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Founded in 1975, Precision Filters, Inc. is a manufacturer and global distributor of high performance instrumentation for test measurements.

Precision Releases New Anti-aliasing Filter Application Note

The transducer signals you measure are the results of your test. When these signals are digitized, however, the sampling process creates aliases — out-of-band signals disguised as in-band signals of interest. At once inherent and insidious, you won’t even know aliases are there in your digitized data, rendering it invalid.

The Sampling Theorem states that an analog signal must be sampled at least twice the highest frequency contained in the signal to prevent aliasing. In other words, no information higher than half the sampling frequency can exist in the signal, otherwise aliasing will occur. Signals above Fs/2 do exist in the signal and require a filter to attenuate them to an acceptable level. If you do not properly filter the input signal, the digitized output will contain aliasing errors that look just like real data. Since the signals that alias are unknown, the errors are unknown and cannot be corrected by post-processing.

In Precision Filters new application note “Anti-Aliasing Filters Reduce Errors in Data Acquisition” you will learn how to use a low-pass filter to achieve the required attenuation of aliases while not significantly attenuating the signal itself. Methodology is presented that is applicable to any low-pass filter.

From the laboratory to the test cell, Precision Filters’ programmable anti-aliasing filter/amplifier system line-up has you covered. Choose from the high-density modular 28000 system that packs up to 128 channels of anti-alias filter/amps in a single chassis, the convenient 16-channel PF-1U rack mount filter/amplifier system, or the compact PFA-2 two-channel desktop unit. We even offer a pair of programmable filter modules for NI’s™ popular cDAQ™ and cRIO™ format.

The only zero-ripple elliptic low-pass filters on the market

100 dB/octave attenuation slopes and 1° phase match

Filtering optimized for frequency or time domain measurements with FLAT or PULSE modes

Choose cutoff frequencies from 1 Hz to over 3 MHz

Fully integrated and distributed programmable gain amplifiers mean more signal and less noise

User control via high-level remote commands over Ethernet or with the supplied GUI interface


We work closely with customers to provide innovative product solutions for today’s measurement challenges.

To learn how Precision Filters’ programmable anti-aliasing filter/amplifier systems provide all the flexibility you need to manage your test measurements, please visit our web site at http://www.pfinc.com or contact Precision Filters, Inc. at 607-277-3550 or by email at sales@pfinc.com.

™ National Instruments, NI, CompactRIO, and CompactDAQ are trademarks of the National Instruments Corporation.