By Walter S. Ciciora,
Ph.D., Recognized Industry Expert on
Cable and Consumer Electronics Issues
My good friend Ted Hartson (a person I admire for his achievements and noble qualities) has long held Edwin Armstrong in high esteem. I've adopted Armstrong as one of my heroes. The fundamentals of nearly all telecommunications receivers are based on one of Armstrong's inventions. Our radio receivers, television receivers, set-top boxes, and cable modems all owe their lineage to the work of Armstrong.
As I write this, we are approaching a sad anniversary. It has been 50 years since Armstrong committed suicide– January 31, 1954. A number of historically minded technologists will gather in Manhattan to have a memorial dinner and raise a toast to the memory of this heroic, tragic figure.
Armstrong's principle achievements in chronological order are: 1) the regenerative circuit, 2) the superheterodyne circuit, 3) the superregenerative circuit and 4) frequency modulation. We can debate the order of importance, because each is a major contribution to communications practice and theory.
Armstrong's story has fascinating (and frightening) aspects concerning intellectual property and bitter patent fights. Armstrong wrestled with other titan figures in telecommunications such as Lee De Forest and David Sarnoff.
Lee De Forest, you will remember, invented the "Audion" in 1906, the first three-element electronic device. He did this by placing a zig-zag wire between the filament and the plate of a "Fleming Valve." The Fleming Valve was a vacuum tube diode, used as a radio detector. De Forest added the third element to make it a vacuum tube triode to be used as a radio detector and amplifier. De Forest is said to have not quite understood how his invention worked, giving explanations that proved to be incorrect.
Armstrong became fascinated with radio as a boy and experimented extensively. In 1912, while still an engineering student at Columbia University, he became interested in De Forest's Audion and reasoned that if the output of the circuit was fed back to the input, it would regenerate the signal and the signal would be amplified over and over again to very significant levels. It worked. The improvement in radio reception was dramatic. In less than a decade, he had issued about a couple dozen licenses to the invention and was receiving monthly royalties of around $10,000, a lot of money at that time.
But the regenerative circuit was a tricky circuit to operate. Adjusted incorrectly, it would behave strangely. It would oscillate. That behavior became the basis for the electronic generation of radio signals. Prior to Armstrong's oscillator, radio transmitters were devices with a spark gap for wireless telegraphy or specialized, mechanical rotating machinery, a high-speed generator for transmitting audio signals using amplitude modulation. Armstrong's oscillator not only made the transmitter more controllable and less costly, it allowed operation at much higher frequencies.
The Institute of Radio Engineers (IRE), one of the predecessor organizations to the IEEE, had awarded Armstrong a prestigious medal in 1918 for the regenerative circuit. Later, De Forest would claim that he invented the regenerative circuit first.
A long and bitter patent fight ensued, ending up with a Supreme Court decision in 1934 which sided with De Forest on the basis of a legal technicality. During an IRE conference, Armstrong offered to give back his medal because of the Supreme Court decision. The IRE refused to accept it, acknowledging its position that Armstrong was the rightful inventor.
During the patent fight over the regenerative circuit, Armstrong developed the superregenerative circuit, a significant
improvement. The Radio Corporation of America (RCA) bought the rights for cash and stock that made Armstrong the largest stockholder in RCA and a millionaire.
David Sarnoff, head of RCA and the force behind the development of the RCA radio entertainment network, told Armstrong that he wished for an invention that would eliminate or minimize the impact of static and electrical interference on radio reception. Armstrong began work on frequency modulation in 1924 and demonstrated it after a decade of long hours and hard work in 1933 to Sarnoff. This was a classic "good news, bad news" story. The good news was that FM worked extremely well; the bad news was that it would obsolete the successful AM network Sarnoff built.
The ensuing fight between Sarnoff and Armstrong would result in financial losses, deteriorated health, marital difficulties, and a depression that resulted in Armstrong's suicide on the night of January 31, 1954.
Of the references on Armstrong, two are readily obtainable: 1) "Empire of the Air," Ken Burns, DVD or videotape from PBS; and 2) "The Legacies of Edwin Howard Armstrong," The Radio Club of America, 1990. The other two references are books which are unfortunately out of print, but are available in limited quantities from used book sellers. "Man of High Fidelity: Edwin Howard Armstrong," by Lawrence Lessing (1956, Bantam Books) was originally published at $1.00. The used book service of Amazon.com got it for me for about $47, but it was worth it, given my high level of interest in the subject. The same is true of "Empire of the Air," by Tom Lewis (1991, Harper Collins). This book is the foundation for the Ken Burns DVD/videotape currently available from PBS.
On another subject, I can't resist the temptation to shamelessly put in a plug for the expanded second edition of "Modern Cable Television Technology, Video, Voice, and Data Communications." Because of a personal health issue (I'm now fine!), I was not able to contribute to the revision. Jim Farmer and Dave Large recruited Michael Adams to help, and they did a terrific job. It is amazing how much has changed between the publication of the first edition in 1999 and the second.
Have a comment? Contact Walt by e-mail at: Walt@Ciciora.com