Your browser is out-of-date!

Update your browser to view this website correctly. Update my browser now


An Open Letter to Leonard Kahn

Guy Wire Says If CAM-D Is to Show Itself As a Viable Alternative, Kahn Must Win Over Industry Forces That Can Make It Happen

Guy Wire Says If CAM-D Is to Show Itself As a Viable Alternative, Kahn Must Win Over Industry Forces That Can Make It Happen

Dear Leonard,

Having read over your recent proxy response sent to us in reply to my Oct. 14 article about anti-HD Radio arguments, I got to thinking.

Here is one of the brilliant radio engineers of our time, having appointed himself as perhaps the most public and outspoken critic of HD-AM, blasting it from every angle as a deeply flawed technology. Leonard, over two years ago you offered your own CAM-D technology as a superior performer that should be taken seriously as a more worthy digital replacement for AM analog.

The claims you have made for CAM-D are breathtaking. You’ve lined up a few old Kahn AM stereo fans who are providing test stations that will hopefully prove whether CAM-D is a real and enduring product of your engineering genius or theoretical vaporware.


Let’s lay out historical perspective. I personally have high regard for your engineering ability and many of the products your company has produced for broadcasting over 45 years. The Symetrapeak was such a product. Almost every station that pursued engineering excellence had one. The all-pass filter that restored full modulation power to asymmetric voices was way ahead of its time.

Kahn AM stereo failed in the marketplace, but it certainly was not a technical failure. To this day, many engineers who understood its advantages over the competing systems still judge it the best performer. As in the VHS vs. Beta controversy, the best-engineered system didn’t win. But unlike the outcome in video, none of the AM stereo systems “won.” The entire industry, as well as the consuming public, lost an opportunity for improved AM. History has ecorded the reasons this occurred.

I cannot tell you how many of my colleagues have lamented the “loss” of AM stereo. Every AM owner and engineer who made the investment and implemented it on his or her station wanted very much for it to succeed. However, amid threats of litigation and under pressure from the NAB, the FCC blinked and rescinded its pick of Magnavox. They took the easy way out and let the marketplace decide.

When receiver companies and most stations realized how bogged down the rollout of AM stereo would be without a clear transmission standard, especially in the midst of lawsuits, few committed to the technology. AM stereo never had a chance.


This brings us to CAM-D. It appears to me that you learned the wrong lessons from the AM stereo experience. Instead of being part of the testing and evaluation process as you were with AM stereo, you have chosen to keep CAM-D veiled in secrecy. Unless you share technical details with the industry and can prove it works, all we can conclude is that it’s mostly driven by a need to grab some limelight in the saga of radio’s conversion to digital.

If you have a real product, if you want to be part of the party, come to the dance. You must have CAM-D patent applications pending or filed by now. Bring the technical details of CAM-D to an IEEE symposium for all to see. Let folks like Bob Orban and Dave Hershberger see what’s under the hood. Enlist some major receiver companies in some open real-world testing. Without them on board, CAM-D will most certainly lose before it can even get to the starting line.

The U.S. radio industry appears to be lining up solidly behind Ibiquity and HD Radio. But it’s no secret that HD-AM is still facing a problematic deployment and will be challenged at night during the hybrid phase. If CAM-D is to show itself as a viable alternative, you need to win over the industry forces that can make this happen. At a minimum, if CAM-D has anything of value that could be implemented in HD technology, consider selling it to Ibiquity. Radio’s digital and economic future depends on the very best ideas and solutions aligning to make its basic delivery technology the best it can be.

If you see the light and change your mind, Leonard, promise me this: After you’re ready to prove CAM-D to the world with a fair and open evaluation by independent experts, let the chips fall where they may and accept the outcome.

Time is running short, Leonard. Unless your over-the-air CAM-D tests happen soon and independent experts are on hand to declare it as wonderful as you say, we must conclude you have nothing to offer radio’s future. But if your claims pan out, CAM-D could in fact be part of AM’s digital future.