On AM, the hotter and more dense your modulation is - the further your station will go. If you're not wasting power transmitting a range of frequencies most modern radios can't reproduce, you can modulate the remaining frequencies that much hotter. It improves coverage and penetration.Yippee!
A big new
bonus courtesy of “HD Radio” – “brutal” audio engineering practices formerly-reserved by AM stations forced to take-on the tundra north of the Artic Circle!
As to transmitters: KNOM runs a Nautel ND-25... Solid as a rock... Processing is pretty simple and brutal. There's an Aphex Compellor at the studio... at the transmitter, a CRL-MBL 100 shortwave limiter... This crunches the BW down to [under 5 kHZ] and drives hell outta the Nautel for maximum "reach". Sounds terrible but it does travel! Remember, most listeners have bare-minimum receivers and are happy to get any service at all.
What a delightful case-study for major-market corporate AM radio to emulate... ‘Just assume the audience mimics a few-thousand Inuit Eskimos across the Bering Straits from Siberia – straining to hear the “Personals” show on their $40 Eton FR-200 wind-up portable radios. Since when do engineering practices common to the likes of 680 KNOM—Nome and 720 KOTZ—Kotzebue, Alaska become advantageous to “The Nation’s Station”—700 WLW? Obviously, since IBOC made its appearance on stage!
Find me ONE competent
AM engineer as late as 2000 that would purposely implement such a Draconian directive. How many of those engineers celebrated their acquisition of a shiny-new Harris DX-50 only to turn it into a screeching “notch-master”? NONE!
This “5kc shill
” is merely another
artifact [joining the infamous codec “chorus effect”] of iNiquity IBOC. Those suddenly singing the praises of telephone-grade audio [allegedly due to “coverage”] coincidentally are simultaneous converts to the new “HD” religion... “Praise our King, Bobby Stubble”
... You may call it “getting saved
” – I call it “selling out”
As for the interestingly
-timed discovery that “honkish” audio equals a fantastic propagation breakthrough, consider a genuine non-iNiquity-assisted AM-undertaking I had personal experience with at the whopping 1kw level:
...we brought in NBC AM engineer John Bailie from WMAQ... Jim Loupas at WCFL... along with the greatest AM antenna engineer of all time, Harv Rees...You’ve just tagged the “Trinity” of AM engineering, Cary! All TOO often, TOO many marvel at their Star Trek-ish Omnia AM box firing a reasonably-modern rig – and think they have all the bases covered... [Recalling a political statement regarding the economy] “IT’S THE ANTENNA, STUPID!” I was fortunate to have a contract engineer [a Harv Rees “disciple”] who worked with me on an AM upgrade in the early-90s... NO transmission hardware [with circuit boards] changed... NOT our stack of CRL components fed via carefully-equalized Telco by an Aphex Compellor – NOT our impeccably-maintained decade-old 1kw Harris MW-1 rig. Save the original steel on the tower, the antenna was completely rebuilt... New Andrew line; a custom-designed folded uni-pole skirt designed to achieve “flat” system impedance/bandwidth and low J-factor...; and a HOME-BREWED antenna ATU in a new Kintronics box – literally built on the floor of our AM control room. Oh what a beautiful sight that finished box with its shiny-new Delta base-current meter was to behold! ‘Shame it lived behind an eight-foot stockade fence to keep people and grazing cattle at bay. While the prior facility sounded good and coverage was a bit beyond the norm – we were entertained by the challenge to [increase quality and coverage]... The result was MUCH BETTER! Audio quality, density, and “impact” were off-the-scale... The 180-watt [ND] night signal bettered the heritage AM in town with 500-watts [DA] at night... It WAS the ANTENNA, stupid!
...And fortunately, those audio improvements and coverage
were NOT mutually-exclusive... And note that I did NOT direct my engineer to re-jumper the CRL limiter to a 5 kHz
bandwidth – we used EVERY kilohertz allowed by law to modulate that Oldies format! Gains weren’t
the result of some mythical RF projection due to an alternative antenna design – they were
the result of “hot ‘n nasty sidebands” – a rip-roaring “here’s my turf” audio signature that was unavoidable on radios 40-miles away. So goes your “convenient
” coverage inducement. I test-drove that 5kc highway on another 250-watt AM station where coverage WAS a consideration [and demands of the Perry Como music genre were fewer] – BUST! Purposely-choking audio provided NO significant increase in the size of the ameba
– ‘just an undesirable decrease
[which no-doubt hindered the former].
...I can pick out a chopped down analog signal on some radios from quiet casual listening... In the car, it's so obvious that I am appalled that others claim there is no difference. I can only assume you have bad hearing or an awful radio. Or both!
I own no-less than a dozen
radios priced from $40-140 where the difference is
apparent – and I’m not including my ownership of several “niche” receivers [such as the CCRadio, Carver TX-11b, and ICOM R71a] which might suggest my flirtation with the “lunatic fringe
The difference is
telling – even on the notorious Delco radio in my GM SUV. SAD
, considering the enhanced state of AM processing and transmission gear in this era – enhanced, that is, before that rotten IBOC egg was hatched.
...Consider the implication: a system so flawed that, before you're allowed to use it, you have to pledge undying allegiance to it! Unless my broadcasting/media/electronics history has a glaring defect, I remember no such iron-lung provision for NTSC color TV, HDTV, stereo FM, C-QUAM AM, VHS v. Beta, 8-tracks, cassettes or LP vs. 45 rpm. Nice system. So valid, so terrific, its perpetrators have to legally muzzle anyone who might have a bad experience with it.EVEN SADDER
– but chilling proof that surreptitious corporate interests that cherish “fine print” are displaying their real agendas with billboard-sized letters.