First-order phase-lock loop

摘要

A first order phase-lock loop that provides lower phase-error variance than classical systems at all frequencies when operated above threshold. The linear, minimum-variance filter described, in preferred form, employs three summers, two integrators, four system parameters, and two gain elements, the first and fourth system parameters being equal and the second and third system parameters being equal. The loop input, which contains a signal corrupted by noise, is connected as one input to the first summer whose output provides input to each of the gain elements. The first gain element is connected as one input to the second summer whose output is connected to the first integrator. The output of the first integrator, which is also the loop output and which is an estimate of the signal, is fed back negatively as one input to the first and second summers and as one negative input to the third summer. The first system parameter is connected in the feedback loop between the first integrator and the third summer, and the second system parameter is connected in the feedback loop between the first integrator and the second summer. The second integrator is connected to the output of the third summer; its output is fed through the third parameter negatively as a further input to the third summer and through the fourth system parameter as an input to the second summer. The second gain element is connected between the first and third summers. In certain circumstances the second gain element and/or the second and third system parameters (and their associated feedback loops) can be removed from the system.