How FM Radio Works: A History and Exploration of Frequency Modulation

Today, we take FM radio broadcasts for granted, and some people even insist radio broadcasts are dead (hint: they’re not even close to dead). However, a gigantic amount of ingenuity went into developing frequency modulation, largely due to the efforts of one inventor and his staff. In this video, I’ll detail some of the history, the struggles, and the reasoning behind FM broadcasting. Along the way, you’ll see something you probably haven’t before: an FM radio signal in slow motion so the mechanics are clearly visible. Major Edwin Howard Armstrong, who also developed the superheterodyne circuit that revolutionized radio receivers, spent years experimenting to make FM the force of nature it became, and always relished coming back to give it to naysayers with an epic mic drop. AM broadcasters and the corporate interests working to develop television may have gotten the upper hand on Armstrong, but he got the last laugh with stereo FM igniting a very real “golden age” for the technology, as well as FM being utilized for the audio portion of North America’s NTSC analog television standard. Armstrong never had the opportunity to see his creation’s heyday; he took his own life in 1954 as the overwhelming stress of drawn-out litigation over infringement of his FM patents crushed his mental health and drained his financial resources. Armstrong’s wife Marion, ever his supporter, continued his fight and saw every single case either decided in his estate’s favor or settled out of court. My landing page: https://BroadcastBlueprint.com Bluesky: https://bsky.app/profile/broadcastblu... The inspiration for this video, from ‪@vwestlife‬:    • MPX Filter - What does it actually filter?   Nyquist-Shannon sampling theorem:    • Nyquist-Shannon; The Backbone of Digital S...   My video on audio processors:    • How Audio Processing is Used in Broadcast ...   Empire of the Air: The Men who Made Radio (PBS official site): https://www.pbs.org/kenburns/empire-air/ Written and edited by Drew Kirkman Script Editor: Dave Andrzejewski Production Assistant: Chris Davis Special thanks to Hive13 (https://www.Hive13.org/) for use of their HackRF Blue SDR Music: "Sunset n Beachz" performed by Ofshane "American Idle" by RKVC ©2024 Broadcast Blueprint LLC 0:00 Introduction 0:40 Wave Properties and Modulation 1:16 Early Broadcasting and AM 2:37 Edwin Howard Armstrong vs. Carson and Others on FM 6:01 Armstrong's Wideband FM System 7:25 Armstrong Drops the Mic 8:49 Quirks of FM 11:04 W2XMN, the First FM Station 12:03 The Guitar String Analogy 12:54 FM Demo Setup 14:01 An Unmodulated FM Carrier 15:03 FM in Slow Motion - Modulated at 1 Hz 16:06 Tracing Music on the Waterfall 16:27 Modulation Index and Audio Processors 18:29 Multiplex (MPX) Operation 20:35 MPX Demonstration and the Pilot Tone 21:14 Stereophonic Sound and Vinyl Records 24:12 FM Stereo Overview 24:56 AM Components of FM Signals 29:10 The Algebra Behind FM Stereo 30:40 Using Carson's Math to Improve FM 31:26 Pre-emphasis and De-emphasis 32:28 Empire of the Air: The Men who Made Radio 33:17 Conclusion