Abstract: A navigation guidance system utilizes an electronic compass to determine a desired linear travel path between two way points and to monitor a direction of travel of a user. The system then determines if the direction of travel is within an established tolerance. If the system determines that the direction of travel is outside of the established tolerance, the system alerts the user through one or more alert indicator components. The alert indicator component can emit a visual alert, an audible alert, a tactile alert, or any other suitable method for informing the user accordingly. The alert can be a simple alert or of varying degrees to inform the user of the magnitude of deviation from the desired travel path. The navigation guidance system can be integrated into a carrying device, such as a pair of goggles, swim goggles, glasses, sunglasses, a helmet, a mountable enclosure, etc.

Abstract: A phase lock loop circuit for a digital radio generates the sampling frequency for sampling an incoming signal by storing the samples of the incoming signal in an accumulator at a first frequency. The accumulator is unloaded at the sampling frequency. A microprocessor monitors the rate in which the samples are stored in the accumulator and provides a switching signal to vary the sampling frequency in small increments to prevent the accumulator from overflowing or underflowing.