NIUSB-4431 Datasheet, PDF (1/5 Pages) National Instruments Corporation – Sound and Vibration Data Acquisition

Sound and Vibration Data Acquisition
NI USB-4431 NEW!
• One 24-bit analog output
• Four 24-bit simultaneous analog inputs
• ±3.5 V output range
• ±10 V input range
• 100 dB dynamic range
• Antialiasing filters
• TEDS read/write
• Software-selectable AC/DC
coupling (0.1 Hz HPF)
Recommended Software
• Sound and Vibration Measurement Suite
• Sound and Vibration Toolkit
• LabVIEW
Analysis Capabilities
• Power spectra
• Zoom FFTs
• Fractional-octave analysis
• Vibration-level measurements
• Order spectra
• Transient analysis
• Sound quality
>> _{For complete specifications, see the NI USB-443x Specifications}
manual at ni.com/manuals.
Overview
The NI USB-4431 is a five-channel dynamic signal acquisition module for
making high-accuracy measurements from IEPE sensors. The USB-4431
delivers 100 dB of dynamic range and incorporates software-selectable
IEPE (2.1 mA constant current) signal conditioning for accelerometers
and microphones. The module consists of four analog input channels for
reading from IEPE sensors with a single analog output. The four analog
input channels simultaneously acquire at rates from 2 to 102.4 kS/s. In
addition, each channel includes built-in antialiasing filters that
automatically adjust to your sampling rate. The USB-4431 is ideal for a
wide variety of portable test applications such as frequency response
audio tests or suspension shaker tests.
Hardware
Each simultaneous signal is buffered, analog prefiltered, and sampled
by a 24-bit delta-sigma analog-to-digital converter (ADC) that performs
digital filtering with a cutoff frequency that automatically adjusts to
your data rate. The USB-4431 features a voltage range of ±10 V and a
dynamic range of 100 dB. In addition, the module can read and write
to transducer electronic data sheet (TEDS) Class 1 smart sensors. The
USB-4431 has ±60 V of overvoltage protection and three software-
selectable modes of measurement operation: IEPE-on with AC coupling,
IEPE-off with AC coupling, and IEPE-off with DC coupling.
The module uses a method of analog-to-digital conversion known as
delta-sigma modulation. If, for example, the data rate is 25 kS/s, then
each ADC actually samples its input signal at 3.2 MS/s (128 times the
data rate) and produces samples that are applied to a digital filter. This
filter then expands the data to 24 bits, rejects signal components greater
than 12.5 kHz (the Nyquist frequency), and digitally resamples the data
at the chosen data rate of 25 kS/s. This combination of analog and digital
filtering provides an accurate representation of desirable signals while
rejecting out-of-band signals. The built-in antialiasing filters automatically
adjust themselves to discriminate between signals based on the frequency
range, or bandwidth, of the signal.
The USB-4431 offers analog output using a delta-sigma modulation
digital-to-analog converter (DAC). The overclocking and filtering is done
in the digital domain. The now-filtered signal is then output using a
DAC. The DAC in the USB-4431 combines high image rejection
performance with good flatness in the passband. The analog output also
has the flexibility to generate a variety of signals from a DC voltage, to
43.5 kHz sine waves, to arbitrary waveforms.
Analysis Software
The USB-4431 is well-suited for noise and vibration analysis applications.
The NI Sound and Vibration Measurement Suite, which specifically
addresses these applications, has two components: the NI Sound and
Vibration Assistant and LabVIEW analysis VIs (functions) for power
spectra, frequency response (FRF), fractional octave analysis, sound-level
measurements, order spectra, order maps, order extraction, sensor
calibration, human vibration filters, torsional vibration, and sound quality.