Sentinel: Setting Up a 1PPS Measurement
Introduction
The following steps are based on the assumption that a GNSS/External reference is connected and the internal Rubidium reference has been disciplined appropriately. See Sentinel: All you need to know about the internal Rb reference and Sentinel: Cable Delays for further details.
Connect The Device Under Test
Connect the 1pps output from the device under test to one of the available unbalanced clock frequency measurement module BNC connections. (Labelled 1 in the image below)
Enable Clock Channels
Select the Mode screen from the Sentinel main screen. Ensure the channels to be used for the measurement are highlighted in blue indicating that they are enabled. To toggle a channel select the button.
Configure Measurement Settings
From the Sentinel’s Main Screen, select the Settings tab then view the Common screen under the Measurement tab.
Set the Duration of the measurement as required.
Set the TIE mode to TIE + 1 PPS TIE
Set the Diff T(I)E reference to 1 PPS Ref
Select OK or Apply
Carry out a Signal Check
To detect and validate the signals, click on the Health Check tab on the main screen, then press the Signal Check button and check either the relevant individual channel, or all channels. This will populate the channel settings with the correct signal details.
If the signal check does not return a 1PPS signal type check the following.
Check all the cables are connected correctly.
It is recommended that 1PPS signals have the input filter enabled for the channel they are connected to. Check that the filter is ON in the Settings > Measurement > Channels page.
Confirm Cable Delays
To enter cable delays see Sentinel: Cable Delays
Start The Measurement
Return to the main screen and click the Start button to initiate the test.
Confirm the location that the measurement files will be stored in.
To view the Time Error measurement graph select the TE graph in the Graph/Metric Selector.
The test will automatically stop when the pre-set test duration is complete, or it can be stopped manually.
At the end of the measurement a Test Complete message will appear.