26-11-2017, 04:16 PM
It's pretty normal to have external X in some form - usually X-Y where one of the Y channels becomes X, so you have full control over amplitude, etc. In addition, some 'scope might have an external X mode, where the BNC normally used for external trigger becomes the X input. At least, that's what my Telequipment DM3 does. It's occasionally useful...
I suspect Ref was thinking about Z-mod.
Modern DSOs are a bit hit and miss when it comes to X-Y mode. It's usually present - often well-hidden in the menu structure - but the results can be a bit strange to look at.
These methods of measuring frequency by comparison to a separate oscillator are only really of use for low frequency stuff in my experience. At higher frequencies it's just too hard to get them to be close enough for comparison on a scope in either mode. However, the exception to that would be when comparing very stable oscillators like the 10MHz timebases in frequency counters. When it comes to setting one up against another, putting both traces on a dual-trace 'scope is actually the easiest way to do it IME
I suspect Ref was thinking about Z-mod.
Modern DSOs are a bit hit and miss when it comes to X-Y mode. It's usually present - often well-hidden in the menu structure - but the results can be a bit strange to look at.
These methods of measuring frequency by comparison to a separate oscillator are only really of use for low frequency stuff in my experience. At higher frequencies it's just too hard to get them to be close enough for comparison on a scope in either mode. However, the exception to that would be when comparing very stable oscillators like the 10MHz timebases in frequency counters. When it comes to setting one up against another, putting both traces on a dual-trace 'scope is actually the easiest way to do it IME
