Multiple Stations on Same Frequency
Digital TV allows a more narrow signal for the TV station and that same station can then put multiple signals on the same channel. I have WVUT-TV, channel 22. Before digital we only had room for one signal. We now have 22.1, 22.2 and soon, 22.3. All are differet programs from the same TV station, each filling a little less bandwidth than before. We have regular PBS on 22.1 and PBS Create on 22.2. Few commercial stations are doing this yet, but eventually many will. In our area channel 10 has CBS on 10.1 and Fox on 10.2.
I think you will find PBS stations to be experimenters and innovators. I know we are. The above is slightly simplified, but gives you the idea of what is happening in the industry.
Radio is doing the same thing with HD. I have WVUB-FM and HD-1 is regular programming, HD-2 is Jazz and HD-3 is in the Spanish, but all are still on the 91.1 frequency. Your HD radio separates th signals as your new digital TV separates the signals and fools your new digital TV to make it look like different channels or frequencies.