AAF-1 low pass anti alias filter board

AAF-1

2 to 8 Channel Anti-Alias Low-Pass Filter Card for Signal Conditioning in Data Acquisition Systems

Features

Compatible with A/D converter boards from top manufacturers
2, 4, 6, or 8 differential-input anti-alias low-pass filter channels per card
Variable cutoff frequency ranges between 0.1 Hz and 200kHz
>120 dB/octave attenuation slope (Cauer filter type)
±0.15 dB passband ripple (Cauer filter type)
Choice of 8-pole Cauer, Bessel, Butterworth, high-speed Cauer, and high-speed linear phase filters
±200V common-mode input
Requires no special software to operate
Creates portable, stand-alone solution when used in AT-SYS-400 system

Overview

The AAF-1 is a multi-channel anti-alias low-pass filter board designed for front-end signal conditioning in PC-based or stand-alone 12-bit A/D conversion systems. It protects and filters 2, 4, 6, or 8 differential analog channels. Each 2-channel pair is available with any one of 8-pole Cauer, Bessel, Butterworth, high-speed Cauer, or high-speed linear phase filter characteristics. The Cauer filter provides rapid attenuation of unwanted high frequencies (120 dB/octave), while only minimally affecting frequencies in the passband (less than 0.15dB ripple).

The cutoff frequency of the AAF-1 is set by an on-board potentiometer, which sets the same cutoff frequency for all filters on the board. Optionally, the cutoff frequency can be controlled with an external clock source for tracking filter applications, very low cutoff frequencies, or other special purposes.

Connection to Your Data Acquisition System

All I/O connections from the AAF-1 are made via a keyed 40-pin dual-row male connector that extends out of the rear of the computer.

Screw Terminal Card - The STA-AAF-1 is a universal screw terminal accessory board that provides one 40-pin male connector for hookup to Alligator Technologies' AAF-1 and AAF-3 low-pass filter boards for anti-aliasing and noise elimination. All signals on the STA-AAF-1 are brought out to labeled screw terminal connections. A breadboard area is included on the board for custom circuitry, including resistors and capacitors for added filtering.

Cable Accessories - A variety of custom cable accessories, including twisted-pair ribbon cables and BNC connector boxes and cables, are available for connecting the AAF-1 to any A/D board.

If you are using a popular Keithley Metrabyte A/D board, you can connect the AAF-1 to the A/D board with the appropriate AAF-1/Cx cable and software set. These sets contain the following components:

Adapter cable - a "y-shaped" cable with connectors for the A/D board, AAF-1 and signal source.
Calibration cable - A thin ribbon cable with one connector for the A/D board and one 40-pin connector for the AAF-1. The calibration cable is used when setting the cutoff frequency and calibrating DC offset.
Calibration utility - A DOS-based program (CA.EXE) for setting the cutoff frequency and calibrating DC offset.

Stand-Alone Systems

The AT-SYS-400 is a stand-alone low-pass filter system designed for cost-sensitive applications requiring 2 to 32 channels of filtering only and simple manual adjustment of the cutoff frequency using an on-board potentiometer. The system consists of a rack-mountable chassis with space for four AAF-1 filter cards, each offering 2 to 8 channels.

The AT-SYS-400 chassis houses a passive backplane and high efficiency switching power supply with removable air filters to exclude dust and dirt. Designed for easy expansion, you can conveniently install and replace cards from the top of the unit. Bidirectional mounting brackets let you conveniently install the AT-SYS-400 on a wall or in a cabinet.

How to Order

AAF-1 - General-purpose low-pass filter card for PC-based and stand-alone data acquisition systems

AT-SYS-400 - 2- to 32-channel stand-alone filter system for cost-sensitive applications needing simple manual control

Accessories
- STA-AAF-1 - Screw terminal accessory card
- AAF-1/Cx - Adapter and calibration cable and software set for popular Keithley Metrabyte and compatible A/D boards

Related Pages

Simplify your system connections. Check out our list of Cable Accessories.
Need help selecting the best filter type for your application? Check out our Filter Type Selection Guide.
What is aliasing and how do filters eliminate its effects to ensure more accurate results? Find out in our Low-Pass Filter Tutorial.

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