Display of signal quality received by radio controlled clock - compares second timing impulses with reference level to drive visual indicator

摘要

If the quality of the signals received by a radio controlled clock is insufficient to operate the clock circuits accurately the time required to produce a correct display can be long. In order to indicate the reason for failure to achieve a correct or full display the received signal strength and quality are compared with a built in reference. The result is then indicated on the clock. The seconds signal is employed for this evaluation. The display may take the form of a visual plus sign on the clock to show correct signal level, and minus for a defective signal state. The indicator may be controlled by a manual switch so that the signal state can be checked when the clock is in operation. Used in this way it is possible to check whether the clock is in synchronism with the transmitted signals or is running autonomously in the absence of satisfactory signals.