Workout for scope and hifi.

[ppppenguin]

Yes, you do need to be pretty close to get a meaningful display either with lissajous or dual trace display. The frequency knob on an average signal generator is rather coarse for this. I have a synthesised generator (part of my network analyser) that can be tuned in very fine steps indeed. When I'm working with TV related frequencies like PAL subcarrier my generator is actually not accurate enough to do an absolute measurement, where I need accuracy of the order of parts in 10^7. Perfectly OK for relative measurements. Most of us won't need that order of accuracy.