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Author: Martin HeffelsMartin Heffels Date: Aug 20, 2007 00:41
On Sun, 19 Aug 2007 18:14:58 -0700, Radium gmail.com> wrote:
>If a digital audio device can play audio back without
>any moving parts, why can't an analog audio device be designed to do
>the same?
Because if it could, there would be no need to invent digital which has the
advantage of non-moving parts....................
-m-
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Author: Martin HeffelsMartin Heffels Date: Aug 20, 2007 00:46
On Sun, 19 Aug 2007 20:54:06 -0700, dplatt@ radagast.org (Dave Platt) wrote:
>Another sort of a purely analog signal-storage device, with no moving
>parts other than the electrons which convey the signal, is a simple
>length of transmission line
Here is a better one: transmit the analogue system to the sun, and you have
16 minute, once-of storage. If you want to save your recording for a longer
time, you can pick more planets and stars, further away, and bounce your
radiosignal off them. It is obviously not random-access, but it is very
analogue.
-m-
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Author: Jerry AvinsJerry Avins Date: Aug 20, 2007 00:51
Don Pearce wrote:
> On Sun, 19 Aug 2007 23:26:16 -0700, dplatt@ radagast.org (Dave Platt)
> wrote:
> >> "Digital" and "subject to aliasing" are two different things.
>>
>> As I believe the term "digital" is usually meant, it implies a
>> two-state (on/off) storage representation. It's not just that the
>> signal amplitude is quantized, but that the quantization uses a
>> power-of-two representation and storage system of some sort.
>
> My reading of the possible systems goes like this.
>
> analogue - a continuous representation of the original signal
> sampled - a representation of the signal at discrete time points
> quantized - a sampled signal, but with the possible levels constrained
> to a limited set of values
> digital - a quantized signal, with the individual levels represented
> by numbers
> ...
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Author: Don PearceDon Pearce Date: Aug 20, 2007 01:04
On Mon, 20 Aug 2007 03:51:54 -0400, Jerry Avins ieee.org> wrote:
>Don Pearce wrote:
>> On Sun, 19 Aug 2007 23:26:16 -0700, dplatt@ radagast.org (Dave Platt)
>> wrote:
>> >>> "Digital" and "subject to aliasing" are two different things.
>>>
>>> As I believe the term...
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Author: Jerry AvinsJerry Avins Date: Aug 20, 2007 01:16
Martin Heffels wrote:
> On Sun, 19 Aug 2007 18:14:58 -0700, Radium gmail.com> wrote:
> >> If a digital audio device can play audio back without
>> any moving parts, why can't an analog audio device be designed to do
>> the same?
>
> Because if it could, there would be no need to invent digital which has the
> advantage of non-moving parts....................
Actually, I did invent something along those lines, but I was foolish
enough yo leave the plans in my (not yet perfected) time machine, and
they disappeared.
Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
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Author: Martin HeffelsMartin Heffels Date: Aug 20, 2007 01:31
On Mon, 20 Aug 2007 04:16:44 -0400, Jerry Avins ieee.org> wrote:
>Actually, I did invent something along those lines, but I was foolish
>enough yo leave the plans in my (not yet perfected) time machine, and
>they disappeared.
Shame on you! Radium will be very disappointed now.
-m-
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Author: Richard DobsonRichard Dobson Date: Aug 20, 2007 03:15
Radium wrote:
> On Aug 19, 6:08 pm, Jerry Avins ieee.org> wrote:
>
> >>Radium wrote:
>
>
>>>This would be a start if I want to decrease the frequency of a video
>>>signal without decreasing the playback speed.
>
>
>>Various compression schemes do that with varying degrees of resulting
>>quality.
>
>
> I am talking about:
>
> 1. Decreasing the temporal frequency of the video signal without low-
> pass filtering or decreasing the playback speed - an example of which
> would be decreasing the rate at which a bird [in the movie] flaps its ...
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Author: glen herrmannsfeldtglen herrmannsfeldt Date: Aug 20, 2007 05:00
Dave Platt wrote:
(snip)
> As I believe the term "digital" is usually meant, it implies a
> two-state (on/off) storage representation. It's not just that the
> signal amplitude is quantized, but that the quantization uses a
> power-of-two representation and storage system of some sort.
It means discrete states, but the base does not have to be two.
Many of the early computers were decimal based, and not
necessarily BCD.
The Fortran standard still allows for any base greater
than one to be used for representing values.
-- glen
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Author: glen herrmannsfeldtglen herrmannsfeldt Date: Aug 20, 2007 05:08
Floyd L. Davidson wrote:
(snip)
> In a digital channel you cannot pass frequencies higher
> 1/2 the Nyquist rate, which in theory is a very sharp
> cutoff but in practice it becomes very similar to the
> gradual analog cutoff.
If you read Nyquist's paper, that is pretty much it.
He was figuring out for fast he could send pulses
through a band limited channel and separate them out at
the other end. Electronic communication was digital
before it was analog.
-- glen
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Author: Floyd L. DavidsonFloyd L. Davidson Date: Aug 20, 2007 05:13
Jerry Avins ieee.org> wrote:>Dave Platt wrote:
>>> I'm curious to why there are no purely-analog devices which can
>>> record, store, and playback electric audio signals [AC currents at
...
>> The net result is that an audio CCD is capable of
>> storing a
>> decent-quality signal for only a few tens or hundreds of milliseconds,
>> from input to output.
>> Another sort of a purely analog signal-storage device,
>> with no moving
>> parts other than the electrons which convey the signal, is a simple
>> length of transmission line (with perhaps some amplifiers mid-way).
...
>Come on, Dave, a CCD is a digital device, subject to
>aliasing.
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