SpectraRTA is installed by running the installation file. In the shareware installation, a temporary registration key is entered, with which you will be able to use the program for a limited time. After payment, you will receive an authorization key that is unique for each computer. After the installation is finished, approximately 3 MB will be left on the disk.
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What can SpectraRTA do?
At first glance, SpectraRTA impresses with its graphics and the number of functions it offers. At the same time, the control is very intuitive. The largest part of the screen is occupied by the virtual display of the spectroscope. On the left are the control buttons that start and stop the measurement, select the display method (continuous/columnar), measurement range and data display. They can be stored in 4+1 memories. Above the display is the program control bar with the most important functions.
The most important features of SpectraRTA
"Settings" sets the properties of the sound card, i.e. sampling, frequency range and channels. "Calibrate" allows you to set the level to 0 dB with an external generator, so that the measured values will be related to the real level, not relative.
The "generator" is an internal shell that provides a number of measurement signals. In addition to pink and white noise and a single-tone signal, a sequence of tones, sweep signal or two-tone for measurement IMD.
"Recorder" is a recorder of the incoming signal. The user has a wide choice of sampling rates, bit depth and channels. The signal filtering function (low-pass, high-pass and cut-off filter) can be characterized as unusual.
"Delay" is a measurement delay, which is used to eliminate transient phenomena arising, for example, after switching on. "Meters" are virtual needle meters for both channels. "Narrowband" is a fine spectroscope. The basic measurement is relatively coarse, but if we require increased resolution during measurement, we activate it with this function. However, it requires a more powerful processor.
"Spectogram" is used to display the amplitude of the measured signal over time. It can be said that it is similar to "waterfalls" of programs DigiPan or MixW. "Reverb" is the measurement of reflections, especially reflections of an acoustic space.
"Phase" is a measurement of the phase shift between two signals. "Macro" serves to predefine the measurement process.
In addition to displaying the NF spectrum, the program allows several measurements: THD (Total Harmonic Distortion), IMD (InterModulation Distortion), SNR (Signal to Noise Ratio), NF (Noise Figure) and SINAD (Signal to Noise and Distortion). The explanation of these measurements is in the excellently prepared documentation, and each of them would deserve a separate well-founded article.
The data can be stored in memory, or printed, or the display screen can be printed. She was also pleased with the possibility of copying the data to the clipboard, which enables their further processing, for example, in Excel.
Measurement range
The theoretical dynamic measurement range at 16 bits is 96 decibels. However, in practice, a range of about 80 decibels is achieved, since the computer itself is a source of noise and interference that reduce the accuracy of the measurement. The fast Fourier transform used by SpectraRTA has a maximum deviation of a few tenths of Hz in terms of frequency resolution accuracy.
Evaluation
If any program deserves five stars, it's SpectraRTA. You can find it at CQ.sk in the "Download" section.