Drive CO Timing Off of Non-TTL Clock?

Hi,

I'm using a PCIe-6321. I'm trying to send a counter output for specified numbers of ticks based on an external clock coming into a PFI input.

The problem I'm having is that my external signal is not TTL, it is an AC coupled 50 ohm 1 volt signal (+/- 0.5 V about the middle). The voltage difference is too small for the DAQ to notice.

What is the best solution to this? Is there a better approach than using an external amplifier to turn the clock into something the DAQ understands (0 - 5 V signal)?

thanks,

Isaac