Propeller Head Plaza

RE: All PCM is digital, but not all digital is PCM

68.186.88.59

In Reply to: RE: All PCM is digital, but not all digital is PCM posted by rick_m on July 01, 2008 at 22:02:46

"But PWM does not transmit numbers, it transmits average voltage levels that are an analog of the data along with a bunch of noise as an artifact."

Looking at this another way, is not PWM simply binary? It's output is either 1 (on) or 0 (off) for each frame of time determined by the switching rate. There may be a million set frames of time and with each the amp is either on or off with those time slots not being further dividable. The combination of those numbers might be, um, an analogue of analog, but their base nature is quantized and thus digital. The result is that a passive component such as an inductor or loudspeaker driver might average the set voltage per its duty cycle of a brief period of time while the voltage outputted by the amplifier is set in level.

However, that's going by ideal PWM as I understand it. Some of the new Class T amplifiers such as those put out by Tripath appear to use a floating clock where the number of time slots for the 0 or 1 amplifier output vary in number and duration according to the needs of the inputted signal. By your argument, those be considered more analog than digital, but then couldn't variable bit rate lossy audio codecs such as vbr MP3 and WMA be considered analog formats as well?

Follow Ups:

RE: All PCM is digital, but not all digital is PCM - rick_m 07:35:42 07/02/08 (0)

Post a Followup:

FAQ

Post a Message!

Forgot Password?

Moniker (Username):
Password (Optional):
	Remember my Moniker & Password (What's this?) Eat Me
E-Mail (Optional):
Subject:

Message:	(Posts are subject to Content Rules)

Optional Link URL:
Optional Link Title:
Optional Image URL:
Upload Image:
E-mail Replies:	Automagically notify you when someone responds.

To view your new posting or follow-up, click on the RELOAD or REFRESH button on your browser.