Hamster has a new project up over at his Hamsterworks site, and he’s got code running both for the Papilio/ Logic Start combination, and for the Arduino. In this project, he has created a filter that can filter out commonly encountered “mains hum” frequencies up to the Nyquist limit of half the sample rate for the frequency in question. Hamster’s example is of using a low-pass moving average DSP filter to remove 50Hz hum from a signal.
To implement a moving average filter on an FPGA is dead simple, and performance is outstanding – you can process one sample each clock tick. This example is for on the Papilio One and the LogicStart MegaWing. It uses 0.5% of a Spartan 3E-250, which is quite a tiny FPGA.
Check out the video above, and don’t forget to get the code for yourself over at the Hamsterworks project page.