Page History

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silke says: "usb4" relative encoder reader can go up to 15MHz5MHz, but maybe not enough space in the vacuum environment. alex found another renishaw that goes up to 15MHz.

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ankush encoder document: https://docs.google.com/document/d/1Ho1IpT4903wkUoJMV06z5hou9to5CfAgtJBDPdBl6I4/edit?ts=600b806d

      → (Silke) this lists the USB version of the encoder we originally used the PCI version for. We now have a box as Ankush laid out, except that it 'splits' the signal, so has in&out for each encoder channel. This device its listed towards the end of Supported Control & DAQ Devices

Matt says we may have an existing board that could do the readout/timestamping

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• 10kHz with interpolation?
• multiple encoders?
  • combine absolute/relative (may be complexity issues)
  • 2 staggered slower encoders
• need fpga timestamping
• 100 microev resolution requirement

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  	Option	max rate	work to be done	drawbacks/other consideration
  A	absolute encoder used for relevant stage	10-20(?) kHz	controls: rework PLC to send data (current solution likely ~1kHz) DAQ: likely FPGA timestamping
  B	absolute encoder used for relevant stage,  interleave with second absolute encoder	20-40 kHz	as above	need to ensure both encoders read back equivalent data, intersperse jitter from both?, same latency
  C	add a relative quadrature encoder on shaft	5 or more MHz	DAQ: need board to read signal & timestamp	complicated and possible not very reproducible mapping of measured & relevant motion
  D	add a relative quadrature encoder in vacuum	5 or more MHz	DAQ: need board to read signal & timestamp engineering: figure out how to add relative encoder

  
  

To do

• fill out the table options and costs (alex and silke)
• talk to mechanical engineers (Georgi)
• meet in two weeks

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