Three-part FLL system for exact frequency stabilization

Three-part frequency locked-loop (FLL) system with identical partial FLLs and connections between them is considered. The mathematical model derived is applicable for any filters and discriminators. A number of new interesting results is derived. Essentially new, in comparison with an ordinary single FLL, is the opportunity of exact frequency stabilization in the 3-part system, allowing us to construct system with precise frequency stabilization without constant current amplifiers with large amplification.