I did some work for HP a few years ago designing just such a device. HP is of course Agilent now. The division that makes the cable test gear was the Callan division at that time; I don't know if the name has changed or not.
These gadgets were handheld testers that pretty much measured all the parameters on each signal--the signal strength of each carrier, of the audio subcarriers, it measured the exact carrier frequencies (IIRC we had a <10 ppm frequency reference in those things), and a few other things that it's been too long ago to recall. I'm sure the current version of one of these units would do the job for you quite nicely.