User Manual

SGD-SB2025NT-TUM, Part 2
Jan 12 Page 57 SOLAR COMMISSIONING
Figure 51. TM Engineering – Sync Timing (Central NIs).
There are two ‘Sync Timing’ pages; one for the Station NI and one for the Central NI, each being
selected by the corresponding tabs as seen in Figures 50 and 51 above. If the number of the NI
in use exceeds the capacity of the display area, the slider to the right of each table allows the
display area to be moved up and down to view every report.
Each page has two buffer settings where values are taken from the drop-down lists. As the buffer
settings are inter-dependant, the Central NI page must be used to complete the set-up process
even on a system that has no Central NI.
5.3.1.1 PAT Reports
A brief explanation of the terminology used on the ‘Sync Timing’ pages is given here for
completeness.
The ‘PAT’ values are calculated by every unit receiving packets. For each NI, that information is
passed back to the TM for display on this page, together with the figures calculated by the arrival
time of packets at the TM itself. The measurements and reports take place once a second.
‘PAT NI’ is the average time taken for packet zero to arrive at a NI (rounded up to the nearest
millisecond).
‘PAT TM’ is the average time taken for packet zero to arrive at the TM (rounded up to the nearest
millisecond).
The ‘PLL’ indication confirms the health of the phase locked loop within the NI and the ‘PPS’
indication confirms the health of the 1PPS timing signal within the NI.
Note.
The PAT value reported from a NI that is indicating loss of PPS may not be correct.
Similarly, the ‘PAT TM’ report depends on the TM PPS signal being present.