> Hi,
>   I have a question using a data acquisition card base on DRS4 chip. How can I measure the time between several samples of one channel，with the accuracy of like nanoseconds , for I am using the internal trigger. Is there any complete work about this problem？
>   One conceivable way is using an global counter in FPGA, but I'm wondering how to synch the counter with the DRS4 sampling.
>   Thanks.
> Chenfei Yang

I do not know exactly what you do, so it's hard to give an advice. All I can say that the DRS4 Evaluation Board from PSI allows time measurements between two channels in the order of a few pico seconds. You can download the software for this board from the DRS4 web site and 
have a look how things are done.

The trigger position is not a good time reference, since the trigger position jitters by a few samples. So if you want to measure the time of a signal versus a trigger, you have to put this trigger in a free channel of the DRS4 and use that as a time reference.

Best regards,
Stefan