Monitoring the Oscillator
The Oscillator Management screen provides current and history status information on disciplining state and accuracy.
To access the Oscillator Management screen:
- Navigate to MANAGEMENT > OTHER: Disciplining.
- The Oscillator Management screen will display. It consists of two panels:
This panel provides comprehensive information on the current status of VersaSync's timing state.
- Oscillator Type: Type of oscillator installed in the unit.
- Disciplining State: State of oscillator control and disciplining; indicates whether or not the internal oscillator is currently being disciplined (steered to an input reference). The states are: "Warm up", "Calibration", "Tracking Setup", "Lock State", "Freerun", and "Fault".
- 1PPS Phase Error: A tracking measurement [scaled time, in ns, or ms] of the internal 1PPSs' phase error with respect to the selected input reference. Long holdover periods or an input reference with excessive jitter will cause the phase error to be high. The oscillator disciplining control will gradually reduce the phase error over time. Alternatively, restarting the tracking manually (see "Restart Tracking" under Configuring the Oscillator), or automatically via a pre-set Phase Error Limit, will quickly reduce the phase error.
- 10 MHz Frequency Error: An internal estimated calculation (in Hertz) of the internal oscillator's frequency error, based on the phase accuracy error at the beginning and end of a frequency measurement window (the length of this window will vary depending upon the type of oscillator installed and the oscillator adjustment algorithm).
- Current DAC Setting: Current DAC value, as determined by the oscillator disciplining system. The value is converted into a voltage that is used to discipline the oscillator. A stable value over time is desirable and suggests steady oscillator performance (see also the graph in the History Panel).
- DAC Step: Step size for adjustments to the internal oscillator, as determined by the oscillator disciplining system. Larger steps = quicker, but coarser adjustments. The step size is mainly determined by the type of oscillator.
- TFOM: The Time Figure of Merit is VersaSync’s estimation of how accurately the unit is synchronized with its time and 1PPS reference inputs, based on several factors, known as the Estimated Time Error or ETE. The larger the TFOM value, the less accurate VersaSync believes it is aligned with its 1PPS input that is used to perform disciplining. If this estimated error is too large, it could adversely affect the performance of oscillator disciplining. The available TFOM range is 1 through 15.
- Max TFOM for Sync: Value, as set under Configuring the Oscillator
- Temperature(s): Three temperatures are displayed:
- Oscillator temperature, which has an effect on oscillator accuracy, and therefore can be used to interpret oscillator performance.
- Board temperature (measured on the main board, sometimes also referred to as 'System temperature')
- CPU temperature
Note: Oscillator temperature is plotted over time in the History panel on the right, while graphs for board and CPU temperature can be found under TOOLS > SYSTEM: System Monitor.
- Last Time Reference Change: [Timestamp: Last occurrence]
- Last 1PPS Reference Change: [Timestamp: Last occurrence]
- Last TFOM Change: [Timestamp: Last occurrence]
- Last Sync State Change: [Timestamp: Last occurrence]
- Last Holdover State Change: [Timestamp: Last occurrence]
The Oscillator History Panel offers real-time graphical monitoring of VersaSync’s internal timing. The following graphs plot key oscillator-relevant data over time::
- Phase Error Magnitude: See 1PPS Phase Error
- Frequency Error: See 10_MHz_Frequency_Error
- Scaled DAC Value: See DAC Step
- Oscillator Temperature, which has an effect on oscillator accuracy, and therefore can be used to interpret oscillator performance.
You can zoom in on any of the graphs by grabbing the handles at either end and pulling them inwards. The graph will focus in on the time interval you choose in real time.
Clicking on the Delete icon in the top-right hand corner will erase all current oscillator log data.
Clicking on the Download arrow icon will download the latest oscillator log data as a .