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Highest and lowest voltage recorded in digital audio.
Highest and lowest voltage recorded in digital audio.
Hi,
After the ADC has converted the sound into voltages in n-bit format,
is there a mathematical way of determining what would be the least and
maximum voltages that could be theoretically recorded ?
Let us limit the discussion to PCM only i.e. .WAV files on a CD.
Regards,
Nags.
Hi,
After the ADC has converted the sound into voltages in n-bit format,
is there a mathematical way of determining what would be the least and
maximum voltages that could be theoretically recorded ?
Let us limit the discussion to PCM only i.e. .WAV files on a CD.
Regards,
Nags.
Re: Highest and lowest voltage recorded in digital audio.
cogitoergosum <NageshBlore@gmail,com > writes:
> Hi,
> After the ADC has converted the sound into voltages in n-bit format,
> is there a mathematical way of determining what would be the least and
> maximum voltages that could be theoretically recorded ?
>
> Let us limit the discussion to PCM only i.e. .WAV files on a CD.
Hi,
The ADC converts voltages into numbers. That is, the input to an ADC is
a voltage and the output is a number, not a voltage. That numeric output
is considered a digital signal.
A DAC converts a digital signal to an analog signal, usually a
voltage. The maximum voltage that can be attained depends on the analog
output circuitry.
Typically, audio DACs are designed to provide "line level" outputs -
roughly a few volts (maybe up to 10 V) peak-to-peak.
If the ADC's numerical output format is two's complement, then an N-bit
converter provides "numbers" (integers) X in the range of
-2^(N-1) <= X <= 2^(N-1) - 1.
Why do you ask?
--
% 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
cogitoergosum <NageshBlore@gmail,com > writes:
> Hi,
> After the ADC has converted the sound into voltages in n-bit format,
> is there a mathematical way of determining what would be the least and
> maximum voltages that could be theoretically recorded ?
>
> Let us limit the discussion to PCM only i.e. .WAV files on a CD.
Hi,
The ADC converts voltages into numbers. That is, the input to an ADC is
a voltage and the output is a number, not a voltage. That numeric output
is considered a digital signal.
A DAC converts a digital signal to an analog signal, usually a
voltage. The maximum voltage that can be attained depends on the analog
output circuitry.
Typically, audio DACs are designed to provide "line level" outputs -
roughly a few volts (maybe up to 10 V) peak-to-peak.
If the ADC's numerical output format is two's complement, then an N-bit
converter provides "numbers" (integers) X in the range of
-2^(N-1) <= X <= 2^(N-1) - 1.
Why do you ask?
--
% 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
Re: Highest and lowest voltage recorded in digital audio.
cogitoergosum wrote:
> Hi,
> After the ADC has converted the sound into voltages in n-bit format,
> is there a mathematical way of determining what would be the least and
> maximum voltages that could be theoretically recorded ?
>
> Let us limit the discussion to PCM only i.e. .WAV files on a CD.
>
> Regards,
> Nags.
That is dependent on how small the LSB that can be resolved may be
and the word size in bits that is being recorded.
The MSB = maximum level, which is an arbitrary level equal to simply
stated "maximum" digital output.
Then you go down in dB below that.
16 bits below, or simply just one bit, that being the LSB, iirc is
96dB below that maximum level. I may have that 96dB thing incorrect,
but I think it is either correct or very close - my memory fails.
CDs are limited to 16bits, while the DAC and ADCs that are used
now are more bits, typically 24bits - that merely insures that the
16 that are usable are properly (if there is such a thing) detected.
Of course in practical recording, these small low level signals are
the "small wigglies" riding on top of much larger "wigglies", not
signals occurring in a vacuum of virtual silence...
- -bear
Btw, unless you put them on a CDR on purpose, CDs do not have "wav files"
per se, they're encoded into a fault correcting format...
cogitoergosum wrote:
> Hi,
> After the ADC has converted the sound into voltages in n-bit format,
> is there a mathematical way of determining what would be the least and
> maximum voltages that could be theoretically recorded ?
>
> Let us limit the discussion to PCM only i.e. .WAV files on a CD.
>
> Regards,
> Nags.
That is dependent on how small the LSB that can be resolved may be
and the word size in bits that is being recorded.
The MSB = maximum level, which is an arbitrary level equal to simply
stated "maximum" digital output.
Then you go down in dB below that.
16 bits below, or simply just one bit, that being the LSB, iirc is
96dB below that maximum level. I may have that 96dB thing incorrect,
but I think it is either correct or very close - my memory fails.
CDs are limited to 16bits, while the DAC and ADCs that are used
now are more bits, typically 24bits - that merely insures that the
16 that are usable are properly (if there is such a thing) detected.
Of course in practical recording, these small low level signals are
the "small wigglies" riding on top of much larger "wigglies", not
signals occurring in a vacuum of virtual silence...
- -bear
Btw, unless you put them on a CDR on purpose, CDs do not have "wav files"
per se, they're encoded into a fault correcting format...
Re: Highest and lowest voltage recorded in digital audio.
On Dec 31, 12:26 pm, cogitoergosum <NageshBl...@gmail,com > wrote:
> Hi,
> After the ADC has converted the sound into voltages in n-bit format,
> is there a mathematical way of determining what would be the least and
> maximum voltages that could be theoretically recorded ?
The definitive answer is, "it depends."
If we assume that the DAC "gain" is the same as the ADC
"gain", and there is no further amplification or attenuation,
then, within the limits of the sampler (determined by
its bandwidth and dynamic range), the output voltages
will be the same as the input voltages.
> Let us limit the discussion to PCM only i.e. .WAV files
> on a CD.
And, actually, again within the limits of the sampler
as defined by its bandwidth and dynamic range,
the voltages will remain the same, regardless of
whether or not its PCM.
But, your question is somewhat puzzling, because
once the signal has passed through the ADC, there
are no "voltages" at all, only digital samples. Voltages
simply don't exist in the digital domain.
On Dec 31, 12:26 pm, cogitoergosum <NageshBl...@gmail,com > wrote:
> Hi,
> After the ADC has converted the sound into voltages in n-bit format,
> is there a mathematical way of determining what would be the least and
> maximum voltages that could be theoretically recorded ?
The definitive answer is, "it depends."
If we assume that the DAC "gain" is the same as the ADC
"gain", and there is no further amplification or attenuation,
then, within the limits of the sampler (determined by
its bandwidth and dynamic range), the output voltages
will be the same as the input voltages.
> Let us limit the discussion to PCM only i.e. .WAV files
> on a CD.
And, actually, again within the limits of the sampler
as defined by its bandwidth and dynamic range,
the voltages will remain the same, regardless of
whether or not its PCM.
But, your question is somewhat puzzling, because
once the signal has passed through the ADC, there
are no "voltages" at all, only digital samples. Voltages
simply don't exist in the digital domain.
