Wednesday, December 31, 2008
Stop IBOC Now!
BY THE NUMBERS
As of September, 2008:
NUMBER OF US AM STATIONS: 4783
AM STATIONS OPERATING “IBOC”: 258
AM STATIONS OPERATING “IBOC” 24-7 DAY AND NIGHT: 87
(the remainer are “digital daytimers” meaning that directional antenna systems used at night will not work properly with HD. The overall figure of 258 includes a number of AM stations noted as “intermittent operation” meaning HD broadcasts may be infrequent or irregular.)
PERCENTAGE OF AM STATIONS OPERATING “IBOC”: 5%
Note: Most AM stations utilizing IBOC do not utilize the system at night. According to IBOC proponents, as of October 2007, “fewer than 100 stations” are utilizing the system because of skywave adjacent-channel interference problems (see “DROPPING LIKE FLIES,” this site.) An unknown number of AM stations using IBOC are “daytimers” meaning they have no nighttime authority under any circumstances, or are “daytimers with post-sunset authority” meaning they have very small nighttime operating power. Since IBOC utilizes only about 1/100th of AM carrier power the system would not work reliably with the usual PSSA authorized station, operating with only 5 to 50 watts, so daytimers are not candidates for nighttime use of the system.
For a running pop-count of AM stations operating IBOC, a constantly updated list including data from numerous sources: http://topazdesigns.com/iboc/station-list.html
Summer 2008: CLEAR CHANNEL STOPS NIGHT IBOC ON WRVA RICHMOND TO PROTECT CO-OWNED ADJACENT-CHANNEL STATIONS IN MIDWEST
Although radio’s biggest company (and a major investor in iBiquity), Clear Channel has moved decisively to end adjacent-channel IBOC interference emanating from its heritage flagship WRVA 1140 in Richmond, VA. CC won’t comment publicly but internal sources tell stopiboc.com that nighttime IBOC has ceased on WRVA because of destructive interference to three high-power AM stations the company owns in Detroit, Milwaukee and Minneapolis operating on adjacent 1130 kHz.
The 1130s all operate with powers between 10 and 25kw at night and utilize complex 9-tower directional arrays, and are highly impacted by the nighttime noise from Richmond.
Summer 2008: 50KW KMJ 580 FRESNO TURNS OFF IBOC
CBS, a stalwart booster of IBOC and investor in iBiquity and the HD Alliance, has stopped IBOC on legendary KMJ. No reason was given publicly.
Summer 2008: KTCT 1050 SILENCES IBOC IN SAN MATEO
The 50kw Cumulus outlet in San Mateo, CA, has stopped its IBOC operation without explanation to the public.