I have done quite a bit of digital equipment testing,
and I have not often see a microprocessor being susceptible in
the 10-20-30 V/m range. And yes cellphones above 1-2 Watts can
easily generate 20-40 volts/m when emitting max power.
What causes the problem in many cases is the analog circuitry associated
with microprocessors:
- scanned keyboards
- supply voltage monitoring circuits
- analog inputs (like temperature sensors)
Where I would give the first category a big chance of
having caused the problems.
The problem is that digital designers do not uncommonly
no nothing about:
- current flowing through ground
- current flowing in loops
- other voltages then 1 and 0
- other signals then wanted signals
Working at companies that:
- do not think about their responsibilities unless penalized
- focus on maximizing revenues and lowering costs
- minimize on test costs "judged" superfluous ("because we never had any
problem" , sounds familiar?)
These companies are managed by "managers" that focus on:
- Lowering the costs of education "hardware"
- Maximizing their personal revenues
- Minimizing their personnel revenues
Digital designers are educated by schools that prefer:
- Simulating electronics instead of experimenting
- Simulating instead of soldering
- Checking functional specifications only
Which are managed by modern managers (ex bank?) that focus on:
- Lowering the costs of education "hardware"
- Maximizing their personal revenues
- Minimizing their personnel revenues
The lists above are in no way:
- complete
- objective
- conclusive
So don't judge the good old microprocessor
and blame the managers !
;<))
Gert Gremmen
Ce-test
Van: [email protected] [mailto:[email protected]] Namens Kunde, Brian
Verzonden: maandag 24 augustus 2009 20:24
Aan: [email protected]
Onderwerp: RE: Ring Of Fire? Cell Phone Turns On Oven - Popcorn II?
Can anyone confirm that a cell phone can generate 10V/m or more at any
reasonable distance? [lets say 1 meter]. I didn't think the transmitter was
that powerful.
We played around with a cell phone and our isotropic probe and we couldn't get
a reading over a few V/m unless we put the phone right up against the antenna
cone. And then, the maximum we read was around 30V/m, but again, that was
with the phone touching the antenna of the probe.
Curious.
The Other Brian
From: [email protected] [mailto:[email protected]] On Behalf Of John McAuley
Sent: Monday, August 24, 2009 12:11 PM
To: 'John Woodgate'; [email protected]
Subject: RE: Ring Of Fire? Cell Phone Turns On Oven - Popcorn II?
It was me, I thought I was replying to all.
John McAuley
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From: [email protected] [mailto:[email protected]] On Behalf Of John
Woodgate
Sent: 24 August 2009 16:33
To: [email protected]
Subject: Re: Ring Of Fire? Cell Phone Turns On Oven - Popcorn II?
In message
<9d04b979323dcd428297dda95108893e0287f...@bb-corp-ex2.corp.cubic.cub>,
dated Mon, 24 Aug 2009, "Price, Edward" <[email protected]> writes:
>OTOH, I would expect to see 5 to 10 V/M at two meters distance from a
>cell phone, so at a half-meter or less, I would be surprised to NOT see
>some interaction.
>
>And then, on yet another hand, proximity of cell phones should be
>expected for household systems.
It was pointed out to me in a private email (why not to the list I don't
know) that the relevant IEC/EN safety standard IEC 60335-1, applying to
all household appliances, imposes in clause 19.11.4 'EMC for functional
safety' requirements beyond those of CISPR 14-2, including an RF
immunity test at 10 V/m (but you need to refer to yet another standard,
IEC/EN 61000-4-3, to find the actual figure!).
--
OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk
Things can always get better. But that's not the only option.
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK
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