Newer TV's do not have the option to select the proper cable system being used in your area because they detect it automatically so no need for it. The funny thing is that there is no much difference between them (Standard, HRC and IRC) with STD and IRC almost the same frecuency for the video carrier and such and HRC only 1.25 Mhz below them. I say funny because in any case if your Vizio TV properly decodes OTA ch 3 and 4 Analog (use an old VCR or any other video component that has a ch 3/4 modulator to test) then it must also detect ch 3 and 4 even if they are HRC (even ch 2 OTA is below them so yes the tuner has to go that low). In any case like you say is better to watch the digital version on 105.1 like your case rather than the analog 3 or 4 or whatever it is.