G'day FFF,
At the risk of being pedantic, and whilst conceding that the rest of what you said gets it across to non-technical people well..:
One is frequency modulated, and the other is amplitude modulated
Isn't it in fact the case that one of the signals is
phase modulated, whilst the other is
continuous (CW)..? At least thats how I thought VORs worked back when I was an avionics engineer in the RAAF (about 20 yrs ago!) - but to be fair I was only ever focussed on the airborne equipment in my role, i.e. the receivers, so this might just be the appropriate description from the receiver's point-of-view.
I love talking about electronics and commnunications systems, so happy to stir this one up a bit
Perhaps someone has a link to some geeky paper online in PDF format which I can read for the fun of it!
Andy
(currently a banker - and yes I know what it rhymes with(!) - but wishing I still worked in avionics...!)
P.S. Forgot to add, in my experience modern VORs all look very similar - as has been said and described above.
NDBs on the other hand take two different forms: either a vertical tower with a "capacitive hat" (I have a photo of one lurking somewhere and will post it later), a good example of this type is the Chiltern NDB - CHT - near Denham, which you can drive past near the M25. Alternatively they may be of the dipole or longwire types (usually inductively loaded due to the LF band on which they operate), which generally take the a wire strung between two vertical poles, usually centre-fed. I think from memory Westcott (WCO) might be this sort (?) and the NDB on the field at Wolverhampton space-port...
P.S.S. - thinking about it, FFF must be right about the AM bit at least for most VORs the CW bit (i.e. the phase reference signal) would presumably be amplitude in order to carry the ident tone and/or ATIS etc. But from point-of-view of a phase discrimator, it would seem CW... I really must look this up..!