GPS is not just for navigation; it’s also the backbone of an idea to help improve AM transmission. Dr. Steve Smith of Kintronic Laboratories discussed AM synchronization as part of a presentation on AM Revitalization at the 2015 NAB Show Broadcast Engineering Conference, “Field Trial Results of AM Transmitter Carrier Synchronization.”
Smith said the FCC should take a three-pronged approach to the problems affecting the senior broadcast band by (first) “fully enforcing the Part 15 regulations that are largely not being enforced; establish AM receiver specifications to provide an effective parity with FM so that AM stations sound pretty good to most people, and then promptly adopt some AM synchronization rules to get rid of a lot of the interference that we don’t need.”
He presented two case studies on synchronization, and explained that synchronization solutions using a GPS timing receiver could derive a frequency lock accurate to one part per billion. Synchronization would yield a quieter low-frequency baseband, and expand coverage areas by eliminating co-channel beat frequencies and beat modulated audio interference effects. It would also allow for booster transmitters on the main station frequency to be deployed.