Electro-Acoustics
In addition to the wide range of acoustic analyzing functions on the SMxx products, there are also several tools that can be used to measure electro-acoustics. These tools include an oscilloscope, AC volt meter, and electric in real time analyzer (RTA), and fast fourier transform (FFT). These functions are described below.
Oscilloscope
The oscilloscope module is intended to quickly inspect acoustic signals, in particular periodic signals, in the time domain. The basic operation of the oscilloscope module is similar to the common (hardware) oscilloscopes that many engineers are familiar with. Note that the frequency response of the system is limited to audio frequencies (up to 20 kHz). If sounds are being measured through the microphone, the amplitude scale will be expressed in the unit Pascal (Pa).If you are measuring without microphone, but directly into the XLR input, the vertical scale will be expressed in Volts (V).
AC Volt Meter
The AC Volt meter module is a simple tool to quickly assess the output level of line-level audio equipment. The line output of a device is connected directly to the XLR input of the SMxx (after removing the microphone). The SMxx then measures the signal level and expresses it in the following three units: V rms, dBU, and dBV.
Electric in RTA and FFT
Dedicated versions of the real-time analyzer (RTA) and fast fourier transform (FFT) analyzer are provided specifically for analysis of electric signals through the XLR input.The RTA and FFT intended for electric input signals are used in exactly the same way as the “ordinary” RTA and FFT, with one difference: the displayed levels are relative to an electric reference signal instead of the acoustic reference of 2.10-5 Pa. The electric reference can be set to display all levels in dBU, dBV or dBuV (corresponding to reference levels of , respectively, 0.7746 V, 1.0000 V and 1.000*10-6 V).
