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
DIY candy, journeys to Mars, coding for road trips, and more. These STEM (science, technology, engineering, and math) activity options will keep kids engaged this summer, from 10-minute activities to more advanced undertakings.
Nothing is more frustrating than developing a plan and then, in the heat of the battle, having to diverge from the plan when chaos happens.
In June, teams from across the US, and several countries worldwide, competed for awards in multiple categories at the 2016 Formula SAE Lincoln competition.
A 45-minute per day free course will take place July 11-15, and will walk engineers through a hands-on approach to debugging real-time embedded software.
Forget doping. Officials at this yearís Tour de France are looking for a very different form of cheating -- electric motors hidden inside the seat tubes of bicycles.
More:Blogs|News
Quick Poll
The Continuing Education Center offers engineers an entirely new way to get the education they need to formulate next-generation solutions.
SEMESTERS: 1  |  2  |  3  |  4  |  5  |  6 |  7 | 8 | 9 | 10


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.
Next Course June 28-30:
Sponsored by Proto Labs
Learn More   |   Login   |   Archived Classes
Twitter Feed
Design News Twitter Feed
Like Us on Facebook

Technology Marketplace

Copyright © 2016 UBM Canon, A UBM company, All rights reserved. Privacy Policy | Terms of Service