AM Stereo, CAM-D inventor Leonard Kahn passes


Kahn Communications CEO Leonard R. Kahn, P.E. (AM Stereo and CAM-D AM digital system inventor) passed away 6/3/12 in Florida from natural causes at 86 years old.

Kahn’s Kahn-Hazeltine AM Stereo design was an independent sideband system that used independently modulated upper and lower sidebands.

One of the best known stations to use the Kahn system was WLS-AM Chicago. His system remained competitive with Motorola’s C-QUAM system into the late 1980s. Kahn filed a lawsuit claiming the Motorola system didn’t meet FCC emission bandwidth specifications, but by that time, C-QUAM had already been declared as the single standard for AM stereo in the US.

Kahn’s AM stereo design was later revamped for mono use and used in the Power-Side system, in which a decreased signal in one sideband is used to improve coverage and loudness. Power-Side became the basis for CAM-D, Compatible AM Digital, a digital system that is still used on several AM stations.

Kahn worked for RCA Labs for many years and turned out over 80 patents (and over 100 foreign patents), many with regard to AM broadcast technology. He is considered one of the five “fathers of the wireless industry.”

Kahn, WB2SSP, was a former Adjunct Professor of Electrical Engineering and was a Registered U.S. Patent Agent and has argued a number of times before the U.S. Court of Appeals for the Federal Circuit. He litigated successfully against General Motors and Motorola, representing himself in the Southern District of New York, The Court of Appeals for 2nd Circuit and the Federal Court of Appeals in Washington, DC.

He was a Fellow of the IEEE and of RCA. He received the RCA’s Armstrong Medal (1980), and was the initial recipient of the RCA’s Jack Poppele Broadcast Award (1989).

Click here for a lengthy list of his patents

In 1997 the United States District Court for the Southern District of New York ruled that Kahn had title to US patent #4,018,994 in a suit. He sued General Motors and won for infringement of that patent for its use of AM stereo in car radios.

[We’ve later learned he  actually lost both suits brought  against Motorola and GM; including the 1994 patent infringement case in Federal court, Southern District of NY. He won some early rulings on procedure but neither the jury or bench trials.]

Kahn also filed a lawsuit in federal court in New York in 2006 alleging that iBiquity Digital, Lucent and Clear Channel violated antitrust laws with the implementation of the iBiquity AM HD Radio (IBOC) system. Kahn said in the complaint that they had formed a broadcast cartel seeking to block others from buying his CAM-D system. That suit was not heard by the Supreme Court on appeal.

In 2009, Kahn filed a complaint with the Southern District of NY Court (Civil Action 08-CV-11368), charging major investment banks and The City of New York and Mayor Bloomberg, personally. He named Oppenheimer & Co. specifically for falsely swearing that he was “senile” because he issued three $10,000 checks and two of them bounced. Kahn says the checks shouldn’t have bounced because he had documents (attached in the suit) that proved that he had over $350K in just one account. In the case, Kahn also sued Wachovia, SunTrust and TD Ameritrade for allegedly “converting” his fortune (he told RBR that in 2008 he claimed $16 million in assets).

Kahn’s suit also asked for emergency relief to hold the NYC Dept. of Social Services from extending their “chase” to his Long Island lab (Kahn Communications) which halted his work on a solution for Homeland Security—the “iSAFE” system. iSAFE would the CAM-D system to alert citizens in an emergency. A small receiver chip would be incorporated into cell phones, Blackberrys, iPhones, iPods, laptops, etc. that would warn of an emergency to citizens that might otherwise be unable to get to a TV or radio—or might not even hear what is going on because they’re “isolated” by headphones, etc. The goal is to bring emergency alerts when the cell phone networks are overloaded and the Internet may be too congested to work (also from a potential cyber-attack). Kahn said CAM-D is robust enough to penetrate buildings, parking garages, etc.

We believe that case was dismissed before going to trial. Leonard’s wife Ruth preceded him in death and the couple had no children.

Later in life, Kahn published a book [click on title for link]: Pro Se, A Fool For a Client
He also had a website,


  1. Leonard, and the Sony wideband multimode AM Stereo receivers that Motorola sued out of production were the last, best hope for AM.

    • Motorola never sued Sony or anyone else over AM stereo. They did state that a c-quam demodulator had to be used if Motorola’s name was used. The sony chipset was a proper decoder for Kahn using the’994 patent (the Barney Loughlin variant of it known as reciprocal inverse modulation; divide by 0.52(L+R) ), but Harris, Magnavox, and Motorola were all compromised by the approach taken. Motorola insisted their system be done correctly or not at all.

  2. I very much liked my Sony multimode “AM” Stereo receiver. While I did not support the Kahn ISB stereo system I did not support the vastly inferior C-Qam system from Motorola either. The best system of “AM” stereo was the Magnavox system that the FCC originally approved.

    I am sorry for our loss, the loss of Lenard Kahn.

  3. Over the years the company I work with has purchased several stations that had the Kahn PowerSide. Either the PowerSide was installed or just sitting in the rack. All of them were removed and sent to be recycled for scrap.

  4. I understood that the Magnavox, Harris, and Motorola systems used tortured, phase-dependent techniques to avoid conflicting with Leonard’s spectrally elegant and simple ISB patent, and thus all employed compromises that made them unworkable in the presence of co-channel interference.

    And that given the FCC “marketplace solution” debacle, the public lost what interest they had. So when Motorola sued Sony for manufacturing the finest AM receiver ever made (because it could decode Motorola, but also Kahn), Sony decided there wasn’t enough of a market to justify any decision other than to cease production.

    So corporate greed reared its ugly head and killed the last, best chance AM had to sound decent in stereo.

    • While the fight went on as to which system was ‘best’, everyone lost sight of a critical point. The PUBLIC wants to turn on their radio, and tune in a station. To listen to. They don’t give a rap as to which or who’s SYSTEM is being used. And they shouldn’t have to. Unfortunately, nobody cared. They fought system. I believe the Sony receiver required you to manually SWITCH between the ‘systems’. FM gave you a switch… Stereo or mono. Same thing needed for AM, even if there were five ‘systems’.

      Sorry about Dr. Kahn’ passing. I have three pieces of ‘Power Side’ rack mount equipment at a station I just took on, and wondered about it. I was in TV while most of the AM Stereo battles were going on.

  5. No matter your view of which AM stereo system was best, Leonard Kahn’s passion for what he believed was best, set a wonderful example for me and others to follow. Leonard made an impact that many of us never will.

  6. Sad to see Leonard pass. One correction to the text: he actually lost both suits brought against Motorola and GM; including the’994 patent infringement case in Federal court, Southern District of NY. I was present for, and participated in, both trials. He won some early rulings on procedure but neither the jury or bench trials. He should be best remembered for his groundbreaking work on diversity reception, EER, CSSB, early AM stereo, and the tenacity with which he fought for what he thought was right. He was one of the great pioneers of radio, and that comes from a person that simultaneously had a lot of respect for while also facing him head on in court on matters of engineering. He is now together again with the love of his life, Ruth, and his mentor and idol in engineering, Armstrong. May he rest in peace.

  7. I was very saddened to hear of the passing of Leonard Kahn. First impressions could be one of the “mad scientist”- genius in nature but also a stubborn, righteous ornery character with a hair trigger temper who was never wrong and would do anything he could to make you believe his way was the right way and the only way! BUT he was also probably one of the most honest and sincere men I have met in my life. Having worked for Kahn Communications for well over 20 years and seeing him on a daily basis , I feel I am qualified to make such a statement. His tempestuousness was only counter balanced by his wife Ruth, who was always congenial, friendly and caring. Talk about opposites attract! After her passing he was never the same. Hats off to the ‘ol boy, he’s probably up there arguing with God!

  8. I just found out about my uncle’s death through the kindness of Carl Marcucci. My father was Leonard’s only sibling, and when they fell out, I saw no more of my favorite uncle. My attempts to re-establish contact with him were never answered, but luckily I left a message on his website, albeit at a rarely visited email address that Carl just found.

    Now unable to even hope to catch up with Leonard, I ask any of you to send me any stories or information that you might be willing to share with me. Carl filled me in with an outine of his recent timeline, but much is unknown. Judging from some of your replies to this post, most of you know him better than his own nephew who hadn’t seen him in 40 years. My email is [email protected]. If you prefer and are willing to share your phone number, I would be pleased to call.

  9. I had the opportunity to speak with this brilliant engineer/inventor on the phone two times. He invented AM stereo, and I have one of the few SONY receivers that can decode it. I use it and an AM stereo transmitter to demonstrate what AM radio can sound like – to the utter amazement of my visitors. Like the case with Telsa, the world shuns genius and money and power corrupts and suppresses truly great ideas. AM stereo died such a death.

    R.I.P. Leonard Kahn.

  10. He was Uncle Leonard to the Musanti family children and my Aunt Ruth was Leonard Kahn’s wife. They visited us after we moved to ft pierce fl in 1970 and we visited them in NY. Lost contact with Uncertain Leonard after my Aunt passed and was so sorry to find out of his passing a few months ago.

  11. I spoke with Leonard on the telephone in November 1984 after hearing a demonstration of AM Stereo on KFRC San Francisco. It was so exciting. As president of CMC California Music Channel, I wanted to help promote AM Stereo broadcasting. Leonard sent me a couple of his car radios Model ST-C66 to give away on the air in an AM Stereo Promotion on TV. This was when CMC was carried on KCSM-TV San Mateo. In 1985 my enthusiasm for AM Stereo continued so I made an arrangement with Kahn station KFRC San Francisco to simulcast our Saturday evening broadcasts of CMC on KTSF-TV San Francisco on KFRC in AM Stereo. Mr. Kahn was a nice guy who’s enthusiasm for his product was an inspiration.

    Rick Kurkjian
    California Music Channel
    CMC Broadcasting Company, Inc.

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