Smear jobs (Electromagnetic Spectrum Division)

[PeteS in CA]

Smear jobs (Electromagnetic Spectrum Division)
EDN Magazine Blog
Dec 5 2005 7:06AM | Permalink | Email this | Comments (7) |

A recent Design Idea entitled "Dither a power converter's operating frequency to reduce peak emissions" has drawn several heated comments from readers regarding the wisdom—or lack thereof—of reducing the EMI signature of an SMPS (switched-mode power supply) by smearing it over a broad swath of spectrum.

Interference production by consumer electronics and electrical appliances has existed since the dawn of the radio age. Certain early-vintage incandescent lamps produced RF that interfered with reception, as did arcing thermostats, neon advertising signs, electric razors, and just about everything that drew juice from the ac line. Some noise sources didn't have to plug in—for instance, automobile-ignition noise plagued television reception in the immediate post-WWII era.

What's new in SMPS design—and, for that matter, in BPL (broadband over powerline) data transmission, frequency-hopping communications equipment, and baseband or extremely wideband systems—is their common tendency to disperse signals and noise over a range of frequencies.

This blog and the comments that follow have some interesting things about an EMI suppression technique.

[arneson]

My teeth occasionally get internet access with all the wifi's in the neighborhood, and you know that strange ringing in your ears once in a while, what could that be?

[stretch0069]

That would be the wife complaining about...........

.....huh?????



Funny...we just got a message about EMI. weird. guess i should go read it now.

[arneson]

My neighbor, a very beautiful german girl, has a pacemaker and was very scared of any device emitting stray EMI.
I on the other hand spent all day next to a 4KW radar array.

Never had really thought of the radio spectrum as being polluted, but theres noise pollution, light pollution, air, water, space, electrolytics, everything is smeared.

I feel like a monkey in a cage being bombarded with intense broad spectrum radio waves.

[MD Willington]

Did you ask to compare scars..could be fun...

[arneson]

She visits sometimes but when she comes in I can almost see the arythmia start.
I have winking blinking wireless stuff everywhere.

As a kid I built the Heathkit shortwave radio and would comb the bands for any signs of intelligence, kind of like SETI. The buzzing sqaucking crackle and pop always fascinated me.
We can allocate FCC bandwidth sensibly, but all it takes is a zit popping solar flare on the suns surface to blind everyone.
Just my 2 cents.