Correct Terminology

[Bryan]

Hello:

What is the correct terminology and technique if you want to modify the Vmax and Vmin of a sine wave so they are equal. I keep thinking level shifting but that is not it. I know some refer to Vmax as Vpp, but I am referring to the voltage above and below the ground baseline.

[Rerouter]

Biasing, Or Removal of DC Bias otherwise known as capacitive coupling

[Richard Crowley]

Perhaps "offset" (DC bias) is the word you seek?

People who edit and analyze Real World audio waveforms (speech, music, natural and artifical sounds) have come to observe that a surprising amount of audio is quite non-symmetrical. For example with much more power above the zero than below it (or vice-versa).  And NO, I am not talking about DC offset or bias.  It is a semi-FAQ in many audio production forums.

[Brumby]

Yep.  I was thinking of DC offset ... the removal thereof.

[vk6zgo]

Hello:

What is the correct terminology and technique if you want to modify the Vmax and Vmin of a sine wave so they are equal. I keep thinking level shifting but that is not it. I know some refer to Vmax as Vpp, but I am referring to the voltage above and below the ground baseline.

Vmax & Vmin are not used if referring to a sine wave with no dc offset.
A moments thought shows that both the positive & negative peaks are "max",& the only "min" is the zero crossing.

The only time they are correct usage is when there is a dc offset of the signal as below:

(1)Vmin & Vmax:-
Amplifier devices & ADDs are normally dc coupled internally,so the input signal will have a dc offset .
If it is a positive offset,the sinewave  positive half cycle will add to the dc voltage,& the negative half cycle will subtract from it.
The inverse will be the case for a negative offset.

The effect upon the dc voltage will thus be maximum at the sine wave peaks,so the dc voltages resulting become Vmax & Vmin

(2)Vpp:-

Vpp is normally used in two situations:
(a)As a convenient way of measuring ac waveforms on Oscilloscopes.
Obviously,the positive & negative half cycles are not present at the same time.

(b)A device,such as an amplifier,or a ADD must be able to handle the whole dynamic range of the sine wave,from peak negative to peak positive without distortion,hence Vpp is a useful  parameter,used in conjunction with Vmax & Vmin as in (1)

[Bryan]

Thank you everyone, that is exactly the explanation I was looking for. So in short AC coupling rejects the DC component of the signal. Effectively, this normalizes the signal to a zero mean. I added a 1nf cap to the circuit and sure enough the signal normalized. However is there a calculation for the capacitor value for a specific frequency and or voltage. I have a signal from a  rubidium output that I want to clean up before sending it to a distribution amplifier. The frequency is 10Mhz and around 3.2v Vpp.

[Brumby]

The capacitance is not going to be too critical - it will just act as a high pass filter for AC signals.  The bigger the value, the lower the roll-off frequency, but for a specific frequency things are a lot easier.  For 10 MHz, you wouldn't need anything above 0.01uF.