[sdiy] Digital VU

[Tim Ressel]

Hi,

I'm looking at doing a VU meter in digital land. Sample the audio and do 
all the work in code. I am wondering what is the best way to approach 
the filtering. There needs to be a lowpass filter thingie with a very 
low cutoff, which makes the ratio of cutoff to sample rate very small. 
The obvious solution is to decimate the signal and get the sample rate 
down to a reasonable number. My concern here is the lp filter is low 
order and tails way out in frequency. Is decimation going to affect its 
ability to display transients? Another approach is to have a huge FIR 
filter, but we are talking lots of calculations per sample.\

Any thoughts?

-- 
--Tim Ressel
Circuit Abbey
timr at circuitabbey.com