Frequently Asked Questions
Q: How many channels does a TTL to blocking pulse converter system have?
Six pulse conversion channels. On any channel, you can input and output any combination between TTL and blocking:
- TTL input to TTL output
- TTL input to blocking output
- Blocking input to TTL output
- Blocking input to blocking output
Flip the TTL switch (SW2.4) on the board and you can use the board exclusively with TTL-BAR:
- TTL-BAR input to TTL-BAR output
- TTL-BAR input to blocking output
- Blocking input to TTL-BAR output
- Blocking input to blocking output
Additionally, you also have four general-purpose inverter channels on the front panel. These can be used to invert a signal locally, without having to remove the board from the rack.
As an example, if your TTL switch is set to TTL signals and you need to repeat/convert a TTL-BAR signal, you don't need to remove the board from the rack, flip a switch and plug it back. You can use one of the INV-TTL channels to reverse the polarity of the TTL-BAR signal and use it to your will. Bear in mind that if you want to repeat this TTL-BAR signal, you need to use another INV-TTL channel to reverse the polarity the CONV-TTL-BLO is outputting, since the CONV-TTL-BLO will output TTL signals.
Q: Can I use the pulse converter system as a TTL or blocking de-multiplexer?
An example of this is covered in Appendix B.2 of the CONV-TTL-BLO user guide. You can input a TTL or blocking pulse signal on one channel, then use the blocking or TTL channels to make a daisy-chain, and output your required signal out of each channel.
Are the input and output lines terminated?
The input lines on both TTL and blocking signals are terminated with 50-ohm resistors. The output lines are not terminated.
Q: What is the width of a pulse output by the converter system?
1.2 us.
Q: What is the maximum input frequency?
The input frequency of pulses should not be higher than 166 kHz. CONV-TTL-BLO boards have pulse rejection logic implemented inside the FPGA, rejects pulses arriving within 4.8 us of a previously-generated pulse.
Q: What is the maximum input pulse width ?
On blocking channels, 3.9 us. On TTL channels, anything up to 5 us.