Watchdog Changeover Unit User Guide - Trilogy Communications

Trilogy Communications LimitedWatchdog3.5 COMPARATORFor all unbalanced inputs the timing difference between inputs A and B is calculated to an accuracy of±10 ns. The GUI is able display a timing difference of ±999 999 990 ns.When channel 1 inputs are 1 PPS and channel 2 inputs are 10 MHz, a comparison is made between 1PPS on input A of channel 1 and the 10 MHz clock on input A of channel 2. The same comparisons willbe made on input B of both channels.3.5.1 1 PPS and 10 MHz ComparisonsFor each channel, the number of 10 MHz clock cycles in the 1 PPS is counted. The countshould be 10,000,000. If the number of clock cycles deviates from this, the difference isreported via the Statesman GUI.The 10 MHz inputs are compared over one second and a fail condition is indicated if theydeviate by more than 0.1ppm. The difference is reported via the Statesman GUI.The 1 PPS signals are compared. A fail condition is indicated if there is a difference of± 200 ns between the two “one-second” pulses. The difference is reported via the StatesmanGUI with an accuracy of ± 20 ns.3.6 ON BOARD JUMPER SETTINGSJumpers J7, 8, 9 and 11 are for factory use only and should be set to the “in” position.Jumper set J1 selects the balanced signal type for Channel 1 when using D-type rearconnectors. Set “in” for LTC inputs: “out” for AES inputs. Jumper set J2 performs the same function for Channel 2.User Guide Issue 1.00 Page 13 of 28