On 5/20/06, Peter Martinez <[EMAIL PROTECTED]> wrote: > > You said: > >If your low 8 bits are truly random with no input, that's a good > >thing! It follows that when you inject a non-random signal, it will > >stand out clearly from white noise. >
I guess my wording was a bit provocative. The point I was trying to make was that even the noise-ridden, seemingly random low 8 bits may contain some information. > But if my low 8 bits are truly random and I inject an 8-bit sinewave, isn't > it then level with the noise? When looking at the whole soundcard bandwidth, yes it is. But the noise is spread out evenly over all frequencies, so you can use a narrow filter to pick up the signal of interest and get only a small fraction of the noise. If you had completely discarded the low 8 bits as "useless", you would have lost all (or at least most) of your signal. > I had a private email from a broadcast engineer who confirmed what I was > saying about dither noise. He said they added 0.5 bits-worth of white noise > to the analogue signal before digitisation, and subjectively that was the > best result. > > But that's half a bit of dither, not 8 bits. > I'm not an expert on dithering (or A/D converters in general), but probably your 8-9 bits of noise contains also something else and not just dither. 73, Sami _______________________________________________ FlexRadio mailing list FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archive Link: http://mail.flex-radio.biz/pipermail/flexradio_flex-radio.biz/ FlexRadio Homepage: http://www.flex-radio.com
