Are purely-analog audio devices immune to aliasing?

Hi:

Is it true that purely-analog audio devices [such as analog cassette, AM
radio, and the pre-digital telephone systems*] are immune to aliasing?

*By pre-digital telephone systems, I am referring to how these systems
operated prior to using digital technology. Nowadays, many analog phone
systems do use DSP somewhere along the line. Similar applies to the
analog AM radio, it used to be just analog but now it utilizes some
amount of DSP indirectly.


Thanks,

Radium

Green Xenon [Radium] wrote:
> Hi:
>
> Is it true that purely-analog audio devices [such as analog cassette,
> AM radio, and the pre-digital telephone systems*] are immune to
> aliasing?
> *By pre-digital telephone systems, I am referring to how these systems
> operated prior to using digital technology. Nowadays, many analog
> phone systems do use DSP somewhere along the line. Similar applies to
> the analog AM radio, it used to be just analog but now it utilizes
> some amount of DSP indirectly.

Um, just because something is digital (ie PCM telephone transmission) does
NOT imply that there is any DSP involved.

Are you troubled by aliasing on your telephone ?

geoff

"geoff" wrote ...
> Are you troubled by aliasing on your telephone ?

He seems to be troubled by aliasing with his own name.
He can't even decide which alias to use, so he uses both.

"Green Xenon [Radium]" wrote:

> Hi:
>
> Is it true that purely-analog audio devices [such as analog cassette, AM
> radio, and the pre-digital telephone systems*] are immune to aliasing?
>
> *By pre-digital telephone systems, I am referring to how these systems
> operated prior to using digital technology. Nowadays, many analog phone
> systems do use DSP somewhere along the line. Similar applies to the
> analog AM radio, it used to be just analog but now it utilizes some
> amount of DSP indirectly.
>
> Thanks,
>
> Radium

No, they are not "immune" (as if that were
some disease) to aliasing.

It would seem you still have much to
learn about communications theory
and the associated math.


Later...

Ron Capik
--

Ron Capik wrote:
> "Green Xenon [Radium]" wrote:
>
>> Hi:
>>
>> Is it true that purely-analog audio devices [such as analog cassette, AM
>> radio, and the pre-digital telephone systems*] are immune to aliasing?
>>
>> *By pre-digital telephone systems, I am referring to how these systems
>> operated prior to using digital technology. Nowadays, many analog phone
>> systems do use DSP somewhere along the line. Similar applies to the
>> analog AM radio, it used to be just analog but now it utilizes some
>> amount of DSP indirectly.
>>
>> Thanks,
>>
>> Radium
>
> No, they are not "immune" (as if that were
> some disease) to aliasing.
>
> It would seem you still have much to
> learn about communications theory
> and the associated math.
>
>
> Later...
>
> Ron Capik
> --
>
>


Do analog, non-electronic musical instruments ever alias?

Green Xenon [Radium] wrote:
> Ron Capik wrote:
>> "Green Xenon [Radium]" wrote:
>>
>>> Hi:
>>>
>>> Is it true that purely-analog audio devices [such as analog cassette, AM
>>> radio, and the pre-digital telephone systems*] are immune to aliasing?
>>>
>>> *By pre-digital telephone systems, I am referring to how these systems
>>> operated prior to using digital technology. Nowadays, many analog phone
>>> systems do use DSP somewhere along the line. Similar applies to the
>>> analog AM radio, it used to be just analog but now it utilizes some
>>> amount of DSP indirectly.
>>>
>>> Thanks,
>>>
>>> Radium
>>
>> No, they are not "immune" (as if that were
>> some disease) to aliasing.
>>
>> It would seem you still have much to
>> learn about communications theory
>> and the associated math.
>>
>>
>> Later...
>>
>> Ron Capik
>> --
>>
>>
>
>
> Do analog, non-electronic musical instruments ever alias?

"Green Xenon [Radium]" <glucegen1@excite.com> writes:

> Hi:
>
> Is it true that purely-analog audio devices [such as analog cassette,
> AM radio, and the pre-digital telephone systems*] are immune to
> aliasing?

Yes.

There is a way to see this very clearly, but it involves some
calculus. If you're prepared for that, go to a library and find the book
"Signals and Systems" and read the section on sampling.

If you're not prepared for that, and you really want to understand this
topic, go take a couple (or three) semesters of calculus at a junior
college or university and then tackle it.

--Randy

PS: Radium, you remind me of a man who says he's thirsty, and yet is
unwilling to walk to a well 1/2 mile away to get a drink. Many of the
questions you ask are fundamental if you'd be willing to expend a little
effort and get some education.

@BOOK{signalsandsystems,
title = "{Signals and Systems}",
author = "{Alan~V.~Oppenheim, Alan~S.~Willsky, with Ian~T.~Young}",
publisher = "Prentice Hall",
year = "1983"}

--
% Randy Yates % "My Shangri-la has gone away, fading like
%% Fuquay-Varina, NC % the Beatles on 'Hey Jude'"
%%% 919-577-9882 %
%%%% <yates@ieee.org> % 'Shangri-La', *A New World Record*, ELO
http://www.digitalsignallabs.com

"Randy Yates" <yates@ieee.org> wrote in message
news:m3k5hzj58s.fsf@ieee.org...
> "Green Xenon [Radium]" <glucegen1@excite.com> writes:
>
>> Hi:
>>
>> Is it true that purely-analog audio devices [such as analog cassette,
>> AM radio, and the pre-digital telephone systems*] are immune to
>> aliasing?
>
> Yes.

Well... AM radio is not immune to aliasing, although we rarely encounter it
in practice (although FM stereo encoders require anti-aliasing filters*).
Pre-digital phones are probably immune to aliasing unless they were doing
analog multiplexing on long distance trunk lines. Analog cassettes might be
immune to aliasing per se, but if the recording frequency gets high enough
(ultrasonic), it will produce audible beats with the bias frequency.

*mathematically, FM stereo is double sideband suppressed carrier, which is
mathematically equivalent to alternately sampling the left and right
channels at 38 KHz. So although it is not quantized (digital), it is
sampled. Many analog systems fall into this category.

"Chronic Philharmonic" <karl.uppiano@verizon.net> writes:

> "Randy Yates" <yates@ieee.org> wrote in message
> news:m3k5hzj58s.fsf@ieee.org...
>> "Green Xenon [Radium]" <glucegen1@excite.com> writes:
>>
>>> Hi:
>>>
>>> Is it true that purely-analog audio devices [such as analog cassette,
>>> AM radio, and the pre-digital telephone systems*] are immune to
>>> aliasing?
>>
>> Yes.
>
> Well... AM radio is not immune to aliasing, although we rarely encounter it
> in practice

How would AM ever alias?
--
% Randy Yates % "Midnight, on the water...
%% Fuquay-Varina, NC % I saw... the ocean's daughter."
%%% 919-577-9882 % 'Can't Get It Out Of My Head'
%%%% <yates@ieee.org> % *El Dorado*, Electric Light Orchestra
http://www.digitalsignallabs.com

Randy Yates wrote:

> "Chronic Philharmonic" <karl.uppiano@verizon.net> writes:
>
> > "Randy Yates" <yates@ieee.org> wrote in message
> > news:m3k5hzj58s.fsf@ieee.org...
> >> "Green Xenon [Radium]" <glucegen1@excite.com> writes:
> >>
> >>> Hi:
> >>>
> >>> Is it true that purely-analog audio devices [such as analog cassette,
> >>> AM radio, and the pre-digital telephone systems*] are immune to
> >>> aliasing?
> >>
> >> Yes.
> >
> > Well... AM radio is not immune to aliasing, although we rarely encounter it
> > in practice
>
> How would AM ever alias?
> --
> % Randy Yates % "Midnight, on the water...

AM is a sampling technique. If the signal bandwidth exceeds the Nyquist rate
there will be aliasing.


Later...

Ron Capik
--

Chronic Philharmonic wrote:
> "Randy Yates" <yates@ieee.org> wrote in message
> news:m3k5hzj58s.fsf@ieee.org...
>> "Green Xenon [Radium]" <glucegen1@excite.com> writes:
>>
>>> Hi:
>>>
>>> Is it true that purely-analog audio devices [such as analog cassette,
>>> AM radio, and the pre-digital telephone systems*] are immune to
>>> aliasing?
>> Yes.
>
> Well... AM radio is not immune to aliasing, although we rarely encounter it
> in practice (although FM stereo encoders require anti-aliasing filters*).
> Pre-digital phones are probably immune to aliasing unless they were doing
> analog multiplexing on long distance trunk lines. Analog cassettes might be
> immune to aliasing per se, but if the recording frequency gets high enough
> (ultrasonic), it will produce audible beats with the bias frequency.
>
> *mathematically, FM stereo is double sideband suppressed carrier, which is
> mathematically equivalent to alternately sampling the left and right
> channels at 38 KHz. So although it is not quantized (digital), it is
> sampled. Many analog systems fall into this category.
>
>


Well, if analog entities are not immune to aliasing...

... then if some extraordinary ultrasonic transducer attempts to
generate a 50 MHz pure sine-wave tone in Earth's troposphere ...

... will the air molecules generate aliased waveforms because those
molecules cannot vibrate faster than 30 MHz??

Note: 30 MHz is the fastest the air molecules of Earth's troposphere can
oscillate.

Green Xenon [Radium] wrote:

> Note: 30 MHz is the fastest the air molecules of Earth's troposphere
> can oscillate.


Really ?!! Well I won't even bother with a super-tweeter then ;-(

geoff

geoff wrote:
> Green Xenon [Radium] wrote:
>
>> Note: 30 MHz is the fastest the air molecules of Earth's troposphere
>> can oscillate.
>
>
> Really ?!! Well I won't even bother with a super-tweeter then ;-(
>
> geoff
>
>


Please answer my question:

"will the air molecules generate aliased waveforms because those
molecules cannot vibrate faster than 30 MHz??"

"Green Xenon [Radium]" <glucegen1@excite.com> wrote in message
news:482a0c74$0$31741$4c368faf@roadrunner.com...

> Note: 30 MHz is the fastest the air molecules of Earth's troposphere can
> oscillate.

They go to 31.53 MHz at my house.

"Green Xenon [Radium]" <glucegen1@excite.com> wrote in message
news:4828deb3$0$5698$4c368faf@roadrunner.com...
> Hi:
>
> Is it true that purely-analog audio devices [such as analog cassette, AM radio, and the
> pre-digital telephone systems*] are immune to aliasing?
>
> *By pre-digital telephone systems, I am referring to how these systems operated prior to
> using digital technology. Nowadays, many analog phone systems do use DSP somewhere along
> the line. Similar applies to the analog AM radio, it used to be just analog but now it
> utilizes some amount of DSP indirectly.
>
> Thanks,
>
> Radium

The pre-digital telephone system used frequency-division multiplexing, each voice channel in
a 4 KHz slot. Nyquist was 4 KHz. Without pre-filtering, they'd have the very aliasing
that digital systems can have. Without post-filtering, you'd hear sidebands around 8 KHz.
No difference, except the sampling frequency.
--
Earl