A preconnected reference is necessary that provides a high accuracy 10MHz clock, a serial time string and a PPS (pulse per second). The accuracy of the measurements is derived from these signals.
The module calculates the frequency as well as the time, based on the mains frequency. The time deviation (TD) is the difference of this calculated time (PLT) to the reference time (REF). This time deviation as well as the frequency itself is sent out via serial interface or is beeing converted to an analog voltage output provided by a DAC.
The board is equipped with a flash memory and a bootstrap loader which allows to update the systems firmware via serial port.
Please note: the shown variant of the FDM511 is equipped with an optional LED display, the standard version of the FDM511 comes without this display!