Having been in a couple of different industries, I often wonder why noise is specified in RMS. RMS makes sense, for example, in video, where the eye integrates and RMS gives you a direct measurement of how the image would look to the human eye. But what about other applications? If you are trying to determine uncertainty in a measurement, wouldn't specifying noise in RMS give you a very large discrepancy in numbers versus performance? Of course, comparing RMS to RMS of different systems will give you the relative performance comparison. Now take a step from comparing systems to Output. What does your output respond to? If it responds to every peak, then giving an RMS noise measurement is marketing not engineering.
What do you think?
I get in trouble with our sales department because I measure in P-P and at the point of greatest noise. This, to our customers, would give them the total uncertainty, rather than a number that tells them the total uncertainty can be 6 to 8 times higher.
Thanks for your comment. It is good to get a peak-to-peak value along with a root-mean-square (rms) value. The latter provides a statistical value that squares amplitudes and thus accounts for positive and negative noise. With a peak-to-peak value you don't know whether you observe that value all of the time, most of the time, or infrequently. So to me, a p-p value represents a worst case and rms represents an average value. Both have value. --Jon
(maybe off topic a bit, but...) As an ME using electronic gear for making vibration and dynamic stress measurements, the prevalence of RMS has always been a nuisance. We measure most things in P-P. Failures occur on the peak stress values and journal bearing damage can occur when rotors move more than the available distance within the bearing clearance. The early spectrum analyzers (like the HP 3582A or 5451c) would make RMS measurements apparently because they came from the EE world. We had to do odd things like use voltage dividers to obtain PP spectral values (or actually 0.1 PP).
Now, although any DAQ system can provide PP, many of the allowable specs were written for RMS and are still used.
It's simple, all signals that do not convey information are noise. A useful concept to keep in mind next time you listen to a speach or watch the news only to see a piece with puppies in it.
LOL walter, that made me laugh. OTOH, when it comes to humans, the signal is in the beholder, so to speak. For some people, those puppies are definitely a signal, just not the one other people may have been expecting when they tuned in. And a speech can certainly contain multiple types of signals meaningful to humans, but not all humans (even those that speak the language) will pick up the same signals from the same speech. This is, of course, assuming that we define "signal" as meaningful content, or information.
I think you've missed my point. The signal is the sound pressure wave, or whatever, that you receive. It contains information and noise. Thus a speach that does not contain information IS noise and a news article that does not contain information IS noise. It also means that signals containing stuff that is self evident are not information, i.e. they are nosie.
Off topic - I always get some sort of error message when I access these pages. Everything looks fine except for the text "Error on page." Is it just me or are others getting this as well?
I got your point. I just disagreed with the definitions of information and noise. My point was that when humans are involved, the definitions are highly variable. So the same speech may contain information for one person, but not for someone else. That's one of the problems with applying facts and processes from the physical sciences as metaphors for human behavior and experience.
By refining topologies and using new fluid technology, Moog's new peak sine drive controller increases available power without increasing controller volume.
Lantronix Inc. has expanded its line of controllers for sensor networks with the release of a rugged controller that improves management of automation systems used in a number of industries, including manufacturing, oil and gas, and chemicals.
Inspired by the hooks a parasitic worm uses to penetrate its host's intestines, the Karp Lab has invented a flexible adhesive patch covered with microneedles that adheres well to wet, soft tissues, but doesn't cause damage when removed.
From Dell / Intel® New Paradigms in Design Work Scott Hamilton, vertical market strategist for Dell Precision workstations, 5/2/2013 3
Early in my career, I worked as a draftsman and remember the days of drawing on vellum with numbered pencils and Mylar with plastic lead. This was a fun experience in the sense that I ...
I've been using workstations for more than 10 years and love finding ways to get more performance from my system. With demanding professional applications that require more power each ...
A lasting memory from my first job as an engineer in an auto assembly plant is standing on hard concrete at six in the morning, vending-machine coffee clutched in hand, listening to ...
A quick look into the merger of two powerhouse 3D printing OEMs and the new leader in rapid prototyping solutions, Stratasys. The industrial revolution is now led by 3D printing and engineers are given the opportunity to fully maximize their design capabilities, reduce their time-to-market and functionally test prototypes cheaper, faster and easier. Bruce Bradshaw, Director of Marketing in North America, will explore the large product offering and variety of materials that will help CAD designers articulate their product design with actual, physical prototypes. This broadcast will dive deep into technical information including application specific stories from real world customers and their experiences with 3D printing. 3D Printing is
To save this item to your list of favorite Design News content so you can find it later in your Profile page, click the "Save It" button next to the item.
If you found this interesting or useful, please use the links to the services below to share it with other readers. You will need a free account with each service to share an item via that service.
Tweet This
7 
