Talk:Pulse-amplitude modulation

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IMHO, the diagram on this page should be remade in PNG format rather than JPG; the image suffers from terrible JPG artifacting. --Jonathan Drain 19:53, 23 Nov 2004 (UTC)

In my opinion, the image isn't useful at all. It's a "graph" of four numbers. I removed it. dbenbenn | talk 07:20, 30 Jan 2005 (UTC)

Factual inaccuracies and distortion.[edit]

The following was removed from the article:

Pulse-amplitude modulation is widely used in baseband transmission of digital data, with non-baseband applications having been largely superseded by [[pulse-code modulation]], and, more recently, by [[pulse-position modulation]].


  1. PAM is not digital. PAM is analog in level and discrete in time. PCM is discrete in level and discrete in time.
  2. While PCM has superceded PAM, PPM has not superceded PCM (PCM is still widely used).

If somebody wants to rework the sentence, please do so. Otherwise, I can do it later. Meanwhile, we should not have factual inaccuracies in the article. Ra2007 (talk) 16:14, 17 December 2007 (UTC)Reply[reply]

I just reverted myself because there are some sources incorrectly defining PAM as a PCM. Strictly speaking, PAM can have any real value in amplitude, while PCM is discrete. So-called N-level digital PAM is not PAM, though it is similar. Givin contradictions between some sources, this article, and reliable sources, it might take a bit of time to sort this out. Ra2007 (talk) 16:22, 17 December 2007 (UTC)Reply[reply]

"A special technique"???[edit]

In the Use in Ethernet section, the sentence, "A special technique is used to reduce inter-symbol interference between the unshielded pairs." is pretty useless. Marking it with "Citation needed". Ideally, the a link to the actual technique, or at least the *name* of the technique, would be included. — Preceding unsigned comment added by Brandon.irwin (talkcontribs) 17:31, 20 June 2011 (UTC)Reply[reply]

I've cleaned up the Ethernet section and removed this. There is a lot of detailed information about the modulation in the linked articles: 100BASE-TX, 1000BASE-T and 10GBASE-T. ~KvnG 15:00, 2 March 2015 (UTC)Reply[reply]

The benefit of PAM[edit]

Should indicate what the benefit of PAM is. That is, why generate it in the first place when compared with sending a typical message analog signal. Is it to reduce wasted power? In other words, what's the point of PAM? KorgBoy (talk) 23:39, 26 March 2018 (UTC)Reply[reply]
Pulse-amplitude modulation has also been developed for the control of light-emitting diodes (LEDs), especially for lighting applications.[1]

This sentence gives me the impression that PAM is a superior technology for LED drivers of LED lamps. But the referenced article does not talk about generic “lighting”, but applications where flicker is acceptable or desired, such as TV studios.

LED drivers based on the PAM technique offer improved energy efficiency over systems based upon other common driver modulation techniques such as pulse-width modulation (PWM) as the forward current passing through an LED is relative to the intensity of the light output and the LED efficiency increases as the forward current is reduced.

This sentence confirms my impression. PWM is by no means “common” for lighting applications, it is only common for signage. The most common and efficient implementation of LED drivers nowadays is probably buck for DC power, and other types of switched-mode power supply for AC power, which all produce constant current, without any kind of modulation.

What I want to demonstrate: Comparing PAM to PWM gives a wrong impression. Especially the second sentence should be removed. If not the whole section. (talk) 14:22, 20 August 2023 (UTC)Reply[reply]


  1. ^ Whitaker, Tim (January 2006). "Closed-Loop Electronic Controllers Drive LED Systems". LEDs. Retrieved 2020-10-29.