The AM Forum

THE AM BULLETIN BOARD => Technical Forum => Topic started by: RolandSWL on September 11, 2015, 02:57:28 PM



Title: Modulation Article.....
Post by: RolandSWL on September 11, 2015, 02:57:28 PM
My brain hurts, but in a good way.

http://www.qsl.net/wa5bxo/asyam/aam3.html

RSWL..............


Title: Re: Modulation Article.....
Post by: W3NE on September 13, 2015, 04:15:31 PM
I wasn't going to respond to this post, but since nobody else so has far, I thought Roland might appreciate some comments in view of his previous interest here.

I didn't notice a date on the articles, which seem detailed and serious enough, but for some reason ignored that the effect of speech waveform asymmetry on modulation depth of AM has been well understood by hams for decades. Also, since I only scanned them, other than selective polarization of the speech system from mike to load side of modulation transformer (or other transmitter ports in cases other than plate modulation), the articles do not appear to mention all-pass phase shift networks, after Kahn, and currently-available fully-populated PC boards offered at a bargain price on eBay, as one approach to reducing asymmetry of speech waveforms, as has been previously covered in depth on this forum.

While the contributors are in earnest about their findings, they are hardly new or any more insightful than long-held understanding of the effect. Maybe that's why nobody else has said anything?

Bob - NE


Title: Re: Modulation Article.....
Post by: K4RT on September 13, 2015, 05:48:27 PM
I believe the article also appeared (and perhaps first appeared) in the AM Press/Exchange, and I think you can find those newsletters by using the "AMPX" link on this site.  Determining the date of the article should be possible - assuming that it was not published earlier elsewhere.
AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands