i am using AT 89S52 microcontroller and we want to measure average value of a signal with frequency between 10khz-15khz. is there any ADC IC available which will directly give me an average value ? if there is any other solution please let me know.
i want to add one more query to my previous one.that is "am using AT 89S52 microcontroller and i want to measure average value of a signal with frequency between 10khz-15khz with voltage range upto 5V. is there any IC available which will directly give me an average value ? if there is any other solution please let me know."
Thank you
You still haven't answered the question: Do you mean RMS?
If not, what do you mean by "average"?
Yes i mean to say RMS.
The datasheet of the AD736 gives the input/output range. It should be no problem to add an opamp and/or voltage divider (with trimm potentiometer) to fit your requirements. Besides - this is not KEIL stuff.
Is that the true RMS value of any arbitrary signal, or is it sufficient to just assume a sine wave?
no its not a sine wave, i want to measure it for rectangular and square wave which have amplitude of 5v.
It is important to know if you need to measure the bandwidth up to 10khz-15khz, or if 15kHz is the fastest frequency of the signal.
If you have a 15kHz signal you may need a lot more bandwidth, depending on the signal shape.
Anyway, RMS becomes trivial for squarewave...
for RMS at 15kHz you need a fast ADC and a fast micro. Just do a rough estimate of how many samples you need in ~66ms
Erik
Well, how lovely if 66ms was enough :)
that, of course is 66us
If your signal is either 5V or 0V (rectangular or in special square wave) it should be sufficient do sample this two states and calculate the on/off ratio.
"If your signal is either 5V or 0V (rectangular or in special square wave)..."
Just to be clear that I'm uderstanding you here:
Are you saying that, if you can assume that the signal is a perfect square wave, and that the two states can only ever be precisely 5.00V and precisely 0.00V, then there is no point in having an Analogue-to-Digital converter?
Yes?
That is one valid method of measuring the pulse quote or the RMS or whatever for a rectangular wave of known amplitude.
If the amplitude isn't known, then it is possible to measure the peak voltage together with edge-detection.
There are a lot of special cases available as long as the wave-form or amplitude is known.
Yes! I thougt, the OP should get some alternative suggestions.