Hi Ken,
Let me try to explain it better. The standard asks that you stop reducing
the signal strength one you cross the 25% threshold. I would imagine that it
would be very hard to get exactly 25% So for example if you got a 10 %
failure rate at one level then reduced the transmit signal strength by 1 dB
and got a 30% failure rate you would stop there. Also many digital systems
would likely have an all or nothing response so getting a 25% failure rate
would be not possible.
As to "restoring to full power" the power level of the transmitter in this
case is fixed, the signal strength of the system is reduced by adding
attenuation in line to the transmitter antenna. This is simply removed once
the threshold is determined and the interference signal is added to the
equation.
Regards
Kevin
-----Original Message-----
From: Ken Javor [mailto:[email protected]]
Sent: Monday, May 07, 2001 10:48 PM
To: Price, Ed; 'Kevin Harris'; EMC-PSTC (E-mail)
Subject: Re: RF testing question
Either I am being dense, or there is not enough info in the
problem
statement. Mr. Harris states that after determination of
the interference
level (that signal which yields no better than 25% error
rate plus 40 dB)
the transmitter is returned to full power. How is full
power defined? The
success or failure of this test will depend on that. Also,
the words 25% OR
MORE of the signals are not understood (my emphasis) are
unclear. If I
wanted to pass this test, I would reduce the transmitter
level until no
signals are understood, then add 40 dB to that number and I
would get a
lower susceptibility signal than if I had stopped at
precisely the 25%
level. So to me it seems that there are two uncontrolled
variables here:
the baseline for establishing the susceptibility signal
level, and the level
at which the desired signal is transmitted. What am I
missing (besides
maybe some of my dear, departed brain cells)?
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