[0026] S203. Based on the clock delay and temperature-compensated clock drift, analyze the clock correction amount of each broadcast terminal, and correct the clock of each broadcast terminal based on the clock correction amount.

[0027] S204. After the clocks of each broadcast terminal are calibrated, the fire control center sends a playback instruction with a preset playback time to multiple broadcast terminals; after receiving the playback instruction, each broadcast terminal returns a receipt confirmation acknowledgment to the fire control center.

[0028] It should be noted that after all broadcast terminals complete clock synchronization calibration, the fire control center sends a playback instruction carrying a preset playback time, i.e., a precise future time, such as "2025-10-23 10:00:00.000", to all target terminals. This time is based on a calibrated global time reference, ensuring that all terminals execute playback according to a unified timeline. After successfully receiving and parsing the instruction, each broadcast terminal immediately returns a receipt confirmation acknowledgment to the fire control center, indicating "I have received the instruction and am ready". The fire control center collects all acknowledgments to confirm whether the instruction is fully covered, whether the terminals are online and in normal condition, thus forming a closed-loop control to avoid some terminals not responding due to network packet loss or equipment failure, and to ensure the reliable start of emergency broadcasts.

[0029] S205. When the local clock of each broadcast terminal reaches the preset playback time, the broadcast audio signal is played synchronously, and the played audio signal is collected and marked as a return audio signal; the audio characteristics of the return audio signal are extracted and sent to the fire control center.

[0030] The specific method for acquiring and playing audio signals is as follows: before starting to play the broadcast audio signal, the broadcast terminal presets an audio acquisition time window, and acquires the playback feedback audio signal through a microphone within the preset audio acquisition time window; wherein, the length of the audio acquisition time window is greater than the duration of the broadcast audio signal, and a first protection time is reserved before the start of playback, and a second protection time is reserved after the end of playback; each broadcast terminal is equipped with a microphone device.

[0031] It should be noted that when the local clocks of each broadcast terminal synchronize to the playback time pre-specified by the fire control center, all broadcast terminals trigger the playback task at the same time, achieving strict time synchronization and ensuring consistent spatial sound coverage. Simultaneously, the terminals activate their local microphones or audio acquisition modules to record the playing audio signal in real time and mark it as a "return audio signal" for subsequent integrity verification. Subsequently, the broadcast terminals extract key audio features from this return signal, such as Mel-frequency cepstral coefficients (MFCC) and energy, and package and send them to the fire control center for comparison with the audio features of the original broadcast audio signal. This comparison determines whether the terminal has truly and completely played the specified content, enabling remotely verifiable playback auditing.

[0032] S206. The fire control center determines the playback integrity of each broadcast terminal based on the audio characteristics of the returned audio signal.

[0033] Based on the above technical solution, this application provides a high-precision synchronous fire emergency broadcasting method with status feedback. Through time synchronization and temperature compensation technologies, millisecond-level precise clock alignment between broadcasting terminals is achieved, ensuring that all terminals start and stop playback synchronously at the same time. The fire control center sends a playback command with a preset time, and the terminal receives and sends back confirmation, forming an execution closed loop. During playback, the terminal collects the returned audio and extracts acoustic features. The fire control center uses a fingerprint comparison algorithm based on MFCC and energy fusion to determine whether the playback content is complete and accurate. This mechanism realizes end-to-end status feedback from command reception, clock correction, playback execution to result verification. This not only improves system coordination and anti-interference capabilities but also promptly alarms and triggers maintenance when anomalies such as frame loss, silence, or distortion occur. It effectively ensures the reliability, traceability, and task integrity of fire emergency broadcasts, meeting the broadcasting supervision requirements in high-security scenarios.

[0034] In one possible implementation of this application embodiment, the above-mentioned S202 can be specifically implemented by the following S301 and S302, which are described in detail below: S301. Obtain some crystal oscillator frequency and temperature data of broadcast terminal i from historical data, and establish a mapping model between the crystal oscillator frequency and temperature of broadcast terminal i: ; Where i is the sequence number of the broadcast terminal, and is a positive integer. For the frequency deviation of broadcast terminal i, The ambient temperature of the current broadcast terminal i. For the target temperature, All are temperature drift coefficients, and all have values ​​of (0,1], which are set by those skilled in the art.

[0035] S302, Based on the frequency deviation of the current broadcast terminal i Through formula The clock drift of the current broadcast terminal i is calculated. :in, Nominal frequency, The time interval for sending Sync messages to the fire control center.

[0036] For example, suppose the nominal frequency of the crystal oscillator of broadcast terminal i is... Reference temperature Current ambient temperature Temperature drift coefficient obtained from historical fitting: , , ; Calculate frequency deviation This means that the crystal oscillator frequency is 20Hz faster than the nominal frequency at this time; Calculate the clock drift, and set the Sync message sending interval. ; That is, every second, the clock on this broadcast terminal is approximately 0.833 seconds ahead of the clock at the fire control center. .

[0037] In one possible implementation of this application embodiment, the above-mentioned S203 can be specifically implemented by the following S401 and S402, which are described in detail below: S401, based on the first timestamp Second timestamp Third timestamp and the fourth timestamp Through formula The clock delay of the broadcast terminal was calculated. ; S402, Temperature-compensated clock drift and clock delay Through formula + The clock correction amount of broadcast terminal i is calculated. ;in, For correction factor, .

[0038] It should be pointed out that, This indicates that the clock of broadcast terminal i has been sped up. Duration This indicates that the clock of broadcast terminal i does not need to be adjusted. This indicates that the clock of broadcast terminal i has been slowed down. Duration.

[0039] For example, suppose the data of a certain broadcast terminal i is as follows: Assume , , , ; , ; Calculate the time delay ; Based on the temperature-compensated clock drift calculated in step 202, but in order to match... Scale matching, this application This indicates a long-term cumulative trend, such as the accumulation over the past 10 seconds. Then take In addition, settings Thus, the clock correction amount of broadcast terminal i is obtained. This means that the broadcast terminal i should be adjusted faster. This aligns its clock with the master controller.

[0040] Based on the above technical solution, this clock correction method integrates temperature-compensated clock drift with time delay based on bidirectional messages, and calculates the final correction using a weighted formula. This method boasts advantages such as high precision, strong adaptability, and good stability. Specifically, a four-step timestamp mechanism eliminates the impact of network asymmetry, enabling dynamic real-time deviation measurement. Furthermore, the introduction of temperature-compensated crystal oscillator frequency drift prediction allows for early prediction of long-term accumulated errors, effectively improving environmental adaptability. This combination overcomes the instability of relying solely on network message synchronization under jitter or packet loss, while also avoiding the inability of hardware calibration alone to respond to short-term fluctuations. The correction coefficient allows for flexible adjustment of the weight of the temperature compensation term, enhancing system robustness and ensuring that broadcast terminals maintain microsecond-level time consistency even in complex environments. This provides a reliable time reference for precise linkage, audio fingerprint alignment, and event tracing in fire emergency broadcasting.

[0041] In one possible implementation of the embodiments of this application, such as Figure 3 As shown, the above S206 can be specifically implemented through the following S501, S502, S503 and S504, which are explained in detail below: S501. Extract the audio features of the broadcast audio signal and construct the original audio fingerprint sequence. The details are as follows: The broadcast audio signal is divided into frames, and the first N order Mel-frequency cepstral coefficients of each frame are extracted. and energy value ; in, The sequence number of the frame. , For frame number, For the first The energy value of a frame. , For the first The first frame of the audio signal The amplitude value of each sampling point; The sampling point number, , is the total number of sampling points; N is the dimension of the Mel frequency cepstral coefficients extracted from each frame of audio, N>0 and is a positive integer. For the first The N-dimensional Mel frequency cepstral coefficient vector of the frame; The original audio fingerprint sequence was constructed. ; Return audio fingerprint sequence The construction process includes: Using the same framing parameters and feature extraction algorithm as the broadcast audio signal, audio features of the returned audio signal are extracted to construct the returned audio fingerprint sequence. .

[0042] S502, Calculate the original audio fingerprint sequence With the returned audio fingerprint sequence similarity distance between ; ; in, For broadcast audio signals Frames The audio signal returned to broadcast terminal i Frames The Euclidean distance between them For broadcast audio signals Frames The audio signal returned to broadcast terminal i Frames The absolute value of the difference between them , , Let y be the path of the y-th frame pair, where y is the number of frame pair paths and is a positive integer. For the y-th path The Middle Frame and the Frame alignment, Σ represents the alignment of the y-th path All frame pairs Summation of the Euclidean distances between them , This is the proportionality coefficient, and its value is (0,1).

[0043] S503, Based on similarity distance Through formula The playback integrity index value of broadcast terminal i is calculated. ;in, This is the preset maximum distance.

[0044] S504, Determine the playback integrity index value If the value exceeds the preset threshold, broadcast terminal i will play the entire message; otherwise, broadcast terminal i will not play the entire message and will be inspected.

[0045] For example, suppose a fire emergency broadcast system sends a broadcast audio signal; Assuming the following parameter settings: audio sampling rate: 16kHz, Each sampling point → Frame length = 256 / 16000 ≈ 16ms, Frame shift: 128 points (50% overlap), Total audio length: approximately 1.6 seconds. Frame, MFCC dimension: (excluding order 0); Original audio fingerprint sequence ; The audio fingerprint sequence transmitted back from broadcast terminal i ; Use the DTW algorithm to find the optimal path Satisfying: Starting point: ,end: Monotonicity, continuity, boundary constraints; such as possible alignment paths. Including the following: Perfect alignment (consistent playback speed): ; The playback on the terminal is slightly slow (the second frame is stretched): Because the playback speed of broadcast terminal i is slow, the duration of the second frame is long. Assumption corresponding =280.5, corresponding =361.4; Since 280.5 < 361.4, the optimal path is The corresponding minimum distance is Assuming a preset maximum distance , =1-280.5 / 500=0.439. If the preset threshold is 0.3<0.439, then the broadcast terminal i will play the complete video.

[0046] Based on the above technical solutions, this approach extracts the dual-modal acoustic fingerprints of broadcast audio and its return signals, and combines this with the Dynamic Time Warping (DTW) algorithm to calculate weighted similarity distance, achieving a highly robust and refined evaluation of the playback integrity of broadcast terminals. Its advantages include: simultaneously utilizing speech content features (MCC) and temporal energy features, it can not only accurately identify whether the audio content is played completely, but also effectively detect situations where the audio is "formally complete but lacks quality," such as abnormal volume or signal attenuation caused by equipment failure; by introducing a weighted distance function, the feature contribution weights can be flexibly adjusted to adapt to different environmental needs; combined with the optimal frame pair path search mechanism, it tolerates slight speed changes, start / end deviations, and time offsets during playback, significantly improving comparison accuracy; finally, it achieves quantitative judgment through normalized indicators, supporting unified threshold decisions, providing a fire emergency broadcasting system with an automated playback integrity verification mechanism that requires no manual intervention, has strong noise resistance, and clear criteria, ensuring the reliable transmission of key voice commands.

[0047] Some of the data in the above formula are calculated by removing dimensions and taking their numerical values. The formula is the closest to the real situation obtained by software simulation of a large amount of collected data. The preset parameters and preset thresholds in the formula are set by those skilled in the art according to the actual situation or obtained through simulation of a large amount of data.

Claims

1. A high-precision synchronous fire emergency broadcasting method with band state feedback, characterized in that, The method comprises the following steps: a fire control center sends a time synchronization message to a plurality of broadcast terminals, acquires a plurality of time stamps of the time synchronization message, and analyzes clock delay; wherein, the time stamp is the time when the fire control center, the broadcast terminal receives or sends the time synchronization message; and analyzes the temperature compensation clock drift of the current broadcast terminal; wherein, the clock drift is the clock error caused by the change of the environment temperature of the broadcast terminal; based on the clock delay and the temperature compensation clock drift, the clock correction of each broadcast terminal is analyzed, and the clock of each broadcast terminal is corrected based on the clock correction; after the clock of each broadcast terminal is corrected, the fire control center sends a play instruction carrying a preset play time to the plurality of broadcast terminals; after the broadcast terminal receives the play instruction, the fire control center returns a receiving confirmation reply; when the local clock of each broadcast terminal reaches the preset play time, the broadcast audio signal is played synchronously, and the played audio signal is collected and marked as a returned audio signal; the audio feature of the returned audio signal is extracted and sent to the fire control center; the fire control center analyzes the play integrity of each broadcast terminal according to the audio feature of the returned audio signal.

2. The high-precision synchronous fire emergency broadcasting method with state feedback according to claim 1, characterized in that, The method comprises the following steps: the time synchronization message comprises a Sync message, a Delay_Req message and a Delay_Resp message; The time when the fire control center sends the Sync message is marked as a time stamp The first time stamp is encapsulated in the Sync message and sent to the broadcast terminal The time when the broadcast terminal receives the Sync packet is marked as a second time stamp ; The time when the broadcast terminal sends the Delay_Req message to the fire control center is marked as the third time stamp ; The time when the fire control center receives the Delay_Req packet is marked as the fourth time stamp and is encapsulated in the Delay_Resp packet and returned to the broadcast terminal.

3. The high-precision synchronous fire emergency broadcasting method with state feedback according to claim 2, characterized in that, the method for analyzing the temperature compensation clock drift of the current broadcast terminal comprises the following steps: a plurality of crystal frequency and temperature data of the broadcast terminal i are acquired from the historical data, and a mapping model between the crystal frequency and the temperature of the broadcast terminal i is established: ； wherein i is the serial number of the broadcast terminal and is a positive integer, is the frequency deviation of the broadcast terminal i, is the ambient temperature of the current broadcast terminal i, is the target temperature, are both temperature drift coefficients and take values in (0, 1]. According to the frequency deviation of the current broadcast terminal i , the clock drift of the current broadcast terminal i is calculated by the formula : wherein, is the nominal frequency, is the time interval of sending the Sync message by the fire control center.​ 4. The high-precision synchronous fire emergency broadcasting method with state feedback according to claim 3, characterized in that, the method for analyzing the clock correction of each broadcast terminal comprises the following steps: Based on the first timestamp Second timestamp Third timestamp and the fourth timestamp Through formula The clock delay of the broadcast terminal was calculated. ; Compensation of clock drift based on temperature and clock delay , the clock correction amount of broadcast terminal i is calculated by formula + ; wherein, is the correction coefficient, .​ 5. The high-precision synchronous fire emergency broadcasting method with state feedback according to claim 1, characterized in that, when the fire control center does not receive the receiving confirmation reply of the broadcast terminal i, the broadcast terminal i is marked as a communication exception, and a device offline alarm is triggered.

6. The high-precision synchronous fire emergency broadcasting method with state feedback according to claim 1, characterized in that, The method for acquiring the returned audio signal comprises the following steps: a broadcast terminal sets a preset audio collection time window before starting to play the broadcast audio signal, and collects the played returned audio signal in the preset audio collection time window through a microphone; wherein, the length of the audio collection time window is greater than the duration of the broadcast audio signal, and a first protection time is reserved before the play starts and a second protection time is reserved after the play ends; a microphone device is arranged at each broadcast terminal.

7. The high-precision synchronous fire emergency broadcasting method with state feedback according to claim 4, characterized in that, The method for analyzing the play integrity of each broadcast terminal comprises the following steps: extracting audio features of the broadcast audio signal to construct an original audio fingerprint sequence ; the original audio fingerprint sequence is a set of audio features of the broadcast audio signal extracting audio features of the backhaul audio signal, and constructing a backhaul audio fingerprint sequence ; the backhaul audio fingerprint sequence is a set of audio features of the backhaul audio signal computing a similarity distance between the original audio fingerprint sequence and the return audio fingerprint sequence ;​ Based on similarity distance Through formula The playback integrity index value of broadcast terminal i is calculated. ; Determine the playback integrity index value Does it exceed a preset threshold? If yes, broadcast terminal i plays the entire message; otherwise, broadcast terminal i plays the message incompletely, and broadcast terminal i is inspected. This is the preset maximum distance.

8. The high-precision synchronous fire emergency broadcasting method with state feedback according to claim 7, characterized in that, the original audio fingerprint sequence a construction process, including: The broadcast audio signal is framed, and the first N order mel-frequency cepstrum coefficient of each frame is extracted and energy value ; wherein, is the serial number of the frame, , is the frame number, is the energy value of the first frame, , is the amplitude value of the first sampling point in the first frame audio signal; is the sampling point serial number, , is the total number of sampling points; N is the dimension of the mel-frequency cepstrum coefficient extracted from each frame of audio, N>0, and is a positive integer, is the N-dimensional mel-frequency cepstrum coefficient vector of the first frame. constructing the original audio fingerprint sequence ; The back audio fingerprint sequence The construction process includes: The audio features of the backhaul audio signal are extracted using the same frame segmentation parameters and feature extraction algorithm as the broadcast audio signal, and a backhaul audio fingerprint sequence is constructed .

9. The high-precision synchronous fire emergency broadcasting method with state feedback according to claim 7, characterized in that, The computing the original audio fingerprint sequence a similarity distance between the original audio fingerprint sequence and the return audio fingerprint sequence comprises: ； in, For broadcast audio signals Frames The audio signal returned to broadcast terminal i Frames The Euclidean distance between them For broadcast audio signals Frames The audio signal returned to broadcast terminal i Frames The absolute value of the difference between them , , Let y be the path of the y-th frame pair, where y is the number of frame pair paths and is a positive integer. For the y-th path The Middle Frame and the Frame alignment, Σ represents the alignment of the y-th path All frame pairs Summation of the Euclidean distances between them , This is the proportionality coefficient, and its value is (0,1).

10. A high-precision synchronous fire emergency broadcasting system with state feedback, based on the high-precision synchronous fire emergency broadcasting method with state feedback of any one of claims 1-9, characterized in that, The method comprises a correction module, and an acquisition module and an integrity verification module connected thereto; the acquisition module is used to acquire a plurality of time stamps of the time synchronization message; the correction module is used to analyze the clock delay and the temperature compensation clock drift of the current broadcast terminal; based on the clock delay and the temperature compensation clock drift, the clock correction of each broadcast terminal is analyzed, and the clock of each broadcast terminal is corrected based on the clock correction; the integrity verification module is used to construct an original audio fingerprint sequence and a returned audio fingerprint sequence, and analyze the play integrity of each broadcast terminal.

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