Hi,
Yes that sounds better now.
Yes, it is erroneous to say that the DC offset starts from the bottom of the waveform as the DC offset is the same as the DC component which is relative to zero, which is the value of the Fourier DC component. Doing it any other way means we would have more to calculate and keep track of and it would get confusing fast.
For example, for the 3vpp triangle and 3vdc taken to be at the BOTTOM of the waveform, the average DC is then not equal to the DC offset. Specifying the DC offset as 4.5v, then it is.
For another kind of funny example, if we always applied the "DC offset" to the bottom of the wave then we would have to specify an ordinary 3vpp triangle that is vertically centered at zero volts as having "-1.5 volt DC offset". You can see how this messes things up.
And since the average voltage is the DC offset, we know right away what the DC offset is if we specify the average, and we can then also say we have "3vpp riding on 4.5v DC" which is a typical description of the wave we're talking about, but we could not say "3vpp riding on 3v DC" because that would not be true.
Here's a quote from the web:
"When describing a
periodic function in the
time domain, the
DC bias,
DC component,
DC offset, or
DC coefficient is the
mean value of the
waveform. If the mean amplitude is zero, there is no DC offset. In contrast, various other frequencies are analogous to superimposed
AC voltages or currents, hence called
AC components or
AC coefficients."