I have to process a RF signal band with bandwith between 75MHz and 100MHz to divide it in up to 8 contiguous subbands, each one with a bandwith programmable between 50kHz and 25MHz, in 25kHz steps.
The objective is to have the capability to attenuate each sub-band differently.
Transition skirts should be aprox. 6dB at 25kHz, on-band ripple less than 0.5dB and out-of-band attenuation better than -85dB at > 500kHz of the transition frequencies.
I would prefer a linear phase filter to ensure a constant group delay (constant, but as low as possible).
My first thoughts were to downconvert the RF signal band to a lower band (or to 0Hz to create a complex I+Q signal), then use 8 separate FIR filters, and finally upconvert the summing result. However, I guess that the contiguity between adjacent filters may lead to some ways to reduce the computation cost. May you give me some suggestions?