I have a 20MhZ digital scope with pc interface. Iwant info about how to expand it frecuency range by software. I know that for repetitive sampling for static signals this is posible by subsampling.
It is very likely that the analog amplifiers before the ADC will limit your bandwidth. You can try making a sampling circuit before the scope. This will alias down the signal to be within the amplifier bandwidth. Many years ago Tektronix made such a box for their analog scopes.