This screen shows the overall system status of the feedback processing chain.
In the Data Flow section, each processing channel has eight monitored stages, each of which shows an alarm state (red on this display) if there is a problem at that stage, as described below. Each PV is prefixed with $(device):$(axis) for each axis.
| Stage | PV | Description |
|---|---|---|
| ADC Loop | :ADC:LOOPBACK_S | This control can be configured so that MBF ADC input is taken by looping back the DAC output instead of from the ADCs. This mode of operation is designed for development only, and should not be used for normal system operation. When loopback is enabled this control shows an alarm state. |
| ADC INP | :ADC:INP_OVF | The magnitude of ADC input is compared against the limit set in PV :ADC:OVF_LIMIT_S, and this indicator shows an alarm state if the magnitude is higher. Typically this means that the MBF input is operating in the non-linear part of the ADC, leading to possible harmonic distortion. To avoid this, reduce the signal gain applied to the ADC inputs. |
| ADC FIR | :ADC:FIR_OVF | It is possible for the input compensation filter |
| BB FIR | :FIR:OVF | At present it is possible for bunch by bunch FIRs with more than 8 coefficients to overflow internally if fed with a full scale input signal. If this occurs this indicator will show an alarm, even if the FIR signal is not currently being sent to the DAC. To avoid this, reduce the overall input signal level or reduce the gain of the FIR coefficients. |
| DAC BUN | :DAC:BUN_OVF | As the bunch by bunch FIR signal is prepared for output it is gated (selected or disabled by bank control) and scaled (by :FIR:GAIN_S). At this point if overflow occurs this indicator shows an alarm. Note that if the FIR signal is not selected for output then no alarm will be shown here. |
| DAC MUX | :DAC:MUX_OVF | The DAC output multiplexer allows FIR and NCO outputs to be combined and scaled. Two or more outputs can add to generate an overflow, in which case an alarm will be shown here. |
| DAC FIR | :DAC:FIR_OVF | If the output pre-emphasis filter :DAC:FILTER_S results in overflow this indicator will show an alarm. To avoid this rescale the filter coefficients. |
| DAC Enable | :DAC:ENABLE_S | This control is used to turn DAC output on or off. When the DAC output is off this control is in an alarm state. |
The Clocks section below shows three separate clock status bits, all prefixed with $(device).
| PV | Description |
|---|---|
:STA:CLOCK | This PV reports the status of the ADC input clock. If this clock does not report as "Locked" then practically no other signals can be trusted and there is something seriously wrong. The simplest possibility is that either the external PLL or the ADC (on the AMC-500 card) is incorrectly configured |
:STA:VCO | If the external PLL is correctly programmed this should report as "Locked", unless clocking has been configured for "Passthrough" mode. |
:STA:VCXO | This will report "Locked" if the system has successfully locked onto the external RF reference. |
The final Turn Clock section shows one status PV:
| PV | Description |
|---|---|
:DLY:TURN:STATUS | This shows the turn clock synchronisation status as described under Clock Fine Delay Control. |