Talk:Envelope (waves)

Error in beating waves

It looks like all the sources use plus and minus half deltas, unlike this section. As used here, the beat frequency would be 2 delta f. It would be better to do it like the sources. Dicklyon (talk) 15:31, 9 April 2012 (UTC)

Thanks for pointing this out. It is corrected. Brews ohare (talk) 15:44, 9 April 2012 (UTC)

Except that you didn't do it like the sources. Dicklyon (talk) 22:02, 9 April 2012 (UTC)

Question about the first figure

This concerns both the text and the first figure, where the upper and lower envelope differences are emphasized. But it should be noted that the difference between the upper and lower envelopes represent a relatively low frequency, possibly for separate message intelligence, that can be transmitted through a cable, but not through the air with any practical antenna. Any practical antenna gets rid of the low frequencies, forcing the upper and lower envelope to be mirror images of each other. This eliminates the low frequency message if different from the main modulating signal. These concepts are hidden in the figure and could cause a lot of confusion if not explained. To avoid all the explanation, just get rid of the low frequency component just like radio systems do. In other words, make the upper and lower envelopes mirror images of each other. Ohgddfp (talk) 16:50, 9 December 2020 (UTC)

While there are lots of sources that talk about upper and lower envelopes, I agree it's unusual, and certainly not what you find in radio systems. The article and illustrations are essentially in the same state as originally created in 2012 by User:Brews ohare, who has been indef blocked since 2015. He has a pretty idiosyncratic take on many topics. Feel free to work toward a more normal viewpoint, starting with "symmetric" envelope as used in AM radio and such, and maybe introducing upper and lower later. Dicklyon (talk) 18:00, 9 December 2020 (UTC)

The second figure is also confusingly inconsistent, as the colored outlines switch between upper and lower envelopes. Dicklyon (talk) 18:16, 9 December 2020 (UTC)

Question about the Lead

About "The envelope thus generalizes the concept of a constant amplitude into an instantaneous amplitude.": Which envelope? The upper or the lower? Each envelope alone as illustrated in the first figure cannot possibly give the "instantaneous amplitude" of the "oscillating signal", because with two different envelopes, a reader might conclude that there must be 2 instantaneous amplitudes represented by the figure. But of course, 2 instantaneous amplitudes of one time function are physically impossible. How to fix this ? ? Ohgddfp (talk) 17:46, 9 December 2020 (UTC)

Feel free to just remove unsourced/uninterpretable stuff, or rewrite it based on a source and cite the source. Dicklyon (talk) 18:02, 9 December 2020 (UTC)

The lead talks about an "oscillating signal", but the first example suddenly jumps to an overly-complicated time–space situation. It would be best to start with an AM modulated sinewave in time; no need for wavelength, though that could be brought in later if desired. For a next example based on beating, two time waveforms are enough; no need for the space dimension. Dicklyon (talk) 18:20, 9 December 2020 (UTC)