WSDZ, located at 1260 kHz in Belleville, IL, is the local Radio Disney outlet. It is also the second most powerful AM radio station in the St. Louis metropolitan area, with a daytime power of 20,000 watts. That means its sidebands, with the unnecessary digital signal added, puts out 2,000 watts. WSDZ’s transmitter site is in Swansea, IL; some 25 miles from the location in which the signal was monitored. The results of the comparison are below.


Frequency                Station/City of License (before IBOC)                           Station/City of License (after conversion to IBOC)


1210 kHz                   WILY Centralia, IL (Fair signal)                                            Blocked out by WSDZ’s digital sidebands

1220 kHz                   KLPW Union, MO (Good signal)                                         KLPW Union, MO (Fair to marginal signal)

1230 kHz                   WHCO Sparta, IL (Good signal)                                         WHCO Sparta, IL (Fair signal)

1240 kHz                   WTAX Springfield, IL (Fair signal)                                      WTAX Springfield, IL (Marginal signal)

                                    KFMO Park Hills, MO (Fair signal)                                     KFMO Park Hills, MO (Poor signal)

1250 kHz                   Blocked by WSDZ’s analog sidebands                             Blocked by WSDZ’s digital sidebands

1260 kHz                   Main channel                                                                       Main channel

1270 kHz                   WEIC Charleston, IL (Fair signal)                                       Blocked by WSDZ’s digital sidebands

1280 kHz                   KYRO Potosi, MO (Fair signal)                                           Blocked by WSDZ’s digital sidebands

1290 kHz                   WIRL Peoria, IL (Fair signal)                                               WIRL Peoria, IL (Marginal signal)

1300 kHz                   WFRX West Frankfort, IL (Fair signal)                               WFRX West Frankfort, IL (Very poor signal)


This is further evidence of the spectral inefficiency of “HD Radio”. Stations that once had good to fair signals are either no longer audible, or have had their signal strength significantly reduced. Note that WSDZ’s digital sidebands have wiped out a station 50 kHz away from the main channel. That’s bad news if you live in Swansea, Fairview Heights, Belleville or O’Fallon, IL. The digital sidebands would also interfere with the reception of KRFT De Soto, MO on 1190 kHz, and KSIV Clayton, MO on 1320 kHz. This is clear evidence that digital radio systems are a waste of valuable spectrum space.