Specifications

CHAPTER 4. THE GPS-BASED CLOCK SYNCHRONIZATION SYSTEM 19
Local Site #3
Local Site #2
Local Site #1
Internet
Figure 4.3: Global synchronization over the Internet
4.3 Testing the method
The setup can be tested by telling all the cards in the system to save in the same time the
values of their clock counters. On a local site this is done using a wire from the m aster
clock card — when a pulse comes on this wire, the slaves save the time in a buffer memory.
The values in the buffers can be retrieved and compared afterwards. On a global scale the
saving of the counters is triggered by the PPS signal. Several tests were performed and we
concluded that the synchronization was functioning very well. For more information about
the tests see Appendix C on page 37.