urgent circuit help

[p.gholap93]

here is some complicated problem i am facing.
I have two DC SHIFTED sine waves-
one with peak to peak amplitude of 5.2V of 1K frequency and other is with 6.4V peak to peak amplitude of the same frequency.
Now i have stored their peak values using simple diode capacitor peak detector circuit i.e. 2.6V and 3.2V.
After that i have fed these peak values to ADC to convert them into their 0 to 255 series.
But the problem is that resolution between them is too low(only 0.6V),of the order of 15 to 20 counts of ADC.
so what would you like to suggest me? Is there any alternative circuit so as to get clear distinction between amplitudes of the two sine waves?
any weired idea will be most welcome
suggest alternative options rather than using 10 bit ADC

 

[#12]

Use an op-amp as a differential amplifier. It only amplifies the difference, so you lose the absolute amplitude, but the difference is amplified as much as you want.

 

[gootee]

Your explanation doesn't include any "DC shifting".

Do you know the resolution of your ADC? If its full range is 5V for 255 values, then each increment would be about 0.02 Volts. So 2.6V would be about 133 and 3.2 would be about 163. How is that not enough resolution? It's more than ten percent of the full-scale range, if your ADC does 5 Volts. And regardless of the voltage range of your ADC, "15 or 20" counts difference would be about 6 to 8 percent of the 255-count range. Is your noise so large that you can't see a 15 or 20 count difference out of 255? Or what is the problem?

 

[crutschow]

You could also amplify the signals so that the maximum is near 5V (or whatever the full-scale of the A/D is). That would improve your resolution by the amount of the amplification.

 

[p.gholap93]

yes it is 5 V for 255 values. Earlier when i did the same, i was getting the difference of 40 to 50(now i don't remember details about previous sine waves) and that's what is expected to get clear distinction.
and there is no noise problem i'm already getting 15 to 20 counts difference.