Sorry about taking so long to reply, but I’ve been “off-line” since about 2 PM Saturday (9/2).
“You have no idea who I am,” wrote IBOCRocks. But in fact, I strongly suspected that he had some kind of financial interest in the success of IBOC, and he very helpfully confirmed that when he said that he has installed “several” IBOC systems.
As for me, I can proudly say I’ve installed none. That’s not surprising, though, since I’ve been out of radio for over a decade -- and I think I made the right career choice in leaving the field, in view of baleful effects the wave of consolidation encouraged by the notorious 1996 Telecom Act has had on the industry!
But while I suspected that IBOCRocks and the other IBOC advocates who are regulars on this board (1q2w3e, autopaint-1, I.B.Iquity and pullitin) had some sort of financial interest, and considered them verbal bullies, I never pictured them as all-around “losers,” the way they’ve tried to portray SayNoToIBOC, Supercaster, vsa, audiophile and other IBOC opponents.
I doubt that the IBOC opponents are adolescents, or arrested adolescents, as the IBOC advocates suggest; but if they were, how would that invalidate their criticisms of the system? (Is patriotism the last refuge of the scoundrel? Not always. Sometimes the ad hominem attack is!)
But let’s turn back to the question of IBOC and first-adjacents.
There are a dozen Class B stations in New York City, or in nearby North Jersey towns, with Class B first-adjacents in Philadelphia, or in nearby South Jersey or SE Pennsylvania towns Let’s just look at one such pair as an example.
New York’s WFNY is on 92.3, and Philadelphia’s WXTU is on 92.5. Look at their 60 dBu contours – AND their 40 dBu’s – as shown on the Radio-Locator maps. (Just go to
www.radio-locator.com and enter the call letters, then click on “View Coverage.”) You’ll see that each station’s 40 overlaps the other’s 60, meaning the difference is less than 20 dB at some locations. And remember that the digital “HD-1” signal of each station is 40 dB below the level of its own analog signal.
It’s obvious that the unplotted 30dBu of each station would also overlap the other’s 70 dBu (the city-grade, or principal community, contour). And of course, in a broad swath of central New Jersey, some of these NY/Phila first-adjacent pairs have a difference in analog signal strength of less than 10 dB. With first-adjacents this close, how can IBOC signals NOT suffer interference – at times even within their city-grade contours, depending on propagation conditions?
(A suggestion for SayNoToIBOC: Maryland, too, is part of the East Coast "Megalopolis," and should be a happy hunting ground for more such unhappy first-adjacent pairs!)
