Lorick wrote:
> Someone suggested another way for me to measure the RMS of a sine wave by
> just multiplying the samples by .707 using floating point methods and
> accumulate that in just 16 bits.

I might be able to make a reasonable suggestion if I know a bit
more about what you are doing. There are often alternatives to the
full blown floating point megamemory approach.

- Do you want the RMS value of a typical sinewave, as someone
else pointed out thats what you get from a typical el-cheapo
multimeter. That would be easiest. Or do you actually need True
RMS to give more correct readings for waveforms that are non-
symteric, have DC offsets, high harmonc content, non-sinusoidal
shpe etc. Even true RMS instruments typically have frequency
limits or 'form factor' limits.
- What is the voltage range input to your A/D converter
- What is the typical frequency range of the AC voltage to be
measured
- How many bits resolution is your A/D
- Are there any time factors to be considered, eg speed of display
update or A/D sample rate.

Brent Brown
Electronic Design Solutions
16 English Street
Hamilton, New Zealand
Ph/fax: +64 7 849 0069
Mobile: 025 334 069
eMail:  brent.brown@clear.net.nz