HOME  |  NEWS  |  BLOGS  |  MESSAGES  |  FEATURES  |  VIDEOS  |  WEBINARS  |  INDUSTRIES  |  FOCUS ON FUNDAMENTALS
  |  REGISTER  |  LOGIN  |  HELP
Jon Titus
User Rank
Blogger
The math behind frequency aliasing
Jon Titus   4/6/2012 11:07:52 AM
NO RATINGS
The next column explains the math (with a few equations) behind the frequency aliasing. Engineers often understand the concept of aliasing, but the math provides details.

Shelly
User Rank
Iron
Re: Who uses this?
Shelly   4/6/2012 10:03:31 AM
NO RATINGS
We use them a lot in vibration testing/measurement.  If you consider the sampling rate of a sine wave, and the apparent measured frequency of high frequency signals measured too slowly, Nyquist is a good place to start, but we typically acquire data at much higher speeds than 2X our filter cutoff frequency.

vimalkumarp
User Rank
Gold
using filters and the Nyquist-Shannon theorem
vimalkumarp   4/6/2012 1:08:01 AM
NO RATINGS

Execellent  explanation on using filters and the Nyquist-Shannon theorem  . This will be of great use to every engineer as Nyquist-Shannon theorem was and is  realy the backbone of communication engineering. Thanks   Jon!


Nancy Golden
User Rank
Platinum
Another Keeper!
Nancy Golden   4/5/2012 7:55:00 PM
NO RATINGS

Very nice explanation on using filters and the Nyquist-Shannon theorem  -  something every test engineer needs to keep in mind when determining their sampling rate. Thanks for another great article, Jon!

Jon Titus
User Rank
Blogger
Use of anti-alias filters...
Jon Titus   4/5/2012 12:27:00 PM
NO RATINGS
I recommend using an anti-alias filter whenever you must measure anuthing more than a DC, or near-DC signal. Some companies include them in data-acquisition equipment or on analog-to-digital-converter (ADC) boards, and some don't, so it pays to ask. If a board or system includes a filter or filters, find out how much control you have over it and get a plot of frequency vs. attenuation (a Bode plot) and a plot that shows phase vs. frequency. I didn't get into phase changes in this column, but people should know that filters change phase relationships of signals, too.  Those changes could affect measurements when you must correlate signals in the time domain.

Engineers can build their own anti-alias filters, but I don't recommend that course unless they have filter-design experience and plan to build a lot of them. Commercial filters are the way to go in almost all situations.

Rob Spiegel
User Rank
Blogger
Who uses this?
Rob Spiegel   4/5/2012 11:21:29 AM
NO RATINGS
Interesting article, Jon. Are these filters widely used these days? And who is using them? Is this mostly for large, advanced organizations or is it more more widely deployed?



Partner Zone
Latest Analysis
Here's a variety of views into the complex production processes at Santa's factory. Happy Holidays!
The Beam Store from Suitable Technologies is managed by remote workers from places as diverse as New York and Sydney, Australia. Employees attend to store visitors through Beam Smart Presence Systems (SPSs) from the company. The systems combine mobility and video conferencing and allow people to communicate directly from a remote location via a screen as well as move around as if they are actually in the room.
Thanks to 3D printing, some custom-made prosthetic limbs, and a Lego set, one lucky dog and a tortoise has learned new tricks.
An MIT research team has invented what they see as a solution to the need for biodegradable 3D-printable materials made from something besides petroleum-based sources: a water-based robotic additive extrusion method that makes objects from biodegradable hydrogel composites.
With Radio Shack on the ropes, let's take a memory trip through the highlights of Radio Shack products.
More:Blogs|News
Design News Webinar Series
12/11/2014 8:00 a.m. California / 11:00 a.m. New York
12/10/2014 8:00 a.m. California / 11:00 a.m. New York
11/19/2014 11:00 a.m. California / 2:00 p.m. New York
11/6/2014 11:00 a.m. California / 2:00 p.m. New York
Quick Poll
The Continuing Education Center offers engineers an entirely new way to get the education they need to formulate next-generation solutions.
Dec 15 - 19, An Introduction to Web Application Security
SEMESTERS: 1  |  2  |  3  |  4  |  5  |  67


Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.
Learn More   |   Login   |   Archived Classes
Twitter Feed
Design News Twitter Feed
Like Us on Facebook

Sponsored Content

Technology Marketplace

Copyright © 2014 UBM Canon, A UBM company, All rights reserved. Privacy Policy | Terms of Service