I made a presentation at the 2016 RSGB convention on Saturday, 8th October, entitled 'What IF?'.
The presentation considered "practical methods for introducing controlled receiving bandwidth in a range of simple receivers, covering direct conversion, superhet and software-defined radios" and introduced a simple measurement method for evaluating the receiving bandwidth. It was presented with an emphasis on practicality and minimalism, to appeal to the ordinary home-brewing enthusiast.
You can find a PDF version of the Powerpoint slides below...