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current Subject:

Continuous Mode

Are cronologic TDCs able to record a continuous data stream over several hours?

cronologic answer:

Please note:

  • The xHPTDC8-PCIe provides an infinite stream of timestamps - one for each input channel.
  • The current TimeTaggers and TDC modules offer a Continuous Mode, and the measurement is not limited in time. In this mode, the device continuously records stop signals even without a start signal connected. The data stream periodically contains packets with an absolute 64-bit timestamp, followed by a list of stops relative to this timestamp. The period of the timestamps can be customized to fit the used evaluation interval. The config.tdc_mode parameter is used for this purpose, which switches between grouping and continuous. In continuous mode, grouping is only supported insofar that it can be performed by the evaluation software. In this case, the measuring card provides packet timestamps with ascending identifiers so that all packets can be evaluated accordingly.
  • The xTDC4-PCIe, on the other hand, is based on a classic common-start architecture in which the arrival times of pulses at the "stop" inputs are measured relative to a signal at the "start" input. The duration of the recording is therefore limited in time.
  • The TDC channels of the Ndigo6G-12 all work in continuous mode to optimally complement the ADC measurements.

Please also note: The previous generation TimeTaggers (TimeTagger4-1G and TimeTagger4-2G) do not offer Continuous Mode.