The time differences of the 1PPS (1 Pulse Per Second, rectangular signal) signals of all clocks are measured versus a reference clock using a time interval counter. A switch provides the 1PPS signals of all atomic clocks to the time interval counter successively (accuracy in sub ns range). The measurement interval for each clock is 100 seconds. The stored data is used than for generation of very stable time scales using data of several atomic clocks together (Ensemble Clock).
DLR’s time laboratory can be divided in an experimental and in an operational part. The research activities are done in the experimental part:
The operational part of the time laboratory is composed of UTC(DLR) and GATE (Galileo Test Environment in Berchtesgaden) system time provision. UTC(DLR) is determined by Common View method using GPS time receivers connected to a Cs clock. The recorded data is provided to BIPM (Bureau International des Poids et Mesures) in Paris which then calculates UTC using Common View data of world wide distributed time laboratories in post-processing. As the offset of each contributing clock is provided in the CircularT by BIPM the time difference of UTC(DLR) to UTC is well known. The second operational part of the time laboratory consists of system time generation for GATE.