TALK
: Loudspeaker Measurement
An overview of EASERA Sys Tune. by Charlie Hughes
A frequency vs. magnitude graph, showing
frequency placed on the horizontal axis.
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EASERA Sys Tune is a relatively new,
patent pending audio measurement
program from the Ahnert Feistel Media
Group (AFMG). It is designed for real-time analysis of acoustic signals and
aimed at those doing system alignment,
tuning and live sound applications. SysTune is not a replacement or upgrade for
the EASERA measurement program.
Rather, it has its own unique features
that allow it to perform measurement
tasks not currently available in other
measurement programs. More in-depth
acoustical analysis of the measurements
made with Sys Tune can be done with
EASERA. Sys Tune runs under Windows 2000, XP and Vista operating systems. It is a multi-threaded application
that is capable of taking advantage of
multiple processors within a computer.
SysTune supports up to eight input
channels simultaneously at up to 192
kHz sample rate. It can operate in a
dual-channel FF T mode, meaning that
one input channel receives a reference
signal (mixing console output for example) to which the other input channels
are compared. Sys Tune can also output
its own signal (sweeps, pink noise or user
selected files) and use this as the reference. Switching between each of the
input channels is accomplished easily
by clicking on its channel button. These
are located just above the mini-meter
for each channel. The mini-meters are
very convenient to tell at a glance which
channels are receiving good signal level.
If an overload (clip) of the A/D converter occurs the meter turns red. After
the overload passes the outline of the
mini-meter stays red until it is reset.
There is a multi-channel mode
which allows two or more inputs to be
averaged in real-time and the result displayed. This feature can be very useful
to spatially average the sound system
response using multiple microphones in
different locations.
There is a very important process at
work under the hood of Sys Tune. This
is the Real-Time Deconvolution (RTD)
engine. This newly developed algorithm
allows for the calculation and display of
impulse response (IR) data of up to 10
seconds in real-time and with fast on-screen display refresh rates. To accomplish this SysTune performs an FFT
Figure 1: Time-Frequency-Constant Window.
