High precision radio signal controlled continuously updated digital clock

A clock responsive to broadcast time-based signals for keeping time in accordance therewith, said time-based signals including encoded timing information, said clock comprising

• receiver means for receiving said time-based signals,
• processing means coupled to said receiver means for decoding said time-based signals to derive a plurality of digits from said timing information representing actual clock time,
• digit verification means for separately verifying correctness of each of said digits,
• display means for displaying said digits, and
• means responsive to said digit verification means for causing any unverified digit to blink at regular intervals on said display means until all of said digits are verified.

A clock responsive to broadcast time-based signals for keeping time in accordance therewith, said time-based signals including encoded timing information, said clock comprising

• receiver means for receiving said time-based signals,
• processing means coupled to said receiver means for decoding said time-based signals to derive a plurality of digits from said timing information representing actual clock time,
• digit verification means for separately verifying correctness of each of said digits, including history buffer for storing each said decoded digit, said history buffer being of sufficient length to store a plurality of each of said digits as received over a plurality of minutes, a guess buffer storing the most recently received of said decoded digits, and comparison means for comparing each of said digits stored in said guess buffer with corresponding digit values in said history buffer, and
• internal clock means for automatically incrementing at least one of said digits stored in said guess buffer when the corresponding digit is not successfully decoded by said processing means, whereby the internal time is maintained when signal is lost.

A method of synchronizing a clock to broadcast time-based signals, said time-based signals including encoded timing information, said method comprising the steps of

• receiving said time-based signals,
• decoding said time-based signals to derive a plurality of digits from said timing information representing actual clock time,
• storing each decoded digit in a history buffer of sufficient length to store a plurality of each of said digits as received over a plurality of minutes,
• storing a guess value for each of said plurality of digits in a guess buffer,
• comparing each said guess value in said guess buffer with the corresponding decoded digits stored in said history buffer;
• and
• separately denoting each said guess value as a verified time value when said comparing step indicates that the number of said corresponding decoded digits which are consistent with said guess value exceeds by a predefined margin the number of said corresponding stored decoded digits in said history buffer that are inconsistent with said guess value.