The IBOC noise has been absent from WBBM AM for a couple of days now! The station sounds so much better without the hiss in the background! I also noticed that the station ID didn't mention HD; it only included the (by now) usual "and now on FM at 105.9". I hope they leave it off! Good riddance to AM-HD!
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The Hiss Is Off on WBBM AM 780!
- Thread starter audioguy
- Start date
Zach said:
This has to be a maintenance issue. I can't see CBS turning off the hash anytime soon (although I wish they would).
Not a chance. They still get better overall coverage on 780 than on 105.9. But FM is better in the downtown office buildings, where 50,000 watts of Ancient Modulation from Elk Grove can't penetrate.
Ha! I don't think they're going to reduce power, but I am curious to see if any of the 50 kW AM's might try carrier controlled modulation to save money. It is not compatible with HD. By the way, people seem unaware that the Heath Seneca and the Knight T-60 used this technique back in the 1960's (for a different reason).
R
rbrucecarter5
Guest
I noticed they were a lot stronger in Houston --- perhaps they made the same discovery that some of the other 50kW formerly clears did - HD saps their signal. I remember how it decimated WBAP - they didn't put up with it for long!
Audioguy,you left out the Heath DX-60.
Late father & I ran a Seneca on 6m...it would idle on the 2E26
driver at 15 watts out,then swing up to 95 when modulated.
Drove the locals to distraction,seeing their s-meters going
crazy.
The Commission let Alaskan stations run controlled
carrier but lately have allowed it anywhere.
Apparently some Nautel transmitters will run it,see
http://www.nautel.com/ResourceCentre.aspx ,
look for the first item under "2009 NAB Presentations".
They see it as an energy saving feature.
(Is no-iBoc energy saving,too?)
Late father & I ran a Seneca on 6m...it would idle on the 2E26
driver at 15 watts out,then swing up to 95 when modulated.
Drove the locals to distraction,seeing their s-meters going
crazy.
The Commission let Alaskan stations run controlled
carrier but lately have allowed it anywhere.
Apparently some Nautel transmitters will run it,see
http://www.nautel.com/ResourceCentre.aspx ,
look for the first item under "2009 NAB Presentations".
They see it as an energy saving feature.
(Is no-iBoc energy saving,too?)
It's been teriffic to have the hiss-maker off on 780!! For one thing, WBBM sounds so much more robust without that hiss crap. The voices sound fuller, the music sounds more dynamic. And, we can get a good signal from WABC now, as well as a clear and unfettered signal from WJR.
It's win-win and I hope it continues. I hope that whatever is wrong with WBBM's IBOC exciter, it's fatal. Not-worth-the-trouble-of-fixing kind of fatal.
It's win-win and I hope it continues. I hope that whatever is wrong with WBBM's IBOC exciter, it's fatal. Not-worth-the-trouble-of-fixing kind of fatal.
Don't hold your breath for it to stay off, KCBS 740 in San Francisco had there's off a couple days..then they turned it back on
I want HD off AM as much as anyone, but I have to admit I just don't hear the hiss at night as much as you guys seem to. 1000-1070 is pretty entertaining sometimes, with no hash. We have a tiny nearby daytimer (WBZR) that hasn't signed off at night in years. It's not unusual to hear KDKA on 1020, Memphis on 1030 (or it was before the floods, now it's WBZ I think), WHO on 1040, something on 1060 I haven't been able to ID yet, either B'ham or Memphis on 1070, Little Rock on 1080, &c.
Our big problem here is not IBOC hiss (except from WWL during the day) but Spanish language broadcasts from Mexico, Cuba, who knows where… Even under WBBM there's Spanish language talk at night. WWL is about the only one immune from it.
Our big problem here is not IBOC hiss (except from WWL during the day) but Spanish language broadcasts from Mexico, Cuba, who knows where… Even under WBBM there's Spanish language talk at night. WWL is about the only one immune from it.
The hiss had returned about a week ago on WSCR 670 for maybe 1-2 days and it was fairly well controlled
with 90% of the regrowth sparkles from analog peaks removed.
WSM 650 was ok if critically tuned to the lower sideband on a wideband AM radio.
You could still tell there was iboc 2 chs off but tolerable.
Then, WSCR is clean after a few days, then both are clear of iboc.
KDKA is clear even though WBZ sounds like it still hisses and 1040 must still be getting it from both sides.
1050 is nothing here in Chicago but mush and 1060 KYW has been OK, but are THEY still hissing?
WLW still sounds hissed and WTMJ 620 Milwaukee is still hissing and still suffers from the worst mushing
of upper end-with-no-peaking to help intelligibility.
with 90% of the regrowth sparkles from analog peaks removed.
WSM 650 was ok if critically tuned to the lower sideband on a wideband AM radio.
You could still tell there was iboc 2 chs off but tolerable.
Then, WSCR is clean after a few days, then both are clear of iboc.
KDKA is clear even though WBZ sounds like it still hisses and 1040 must still be getting it from both sides.
1050 is nothing here in Chicago but mush and 1060 KYW has been OK, but are THEY still hissing?
WLW still sounds hissed and WTMJ 620 Milwaukee is still hissing and still suffers from the worst mushing
of upper end-with-no-peaking to help intelligibility.
R
rbrucecarter5
Guest
ddsparxx said:
It must have still been off - loud and clear again in Houston last night, almost like a local! I haven't heard a Chicago station that well in many years, even when I lived in Dallas. I may try for daytime reception with a large loop. Without HD, these stations get their coverage back. Which leads me to believe HD AM may have much more of an impact that I originally thought on AM coverage. They whine about not penetrating buildings - maybe if they shut down HD they would penetrate a lot better! There is definitely more involved here than just the gain / bandwidth of the receiver. HD is sapping the ERP somehow, independent of the receiver!
Locally, WHAM has definitely lost coverage when they operate with IBOC during daylight hours. As you travel 40 to 60 miles out, there is a loss of clarity and the ambient noise rises to an objectionable level. My theory is it's a combination of the necessity of lowering modulation density with HD, plus the high-level adjacent-channel noise is throttling back the AGC, reducing overall receiver sensitivity for the desired signal.
R
rbrucecarter5
Guest
Savage said:
That adjacent signal idea is what I thought, too, but it doesn't explain loss of nighttime coverage when there is plenty of adjacent channel interference, even a local 790 in Houston, yet the all analog WBBM punches through like a local. I think the loss of coverage must all be due to the HD characteristics, which makes the solution to penetrating buildings crystal clear: shut down HD!
No daytime reception of WBBM in Houston, the frequency is dominated by Spanish language station, quite likely XESFT 780 AM, San Fernando, TA. It may be possible with atmospherics later in the winter season.
Here in Valeejo..even on my walkman at my house, 106.9 comes in good.even if I have local/DX to Local
on my DX-380 in West Sacramento, 106.9 comes in weak but good with my antanna up
on my DX-380 in West Sacramento, 106.9 comes in weak but good with my antanna up
Another thought about range reduction for AM stations running IBOC. A 50 kW, DA night is running it here. During the day, the IBOC noise overtakes the analog under powerlines, overpasses, downtown, etc. Anywhere that the sidebands reach the receiver out of phase. At night, the IBOC self interference is terrible in the stations nulls (which are quite broad).
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