Understand the detector of the noise meter
In order for the amplified signal to be displayed through the meter head, a detector is also needed to convert the rapidly changing voltage signal into a slower changing DC voltage signal. The magnitude of this DC voltage is proportional to the size of the input signal. According to the needs of measurement, there are two types of detectors: peak detector and average detector, and black root mean square detector. The peak detector can provide the maximum value at a certain time interval, while the average detector can measure its absolute average value at a certain time interval. Except for pulse sounds like gunfire that require measurement of their peak, root square detectors are used in most measurements. The root mean square detector can square, average, and square the AC signal to obtain the root mean square value of the voltage, and finally transmit the root mean square voltage signal to the indicator head. The indicator head is an electric meter, and as long as its scale is calibrated to a certain extent, the decibel value of the noise level can be directly read from the head. The damping of the sound level meter head generally has two gears: "fast" and "slow". The average time of "fast" gear is 0.27 seconds, which is very close to the physiological average time of human auditory organs; The average time in 'slow' gear is 1.05 seconds. When measuring steady-state noise or recording the process of sound level changes, using the "fast" gear is more appropriate; When the fluctuation of the measured noise is relatively large, using the "slow" gear is more appropriate. In order to meet the needs of the measurement site, the sound level meter generally has a triangular bracket, which can be fixed on the triangular bracket as needed.
Generally, there are also some sockets on the panel. These sockets, if connected to a portable octave band filter, can form a simple spectrum analysis system for small on-site use; If combined with a tape recorder, the on-site noise can be recorded on magnetic tape and stored for further detailed research in the future; If combined with an oscilloscope, the waveform of sound pressure changes can be observed and captured by a camera; It is also possible to combine and use instruments such as analyzers and recorders with sound level meters, depending on the testing conditions and requirements.
