No. ErnieM's reference to 'daylight' means how many instruction cycles do you have left over after all the interrupt processing so that you main loop doesn't get starved of CPU time.Talking about 'daylight' if I understand well what you guys mean by that...I'll say given that I sample at 4Hkz --> my daylight is 250us --> all the DSP processing must take less than 250us for each sample...
I think that 2khz is pushing it without a hardware mulacc solution (like in the dsPIC).I recently had a discussion on 'general electronic chat' , thread 'Capacity ID' and it was said that by limiting the frequency at 2000Hz I will have problems with the 'consonants' meaning words with same vowels but different consonants will be confused...
I also did a little google about that...yes consonants have higher frequency compared to vowels....range ~1800hz to 2500hz or more for important consonants....
So now I'm considering 3000Hz as my highest frequency --> sampling rate will now be 6Khz...in my circuit I'm going to use a LPF to limit the highest frequency to ~3000Hz....I was thinking of sampling at 8KHz but that would give me only 125us for my DSP processing....
The more I help you with this, the more I realize how little understanding you have, both wrt what you are trying to do and the (limited) capabilities of the PIC18F (given what you are trying to achieve).
My advice: start small and add capability later as you/the cpu can. You're going to find that you run out of bandwidth quickly!