[BC] Modualtion Monitors (do we need them?)

[Jeff Welton]

Dave Dunsmoor (hi Dave!) queried...

> Is your Fluke scope the 199C? If so, how do you actually confirm that
your
> modulation envelope is accurate?

That's an easy 3 step process.

1.  Center the scope trace on the display, using the 0 ref indicator on
the left side of the trace.

2.  Apply the modulated RF signal, with no audio, turn cursors on and
set them to measure the peak (center line to top of waveform, for
example) voltage.

3.  Turn the audio on and move the top cursor to the audio peaks.  Then
do the math to calculate the peak mod.  For example, if you have 2.5V pk
in step 2 and 5V pk in step 3, you have 100% mod.  If you have 2.5V in
step 2 and 7.5V in step 3, you have 150% mod.

You may have to play with the time setting to get the display to stay
steady enough, although it works better on the 199 than on the 196.
I've used our 196 to check mod quite a bit and it gives pretty good
results.  You can also turn on the MAX HOLD feature and wait until the
display has totally filled up, then set the cursors (in step 3) for more
accurate results.

Been there, done that, love my ScopeMeter (time to retire the model 97
now and talk the boss into buying us another 196 or a 199 <g>).

Best,

Jeff Welton
Customer Service Department
Nautel 
+1.902.823.3900 x 127
www.nautel.com
MAKING DIGITAL RADIO WORK