Research On High Dynamic Lock-in Technology And Detection System For Speaker Failure

The detection technology has penetrated into all walks of life,when conducting manual inspections on the sound state of broadcast speaker in nuclear power plants,the detection accuracy and speed cannot meet the requirements of factory automation.The aging and damage of the broadcast speaker and transmission lines will be accelerated by the harsh environment of the nuclear power plants,and in order to respond to the sudden danger and evacuate relevant personnel in time,a highly reliable and intelligent online speaker fault detection system is needed,which can ensure the stability of the operation of the public broadcasting system and provide the last strong defense for the security of the nuclear power environment.Combined with the actual application requirements of a nuclear power plant,focusing on the three application limitations of the in-service speaker:the inability to accurately collect the speaker’s sound signals in strong noise environment,the inability to independently construct detection system’s cabling,the inability to operate intelligent monitoring under long distances,this paper proposes a high dynamic lock-in technology based on correlation and an intelligent online fault detection system.The main task and innovations are as follows:Firstly,according to the performance requirements of the detection system,a system software based on finite state machine is designed,and combined with the hardware system,this paper designs a overall online speaker fault detection system.With the improvement of SM2400 networking communication principle in SM9400 EVK,this paper presents a remote audio line data communication based on PRIME.After physical verification,the stably of the communication between a host and five slaves system is realized,and the goal of not independent wiring and returning results is completed.Secondly,aiming at the problem of fault determination error caused by the uncontrollable random phase-shifting in the traditional phase-locked detection,this paper proposes a high dynamic all-digital phase-shifting lock-in detection method.By introducing the digital phase-shifted factor and the opportunistic factor,the reference signal is subjected to 32 consecutive phase-shifted whose phase of every cycle leads?₁₆to the former one,and make the phase-locked process with a dynamic characteristics in sinusoidal changes,which greatestly avoids the detection error caused by random phase-shifting.It is tested and verified that the detection accuracy of this detection method is 0.995,the detection error is 0.5%,the lowest signal noise ratio（SNR）of stable detection is-46.4dB,which satisfy the application requirement of the system to accurately detect the weak signal in 90dB ambient noise.Then,combined with the demand analysis of speaker fault detection,this paper proposes a fault feature determination based on peak to average ratio（PAPR）and maximum mean value,a speaker fault detector is designed by using high dynamic lock-in technique.After testing,the application SNR for speaker fault determination is-18.5dB,and the detector is successfully used to diagnose the working state of the in-service speaker in two states（normal sounding and abnormal sounding）.Finally,simulating the actual nuclear power application environment,performing the whole detection system,and accurately receive the“normal loudness”feedback to the healthy speaker and the“loud low alarm”feedback to the faulty speaker in PC.The entire testing process eliminates the operation in terminal of the speaker and takes only 1 minute to successfully implement the intelligent monitoring function.