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Interference-cost tradeoffs and cheating

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Daryl Gerke
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re: Interference-cost tradeoffs and cheating
Daryl Gerke   2/5/2012 1:37:58 AM
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Thanks for the kind comments on our EMC series. For me, it all started with a ham license. Fifty years later, still dealing with interference. 73, Daryl Gerke - K0FBF Kimmel Gerke Associates

krisi
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CEO
re: Interference-cost tradeoffs and cheating
krisi   11/24/2011 10:18:12 PM
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FCC regulations would not prevent this supplier from removing the filter when shipping its products...but it was probably low cost item...sometimes you get what you paid for, unfortunately I see no solution for this problem...Kris

jgruszynski
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re: Interference-cost tradeoffs and cheating
jgruszynski   11/17/2011 4:44:03 PM
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Quite possible. Even likely. I was told by a local _US electrician_ that US companies routinely buy all the necessary regulatory stickers they need including those that are nominally "serialized" by standards bodies and agencies and slap them on products without any testing. He apparently knew directly of a dozen or so in Silicon Valley. Of course when you do actually though the real certification, you have to buy the same raw stickers too. Printing stickers is not rocket science and you can't do the "Soviet method" of controlling them like printing presses and copy machines without destroying what little innovation still goes on in the US.

sharps_eng
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re: Interference-cost tradeoffs and cheating
sharps_eng   11/16/2011 10:38:12 PM
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Trouble is brewing in Britain where BT (our Ma Bell) has been selling Comtrend Power-Line Transmission (PLT) home systems that are 30dB over the permissible limits. OFCOM (=your FCC) have been refusing to acknowledge the problem and when called upon to intervene, our public representatives (MPs) just quote OFCOM's press releases claiming there is no problem. Effects like blanking of car remotes, garage openers and other 2.4GHz products are increasingly widespread, not all due to PLT but emissions 1000x over the limit is like fouling the well in your village, nothing to be proud of, surely! Check out www.theemcjournal.com if interested...

masher
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re: Interference-cost tradeoffs and cheating
masher   11/16/2011 6:41:55 PM
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I had a similar problem here but mine was a electric lawn mowers charger, so much for green technology huh, It makes me want to go back to gas mowers. This charger knocked out HF and VHF receivers from 3 Mhz to 138 MHz and even created a nice buzz in the TV audio, it was detectable and still killing receivers at over a 1/8 mile from the source. Within 1 block the wideband noise floor increased over 40 dB. Does the FCC really care about issues like this anymore what with the selling of our GPS frequencies to lightsquared all in the name of creating jobs which we all know will only create them overseas ?

apummer945
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Rookie
re: Interference-cost tradeoffs and cheating
apummer945   11/16/2011 1:25:08 PM
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Bu basically the FCC is asking you to cheat, since that clock frequency wobbling to reduce the reading of the spectrum analyzer to pas the test is nothing else but cheating.

Sanjib.A
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CEO
re: Interference-cost tradeoffs and cheating
Sanjib.A   11/15/2011 4:37:04 PM
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Nice EMI troubleshooting story! If your speculation is proven to be correct, then the manufacturer must be penalized. My doubt is whether the tests required for certification was performed at all. Now a days any electronic equipment we buy from anywhere, however small it might be, we see those fancy markings indicating compliance to various standards. Are all of them sincerely getting the tests performed before those markings are stickered on the product?

zeeglen
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re: Interference-cost tradeoffs and cheating
zeeglen   11/15/2011 12:44:25 AM
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At one company the management types had a wonderful idea - buy product from an established manufacturer and under license re-label and re-sell under their own name. (Yeah, I know, but these were MBAs). The product was an Ethernet hub for UTP (unshielded twisted pair) cable. I asked for the EMI test reports. Was very interesting to see that the radiated emissions testing had been done using SHIELDED twisted pair cable...

zeeglen
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re: Interference-cost tradeoffs and cheating
zeeglen   11/14/2011 11:13:37 PM
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I remember a software department director who at first would not believe me when I told him the product could not be sold until it had been tested and proven to comply with radiated and conducted regulatory limits. Then he learned just enough to be dangerous - he asked what was the clock frequency, I told him 20 MHz, he said no problem, FCC doesn't care unless the clock is above 30 MHz. (Sigh....) Another company called on me to solve an emissions problem with a product they had modified, sold, then finally got around to the emissions testing and discovered extreme levels. After I cleaned up the problems with highly visible hardware fixes, the head honcho of marketing asked how they were going to explain the recall and rework to their customers. My answer was very straightforward and succinct - "That's not MY problem."

David Ashton
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re: Interference-cost tradeoffs and cheating
David Ashton   11/14/2011 10:04:12 AM
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You can and you should. Otherwise the problem will never get fixed.

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