Time Controller Series User Manual
Section 6: Operating the Time Controller Software
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Timestamp data is recorded in pairs of numbers (see Figure 21) , written in binary format (uint64) or
directly into a text file:
1.
The timestamp
: the time in picoseconds between a detection event on the input channel
(
the ‘
Stop
channel’ or ‘
2nd
channel’ in the Start
-stop / Coincidence histogram views) and the
last detection event on the reference channel
(the ‘Start channel’ or ‘1st channel’ in the
Start-stop / Coincidence histogram views). There is one timestamp per input channel
detection event. This number serves as the fine
‘micro
-
time’, the
precise timing information
within a given clock cycle / reference period.
2.
The reference index (optional)
: the number of detection events that have occurred on the
reference channel, until the latest input channel detection event occurred. This number
serves as the coarse
‘macro
-
time’
, sufficient to reconstruct the fully precise time-tag when
paired with a timestamp and precise clock reference signal, or to identify which detection
events on different input channels occurred within the same clock cycle / reference period.
Timestamp data for each pair of selected channels is written to a binary file or text file as follows,
with up to four files for up to four pairs of selected channels per acquisition:
Binary format
, ‘*.bin’
Text format
, ‘*.txt’
Without start index
<timestamp>
<timestamp>
With start index
<timestamp><index>
<timestamp>;<index>
Table 10: Format of data in Timestamp datafiles
Caution: Ensure the number of timestamps processed per second is lower than
10 million, across all channels.
If higher than 10 M events/s, the buffered
timestamp events may overflow and cause a conflict in the internal device logic,
requiring a manual restart of the Time Controller unit.
Note
: If a reference signal is not used or the reference channel receives no signal,
the timestamps generated grow until they roll over after 2
60
picoseconds
(approximately two weeks).
Note
: To optimize the transfer rate and to avoid data loss, binary format is
recommended. For high data transfer rates, also consider the specifications of the
host computer.
Figure 22 shows an example of a timestamp datafile. In this example, 1,024,875 timestamps have
been recorded, corresponding to 1,024,875 events being registered on the defined input
(‘stop’)
channel, and 6,000,832 events being registered on the reference
(‘start’)
channel. Note that the
timestamp will reset to zero every time there is an event on the reference channel, and thus appears
random in this example. The reference index, however, will always increase monotonically, though
there may be more or less than one input events between timestamps, so each increment in the
reference index may appear random.