Specifications

EAW Smaart 6 Operation Manual Smaart 6 Commands
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5.3.3 IR Analysis
Figure 5-5 IR Analysis tab in Options dialog
Choose Options
-
>Impulse/Locator or click the IR Options button in the Impulse
Response window. Choose Options->IR Analysis or click the IR Options button in
the Impulse Response window.
The top line displays the current Sampling Rate, which is set in the Audio I/O tab.
IR Measurement Parameters
Type: Select LogIR, LinIR, or ETC views for the impulse response time display.
Averages: Type in the desired number of frames to use in average calculations. For values
greater than 1 is, the impulse recorder collects the specified number of frames and
averages the results. The benefit of doing this is noise rejection: every doubling of the
number of averages increases the S/N by 3 dB (down to the actual noise floor of the SUT
or the measurement system, whichever is higher).
FFT: Select the desired FFT size (32k, 16k, 8k, 4k, 2k, 1k, 512, 256, 128). This sets the
number of samples collected from the sound card inputs to use in the FFT calculations
for the selected measurement type. Each new selection of FFT size recalculates the
Time Constant shown below the FFT field. The time constant should be significantly
longer than the longest expected reverberant decay time for the system under test. If you
are not sure what this time is, remember that aside from the increased measurement
time, there is no downside to setting the time constant too large. As with averaging,
each doubling of the FFT size theoretically yields 3 dB better S/N.
Overlap: Select the desired percentage of overlap (0, 25, 50, 75). Setting this value to
a number greater than zero uses overlapping, rather than contiguous time domain data,
to calculate multiple FFTs. This is particularly useful in measurements using large FFT
size and/or a high number of averages because it significantly reduces the amount of
data (and time) required to collect the data without increasing the noise component.