Austin wrote:
>Reference this diagram:
>
>
>
>"largest" is shown on this diagram to be the maximum signal level minus the
>minimum signal level, and is the largest range or absolute range that the
>signal can go from <=> to. Example, maximum signal level is 5, minimum
>signal level is 2, the absolute range/largest range is (5 - 2) or 3.
Hi Austin,
Above is the part of your explanation I don't have the background to
understand. What type of signal will have a max signal level of 5 and a min
signal level of 2? I understand that some signals may be +/-3v, or
something like that, but are there really signals that are +5-2?
If we are feeding a range of signal levels through a device to determine the
device's DyR, isn't it done in a way that starts with a signal of zero, or
so close to zero as to surely be below the noise of the device? Then
progressively stronger signals are fed till we can determine what signal
strength becomes just distinguishable from noise, which tells us the devices
MDS? Then progressively stronger signals till we see at what point the
signal is no longer distinguishable from clipping/distortion? Isn't this
point of clipping/distortion what the Analog Devices white paper uses for
it's "Peak Level"?
See again, sec 3.1 fig 5. They show peak level as a point, not a range:
<>
So by feeding a range of signal levels we determine the TWO values we need
for our short-form DyR equation, max and min: max/min, or max - min?
I'm having trouble to imagine the scenario where one has a device that
produces a Largest/Peak Level/Dmin of 5-2, but I accept that is due to my
lack of understanding. Please explain.
This gets to my comparison of the Higgins diagram to fig 5, which you
dismissed because ""One diagram is in log (the paper), and one is in non-log
(Higgins). You can not compare the two."
I take issue with that, those are mathematical differences, but I'm
discussing this conceptually and via the terms of the definition, and how
the diagrams illustrate those terms.
Todd
>"smallest" is shown as the noise. It is the same thing as "smallest
>discernable signal", which means the smallest change that can be detected.
>
>Where the signal is at it's lowest point, is what I am calling "minimum
>signal level".
>
>Where the signal is at it's highest point, is what I am calling "maximum
>signal level".
>
>The dynamic range equation is, using these terms, and the provided diagram,
>can be either of the following:
>
>DR (dB) = 10log10 (largest/smallest)
>
>DR (dB) = 10log10 ((maximum signal level - minimum signal level) / smallest)
>
>You can substitute "smallest DISCERNABLE signal" for "smallest" in these
>equations. Do NOT confuse "smallest"/"smallest discernable signal" with
>"minimum signal level", they are not the same thing, though in some
>circumstances they MAY have the same value.
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