Variable range frequency divider for 0-200Mhz shifted down to 50Hz-15khz

Hi, I need a frequency divider with VARIABLE input/output range from 0 to ~200mhz to convert it to audio range 50hz to 15khz. By variable i mean there are multiple frequencies on the input line, like a radio, and i need to be able to easily tune the input frequency range from 0hz to ~200Mhz and always get 50-15k in the output. For example, i want to be able to "listen" to 40Mhz to 70Mhz range, and everything in that range should be shifted down to 50Hz-15khz. In the end there will be 2 potentiometers, one for setting the width of the input range, and one for setting the shift of the input range. Specifications are not strict, if you find components that work higher or lower frequency for the import, i am open to suggestion. In the end, the output must be in 50Hz-15k range however. I need schematic and PCB done in EasyEDA if possible. If you use an other software for the pcb/schematic that is free and i can install it too, i can use that too, but i need it in editable format. I have future work and modifications for the same design paid separately. Thank you