Real Time Audio Spectrum Analyzer with Signal Generator
EasyRTA is a powerful, yet light-weight Spectrum Analyzer software. It can work on low performance computers as well as on much powerful platforms. EasyRTA also has an on-screen measuring labels which are presenting true RMS amplitude in Volts and dBu.
Graphic presentations of measurements are intentionally not polished - EasyRTA graphic does not have any makeup just to look better, or to have less tremble, because that way of presentation hides various flaws and harmonics in the measured signal. So, if the FFT analysis has some odd results, a user can simply try to increase or decrease the amplitude, or to change FFT window type.
EasyRTA has an automated calibration procedure which allows a user to make very precise measurements. It is desirable to have a True RMS AC voltmeter, which has mV range, as an external calibration tool, but any decent AC voltmeter will also be good enough to achieve a straightforward calibration. A user must take into account that audio cards in computers can differ substantionally in the quality and performance aspect. Some audio cards cannot measure signal levels of 0 dBu (0.775 Vrms) without distortion, some cannot output signal with higher amplitude of -10 dBu (0.245 Vrms), etc. But, they can offer wide possibilities for measurements and fulfill most tasks.
It is important to know that sample rate is fixed to 48000 samples per second, and that FFT numbers of points are fixed to 8192 points. Therefore the latency time (period which is needed to collect a packet of FFT points) is 171 ms, providing measurment from 6 Hz to 24 kHz. Latency time has nothing to do with software application or computer speed. It is just a result of a simple equation: Latency Time = 8192 points / 48000 samples per second = 171 milliseconds.
As a useful add-on, EasyRTA features a Signal Generator with many signal types, frequency and amplitude options, which, in correlation with Spectrum Analyzer, provide a complete measuring tool. Signal generator can produce signal frequencies from 20Hz to 20 kHz.