[BC] Outside source for checking Modulation Levels

[Cowboy]

On Tuesday 22 July 2014 12:08:08 am Harold Hallikainen wrote:
> It's part of the requirements for stereo monitors. It's 73.332(d)(4).
> 
> For a while, I thought I'd imagined it... 

 Back to the original question, before this whole Eric Small
 muddying of the water history, the short version is that yes,
 you can clip a garden variety O-scope to the un-deemphasized
 audio output of an FM discriminator, then modulate the transmitter
 with an accurate 13586 hz tone.
 Increase audio level until the second carrier null is observed on
 something capable of seeing carrier level, like a narrow band
 communications receiver, or a spectrum analyzer.
 At the point that second carrier null occurs, you are deviating exactly
 74.99472 kilohertz, or are modulating exactly 99.99296%.
 Close enough for government work.
 Mark that level on the O-scope.
 Modulate program up to, but never exceeding, that line,
 and call it 100%.

-- 
Cowboy