[BC] AM Stereo On A Mono Radio-FM Loudness

[Thomas G. Osenkowsky]

It was once explained to me that the FCC van
used a receiver that they 'calibrated' for each
measurement. Hook a DC coupled scope to
the discriminator output when fed a dead carrier
at operating frequency. Set scope trace to middle
of scale. Now change osc freq +75 KHz. Mark
screen with grease pencil. Repeat for - 75 KHz.
Connect receiver to antenna and observe if
peaks fall within penciled lines. All they need is
an accurate frequency counter, RF oscillator and
receiver.

Tom Osenkowsky, CPBE

> At the NAB a few years ago, I was shown by the FCC how they measured it
there.
> They took a lab grade FM tuner and connected it to an oscilloscope that
was
> calibrated to the tuner for 100% modulation at their lab. After adjusting
the
> directional antenna to eliminate multipath, they looked at the modulation
> peaks on the calibrated 'scope. Too many and you got a pink slip. That
sure
> DOESN'T sound like using occupied bandwidth to me!