you're not an idiot, I only learned it recently myself by investigating the pain that
WEAE's digital signal was causing me.
IBOC stands for In-Board-On-Channel. It is a method of digital broadcasting whereby a digital signal
is sandwiched around the existing audio signal on an AM station. In order to accommodate this the
analog signal's bandwith needs to be scrunched down, making the analog audio sound like a phone
call on the old Export Telephone Co. On an analog receiver it sounds like that streaming noise you get
on a dial-up modem. Not working as advertised, the buzzing noise of the sidebands seems to extend
far beyond the 10kHz channel assignment. (minds more witty than mine have referred to it as In-
Board-Adjacent-Channel). WEAE's tower is close enough to my home that it blows away an entire
60kHz of my AM band. (I mis-spoke earlier when I said 60MHz. They don't blow away the whole band,
yet). The thing I fail to grasp is why stations want to make their analog signal sound like crud when
that is the way 99.3% of their audience is hearing them.
I would have to guess on the HD Jammer, but I believe that some vigilantes have taken after IBOC, much as some irritated people have acquired illegal cell phone jammers. In theory it would be very easy to disrupt IBOC. You would not even need a carrier to be on full time, you would just need to send out an occasional disruptive burst of code to disrupt the stream. A jumpy, erratic and congested stream will not do wonders for HD receiver sales.