Also, Prms
Of course there is such a thing as Prms. RMS is just a mathematical function which can be applied to anything. Though often people are more interested in Pavg than Prms, and therefore don't refer to Prms.mtweig,
There is no such thing as Prms, only Vrms or Irms. Pave = Vrms*Irms*cos(θ)
Still I don't get the point. Yesterday I tried to calculate and measure such a frequency (puls) using multiple multimeter with True RMS and without. Using Oscilliscope avg and rms. Each device gives a reading.
Actually I am trying to measure and calculate power consumed by XBee module while it is with sleep mode- AT mode. I use a 7 ohm resistor in series to the Vcc of the XBee and I capture the waveform using oscilloscope on the 7 ohm resistor. I used the rms to calculate the power consumed but my teacher says it should be average and I shouldn't think about rms since it is only for AC voltage/current.
As we know, none of the pulse waves are only positive part, if we think in Fourier series/transformation, there are always a sin wave with + and - parts. so it should be rms.
this is why I am so confused.
Still I don't get the point. Yesterday I tried to calculate and measure such a frequency (puls) using multiple multimeter with True RMS and without. Using Oscilliscope avg and rms. Each device gives a reading.
Of course there is such a thing as Prms. RMS is just a mathematical function which can be applied to anything. Though often people are more interested in Pavg than Prms, and therefore don't refer to Prms.
now when you multiply I avg with 3.3 v ---> what is the result? what you call it (I call it Pavg)
Then if you multiply Irms with 3.3 V ---- > what is the result ? what you call this (I call it Prms)
it is confusing .. believe me .
Pavg=V*Iavg for constant V
Yes. But although you can apply RMS calculation (square root of averaged square value) to power quantities, it makes no technical sense.Of course there is such a thing as Prms. RMS is just a mathematical function which can be applied to anything.
If I understand the problem correctly (constant battery voltage, time variable current), the below equation given by mtwieg is all you need:
It's not clear how the instruments are connected. Even the oscilloscope measurement is unclear. You say, you measure the voltage across a series resistor. The shown voltage is 2.88 V peak, the supply voltage is said to be 3.3 V. So there would be only 0.42 V remaining for the RF module, rather unlikely.
Is the 2.88 V actually the voltage across the resistor? Or is it the module voltage and 0.42 V is the resistor voltage? In any case, a shunt resistor should be selected for a voltage drop that doesn't reduce the remaining supply voltage too much. But even 0.42 V voltage drop would be unwanted high.
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