Rotate 180 Degrees

The output of the slip counter is cyclical. Think of the hourly numbers as points on a circle. Divide the circle into quadrants. Quadrant one is 0-63, quadrant two 64-127, quadrant three 128-191 and quadrant four 192-255. The program monitors the 25 accumulated numbers. If any number appears in quadrant one or four within a 'forbidden zone' near the 255 to 0 transition, the program executes a bitwise excusive-or operation on all the numbers against the number 128. This rotates the numbers 180 degrees. The relationships among the numbers (the dNs) remain unchanged. The forbidden zone is defined as any number greater than 244 or less than 11.

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WWVB-Based Precision Frequency Comparator

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