Universal actually refers to the fact that the LNB has 2 internal DROs (Dielectric Resonator Oscillators), 1 at 9.75 GHz & the other at 10.6 GHz , with switching between them via the presence or absence of an (approximately) 22 KHz tone whcih is sent up the coaxial cable from the STB to the LNB.
All modern universal LNBs should be ok for digital in terms of oscillator stability.
When the STB is correctly configured, the tone is sent automatically when a channel is selected in the higher band
Chris Muriel