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The PVs here are divided into a number of groups. All PVs are prefixed with $(device):$(axis).
Long waveforms of Tune PLL data can be captured using the Matlab Tune PLL capture script.
NCO
This group includes the readback waveform at the top.
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| Name | PV | Description |
|---|---|---|
| Freq | :PLL:NCO:FREQ_S | When written this will set the PLL NCO to the given frequency. If feedback is running the offset will briefly be forced to zero. |
:PLL:NCO:FREQ | This reads back the current NCO frequency. This PV updates at 10Hz. | |
| Offset | :PLL:NCO:OFFSET | This is the current PLL offset, updated at 10Hz. |
| Gain | :PLL:NCO:GAIN_DB_S | The NCO signal strength is configured here. Clicking here links to NCO Gain Configuration. |
:PLL:NCO:ENABLE_S | This PV turns the NCO output on or off. | |
| Mean | :PLL:NCO:MEAN_OFFSET | This is the mean offset computed over the last full OFFSETWF waveform. |
| Std | :PLL:NCO:STD_OFFSET | This is the standard deviation computed over the last full OFFSETWF waveform. |
| Tune | :PLL:NCO:TUNE | This is the fractional tune computed from the MEAN_OFFSET value and the base frequency. This PV updates when MEAN_OFFSET updates, and is forced to NaN when feedback is not running. |
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| Name | PV | Description | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| I, Q |
| Detector readbacks in I and Q components. To regard the response as a complex number, compute
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| Magnitude |
| Magnitude of the detector response and converted to dB, relative to overflow at magnitude = 1.0. | ||||||||||||
| Phase | :PLL:FILT:PHASE | Phase of the detector response. | ||||||||||||
| Debug | Links to the Tune PLL Debug for a detailed view of the detector response. | |||||||||||||
:PLL:DEBUG:ENABLE_S | This PV indicates whether the debug readbacks are enabled. This readback is normally not required, and the extra processing load can usefully be avoided by leaving this disabled when not required. | |||||||||||||
| Mag rel std | :PLL:DEBUG:RSTD_ABS, :PLL:DEBUG:RSTD_ABS_DB | "Magnitude relative standard deviation". This pair of fields and "IQ rel std" below are an attempt to capture the quality of signal and lock as a single number. This number should be small if there is a strong detector signal, but is not affected by the quality of the lock. Given a debug IQ waveform
The
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| IQ rel std | :PLL:DEBUG:RSTD, :PLL:DEBUG:RSTD_DB | "IQ relative standard deviation". This is intended to capture the quality of the PLL lock as a single number: this number should be small if there is little deviation in angle. Give waveform
Again,
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Status
The status indicators here show the status of the detector and the feedback controller, and show the reason for stopping if feedback is not running. When feedback is running all indicators in the left hand column will be green, otherwise one with be red to indicate a reason for stopping. Similarly the right hand column shows the current active state of each part of the Tune PLL system.
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