Table Of Contents

Filtering

Version:
    Last Modified: August 1, 2019

    You can configure a filter for each bank on the FieldDAQ device.[1] FieldDAQ supports three types of lowpass filtering:

    • Brickwall (default)
    • Butterworth
    • Comb
    Table 1. Comparing FieldDAQ Filters
    Attribute Brickwall (Default) Butterworth Comb
    Passband Tracks sample rate Configurable independent of sample rate Tracks sample rate
    Alias Protection Best—Full protection Better—Configurable protection level Good—Partial protection
    Latency High Medium to high (configuration-dependent) Low
    Input Delay Variation versus Frequency Constant input delay Variable input delay Constant input delay
    Flatness Best Best Good
    Step Response (Time Domain) Most delay, ringing (overshoot/undershoot) Mid-level delay, overshoot Short delay, no overshoot/undershoot
    Typical Applications

    Analyzing dynamic properties of signals

    Analyzing spectrum of signals

    Filtering out specific noise sources

    Analyzing signals in the time domain

    Reducing measurement noise

    Filtering out specific noise sources

    Analyzing signals in the time domain

    Control applications

    spd-note-note
    Note  

    Update to NI-DAQmx 18.6 for Butterworth and comb filter support.

    Refer to the FD-116xx Specifications for details on the amount of variation in the response you can expect for different input frequency ranges.

    • 1 Configurable filtering is supported in NI-DAQmx 18.6 and later. Previous versions of NI-DAQmx support only brickwall filtering.

    Recently Viewed Topics