An NI document explains "high frequency" two counter measurement using this diagram:
If I understand the Device Specifications correctly, my USB-6259 BNC has "Internal base clocks" with frequencies of 80 MHz, 20 MHz, 0.1 MHz. Is an "Internal base clock" the same as the "Internal Timebase" shown in the diagram above?
How do I know which clock/frequency is used in a given measurement? Can I specify which one to use?
The document also says to use two counter measurements for "high frequency" measurements. What's a "high frequency" measurement?
Why does the device have more than one clock/frequency? Why would I want to use any frequency other than the fastest one?
thanks!