I'm using an arbitrary waveform generator that is generating a 1 MHz ramp waveform. I'm triggering on a marker sent out by the waveform generator which is tied to the same memory location as the start of the waveform. So although there is supposed to be a small latency (1-3ns) between the marker and the waveform it should be roughly fixed in relation to the start of the ramp. I'm measuring this output on a 2 GS/s oscilloscope with a 200 MHz bandwidth, but when I trigger on the marker it seems that the spacing between the marker and the ramp can vary as much as 15ns, so when captured by the trigger the waveform continually shakes around on the order of that magnitude. The marker has a fall time of less than the min resolution of the oscilloscope which is 2.5ns. I have the input to the oscilloscope (1 M ohm input impedance) connected in parallel with a 50 ohm termination because the waveform generator is 50 ohm back terminated. What I'm unsure of is whether this shaking/poor timing is coming from the waveform generator itself or from the oscilloscope's inability to trigger properly. Since the AWG can produce much higher frequency waveforms I suspect it is the oscilloscope but I can't come up with a reason why. Any ideas or suggested reading would be appreciated.