# Variable Input Voltage Power Measurement

I've looked around the site for suggestions, but think this question is a unique one and would love some conversation.

I need a method to measure the average power in to a transducer.

This method must

1. Be able to measure the power of complex input waveforms (audio input, in this case)
2. Be able to measure the power of a signal oscillating around a DC voltage
3. Be able to measure the power of a signal oscillating around 0 V (AC)
4. Be able to measure the power of a signal which oscillates around some DC value, and not fail when the oscillation is of such a magnitude that portions of the signal fall below 0 V

The general parameters of the waveforms I'm measuring are

• Audio, with and without DC bias
• Chirps, with and without DC bias
• Single frequencies, with and without DC bias

Before you ask, the DC bias is absolutely necessary! The physics of the devices for which I must determine the average power input require that I test signals with and without a bias.

In sum, I need a method of measurement which can accept voltage and current frequencies from 0-25kHz, is minimally invasive, is accurate to within a hundredth of a Watt (tenth might be okay too), and can handle voltages both with and without a DC bias that have peak to peak values from 0.1 V - 50 V.

An idea I've been given is that I could use transformers to remove the bias, measure the bias and the alternating component, and add them to obtain the average power.