Sometimes, time-mark generators are overrated. The advantage of them
is that they make vertical marks for easily matching marks to
graticule lines. But if you need faster timing checks, you don't
need to be slaved to an older time-mark generator that won't give you
fast marks. As long as you have a signal generator and a counter (or
built-in counter on the generator), you can get accurate timing
references. A generator capable of 1 GHZ will give you
1ns/div "marks". And if you have a 100ps/div timebase, that only
means that you'll have a "mark" every 10 divisions. You don't HAVE
to have marks every division to calibrate, although it is nice to
check out linearity, of course. Many of the Hewlett-Packard
microwave generators can go higher yet.
I had a Navy chief who thought he knew everything tell me once that I
couldn't calibrate oscilloscopes if I didn't have a time-mark
generator. Pulease!
