1/f noise - Page 1
Forum section: electronics / projects

author: CaptnYellowShirt
author_rank: Frequent Contributor
timestamp: February 15, 2014, 07:42:01 pm
content: Here's a good read on the subject:"1/f noise: a pedagogical review"http://arxiv.org/pdf/physics/0204033But it makes me wonder, is there really no lower limit to the 1/f noise?And if not, is there really such a thing as a 'DC level' of a signal?

author: hamster_nz
author_rank: Super Contributor
timestamp: February 15, 2014, 09:38:33 pm
content: I often wonder about 1/f noise in biological systems (eg human vision) and somehow think our senses and perception of time have evolved to find the balance between thermal and 1/f noise.

author: CaptnYellowShirt
author_rank: Frequent Contributor
timestamp: February 15, 2014, 10:04:52 pm
content: I've never thought about it like that.The weight of my key fob or cell phone never seems to *perceptively* change.I wonder if you put load sensors in a pair of shoes and walked on them for a day, week, month if you'd find 1/f noise in the foot you favored for balance.

author: Sam__
author_rank: Regular Contributor
timestamp: February 15, 2014, 10:31:33 pm
content: As much as I don't understand the maths, it's an interesting read.

author: CaptnYellowShirt
author_rank: Frequent Contributor
timestamp: February 15, 2014, 10:41:25 pm
content: maths are just fancy logics, and logics are just fancy common sense. personally, i've never been one to assume that maths are required to understand a subject -- sometimes they simply obscure the essential nature of the problem.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 15, 2014, 10:42:21 pm
content: Nice paper, thanks.

author: tszaboo
author_rank: Super Contributor
timestamp: February 16, 2014, 12:52:50 am
content: Quote from: CaptnYellowShirt on February 15, 2014, 07:42:01 pmThere is no lower limit. There is drift, a very low frequency noise. There is the temperature changing for a 24 hour period. Ultimately, your circuit will be destroyed in the next 30-3000 years, so that frequency component will be actually quite large.

author: CaptnYellowShirt
author_rank: Frequent Contributor
timestamp: February 16, 2014, 01:22:49 am
content: Quote from: NANDBlog on February 16, 2014, 12:52:50 amheh. I thought about things like that after I wrote the question. A few times a year the power grid gets interrupted for long periods of time... AC and Heating systems break.... people trip and bump into things... earthquakes... Sun going super nova ... etc etc

author: vk6zgo
author_rank: Super Contributor
timestamp: February 16, 2014, 03:38:11 am
content: This seems to be a serious study,but it is so close-packed with jargon,& throwaway references to other studies,to say nothing of the mandatory reference to Mandelbrot & fractals,that I doubt that I could really pick a serious study from a leg-pull.

author: hamster_nz
author_rank: Super Contributor
timestamp: February 16, 2014, 04:22:30 am
content: As usual Wikipedia has a good article too -http://en.wikipedia.org/wiki/Pink_noise

author: Mechatrommer
author_rank: Super Contributor
timestamp: February 16, 2014, 04:44:46 am
content: Quote from: CaptnYellowShirt on February 15, 2014, 10:41:25 pmmath is an incomplete system of approximation. it does wonder though and make us closer, but still its an incomplete system of approximation.

author: Unknown
author_rank: Unknown
timestamp: February 16, 2014, 05:05:22 am
content: More than anything, it looks like an EE's version of Cosma Shalizi's classic"So You Think You Have a Power Law — Well Isn't That Special?"post, and the related paper"Power-law distributions in empirical data".I actually laughed at the 'power law ... power law ... power law ... power la... - oops, no, see, when you look at it properly that's not really a power law' format. Although I'd happily argue in disagreement with the conclusion in Section 9 - from the data presented, I think that's another example of not-a-power-law, despite his argument of a biochemical basis suggesting it is.(I'm not an EE; my postgrad work was/is in the modelling side of one of the applied sciences where power law relationships were once the flavour of the month. We've learned a lot since then, but it still crops up with enough regularity that most view them with well-deserved suspicion.)I do like the overall conclusion though (and the bit of academic snark hidden within):"My impression is that there is no real mistery behind 1/f noise, that there is no real universality and that in most cases the observed 1/f noises have been explained by beautiful and mostly ad hoc models."

author: CaptnYellowShirt
author_rank: Frequent Contributor
timestamp: February 16, 2014, 05:58:44 am
content: Quote from: Tac Eht Xilef on February 16, 2014, 05:05:22 amWhat do you think of the -5/3 turbulence cascade?

author: Unknown
author_rank: Unknown
timestamp: February 16, 2014, 02:42:59 pm
content: Quote from: CaptnYellowShirt on February 16, 2014, 05:58:44 amNo idea; physics / fluid dynamics isn't my field either(Sorry for being cagey; for various reasons I like to keep real-life and internet-life well apart, so it's enough to say it has absolutely nothing to do with electronics or physics. Think more Taylor or Kleiber than Navier, Stokes, or Richardson - although all have their basis in Kolmogorov's works, power laws, etc...)

author: CaptnYellowShirt
author_rank: Frequent Contributor
timestamp: February 16, 2014, 05:18:55 pm
content: Quote from: Dawgie on February 16, 2014, 06:10:57 am$5 says it will. We'll decide the winner after it happens.

author: ejeffrey
author_rank: Super Contributor
timestamp: February 16, 2014, 06:21:36 pm
content: "1/f" noise is also often used as a catch-all for low frequency noise of an unspecified origin, i.e. the slope is not necessarily exactly 1/f -- it could be anywhere from 1/sqrt(f) to 1/f^1.5, and it isn't necessarily even a constant slope, so the noise density isn't a true power law at all. You can see this in the linked document, the slopes are actually varied and often curved.The reason is quite obvious: although "1/f" noise is ubiquitous, there is no single source for it. Instead, 1/f noise generally comes a bath of defects/fluctuators each with their own energy and time scales. They generally average out to approximately a 1/f spectrum, but only approximately.