We will see a fascinating project on the Internet at some point, only to find that there is not enough information to truly appreciate and understand it. Such a project is coming [Bill Meara]The way On the SolderSmoke podcast, and Fortunately, he was able to gather more information from its creator. what [Tom] The 20m amateur band made of trash can components is quite a traditional analog receiver, which is a considerable achievement in itself, but its special feature is that it uses FPGAs to enhance analog tuning.
Traditional analog radio has a local oscillator, which is mixed with the signal from the antenna, and the intermediate frequency of the difference between the oscillator and the desired signal is filtered and amplified from the result. The oscillator on the old receiver will use a free-running tuning circuit, while newer equipment may use a phase-locked loop to obtain a stable frequency from the crystal.
what [Tom]What the receiver does is take a free-running traditional receiver and use the FPGA as an assistant. It has a frequency meter that drives the display, but it also uses the measured numbers to adjust the oscillator and keep it at frequency. It has two modes; when adjusting it, it is a traditional analog receiver, but when placed alone, the FPGA prevents it from drifting. We like it, this is definitely a special project.
Over the years, we have introduced many radio receivers, and this is certainly not the only one that is somewhat unconventional.