Functional
Description
ComTec GmbH
3-2
3.2.3. Time-to-Digital
Conversion
In this mode both channels measure the time interval between the falling edges of
GATE / START and STOP signals. This time interval is converted to a digital value in the time
range as been set with the yellow Up/Down buttons. The conversion range can be changed by
temporarily switching into PHA or SVA mode. The START and STOP signals can be any Fast-
NIM signals. If no stop signal is within the time range after a start, channel 8191 will be
incremented.
3.3. Setting device parameters
Pressing the Mode button with a small screw driver, pencil or similar will cycle through the
following adjust modes:
Adjust TDC threshold --> Adjust ADC threshold --> Adjust LLD --> Adjust ULD
--> Adjust Coincidence / Anti Coincidence --> Normal operation
An indication of beeing in the adjustment mode is the AGJUST LED lit.
The TDC and ADC threshold levels are set in steps of 1.22 mV while the LLD and ULD
thresholds are set in steps of 4.88 mV.
The selected voltage levels can be measured on the monitor outputs.
3.3.1. Adjust TDC threshold
Using the yellow Up/Down buttons the TDC threshold of the corresponding channel is set in the
range of -1.0 … -0.1 V.
3.3.2. Adjust
ADC
threshold
Using the Up/Down buttons the ADC threshold of the corresponding channel is set in the range of
-100 mV upto +1 V. If the ADC threshold reaches the LLD threshold the LLD level is “pushed” to
keep it equal (not lower!) to the ADC threshold.
3.3.3. Adjust
LLD
Up/Down buttons set the lower level discriminator, continuously adjustable from ADC threshold to
ULD threshold. If the LLD threshold reaches the ADC threshold on the way down the ADC
threshold is “pushed” down to keep it equal (not higher!) to the LLD threshold.
