Microcontroller Clock-locking: Frequency Reference Synchronization

摘要

Michael built an accurate frequency reference synchronized to a GPS clock. The frequency counter can count to 50 MHz with 1-Hz accuracy. You can also use it to generate GPS-locked output signals as a frequency reference or as a component in a radio receiver. The device can display GPS information such as time, location, and velocity. An old aphorism goes, "Give a man a clock and he knows what time it is. Give a man two clocks and he is never sure." However, when one of those clocks is synchronized to a series of rubidium clocks, which are routinely adjusted, he may not know exactly what time it is, but he can be assured that the errors are small. Now that GPS units are widely used in consumer devices, employing them as time references is easy and inexpensive.