DATE: FEB. 16, 2005
WEEK FOUR: Cam-DTM System on KOLE by Ralph H. Mc Bride, President and Owner of Voice Broadcasting
Continuation, Part II
When the Cam-DTM system installation on our first station, KRCM,
1380 AM (last weeks Wrath), was so successful, I immediately exercised my option with Kahn Communications to buy a second Cam-D for KOLE .
KOLE 1340 AM is 1,000 Watts day and night, non-directional, licensed to Port Arthur Texas. Port Arthur is on the gulf coast, just at the Texas border with Louisiana. Being so near salt water, ground conductivity is very high, which extends our signal from Galveston to Lake Charles. However, going north, ground conductivity becomes horrendous, making coverage a very serious problem.
KOLEs transmitter was center tuned according to the Harris instruction book for the MW-1 transmitter, at no cost by Kahn Communications installation engineer, providing optimum performance.
KOLEs transmitter/antenna plant performed even better than KRCMs older plant. I first drove my signal to the north, which is away from the Gulf of Mexico, since the signal attenuates faster with the rapidly reducing ground conductivity in that direction. I used my older truck for a more subjective measurement of receivability. I know very well where my signal becomes unlistenable. It has been my major constraint for many years now. The radius of the signal to the north-northeast was extended by approximately 17%. And that was above the old Powerside operation, which had already in its time, increased our receivability when it was installed in 2002
If you compare Cam-D operation to the pre Kahn equipment install operation of 2002, i.e. with normal AM operation, the increase in coverage is conservatively 55%.
I next drove my Houston signal in my wife's new Avalon, which has a much better radio. I lost the signal for both stations when I passed near Baytown, with a signal on 1360AM. And then imagine my surprise when I picked up both KOLE 1340 AND KRCM 1380 in Houston itself fully 90 miles from Beaumont! I was beyond twice the distance away from the transmitter of our predicted urban contour for either station!
Broadcast engineers tell us that receivability is so dependant on the quality of the receiver, interference levels, weather conditions, etc. But as an owner, let me say this unit delivers, period. I hope someday very soon that we have an abundance of digital stereo receivers in Beaumont and Houston. But until then, I am providing the best, legal, extension of receivability for my market available now. And when the new Cam-D equipped receivers get out there, we will be ready.
In my opinion, Cam-D is the bridge from regular analog AM, with all its fading and atmospheric problems, to a compatible digital system that enhances the medium, in its analog AND digital forms.
Last week in our studios before local TV cameras, we had our mayor of Beaumont, Evelyn Lord; throw the switch on the first continuous AM digital stereo in our market. It is great to have something so exclusive to sell, with so much promise for AM broadcasters and their American audiences. Everyone is excited about our compatible digital operations and the modernization of AM Radio. It really means a bright future for our entire AM Radio Industry1.
I, Ralph H. Mc Bride, President and Owner of Voice Broadcasting, truly believe the above stated facts and opinions are accurate and are not meant to mislead.
1. A word from The WRATH
Mr. McBride is not the type of person who likes to speak of his or his broadcast companys achievements. I had to sort of drag this out of him, so let me insert a word or two that has nothing to do with the Cam-DTM System.
Mr. McBride participated in "The Taste of the Triangle," a local event at the Beaumont, TX Civic Center, featuring food from over 60 local restaurants and media companies, with proceeds from ticket sales going to local charities. There he competed with such little guys as every television station in the market, the main cable company, and even Clear Channel. And, can you imagine he came out first, and clear channel came out as runner up in the competition for "Best Media Booth." My guess is that Mr. McBride will keep Clear Channel "running up" as long as they are around.
WEEK FIVE: FEB. 23, 2005
Cam-DTM Installation Notes by Timothy C. Cutforth1, President and Owner of VIR JAMES, P.C., Broadcast Engineering Consultants.
I have installed the first three production Cam-DTM installations and I would have to call them each a raving success. Of course with any new technology there is a learning curve. I expected that since I had installed 100 Kahn POWER-sideTM systems it would be a snap to install a Cam-D, but I found that the sweet spot for the adjustment is somewhat different than for the previous POWER-side and a few of the most important setup details are a bit different. One significant result of the difference is that the Cam-D can be driven even harder than the POWER-side before audible artifacts appear once the sweet spot is found. Who could imagine something that could be louder than a properly set up POWER-side?
There is a slightly different frequency response curve for the overall transmitting system (processor, Cam-D, and transmitter together) than resulted with the POWER-side, and that is part of the difference in finding the best overall audio chain setup. One thing that is critical is not to clip before the Cam-D system. Clipping ahead of the Kahn Cam-D system is not as detrimental to audio quality as it was with a POWER-side but the best results, by far, still come when the Cam-D is allowed to take care of ALL peak clipping. A second thing that dramatically improves the quality for listeners is to keep the bass and sibilant frequencies out of the clipper. If you feel you need to equalize or premphasize, please keep the highs below the clipper threshold...especially in the critical region around 2.5 to 3 kHz, where car radio IF filters tend to ring. Your public will thank you and your listening times will rise dramatically...even if you don't have a Cam-D yet.
The installed performance of the first three Cam-D systems have proven the system to work well with the existing processing and transmitter technology. The first system was a music station with an Optimod 9100 processor and tube type transmitter. The KDYL cymbals sing loudly and sweetly behind the vocals. And yet with heavy 125% positive modulation the energy at 10 kHz showed 40+dB down with a 10-minute spectrum analyzer scan. This was true on both the CCA 1 kW night transmitter as well as the Continental 316 10 kW Dougherty transmitter, each more than 30 years old. The digital data energy is inaudible on an analog radio receiver even during pauses and since it is totally within the 8 kHz audio bandpass it cannot be observed with analog modulation present. The next two Cam-D installations were on talk stations. Both KRCM and KOLE have 1970s vintage Harris MW1-A transmitters. I found that KRCM was modulation and distortion limited by a poor ATU impedance match and after tweaking the ATU the KRCM signal went from loud to booming loud!
The final adjustment of the modulation density and peak levels is critical with these early solid-state transmitters (as with quite a few other transmitters!). When pushed to the limit the clarity falls apart just a fraction of a dB beyond the loudest setting. Clearly the Cam-D could push these venerable transmitters to the absolute limit of the linear modulation capability and yet be set to hold the absolute levels just below that limit. Beyond the transmitter power and linearity capacity the distortion levels increase exponentially. Don't rely on the mod monitor alone to determine what setting is the loudest, since distortion products register on the mod monitor the same as audio does. Listen and make the final adjustments based on audio quality. If you can hear a rough edge on the voices you most likely have the clipper drive (density) or peak modulation set higher than the transmitter can handle and you need to back it down a dB. On the other hand if you have not run the level up enough to HEAR the roughness appear you really can't be sure how close you are to the transmitters maximum modulation capability and you may be 2, 3, or even 10 dB below the maximum useable modulation density level...you really still don't know what the transmitter can do.
Overall what I have seen so far with my own eyes and heard with my own ears is an analog core signal that sounds better than ever, an analog core signal that has excellent transparency and apparent wide frequency response, an analog core signal that is more robust and that cuts through interference whether cochannel, adjacent channel, or power line noise, day and night, and an analog core signal that sounds clear and loud on car radios FAR BELOW the protected 0.5 mV/m level.
Finally, by the third installation there is not much mystery left to finding the sweet spot or how to set up the audio chain so that the whole system cooperates to produce a superior AM analog signal that extends the station coverage and improves the AM listening experience for everyone.
I, Timothy C. Cutforth, President and Owner of VIR JAMES, P.C., Broadcast Engineering Consultants, truly believe the above stated facts and opinions are accurate and are not meant to mislead.
1Tim Cutforth is a legend in broadcast engineering. When stations in Detroit, Houston, Miami and New York sound wimpy, he is and has been for many years, the man to call. The reason for his popularity is that he is comfortable with every single part of the broadcasting plant: narrowband antenna, sick audio processors, transmitters that run out of power at +125%, or a bad satellite feed, he knows them all. He is also known for getting results at the FCC, where he is well respected. His firm, VIR JAMES, has enjoyed a sterling reputation for over a half-century. And after all these years, he is still in love with AM radio. So now you know one of Kahn Communications secrets, we get Tim to do all of our out-of-town instals.
Mr. Cutforth is the first of a number of prestigious engineers to appear in the WRATH... I am so delighted that we now have a list of eminent engineers who will appear in future issues and share with you there latest thoughts on all phases of broadcasting.. it makes me feel so honored as to almost dissipate my WRATH. Leonard Kahn
wrathofkahn.ORG
WEEK SIX: MARCH 2, 2005
A REALLY WRATHFULCHALLENGE TO THE
OWNERS/USERS OF THE "OLD" IBOC SYSTEM
In my very biased opinion, it is about time to issue a "put-up-or-shut-up" DOUBLE DOUBLE challenge to those huge broadcast groups that think they can bluff their way into realizing a share of the TRILLION DOLLAR
(yes, thousand Billion dollar) receiver market they expect to create by obsoleting the almost billion working radios Americans own. Can you believe how naive they must be to expect the Public to allow that to happen and do they really expect the politicians to remain quiet while the voters start shouting?
But before I issue the CHALLENGE, I need to answer those friends, and some "unfriends," who are urging me to tell them just how the Cam-DTM System works so as to satisfy skeptics, such as our competitor. They argue "Pat. Pending" will protect us and other such legal nonsense. They must think they can goad me into trying to do the impossible, convince my competitors to agree that Cam-D is the better system. That makes about as much sense as the Coca-ColaTM firm being goaded by its competitors into disclosing cokes 100-year-old secret formula. It is not how Cam-D works, but what it does that counts. Just listen to any station broadcasting with Cam-D.
Nevertheless, when I was in knee pants you never double double dared anything you could not do yourself.. So... you now know of 3 Cam-D stations that are on the air, KDYL, KRCM, and KOLE.. Tune them in ANYTIME, day or NIGHT for proof that Cam-D isnt afraid of the dark.. Also tune to their first adjacent channels, you have never heard it so clean., then get a Clear Channel IBOC investor station in town to use a spectrum analyzer to further see the clean spectrum and, if they know where to look, see the 10 channels of digital data.. And THEN get them to drive any one of the Cam-D stations, since Clear Channel probably thought of trying to buy them, considering the HUGE INCREASE IN COVERAGE.. and also the Cam-D FULL HIGH FIDELITY sound.
Anyway, back to our CHALLENGE to those who threatened to bury me if I tried to compete with their ancient IB0C system.
IRREFUTABLE PROOF THAT THE "OLD"
AM IBOC SYSTEM VIOLATES FCC RULES
There are two separate indisputable means for proving that the system championed by the owners of the old IBOC system, including all of the major broadcast groups who own equity in that system, Clear Channel, Viacom, and Susquehanna Radio, etc., which cannot meet FCC Rules:
1. There is not one single report on file at the FCC, after 13 years of intensive efforts by Bell Labs and other prestigious researchers, proving that their system can satisfy FCC Rules and Regulations. (Arguably, there has been more money spent (wasted) on developing this fatally flawed System than any other radio system, including FM Radio and all AM and FM Stereo Systems COMBINED!)
2. None of the stations now experimenting with the old AM IBOC System, (when I last looked there were some 18 stations) have operated at night, they KNOW their system is afraid of the dark. If they really believe the System will work at night, WHY DON'T THEY OPERATE AT MIDNIGHT, THE PROPER TIME TO CONDUCT ON-THE-AIR TESTS? They don't need any permission to experiment late at night, IF they do not create interference. All of our Cam-DTM test stations started initial tests after midnight to make certain that each of our test stations complied with all of the FCC Rules before they started FULL-TIME operations. Cam-D stations now have logged over 2500 hours of legal nighttime operation (over 5000 Full-time hours) compared with old IBOCs ZERO nighttime hours!)
The real bottom line is, the old IBOC system does not satisfy the basic rules of the FCC to guard against interference, and the Cam-D system does. If they did, they would be on full time, and no one would be so violently opposed to their system.
ACCORDINGLY, I, LEONARD R. KAHN CHALLENGE ALL OLD AM IBOC DAYTIME STATION OPERATORS TO OPERATE FULL-TIME, FOR EVEN A SINGLE WEEK, JUST TRY IT... I EVEN DOUBLE DARE YOU!
And I, Leonard R. Kahn, truly believe that the above stated facts and opinions are accurate and are not meant to mislead.
cc: iBiquity, Viacom, Clear Channel and Susquehanna Radio.
Please note that the above-copied firms are hereby invited to submit their responses as long as the senior officer signs said response and uses the same affirmation statement that all wrathofkahn. ORG publications require.
WEEK SEVEN: MARCH 9, 2005
Welcome to WRATH... But since your visit may convince you to enlist in saving AM Broadcasting from those who wish to destroy it and sell it out. We want to make your visit most time efficient:
1. If this week's article is written by me, or any other person employed by Kahn Communications, skip it for a future visit.. You know that we are biased.
2. Click on the "previous weeks" button on the left side and scan the articles... Look at the authors... Station owners are relatively unbiased and they will view the controversy from the broadcasters side... Also they bought with their own money Cam-DTM units and they can tell you if it was a good buy.
3. See if any engineers that you respect wrote an article. The first one was by Tim Cutforth, President of VIR JAMES. If you know Tim, get his advice.
4. After all that, if you have the time, read my WRATHFUL stuff and see why I am so wrathy. And finally,
5. Talk to the other side... Why not? But I make such a recommendation only if you promise to make your very last question to them... But how come it doesn't work in the dark?
Belated Answer to the '05 New Years Guy Wire Attack
It is now over three months since the "Dear Leonard" attack on me by the masked writer Guy Wire via Radio World's website and I have decided not to wait any further for an opportunity to respond, hopefully without helping sell more RW publications. Therefore, please see the following which was actually written during the '05 New Years week and not updated.
If you believe that RW was at least somewhat less than professional by providing a regular place for anonymous spokesmen for its main advertisers, you may find the history of how the Radio broadcasting press started on a slide down to a vanity press level over the past two decades interesting. So let me spin-back the clock to the early 1980s when our industry first experienced what might be called "Real World" journalism when some magazines first offered for sale control of their contents to the highest bidder.
My wife, Ruth, (see her pre-illness photo above) and I were at its real start. Believe it or not, Kahn Communications was RW's first major advertiser . . . and also most importantly the only one that paid on time, at least thats what the founding editor told me. Anyway, this editor, who like RWs anonymous Guy Wire we will keep nameless, phoned me and invited himself to meet Ruth and me at our NYC home during a weekend. He started our meeting with what appeared to be a general interview. I thought he might be planning to provide biographical sketches for various participants in the Stereo War. As this went into the late afternoon, Ruth took me aside and said that this chap seemed like he wasn't doing well financially and suggested we take him to dinner early so he did not have to stay overnight at a hotel. Ruth was always concerned about people she thought were struggling. So we took him to dinner across the street at a nice hotel where I made it clear he was my dinner guest.
Then the meeting got interesting. The interview swung into substance meaning he wanted to know why my system was better than the competition: Motorola, Harris, Magnovox, RCA, etc. and I asked him what he would do with that argument. He said he would publish it; after all I was his chief advertiser. Frankly, I was shocked having reviewed articles for publication for the Institute of Radio Engineers, the IEEE and others and what he was suggesting to me was that he, the editor, would argue my case in his magazine as the view point of the magazine. I told him that I would not go along with any such plan, and since he was just starting out I said he would destroy his credibility . . . he should be strictly impartial.
Sounds like I am patting myself on the back, ethics and all that good stuff, however, it also has to do with good business. I knew my competitors could and would once they saw RW was for sale, out-bid me. You see, sometimes good business and ethics go together, but of course, he never really listened and so we have RW continuing on into the new century with the same new style journalism we have grown to expect, unfortunately. With more of a preamble than you ever wanted, let me go back to my January response to Mr. Guy Wire.
FINAL RESPONSE TO RW's ATTACK PUBLICATIONS
My initial draft of this response was deemed, by close advisers, to be too legalistic obfuscating a clear response to an unfounded attack by an alias engineer's rewrite of the history of the AM stereo "war" falsely accusing me of "killing" AM Stereo by arguing too adamantly.. as though the Public cared what I, (an unknown engineer), said or even what GM, Ford, NAB, and NRSC said. The Public rejected Motorola Stereo because of what listeners heard with their own ears... "platform motion" that made many listeners literally sick to their stomachs, and fatal flaw, Motorola stations lost coverage, EVEN FOR MONO RADIOS! But Mr. Wire blames me. Want my complete answer, visit the WEB... wrathofkahn.org.
Let me opine on just one legal matter raised in Mr. Wire's personal attack on me, the Cam-DTM system, and my business tactics... Mr. Wire deplores my use of trade secrets prior to issuance of patents, yet he hides behind an alias. Also his full alias, Guy Wire, invokes a fact broadcasters will appreciate.. "guy wires" are generally considered inferior to "self supporting" antennas...My guess, gleaned from Mr. Wire's unsolicited business advice is that he is not "self supporting" and has never gambled millions of his own dollars on developing new technology. I have.. (not only broadcast systems) but the Patents that were key to such developments before ATT/BELL, issued large orders (Coastal Harbor Ship-to-Shore)..(Airfone) before Jack Goeken/GTE issued huge contracts, and a new Reading Machine for the blind...totally funded in-house. I am not unique in risking large amounts of money in "growing" my business... independent station owners and engineering consultants repeatedly risk their fortunes and are true "self supporters."
Issued Patents protect research investments, Mr. Wire, while a Patent Pending notice doesn't provide any protection against major infringers until a patent issues. Publication, prior to patent issuance, just gives copyists a head start in finding ways to steal an inventor's work.
Also when you attack my "proxy writer", I don't know whom you are talking about since I don't have one. But there are hundreds of real smart engineers who know why the system that you are pushing is not viable, and they don't need me to tell them why. If you are talking about a really, really great engineer, Mr. Mike Dorrough, who has done more real innovative work in processing speech and music than any other engineer in history Mr. Dorrough is no "proxy writer"... why don't you show a little respect?
Enough law and history, now compare, side-by-side, the old IBOC system with the new, 18 month old baby IBOC, Cam-D...
NIGHT & DAY
Old IBOC has NEVER, not for a single hour, worked successfully at night...
Cam-D has been on 24 hrs per day for over 2 months in Salt Lake City and has been on 24 hrs per day for over a month in Texas (and the Owner bought a second one, with an option for a third.) We expect to deliver 10 units before June for other sections of the USA.
COVERAGE
Old IBOC claims coverage to near 1 mv during the day, while Cam-D Stations, all 3 of them, claim huge increases in coverage BEYOND POWER-side, (PS) and these stations claim they cannot cover their 0.5 mv without PS. (Contact KDYL, KRCM and KOLE, or drive their radials yourself.)
SPECTRUM
Old IBOC jams adjacents to the third channel.. see Clear Channel's early FCC report & my FCC analysis proving IBOC violates FCC Rules.. and U.S. Treaties.
Cam-D Spectrum using a 30 year old tube transmitter reduced interference FOR FIRST ADJACENT CHANNELS WITH TEN CHANNELS OF DATA..
Drive to a site a mile from the stations and check them out with your own spectrum analyzer.. Call for test procedures.
QUALITY
OLD IBOC
With the 800 million radios, 5 kHz "quality."With new radios.. "almost as good as FM."
But what about KRVN and the failure of Cam-D?
Well, KDYL's super engineer, Ken Meyer, installed Cam-D correctly and KDYL received a good percentage of Utah's Best Sounding Stations Contest votes in comparison with FM stations, using old Sony Kahn radios! Make your own listening comparisons.. and coming soon inexpensive Cam-D super sound radios, with crawl LCD data displays and the Emergency Alarm Light.
Listeners and the FCC will not care what NAB, NPR, Viacom, Lucent or even GM or Ford says.. just what the Public hears when they lose their nighttime game. And when they hear the comparison with Cam-D, the contest is over, and the FCC will let the free marketplace rule, the American way.
Future, developers and their financial backers, should never forget the Power of AM radio over satellite radio, the WEB, cable, etc... The Public's habit in tuning in, night and day, to their favorite station on one of the 800 million radios they bought with their own hard earned money. No entity, public, private or international corporation, can overcome the PUBLIC'S WRATH if they dare attempt to turn-off Free American Radio.
Want information on Cam-D operation, including reports from operating stations? Get your free weekly subscription to "wrathofkahn.org" which will be "ORGanized" to only report "signed" expert opinions, on AM/FM, satellites, HDTV and anything else real live Experts want to publish..as long as they conclude as in the following: I, Leonard R. Kahn, truly believe the above stated facts and opinions are accurate and are not meant to mislead.
Any entity specifically mentioned in the above may respond, if and only if, the firms senior executive personally signs using the above signing procedure.
WEEK EIGHT: MARCH 16, 2005
Stumblin' In by Frederick R. Vobbe,
Publisher, DX Audio Service.
Introduction by L.R.Kahn
BV (BEFORE VOBBE) THERE WAS NO Cam-DTM SYSTEM
On February 28, 2003, at precisely 5:36 pm the challenge was issued that caused me the longest string of sleepless nights in my life, and when I don't sleep my associates Dr. Gordon & VP Salzman, and others, at Kahn Communications, Inc. (KCI) don't get that much rest either. It was Mr.Vobbe, who in a lengthy interview during which I described the reasons why the then sole system before the FCC for digitizing AM broadcasting violated basic mathematical spectrum concepts that made the "old IBOC" system a certain failure, his challenge reminds me of when I was six years old and this old guy, he must have been at least 25, challenged me to climb down the ladder off the pier leading to a lake in upstate New York. After convincing me I could do it and watching over my first few successful minutes of swimming until I was safely back up that ladder, he admitted his fear of water and couldn't swim and I had been on my own. BUT he had faith, as there was no theoretical reason I couldn't swim.
But why was Mr. Vobbe interviewing me in New York City from his office in Lima, Ohio about a Bell Labs decade long development in New Jersey? Because I had attacked the system in a published opinion piece when it first was proposed, in the early 1990s. Also I had just (1/24/03) filed a lengthy formal submission to the FCC arguing:
1) That the FCC should appoint a "Blue Ribbon" Committee to investigate how the Commission processes petitions re complex new technology falsely relying on NAB committees using advisors with huge conflict of interest members and,
2) Why the proposed IBOC system would destroy AM radio and deny the Public its main source of information and emergency alarms, and was clearly a serious blow to the defense of our Nation during these dangerous times.
Then, at the close of the lengthy interview Mr. Vobbe asked the crucial question: Mr. Kahn are you saying that it is impossible to make a compatible digital system that does not destroy AM radio? The answer was "I see no such impossibility mathematically" and once again I found myself jumping in that cold water.
Mr. Vobbes final words to me sounded like a clear challenge to that six-year-old ego...
Thus Dear Reader you can credit Mr. Vobbe for his instigation as a blessing (my friends and KCI associates think so) OR the blame for just another WRATHful development from those wrathy Kahn guys who (surprisingly) haven't many friends at NAB, nor at Clear Channel, Viacom and the other owners of iBiquity.
"Stumblin' In", By Frederick R. Vobbe
As a publisher of one of the National Radio Club's magazines I've reported on several issues involving broadcast. My magazine, the DX Audio Service, is an audio book on tape. Unlike the print medium I have the ability to describe by example the issues we discuss.
The National Radio Club is a non-profit organization, and is made up of over 700 DXers and general radio listeners. Many of the members are keenly aware of the technical and real issues in broadcasting. The club has members in the trenches of engineering, programming, and finance. The club also has many people who depend on radio as their primary source of news, information, and entertainment. For example, the blind need a medium such as radio as their window to the world.
First, a little about me. Although I was born in Ohio, I probably should have hailed from Missouri. I've always been skeptical of claims and statements made by people without substantial evidence to prove their claims. I want proof. Hard, indisputable truth!
Sir Winston Churchill once said, "Men occasionally stumble over the truth, but most of them pick themselves up and hurry off as if nothing ever happened." Stumbling over the truth seems to be a hallmark with advertising, political campaigns, and with various radio discussion areas. This has never been so evident as with discussions about AM radio. Some stumbles trace their roots to misinformation, and sometimes a monetary reward can entice the writer to bend the laws of physics.
The first stumble is that AM radio is "technically quality challenged", and this is why listeners are leaving for other mediums. AM radio's problem is content, not quality. If quality is an issue, then why do so many teens and young adults listen to 24 and 32 kbps MP3 and RA files to get the content they want? Why are Ipod, Sirius, XM, Napster, Kazaa, and others so popular among my generation? Simply, it's about content.
To address the quality issue, for the past couple of months I have been preparing a report for our magazine titled, "The Quality of AM". In the audio report I demonstrate the plusses and minuses of the analog transmission. To be blunt, the quality is not as bad as it's made out to be. In one of the tests I set up an AM transmitter, and FM transmitter, and used several common radios available to the public. I played selections of music and spoken word through the systems and asked listeners to thumbs up or thumbs down. It was interesting to note that the average person had no problem with the quality of the AM test transmissions.
In fact, in several sidebar tests I found the test station was more appealing to the listener than local commercial AM stations. The reason, I feel, was the differences in processors, quality of equipment, and the care in setup. It should be noted that the AM test transmitter was an LPB Model 30B, fed by an Inovonics 235 audio processor. The output of the transmitter was fed to a 50W dummy load with RF probe, and the probe fed the transmitter's signal to a radio where the level was set to approximate a 2.5 mv/m contour and mixed with outside signals in the air.
So, is the fact AM radio is struggling is due to technical issues? As the guys on the Discovery Channel would say, "Sorry, the myth is busted".
Now, let me deal with Leonard Kahn. Leonard is outspoken, and brash, but I've never seen any proof that his claims are without merit. So when I saw his paper submitted to the Federal Communications Commission I took note. At the same time I was reading Leonard's thoughts, I was hearing a lot of discussion over the adjacent channel noise issue caused with Ibiquity's In Band On Channel (IBOC) transmission scheme. It was then I picked up the telephone and called Leonard for one part of a lengthy discussion.
Let me say for the record that I'm not against digital. It does have its place WHEN properly implemented. As a V.P. and Chief Operator for a network affiliate TV station, my station built and is operating a digital television station. Further, I have experimented with digital on the HF ham bands. However, the medium wave band implementation of digital often resembles the fights between cattle ranchers and farmers in the old west.
The cattlemen's needs to get their herds to market often had them encroaching on rancher lands. In the end, the rancher's crops and profits were ruined as the cattle stomped down the land as they propagated to market.
I was personally introduced to the issue of medium wave first adjacent channel interference one late afternoon when my wife and I were driving west on US-30 to North Dakota, via Chicago, in her 2001 Buick Century. The weather was turning bad and we wanted to hear the weather forecast to find out what we were driving into. I tuned the car radio to 720 kilohertz.
Well within normal range of WGN, (a 50kw non-directional Chicago station), their programming was covered by a dull hiss making it hard to hear. At first I scrambled to see if it was my amateur radio, GPS, or cell-phone causing interference. Then I noticed that the problem also persisted on WLW, a 50kw Cincinnati OH station on 700 kHz. The hiss was caused by WOR on 710, more than twice the distance of the other stations.
Since that time there has been much discussion over this artifact. I can't say that I've seen a month go by where the second channel hiss was not brought up in some manner. Further, it's interesting to note both the passion and tirades in both camps. I can't recall in my thirty years in the business where tempers raged, statements stumbled, and friendships parted.
A big stumble is the interference issue. I've heard it stated that interference is acceptable due to the "need" of transitioning to digital. Acceptable? Since when is ruining something acceptable?
Still another stumble is that interference is only a wacky DXer issue. Each week my son and I attend a local HO train club meeting. One night I heard the fellow nearby say, "and I heard on WBZ" My ears perked up! I asked the fellow, who lives in Lima OH, if he really does listen to a Boston radio station. "Sure do", he said. Another fellow chimed in that he listens to Detroit's WJR radio. At work I found employees listening to out of town AM radio stations such as WLW, and WTAM. And, yes, I admit that while in the car I listen to WTVN in Columbus OH or CFCO in Chattam Ontario. Why? See the paragraph above on program content.
As I lurk on E-mail lists, and listen to what people say on the ham bands, folks are conscience of the interference issue. Recently WTOP-1500's digital transmission lead to many a comment about interference to a station on 1520 in Brunswick MD, as well as stations on 1490 and 1510. A message in one list questioned if WLJM-940 should be concerned due to WWJ-950's digital transmissions. The author explained that while he was listening to WLJM, while driving through Findlay OH, he heard commercials for Findlay advertisers. WOWO-1190 had issues with WCHB-1200. WLAC-1510's transmissions were noted causing problems with WWKB-1520 and WTOP-1500. And when WSAI-1530 ran digital, many a comment was heard about the interference to WWKB. And it was amazing to see how many people listen to WWKB-1520 in Pennsylvania, and Virginia. Still more amazing is how people notice it. Even before there was an NRSC standard I don't recall in history when adjacent channel interference was such an issue.
At this point, let me address a safety and security issue. As a co-chair of our area EAS district, and a communications officer for our county's Homeland Security office, I'm aware of the need for quick and precise emergency information. During 9-1-1, the Blackout of August 2003, and many weather events, the public turns to radio. I can remember many of my neighbors talking about listening to out of town radio stations to gain information on events. Suppose we ruin the ability of the public to listen in the future. Is it fair to the public, or again, are we driving our cattle across someone's grass?
Another stumble is that somehow this is my fault. I was told in a radio list that because I own a GE SuperRadio III, Sony ICF-2010, Panasonic ST K-550, and a decent car radio, I am the problem. I need to adapt. I need to get a new radio. I need to quit standing in the road of progress. The author even indicated that my desire to listen to non-local radio on my 5-year-old receivers was holding back his ability to listen to crisp, clear, CD quality radio. GASP! This isn't a stumble it's a major fall!
And now, allow me to fire a few salvos towards KCI, while I like Leonard Kahn for his honesty, I need to challenge Leonard on his CAM-D system. Leonard, I need to see the proof that Cam-DTM works!
I would suggest, Leonard, that you run Cam-D on all stations utilizing your system, 24/7/365. Likewise, stations running the Ibiquity system should run it 24/7/365. No STAs. Run your modes for 3 months, regardless of interference complaints. Let us radio listeners know what stations you're on so we can monitor them.
Cam-D needs to be tested on 1A stations, and possibly scenarios such as groups of stations like WSM/WFAN/WSCR, or WJR/WABC/WBBM, or WLAC/WWKB/WCKY, at the same time. Will we have the same problem we have now on 1520/1530/1540 or not?
Cam-D needs to be tested on the local channels, such as 1230/1240, as well. The local channels are the ones most likely to loose on any interference issue. Let's see how well Cam-D works for them as well as protecting their close spaced neighbor.
I would like to see a Cam-D station operate whereby a significant amount of signal transitions into Canada or Mexico. After all, even if Canada and/or Mexico do not buy into Cam-D, they will have to deal with it. It's only fair that tests are made and each country has the opportunity to comment on the technical merits and protection to their stations.
I would also encourage you to test Cam-D on a station with an independent review committee. Allow someone like myself to audit the test data. We would all feel comfortable knowing that what we read in the trades is honest observations, and not a P.R. writer's best take.
Leonard, you claim your Cam-D has the potential for EAS use. Might I suggest focusing efforts to assist the LP-1 and LP-2 stations to cut down on program interruptions? A secondary path in which to transmit messages of importance in an EAS system would be worth its weight in gold, IF it works!
I agree with your concept of a Blue Ribbon Committee, Leonard. I think we, as broadcast professionals need an independent review process. I would, however, take it further. I suggest that this committee ruggedly test your system and Ibiquity's system by announcement, allowing the public to review and comment on the use and effects of the transmissions. I think it's only fair that since KCI and Ibiquity are asking for this technology to be used on the public's airwaves, the public should have the opportunity to comment.
I look forward to your comments, and hope that my challenges to KCI do not ruin what has been a good relationship with club, our radio listeners, or myself. My comments are not to stumble towards anyone's camp, but just to do the right thing for the public.
I, Frederick R. Vobbe, Publisher, DX Audio Service, truly believe the above stated facts and opinions are accurate and are not meant to mislead.
Appendix
Fred Vobbe sent along some recent spectrum pictures taken on Monday, March 14, 2005. The picture at the top shows three stations, (L-R) WIMA-1150, WOWO-1190, and WERT-1220 all operating in analog mode at 2:25PM. The bottom picture shows the same stations, this time with WOWO transmitting hybrid digital at 12:37PM. Fred commented that he believes that this was WOWO's first day testing, and he took the pictures after discovering the signals while tuning from WERT to WIMA.
wrathofkahn.ORG
DATE: MARCH 23, 2005
WEEK NINE:
JUST HOW BAD IS THE IBOC-ui SPECTRUM? YOU WOULDNT BELIEVE IT!
The following analysis is of the spectrum of the IBOC-ui system, where ui stands for "under investigation". I know I have heard all those jokes as to what it really stands for, very clever, but somehow I an not sure the FCC has a sense of humor or it would have caught the real joke; a radio system that doesn't work at night!
You may be surprised how simple the calculations of this analysis are so that any intelligent layperson can understand it. That was the genius of my mentor, Mr. J.L. Finch. As discussed in the following July 2004 FCC filing, he used the basic logic of mathematics to relieve the tedious, time-consuming calculations that even in this computer age make some problems incapable of solution using standard procedures. Anyway, I hope you enjoy the following.
Please note that this analysis was submitted to the FCC over eight months ago and I sent copies to Lucent and other supporters of the IBOC-ui system. By now, given the fact that Bell Labs still has world-wide respected mathematicians, don't you think they would have attacked the Finch style analysis if there was a flaw, I do.
Finally, I have had the great honor of knowing and working on projects with some superb engineers and mathematicians from Bell Laboratories, but prior to Lucent taking control. Thus, the present IBOC system is not, and I believe, would not be sanctioned by the good old Bell Labs. Furthermore, Bell Labs. pre-Lucent, made its own technical decisions and wasn't forced to support substandard technology. Accordingly, I do not want anything I say here or any remarks made by Wrath guest experts to be considered to be disrespectful to former Bell Laboratory Scientists or those still at Bell Labs finishing out their prestigious careers.
PROOF OF THE ASTONISHING FACT THAT THE IBOC SYSTEM UNDER INVESTIGATION VIOLATES FCC RULES BY OVER A HALF A MILLION TIMES
As pointed out in the June 14th filing, because of the Sampling Theorem the sampled 15 kHz wave has to be present well within the sweep of the spectrum analyzer to provide the required resolution. Actually, the fact that the carrier structure used by IBOC-ui stations is present even absent program material, resolves the question. These components are present all the time. (See the Important Comments of Chad. Hutton that by a very conservative analytical procedure he has proved that the "IBOC sub carriers are each transmitted 100% of the time.")
This then means that all we must do is multiply the test period as required by 47 CFR, 73.44, i.e. 10 minutes, 600 seconds. The following type of analysis will now be named "Finch Analysis "in honor of Mr. James L. Finch, the man in the 1950s who was RCAs highest analytical authority, revered and admired by all of us in his 20 man RCA team, respected for his genius by Bell Labs, and venerated by the Navy as its Chief Communications Consultant and as the designer of the Jim Creek Mountain Antenna for long wave transmissions to submerged submarines. Mr. Finch was a Mechanical Engineer by training and used mechanical engineering techniques to solve some of the must complex problems in communications engineering.
Now, let us describe one of the techniques, which will be applied to the most difficult problem of determining by just what factor IBOC-ui stations violate FCC rules. The "Finch Analysis" we adopt herein is a form of "worst case" determination and is based on a single unchallengeable Law of Nature.
In the instant case, laymen readily understand the law I use. A worst-case analysis is, for example, commonly used by mechanical engineers in the design of structures, such as the design of bridges. Clearly, the designer is most concerned that under any foreseeable condition the structure does not fail, and of course, the designer will then provide generous safety factors. In this IBOC-ui case, we will assume that the "worst case" factors are always made most favorable to IBOC-ui stations.
First of all, let us state the basic law of physics that controls this analysis.
Energy = Power x Time
For example your electric bill is in kilowatt-hours. Surely, such a simple relationship satisfies the "Finch Analysis" criterion, especially since only a single Law of Nature is used in the entire analysis.Now, let us determine what the energy of an IBOC-ui signal is under conditions most favorable to the IBOC-ui station. Clearly, if there is no program material present,
("dead air"), the IBOC-ui signal energy is minimized. Under these "dead air" conditions, the designers of the IBOC-ui system could not do more than fill the FCC power "mask." Thus, we choose to accept a most favorable condition for the IBOC-ui signal and provide no safety margin or even space for the components created by the program material. (Published spectrum photos of WOR off the air indicate that only a small safety factor was used to maximize coverage.) But in any case, it washes out in the final step of the analysis.
Since the spectrum frame components are present all the time, we can just make the simple arithmetic calculation: Energy = Power of Framework x 600 seconds, as the test time under 47 CFR 73.44, is 10 minutes.
The next step is to determine the energy of the analog signal splatter. This is, of course, by FCC rules a condition that can only occur once every 10 minutes. Again, we must agree to the "best case" situation for this calculation so as to favor IBOC-ui stations. Actually, it is a practical impossibility for an analog station to produce splatter components that fill the "mask" power levels. There is no way that an analog signal could produce such a spectrum signature from the statistics of voice and music. The only situation that remotely would fit would be some sort of parasitic oscillation that was "clean" for 10 minutes and then suddenly becomes parasitic for a millisecond - Not very probable. Clearly, this analysis is not applicable to defective transmitters.
From the well-known statistics of voice and music, the most powerful component of such waves would fall at approximately 500 Hz which would, if producing maximum negative over-modulation, be the condition which produces the largest amount of splatter, i.e. carrier "pinch off" which amounts to a duration of 1 ms (1,000 of a second). Over-modulation by higher frequency components would probably do a better job of creating interference more closely approximating the "mask," but this would make the duration of the splatter even shorter and less favorable to the IBOC-ui station.
So we conclude with a simple approximation:
Energy of lBOC-ui = 600,000 x (Energy permitted by present rules),
A LITTLE MORE THAN A HALF A MILLION TIMES.
Note: Some IBOC-ui stations believe that the problem of interference can be solved by a 6 db reduction in the IBOC-ui signal. Thus, they conclude that instead of a 50 kw station transmitting full power, all they need to do is drop it to 12.5 kw. Unfortunately, the instant analysis indicates that the factor has to be 600,000 reducing the 50kw station to less than .1 watts...To be precise 83.33 mw...mw is a thousandth of a watt. Thus, those IBOC-ui stations who think that they can cure the interference problem by reducing power by 6 db (4/1) are wrong by over a 150,000 times!!!
March 22, 2005 Update
Now just a few words to update the above 8 month old filing with the FCC. During this period much has happened. Early in October 2004, we had the first successful Cam-DTM System installation at KDYL in Salt Lake City, followed by two more in the Beaumont-Houston TX market, KRCM and KOLE,all working 24 hours day & NIGHT. And just yesterday we had another Cam-D install. This station is expected to announce the event shortly in the WRATH. The important thing is that not only do these stations not increase interference, they actually reduced interference even to THEIR FIRST ADJACENT CHANNEL NEIGHBORS. Check it out yourself if you are close to the stations or have a friend in the market check it for you. Also get them to check the huge increase in their COVERAGE.
Maybe more importantly, in the past few weeks a number of IBOC-ui stations went on that provide experimental proof of the above Finch Analysis. See for example last weeks WRATH by Mr.Voppe.
Finally, we at Kahn Communications confirmed the fact that the 600,000 times interference figure is conservative. Each time we do the final tests on Cam-D, we make certain that the interference caused by our system does not violate FCC Rules, the REAL RULES. When you put on a new system, no one, especially not your friendly FCC Inspector, can hear ANY increase in interference. We had to drop the level of the digital signal over 60 db, a million to 1 in power. Therefore we, as expected are conservative, but who cares if the IBOC-ui Buzz is a million or 600,000 times too loud, THE FCC SHOULDN'T.
I, Leonard R. Kahn, truly believe the above stated facts and opinions are accurate and are not meant to mislead.
WEEK TEN: MARCH 30, 2005
THIS 10TH WEEK IS REALLY, REALLY WRATHFUL
Hopefully, we will soon be back to publishing reports of new stations on-the-air results using the Cam-DTM System. The 4th station seems to like the results, they are ordering FOUR MORE Cam-D Boxes, and we are installing the 5th & 6th stations during the next three weeks... However, before we get back to the "good-stuff," I am being forced to respond to some really silly stuff from those who apparently have picked the wrong technology when they supported the "iBOC" system. First of all, I now am being attacked for not participating in NABs committee games, the same committees that reduced your fidelity, gave you the ringing filter, and destroyed AM Stereo by helping cause the FCC to abandon the American Free Marketplace System, and the same group that drove Major Armstrong to waste years of his life delaying his FM masterpiece. No way will we ever get suckered into allowing KCIs work to be destroyed by committees heavily controlled by Clear Channel and Lucent, or any other powerful organization. We may not be too smart, but we are not quite that stupid.
But the real, real reason for this weeks WRATHLY WRATH is the continuous mantra, the chant telling us to disclose how Cam-D works. Bell Labs and anyone who can do a patent/ IEEE literature search knows all they need to know about how Cam-D gets the dramatic increase in coverage and also almost eliminates power-line buzz and fading.
(The same way it is now alleviating, but, of course, not eliminating fatal flaw iBOC BUZZ JAMMING.)
Therefore, for you Dear Readers who do not have the time to do such searches, I will now publish for the FOURTH TIME (IEEE Transactions on Broadcasting, Vol. 34, No. 3, Sept. 1988 and simultaneously in Japan's "Broadcasting Engineering"Vol. 41, No. 8, also the Radio Club Transactions where Major Armstrong published after returning the IRE FM award) text re the POWER-sideTM advantage.
POWER-side provides only half the increase in coverage of Cam-D, but the theory is almost the same. But how about the data details; not until patents issue. But didn't you notice that Bell Labs isn't disclosing its detailed information while their patents are still pending. Don't we still believe in private property? If I hear anymore of this nonsense, I may really, really get WRATHFUL!
WHAT IS POWER-side?
The POWER-sideTM system is a form of amplitude modulation which offers some of the transmission advantage of single-sideband (SSB) and which is compatible with both envelope-detector type receivers and SSB receivers incorporating synchronous demodulators. Furthermore, since a POWER-side signal better matches SSB receivers than does a conventional AM signal, this new form of transmission should help to expedite the widespread use of these superior SSB receivers.
Block Diagram of a Practical Power-sideTM Transmission system
FIG. 1 shows, in block form, the basic structure of a POWER-side system. The audio signal, that comprises all of the necessary components for monophonic listeners, feeds a de-emphasis circuit. This de-emphasis circuit should be adjusted to match the inverse of the pre-emphasis curve used by the station. Thus, a signal with relatively flat frequency response should appear at the output of the de-emphasis circuit. The output of this circuit feeds an attenuator, which reduces the audio level so that the signal has a level that will produce a weaker sideband approximately 15 dB below the stronger sideband.
Figure 1.
In other words, assuming the total envelope modulation produced by both sidebands is 100%, the sideband level for the weaker sideband should cause approximately 15% envelope modulation and, therefore, the stronger sideband is increased from a level that would normally cause 50% of the envelope modulation to one that causes 85% of the modulation.
The output of the attenuator feeds one of three equal sections that produces the desired increased pre-emphasis for the weak sideband. The first segment of Section 1 is actually a low pass filter with a "stop" region limited by a bypass stage.
The second segment of Section 1 introduces a rising response characteristic, which is greater than the effect of the prior block. Accordingly, the overall effect of the two segments is to produce a characteristic peaking at 5 db, for 5 kHz (relative to 500 Hz).
Sections 2 and 3, since they are identical to Section 1, make for a total response of three times that of Section 1, i.e. producing a 15 db peak on the weaker sideband.
As shown in FIG. 1, the output of the de-emphasis circuit, in addition to feeding the increased pre-emphasis circuitry for processing the weaker sideband, feeds an amplifier. This amplifier causes the audio level driving the stronger sideband to be proper to elevate the level of the sideband to 85% of the total envelope modulation at 1 kHz. The output of the amplifier feeds an "all-pass"network, which has a phase characteristic that closely approximates that of the overall additional pre-emphasis network in the weaker sideband path. Accordingly, the two sidebands should be approximately in phase, maximizing envelope modulation.
The two-path audio processing system feeds the appropriate L and R inputs of an independent sideband type AM stereo exciter, such as Kahn Communications' Model STR-84.
For example, if it is desired to enhance the lower-sideband, the output of the all-pass" network is connected to the L input of the exciter and Section 3 output is connected to the R input. The stereo exciter causes the transmitter to produce the desired POWER-side RF wave. It should be noted that a "stereo effects" wave may be added to the audio signal feeding the weak sideband so as to enhance the wave received by stereo listeners. The "stereo effects" signal can take many forms, including a special stereo component or certain stereo sounds such as "crowd noise" for a sporting event (A future paper is planned to discuss further POWER-side developments as well as those pertaining to stereo transmissions effects.)
Reduction of Sideband Cancellation Effects
The classical amplitude modified wave has a serious weakness. The two sidebands of an AM wave are of equal amplitude, thus making the wave particularly sensitive to the relative phase of its three components. For example, if the carrier is rotated relative to the sidebands by 90 degrees, the wave is converted from a pure amplitude-modulated wave to a form of phase modulation (quadrature modulation) where there are no desired signal components present in the envelope of the wave.
In other words, the fact that the sidebands are equal in amplitude makes it possible for the desired demodulated audio waves derived from the two sidebands to completely cancel under certain conditions, such as selective-fading multipath conditions, etc.
Since the sidebands of a POWER-side wave are unequal, it is a much more rugged wave.
For example, conventional equal amplitude sideband AM waves suffer from a complete loss of fundamental modulation whenever the carrier is shifted odd multiples of 90 degrees; i.e., 90 degrees, 270 degrees, etc, In comparison, the POWER-side- wave loses only 2.7 dB under these same conditions
(See FIG. 2)
A beating sound is most annoying and creates far more listener annoyance than does normal interfering speech or music. Thus, a clean voice signal (absent beating effects), say 30 dB below a desired signal produces far less disturbance than does a voice signal having the same level but suffering from beating effects.
The term "carrier beating" is generally used to describe this phenomenon. However, it is believed that this term is not truly descriptive of the problem. Typically, co-channel interference beat rates are less than a few Hertz. Such low frequency waves are greatly attenuated by the frequency response of a receivers amplifier and loudspeaker system. Indeed, listeners cannot hear such low-frequency sound waves even though they can feel very-low-frequency vibrations.
One can hear the slow variation in noise level caused by the variation of gain of AVC controlled amplifiers. However, even moderately severe co-channel Interference of 20 dB, causes the gain of the AVC controlled amplifiers to vary by only 1.74 dB, and for interference 30 dB, below the desired signal the total variation is 0.5 db.
Actually the phenomenon that listeners do hear might best be called "sideband beat. The fact that sidebands beat undernormal interference conditions can be understood by considering the following situation where:
1) The frequency of the desired (strong) signal is 900 kHz and the weaker
co-channel carrier is 1 Hz higher, i.e. 900.001 kHz.
2) The desired signal is temporarily free of modulation. ("Dead air"); and
3) The interfering signal is modulated by an 1 kHz tone.
Since the stronger (900 kHz) carrier dominates the demodulation process. (The envelope detector controls the switching function) the lower sideband will produce a significant demodulation product at a frequency of 999 Hz. The upper sideband produces a demodulation product having a frequency of 1001 Hz. Both of these equal amplitude waves easily pass through the receivers audio system and are audible to listeners. The beat rate caused by the difference in the frequencies of the upper and lower sideband demodulated audio signals will be 2 Hz, or two times the carrier frequency difference. (See Appendix A.)
Thus, under normal two-station co-channel interference conditions, the receiver output will be contaminated with two distinct audio signals having a difference in frequency of two times the carrier error.
Referring to FIG.2, it is seen that conventional AM waves suffer a wide range of effective modulation, from full to complete nulls. On the other hand, a simplified analysis shows that a Power-side wave only suffers a total variation of 2.7 dB, under the same conditions.
In order to experimentally verify the reduction of co-channel beat type interference, a simple, but convincing, experiment was performed. A multi-system AM stereo "boom box" type portable radio, Sanyo model MW-250, operating in the monophonic mode, was tuned to two POWER-side stations (WMCA 570 kHz, New York, and WTHE 1520 kHz, Mineola, Long island) at Kahn Communications laboratories in Westbury, New York.
The output of a Hewlett Packard model 6068 signal generator was loosely coupled to the input of the Sanyo MW-250 receiver. One of the two POWER-side stations was tuned in and the signal generator was adjusted to match the received carrier frequency within 2 Hz.
The output level of the signal generator was adjusted for maximum beat effects, indicating that the signal generator was producing the same signal strength as the received broadcast signal. The output attenuator of the signal generator was then switched, so as to raise the level of the signal generator by 20db. This properly simulated a strong unmodulated local signal being interfered with by a POWER-side signal. The resulting audible interference from voice and music signals was almost completely free of any beat-type phenomenon.
For comparison, the receiver was tuned to WOR a New York station transmitting a conventional AM signal and the same procedure produced the very annoying conventional beat-type sound. It is believed that this simple test produced excellent substantiation of the reduction of the so-called "carrier beat" phenomenon by use of POWER-side transmission.
By reducing the sensit
