I would call it crosstalk.
It can be modelled by a coupling capacitance.
For digital signals it mainly depends on the rising and falling times, not on frequency.
You need a complete model to see the effect as it not only depends on track distances.
Ah! Crosstalk! That was the word I was looking for!
I was on the right track with what I was thinking at least (and that pun
actually wasn't intentional btw) - I should really have termed it "noise" rather than "RFI" - as I was meaning any sort of noise being passed between traces (capacitively or radiatively... which is a
real word apparently! Cool!)
I had actually forgotten about the involvement of the rise/fall time in crosstalk - I would have just termed it "noise" and tried to deal with it from there: rather than worrying about the trace capacitance and resistance acting as a differentiator/integrator and whatnot.
I will also add controlled impedance tracks to the subject although it may not apply for simple PCBs.
For high frequency content lines you usually lay controlled impedance tracks and having a track too close can change the impedance and give bad signal transmission or generate EMI.
Ah, yes - luckily I haven't had to deal with that
yet - I might do a radio-based project in the near future (as in within the 12 months or so) just so I can try out all this RF voodoo I've heard so much about
- depending on what I do I can also work in some practice with controlled impedance inputs. That should also give me a chance to work on impedance matching and related topics.
Of course, the real problem I've found with impedance is trying to say it in such a way that the person I'm talking with is unambiguously aware that did NOT just say I was having problems with impotence in my latest project...
Anyhoo - thanks for the info folks! This is one of the problems with being self-taught and only working in a hobbyist capacity - lots of things that are easy to glance over (if you're only looking at the practical side and not the theory that is!)
I should probably go about getting a formal education in EE at some point - the problem is finding the time and money to take a course