In Reply to: Re: Hi Ted. posted by Ted Smith on August 23, 2003 at 05:16:51:
Thanks for the pic info Ted..""And if you are bandlimited you have many cycles of your signal so you see the correct peaks, etc.""ted
Agreed..but look at your 14 khz waveform...you really have to wait around to see the sample coincide with the actual peak of the waveform. You are making the connection in your thinking that when the two coincide, that is the actual wave amplitude..
Reconstruction of that signal by a DAC...For the dac to really output the correct amplitude of that signal, it has to look over many samples to get the right amplitude..Hence, my point..
Now, if you were to "connect the dots", so to speak, with some filtering, you should see some envelope modulation..what is interesting is that the top of that envelope is not symmetric with the bottom one, there will be a frequency component there. And, nyquist math does not produce that artifact, unless you include the FIR response of real filters, representing the very few samples that are actually available to the filter. Also, don't forget, Nyquist math requires sample lookahead in order to work..
Thanks Ted
John
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Follow Ups
- Re: Hi Ted. - jneutron 07:02:30 08/23/03 (12)
- Re: Hi Ted. - Ted Smith 07:24:03 08/23/03 (11)
- Code correction - Ted Smith 19:22:23 08/23/03 (0)
- Re: Hi Ted. what you do??edit a typo? - jneutron 07:44:47 08/23/03 (9)
- Re: Hi Ted. what you do??edit a typo? - Ted Smith 08:09:33 08/23/03 (8)
- Re: Hi Ted. what you do??edit a typo? - jneutron 09:13:54 08/23/03 (7)
- Re: Hi Ted. what you do??edit a typo? - Ted Smith 09:41:40 08/23/03 (6)
- Re: Hi Ted. what you do??edit a typo? - jneutron 10:28:39 08/23/03 (5)
- Re: Hi Ted. what you do??edit a typo? - Ted Smith 11:25:20 08/23/03 (4)
- What's confusing to most people about this - Commuteman 17:37:13 08/23/03 (2)
- Re: What's confusing to most people about this - Ted Smith 19:13:42 08/23/03 (1)
- Re: What's confusing to most people about this - jneutron 07:47:01 08/25/03 (0)
- Re: Hi Ted. what you do??edit a typo? - john curl 13:20:02 08/23/03 (0)