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3.3.4
Delay
Logic16 enables user to define individual delays for each input channel. This feature is very useful in the
logic mode, where the delays of individual channels can be fine-tuned to maximize coincidence signals.
3.3.5
Function Generator
Logic16 has its own simple function generator located on Output 4. Frequency and duty cycle can be
adjusted. The cycle time and high time can be adjusted in 5 ns increments, from 10 ns to 1.3 sec.
Note: The function generator always uses the internal frequency reference and not the external 10 MHz
signal.
3.3.6
External Clock Input
The external clock 10MHz input can be used for local synchronization to access more change for even
larger multi-photon experiments as well as long distance synchronization, e.g. in quantum communication
(including Quantum cryptography and quantum key distribution).
The 10 MHz input is located on the rear side of the device. It can be used to increase the stability of long-
term measurements by connecting a stable clock source. The input is AC coupled. For this reason it can
be driven by a variety of digital signals. As long as the corresponding 10 MHz error flags do not raise, the
time base can be considered as valid. When using digital signals the rise and fall time should be greater
than 5 ns to avoid ringing.
Levels: There are two possibilities to drive the 10 MHz input:
Note: Use of external time base makes channel 16 inactive in configuration A and channel 8 inactive in
configuration B.
Level
Termination
Sinus
1 Vpp nominal
1 kΩ internal
Digital
Minimum level 500 mVpp
External 50 Ω termination required
