Systems and Methods for controlling one or more mechanical resonators and determining information from resonant shift of the reonator(s) behavior, including at least one mechanical resonator, an excitation element for driving the resonator(s), a sensor for monitoring the motion of the resonator(s), at least one phase locked loop (PLL) in feedback between the excitation and monitoring elements, wherein each PLL is configured to operate at or near a different resonant mode of the resonator(s), and a processor for determining information from PLL internal signals indicative of a resonator frequency shift.