Howdy Ed. Edward B Richards wrote:
> 1. It is hard to tell modulation percent with voice as the waveform keeps > changing and unless I use a sine wave I can't sync it to get a good > envelope pattern. Any trick to this? You're not going to get it to sync reliably to a complex waveform like speech. But it's not necessary in order to use it as a mod indicator anyway. As long as you can clearly see what the negative and positive peaks are doing, that's all that matters. Just adjust the sweep rate to a slow enough rate where low frequencies are easily seen. Calibrate your scope so that your dead carrier occupies 4 vertical divisions, (2 above and 2 below zero axis). Then 100% positive peaks will be where the envelope extends to 8 total vertical divisions, (4 above and 4 below the zero axis). 100% negative is where the carrier pinches off in the center, of course. > 2. Using the mod mon I see that it is very easy to over-modulate. If I > keep the modulation down so I don't see short bright lines in the center > of the screen (carrier disappearing, I think) , the average modulation is > around 50% except for occasional peaks. Is this normal? would a > compression amplifier help? Thank you. Very normal. To get the average up, at the very least you'll need to tightly control peaks and limit them to never negatively overmodulate the carrier. Positive peaks you can let go if you like. IMHO everyone needs at least a peak limiter of some sort. 73, g
