WBZ-AM 1030 SIGNAL

[DCBurns]

OK... What the hell is IBOC?

Also, whatever the reason, I have 3 hours of local programming here in the Lakes Region and whatever the reason BZ... Get back to full power. A little RF never hurt anyone!

ps... remember AM Stereo??? Sure.. now it's call HD Radio. Ha ha... !! Pretty soon we won't remember that either.

 

[DanStrassberg]

Maybe Dan S. knows the answer to this.

Would the WBZ aux setup be more efficient from one of the WMKI (1260) towers in the marsh at Quincy?

Didn't WBZ have to go to the 10KW Soldiers' Field aux during part of the '78 blizzard due to extreme conditions in Hull?

WBZ could use the any one of the WMKI towers ND. Compared with the WEZE towers, efficiency would be relatively low, however, but would be quite adequate for an auxiliary antenna. Power would presumably be limited however, because, believe it or not, any new WBZ aux facility would have to protect a co-channel Class B AM in Pierto Rico. (WCBS's aux has to reduce power at night to protect WAMG! The reason is that WCBS's aux tower is shorter than its main tower. The result is that, despite the lower power, the high-angle skywave is greater, and since the airline distance between WCBS and WAMG is something like 160 miles, high-angle skywave is crucial. Without the power cut, WCBS would have caused interference within WAMG's 12.5 mV/m NIF contour.The FCC has gotten incredibly picky about AM aux facilities within the last five years!) WBZ's aux at 1170 SFR is obviously grandfathered. For WBZ, the neat things about the WEZE site are 1) the towers are pretty tall; not enough to meet Class A minimum efficiency at 1030 but not too far off--and WAY more than adequate for an aux antenna, and 2) the towers are on a due east-west line--just like WBZ's own towers in Hull. So WBZ could place a radiation minimum to the east to mimic that in its normal pattern. Adequately covering the North Shore would require a less than perfect null to the east, but it would be possible to use those two towers to create a pattern that covered the market nicely (including southern NH and the South Shore--it would be a three-leaf clover, not a cardioid; the Hull pattern is a cardioid).

And yes, WBZ did have to transmit from SFR during the Blizzard pf '78. I believe the Tx building was flooded, and the ATUs MUST have been swamped.

 

[aaronread]

Christ, Dan. I respect your knowledge but listen to yourself. ONE failure in THIRTY-TWO years?!?! That's a HELL of a lot more reliable than most facilities!!!

IBOC is an acronym for "In-Band, On-Channel", a reference to the type of digital radio solution that iBiquity's HD Radio is. HD Radio is the only IBOC DAB (Digital Audio Broadcasting) system there is at the moment. Technically there can be other digital radio solutions that also operate as IBOC, the FMeXtra digital radio system is one. But the NRSC (Nat'l Radio Standards Committee) has given its blessing to HD Radio, and won't presumably give it to any other system.

If it helps, think of DTV as IBDC, or "In-Band, Different Channel" since the DTV channels operate in the same band of frequencies, but had to transmit the digital ATSC signal on different channels. Or you could even call it DBDC, Different Band Different Channel since one could say the VHF-Lo, VHF-Hi, and UHF ranges of frequencies are all different "bands".

And yes, there are nitpickers who say it should be called "IBAC" for In-Band, Adjacent-Channel because the HD Radio system puts RF energy into frequencies that span into the upper/lower first adjacent channels. Well, for AM it literally does that. For FM, it actually doesn't put energy outside of the 200kHz channel, but it DOES put more energy further out from the center frequency than analog-only signals do. Enough so that most radios will hear the white noise/static of digital signal when you tune one channel up/down from an FM HD Radio-equipped station.

I generally prefer to call digital radio "IBOC" unless I'm specifically talking about the HD Radio system. Despite their sincerest efforts, iBiquity does NOT own the entire concept of DAB in America.

 

[DanStrassberg]

Christ, Dan. I respect your knowledge but listen to yourself. ONE failure in THIRTY-TWO years?!?! That's a HELL of a lot more reliable than most facilities!!!

Sorry, Aaron, but you absolutely AMAZE me. You work in radio and YOU DON'T SEEM TO HAVE A CLUE! There are times when people's lives depend on radio. The Blizzard of 78 was, thank heavens, the most serious such event I can recall in the 53 years I've lived here. At times like that, WBZ must be on the air with as much as possible of the huge signal that people have learned to depend on day in and day out.

Oh, and one other reason for their considering an aux site other than 1170 SFR: A year or so ago, CBS was reported in negotiations with Harvard U to sell the SFR site to Harvard, which was planning an expansion of the Boston part of its campus. The financial meltdown that you seem to believe could not have happened has apparently brought those negotiations to a halt (Harvard's massive endowment was decimated). But should WBZ AM/TV move from SFR, a new aux site (not Hull) will be necessary. It was, in fact, that possibility that first got me thinking about aux sites that would not involve new tower construction (unacceptable to our great NIMBY consitiuency). The 590 site has, besides suitable towers in suitable positions and a more than suitable ground system, great soil conductivity (for New England): WEZE has a gem of a signal for 5 kw.

 

[Greg Strickland]

As touched on by Dan, the vertical elevation pattern of a tower is significant in nighttime skywave coverage out to about 200-300 miles. Moving from a 1/4 wave to 1/2 wave tower would result in less close-in skywave. This is how a new aux site for a Class A station can get the "ratchet" in a way that might be a surprise. The 1/4 wave tower could create interference to close-in adjacent channel stations that a 1/2 wave tower would not.

 

[aaronread]

I trust this won't make you feel TOO smug, but while I never said anything about not believing that the financial meltdown couldn't have happened....your point about Harvard's relentless expansion is a good one.

Even if Harvard doesn't actively buy the land where WBZ sites, when (someday) they do build out the Allston campus, all it'll take is one time during business hours for WBZ to fire up that aux tower, and a lot of angry professors to whine about hearing WBZ in all their phones, computer speakers (and probably their teeth fillings). And yeah, I wouldn't be surprised if Harvard eventually tries to effectively buy out WBZ and force them to move. If that comes to pass, then it actually benefits WBZ to wait and do nothing in the interim, as if forced to move, they can negotiate having Harvard pay for the inevitable costs of moving the aux tower...and I wouldn't be the least surprised if they take a hard look at WEZE's site.

BTW, I think this has been mentioned before, but why doesn't WJIB move to the WBZ aux tower and diplex it? Is it too hard to put a NIF signal over enough of Cambridge from there? Rachet rule issues? Simply because Bob owns the 740 tower and doesn't need the hassle of paying tower rent when what he's got works "well enough"?

 

[Greg Strickland]

btw I ran some studies on WBZ from Provincetown as a 500 KW station with a 2 tower cardiod half wave. As you might guess the coastal signal extension is huge. In areas of the Boston metro (beyond near the Hull site) the 500 KW results in less signal than Hull.
Once the signal moves ashore, the ground does its thing regardless, and Hull has more signal hitting the land mass than Provincetown.

It goes to show that a well chosen historic site is frequently the best spot, even decades later.

In Miami WQAM moved to another site many years ago. The historic site (the tower in Biscayne Bay) was licensed as an aux at greatly reduced power.
Both sites are comparable electrical height. That tells you something.

In fairness to WQAM, the Biscayne Bay tower is impaired by nearby buildings, which the M3 coverage curves do not show.

I've run the same study with 690 in Jacksonville FL moved east to the shore. It needs a half wave, two tower cardiod to maintain the 2 mv contour inland.

 

[DanStrassberg]

BTW, I think this has been mentioned before, but why doesn't WJIB move to the WBZ aux tower and diplex it? Is it too hard to put a NIF signal over enough of Cambridge from there?

AFAIK, WBZ's aux antenna at SFR is a long-wire--an L, not even a T. AFAIK, the FCC doesn't license those anymore, except under STA for AMs that, for whatever reason, have lost their tower. I don't know whether the FCC would license a new long-wire even as an aux. That's why I'm pretty sure that that WBZ's use of the antenna as an aux is grandfathered. If the antenna came down, WBZ might be able to replace it with another identical aux antenna, but I very much doubt whether any station that wasn't already using it would be allowed to diplex into it--except maybe under STA in an emergency. As for its location, Bob likes Fresh Pond for a very good reason. With only 5W at night, WJIB's signal doesn't get very far, especially on nights when CFZM is booming in. The Fresh Pond location is near a large number of homes, so 5W manages to reach quite a few people. I doubt whether the residential population surrounding the SFR site is nearly as great. I also suspect that the L antenna wouldn't come close to meeting minimum efficiency for a Class D AM--especially one low on the dial like WJIB. And if the SFR site were legal for WJIB, what makes you think that CBS would charge less rent than the self-storage place does for WJIB's space on Concord Ave?

 

[Oldbones]

I remember it was on a July 4th maybe five or six years ago that WBZ made a big deal of promoting that they would go "AM stereo" for the July 4th evening broadcast. .......... No stereo light, nothing. I think I read that they weren't aware that AM stereo had been disconnected or dismantled on that Hull auxiliary. That time was the last I ever heard about AM stereo on WBZ.

ISTR that they did the same thing when the Beatles' "Let It Be: Naked" was released & they broadcast the entire album. I don't have an AM stereo receiver, but I heard somewhere that they actually aired one channel of the CD in mono.

 

[DanStrassberg]

I've run the same study with 690 in Jacksonville FL moved east to the shore. It needs a half wave, two tower cardiod to maintain the 2 mv contour inland.

But when you talk about a two-tower day setup for WOKV, you must still be talking about a two-site operation--right? The six-tower 25-kW night site is located pretty far inland and the teardrop pattern throws everything eastward. Even so, IIRC, the NIF does not cover 100% of J-ville's massive land area. If your goal is to replicate the current day coverage from a less vulnerable spot, you'd still need a more easterly (though maybe not quite coastal) site for days with your cardioid aimed inland (that is, to the west). As long as the ratchet rule remains in effect, though, that might not be allowed because of overlap with the co-channel station in New Orleans (once was WTIX but I think it has different calls now).

As for WBZ with 500 kW from P-town, I quickly ran some numbers a few months ago and I was surprised to find that the signal in Boston, though still a killer, would not be as strong as it is with 50 kW from Hull. I believe, though, that the 0.5 mV/m groundwave contour would extend quite a bit further inland than the present 0.5. And heaven knows where the 0.5 mV/m 50% skywave contour would end up. Somplace in the Pacific Ocean?

BTW, are you aware that WNVR, the 1030 Class D in IL west of Chicago (Vernon Hills) has just applied to replace its four-tower array with six towers, increase power from 10 kW-D/3.2 kW-CH/120W-N DA-3 to 27 kW-D/8 kW-CH/210W-N DA-3, and change its night DA from two towers to five? Most of the gain in daytime coverage would be in areas north and northwest of the CoL. I don't think coverage of Chicago would improve much. When it comes to calculated skywave coverage inland, WBZ doesn't pick up as much land area as you might think from being directional to the west. And interestingly, the ex-IIA on 1030, KTWO, is one of the very few ex-IIAs that uses only a two-tower array. KTNN, which AFAIK was never a IIA (it would have been had it been granted sooner), also uses a two-tower array.

 

[chrish]

The original SFR setup was a Gates BC-10P into a slant feed taken off an ATU on the roof of the studio building, while I was working for CBS at 1200 SFR the SS tower was made
into a skirted unipole with the ATU at the tower base with a Harris DX-10
At one time there were RF problems at WBZ-TV when running the AM at SFR, they may not exist now.

At the time of the 1978 blizzard I was friendly with the CE Norm Graham, during the storm they lost all Bell system facilities (audio and remote control) and they had the R/C fail safes bypassed. In those days they had no RF STL link, when the audio loops failed they
had no way to shut off either of the Continental 317C-1's. The result was a carrier with dead air that could not be shut off, using the SFR was only effective in areas that had a stronger signal that receivible from Hull.
I was living on the Salem-Swampscott line on the 12th floor looking right at the WBZ towers and got a carrier but no audio until the wind driven water got into the exhaust
plenum and caused a fire finally shutting down Hull. The Continental was a total loss.

 

[DanStrassberg]

while I was working for CBS at 1200 SFR the SS tower was made into a skirted unipole with the ATU at the tower base with a Harris DX-10

Thanks Chris. I stand corrected about the long-wire. Form what you say, WBZ's aux antenna at 1170 SFR was never a long-wire.