Note that Annandale Terrace said "When AM goes digital..."
Perhaps he means "IF AM goes digital."
It has not yet been formally decided to shut down Amplitude Modulation and mandate a switch to digital broadcasting on the medium wave band, and for now it's only a political push by special interests who stand to gain by the proprietary nature of the iBAH technology.
The only reason being advanced for making such a change is to "save" or "enhance" the medium wave band, and counter arguments including some already made in this thread are not being voiced.
As two reasonable sane people agree, poor programs cannot be inproved by transmitting them digitally.
Some have said, "Digital on AM sounds like FM." Ya but, FM already sounds like FM.
Perhaps he means "IF AM goes digital."
Except for a few recent and limited-time experiments, no licensed AM broadcast station in the US has been permitted by the FCC to use purely digital transmission with carriers in the band 530 kHz to 1700 kHz.
They are still required to transmit an analog-only signal centered around their assigned carrier frequency, which can be received by legacy analog AM receivers.
But at this point, any licensed AM station can transmit in HD "hybrid" mode, which includes both the analog and digital spectra.
Even though the r-f sideband spectra occupied by those digital carriers in hybrid mode may not interfere very much with analog-only reception of that station in its day/night coverage areas, those digital carriers can GREATLY interfere with the nighttime reception of the analog AM signals of adjacent-channel stations.
One well-known example of this is the mutual hybrid HD interference produced by WBZ, Boston (1030 kHz) and KDKA, Pittsburgh (1020 kHz) to the useful nighttime, analog reception of both of those stations prior to those HD transmissions.
In agreement with Rich(F)...
The sideband interference that has trashed the AM dial since some stations have been sending digital signals had me wondering from the very outset whether the FCC was sound asleep (make a pun of that if possible) when they approved such a thing. It's terrible noise.
I am so proud of most of the stations here in the St. Louis area for never fiddling with iBAH, but there are a few who have.
For unknown reasons the 50kW local, KMOX 1120, sometimes turns their iBAH off at night, but not often enough.
The 5kW Lutheran daytimer runs iBAH but I think it's because the manager has a digital radio, otherwise the station has two shut-ins who anticipate the return of Christ, although they listen on analog sets.
The Disney station runs iBAH even though Walt is not expected to return.
And there was one more...
1600, 6kW, WAS doing iBAH, until a month ago when it was shut off - HALLELUJIAH! And conveniently, that is their slogan. Now I can finally DX on 1590 and 1610.
I have thought of running an electric shaver on 1680 AM and claiming to be an iBAH station. Nobody would check it out.
After spending the last half-hour reading the article posted above by WDCX, I praise the writing skill of Leslie Stimson who wrote the item for Radio World. It gives a detailed description of the HD situation as it now stands with the Nation's AM stations, as well as a correctly uncertain view of the future of AM HD.
I hope to hear your responses to what is said.
"Stasis" a word for "standing still."
In this Engineer Blog entry by Paul Thurst he gives the best description of an HD Radio setup that I've ever found:
http://www.engineeringradio.us/blog/2015/01/hd-radio-development-stasis/