What is the analog equivalent of aliasing?

Started by Green Xenon [Radium] May 12, 2008
Hi:

Aliasing is a digital entity. What is the analog equivalent of aliasing?


Thanks,

Radium
On May 12, 8:20 pm, "Green Xenon [Radium]" <gluceg...@excite.com>
wrote:
> Hi: > > Aliasing is a digital entity. What is the analog equivalent of aliasing? > > Thanks, > > Radium
Why does there need to be an analog equivalent? Aliasing is an artifact of the conversion of a waveform defined on continuous-time into a set of discrete samples, occurring when the spacing between samples isn't small enough to unambiguously capture all of the spectral content of the original signal. What makes you think there's an analog equivalent? Jason
Green Xenon [Radium] wrote:
> Hi: > > Aliasing is a digital entity. What is the analog equivalent of aliasing?
Aliasing is a digital phenomenon. There is no analog equivalent of aliasing. Jerry -- Engineering is the art of making what you want from things you can get. &#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;
cincydsp@gmail.com wrote:
> On May 12, 8:20 pm, "Green Xenon [Radium]" <gluceg...@excite.com> > wrote: >> Hi: >> >> Aliasing is a digital entity. What is the analog equivalent of aliasing? >> >> Thanks, >> >> Radium > > Why does there need to be an analog equivalent? Aliasing is an > artifact of the conversion of a waveform defined on continuous-time > into a set of discrete samples, occurring when the spacing between > samples isn't small enough to unambiguously capture all of the > spectral content of the original signal. What makes you think there's > an analog equivalent?
The OP suffers from the delusion that his imaginings are pears, a delusion shared by many children of doting parents. Jerry -- Engineering is the art of making what you want from things you can get. &#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;
cincydsp@gmail.com wrote:
 > On May 12, 8:20 pm, "Green Xenon [Radium]" <gluceg...@excite.com>
 > wrote:
 >> Hi:
 >>
 >> Aliasing is a digital entity. What is the analog equivalent of aliasing?
 >>
 >> Thanks,
 >>
 >> Radium
 >
 > Why does there need to be an analog equivalent? Aliasing is an
 > artifact of the conversion of a waveform defined on continuous-time
 > into a set of discrete samples, occurring when the spacing between
 > samples isn't small enough to unambiguously capture all of the
 > spectral content of the original signal. What makes you think there's
 > an analog equivalent?

The OP suffers from the delusion that his imaginings are pearls, a 
delusion shared by many children of doting parents.

Jerry
-- 
Engineering is the art of making what you want from things you can get.
&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;
"Jerry Avins" <jya@ieee.org> wrote

> There is no analog equivalent of aliasing.
How about an analog "analog"? An anaolog "analog" might be an image frequency folding into an IF frequency during a mixing process. Brent
Blocher's spokesman wrote:
> "Jerry Avins" <jya@ieee.org> wrote > >> There is no analog equivalent of aliasing. > > How about an analog "analog"? > > An anaolog "analog" might be an image frequency folding into an IF frequency > during a mixing process.
IF images come close, but that's not what our radioactive friend asked about. Like AM sidebands -- very similar in principle -- they aren't superposed. Jerry -- Engineering is the art of making what you want from things you can get. &#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;
"Green Xenon [Radium]" <glucegen1@excite.com> wrote in message 
news:4828ded3$0$5698$4c368faf@roadrunner.com...
> Hi: > > Aliasing is a digital entity. What is the analog equivalent of aliasing? >
Aliasing isn't a digital entity it's a sampling entity. That you digitize the samples has nothing to do with it. Sampling is a modulation process. A sample stream is modulated with the signal that's sampled. Because it's a modulation process then one looks for other modulation processes that might have similarities. Plain old amplitude modulation would be a good example where aliasing can occur. Assume a baseband signal with bandwidth +/-B. Modulate a carrier with it which is at afrequency greater than 2B. You get sum and difference frequency components as a result. Now, reduce the carrier frequency to less than 2B and you get aliasing in the general case. Fred
Fred Marshall wrote:
> "Green Xenon [Radium]" <glucegen1@excite.com> wrote in message > news:4828ded3$0$5698$4c368faf@roadrunner.com... >> Hi: >> >> Aliasing is a digital entity. What is the analog equivalent of aliasing? >> > > Aliasing isn't a digital entity it's a sampling entity. That you digitize > the samples has nothing to do with it. > > Sampling is a modulation process. A sample stream is modulated with the > signal that's sampled. > > Because it's a modulation process then one looks for other modulation > processes that might have similarities. > > Plain old amplitude modulation would be a good example where aliasing can > occur. Assume a baseband signal with bandwidth +/-B. Modulate a carrier > with it which is at afrequency greater than 2B. You get sum and difference > frequency components as a result. > > Now, reduce the carrier frequency to less than 2B and you get aliasing in > the general case. > > Fred > >
But won't an analog device just smoothly cut-off a frequency that is too high -- i.e. at a certain point the cut-off gradually beings and the higher an incoming frequency is, the more it will be attenuated -- without any aliasing?
Green Xenon [Radium] wrote:


> the cut-off gradually beings
Sorry, that should read "the cut-off gradually *begins*"