The FMC TDC 1ns 5cha Time to Digital Converter mezzanine board houses 5
input channels. It can calculate time differences between pulses
arriving to the channels with a precision of ±700 ps.
It can be carried by any of the carrier boards:
SVEC. It is implemented using
a dedicated time-to-digital converter chip from the European company
SVEC carrier with two slots for TDC mezzanines and SPEC carrier with
one slot for a TDC mezzanine (more TDC
|Input Channels|5 channels TTL with software selectable 50 Ohm termination (CDCLVC1102PW)
Inputs are protected against +15V pulses with a pulse width of at least 10us at 50Hz|
|Channels enable|Software controlled switch that enables/disables all 5 channels|
|Timestamps buffer|Circular buffer that keeps the last 128 pulses (256 rising and falling edges);
programmable interrupts implemented based on the number of accumulated timestamps or the amount of elapsed time|
|Timestamps precision (deviation)|± 700 ps
Outliers of ±4 ns are observed at the expected frequency of ~ 1 outlier/10M measurements.
More information at Board Performance documents.|
|Timebase accuracy|With White Rabbit: < 1ns
Without White Rabbit: ± 4 ppm from a local TCXO on the FMC card|
|Maximum input pulse rate|31.25 MHz from all 5 channels|
|Timestamps|Timestamps apply to both rising and falling edges of incoming pulses;
on the software level the falling edges are only used for the calculation of the pulse width, ignoring pulses < 100 ns;
With White Rabbit, the TDC offers absolute timestamping and timestamps from different boards in the same White Rabbit network can be correlated.
Without White Rabbit the timestamps from one board need to be always subtracted between them, to calculate time differences|
|Minimum input pulse width|100 ns, narrower pulses are ignored on software level by subtracting a falling edge from the previous rising one|
|ACAM mode|I-mode, 81ps resolution, +/- 500ps precision (6σ)|
|FMC connector|Low Pin Count|
The FMC TDC development consists of the following sub-projects; each
sub-project has its corresponding release.