... | ... | @@ -7,17 +7,18 @@ |
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parts: 32 bits for the UTC second and as many bits as needed for the
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fractional part within the second (will depend on final choice of
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resolution).
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- 1 ns resolution or better.
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- Accuracy (of time-tag differences between channels): */- (500 ps*
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- 500 ps resolution or better.
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- Accuracy (of time-tag differences between channels): */- (250 ps*
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timebase accuracy).
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- Timebase accuracy: +/- 4ppm.
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- Implementation details: timebase from a local TCXO on FMC card
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and needs calibration. The 4ppm accuracy will only be reached
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when used on a White Rabbit enabled FMC carrier.
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and needs calibration. Much better accuracy will be reached when
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used on a White Rabbit enabled FMC carrier.
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- External inputs need to be protected against +15V pulses with a
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pulse width of at least 10us @ 50Hz (with protection diodes if
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possible).
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- SMC connectors for all inputs.
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- SMC connectors for all inputs. Actually lemo connectors are
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preferred by the main client (CERN's TE-ABT group), to be discussed.
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- Minimum input pulse width: 100 ns. Narrower pulses should be
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ignored.
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- A circular buffer will contain time tags for at least the last 100
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... | ... | @@ -27,10 +28,6 @@ |
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channels will not suffer from this accuracy problem because the
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offset with respect to UTC will cancel.
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- Programmable (enable/disable) host interrupts on all 5 channels.
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- Clock for internal time base is fed to a 6th TDC channel from the
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FMC connector. This allows usage of the TCXO in the carrier, a
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WR-derived clock or one coming from alternative sources such as the
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e-SATA connectors in the PFC board.
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- FMC mezzanine using a Low Pin Count (LPC) connector.
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- Vadj is 2.5V.
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... | ... | @@ -46,6 +43,8 @@ |
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(implementation)
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- [Time intervals measurements and generation methods
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review](https://www.ohwr.org/project/fmc-projects/wikis/Documents/Time-intervals-measurements-and-generation-methods-review), P.Alvarez, 2008
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- Fermilab's [Wave Union
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TDC](http://www-ppd.fnal.gov/EEDOffice-W/Projects/ckm/comadc/PID765918.pdf)
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-----
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... | ... | |