I'm currently setting up my lab for functional studies of bird legs
during terrestrial locomotion. I've adopted an "antique" treadmill that
produces nasty noise within the frequency range of the EMG's I'm trying
to record. Artifact amplitude increases with tread speed. I contacted
the manufacturer (Landice) and was told that I needed a PWM (pulse width
modulation) controller, which would put out a much higher frequency
(15-20 kHz). They offered to install one into one of their top of the
line treadmills, which ended up costing more than I'd like to pay, if
I can avoid it.

Controllers are a mystery to me. Does anyone have alternative solutions
to controller noise? I'm particularly interested in hearing from folks
recording EMG's on treadmills. My needs don't warrent making a treadmill
from scratch, but I do need good performance at very low speeds.

If this is a popular topic I'll post a summary. Thanks.

Steve Gatesy
Department of Biology
Wake Forest University
Winston-Salem, NC 27109