Stabilization of a variable quantity with respect to a single valued reference

A feedback system consisting of two interacting loops is studied, which stabilizes an output variable using a single valued reference. The deviation of the output quantity caused by an external disturbance depends on the equality of the two loops, and can be made to approach zero by suitable adjustment of system parameters. Results of the theory were confirmed experimentally using a system of two variable frequency oscillators and a quartz crystal as a reference.