Broadcast Blueprint
Broadcast Blueprint
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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:
BroadcastBlueprint.com
The inspiration for this video, from @vwestlife:
ua-cam.com/video/Qzeam3qm4Tk/v-deo.html
Nyquist-Shannon sampling theorem:
ua-cam.com/video/pWjdWCePgvA/v-deo.html
My video on audio processors:
ua-cam.com/video/ZlE59wCPWr0/v-deo.html
Empire of the Air: The Men who Made Radio (PBS official site):
www.pbs.org/kenburns/empire-air/
Written and edited by Drew Kirkman
Script Editor: Dave Andrzejewski
Production Assistant: Chris Davis
Special thanks to Hive13 (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
Переглядів: 2 443

Відео

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Introducing Broadcast BlueprintIntroducing Broadcast Blueprint
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Переглядів 2689 місяців тому
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Dummy Load In Depth (and resistors!) [Broadcast Engineering TikTopics]Dummy Load In Depth (and resistors!) [Broadcast Engineering TikTopics]
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Переглядів 52810 місяців тому
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In this video, I'll teach you about some basic concepts surrounding antenna theory and what we do in broadcasting to apply it. You’ll learn the very basics of the decibel or dB, wavelength, radio wave polarization, collinear antenna arrays, and effective radiated power. Landing page: AirwaveArchitect.com
Broadcast Engineering: UPS replacement in the transmitter roomBroadcast Engineering: UPS replacement in the transmitter room
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Переглядів 1,9 тис.Рік тому
We're back in the transmitter room replacing old APC line-interactive UPS devices with new Liebert GXT5 double conversion units. Watch as we turn off the FM HD transmitter and other equipment, then rack the new UPS devices and set them up. I also have a confession: I went through the entire writing and editing process thinking we did this on a Saturday morning, when in reality we did it on a Mo...
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Переглядів 616Рік тому
Move over, VHS vs. Beta… and Blu-Ray vs. HD DVD… and K56flex vs. X2. American radio broadcasting had its own format war! When the Sirius and XM all-digital satellite radio services came about, American terrestrial radio broadcasting scrambled to go digital as well. In this video, you’ll learn about the competing standards that eventually became HD Radio. Produced for my TikTok channel. My landi...
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Переглядів 9 тис.Рік тому
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Переглядів 33 тис.Рік тому
Come along as my boss and I work on a Harris HPX FM broadcast transmitter. This is a cold spare backup for one of our radio stations, but we try to run all our backup transmitters at least once every three months. This transmitter uses a vacuum tube (Eimac 4CX20000C) as its final amplification stage and was built in 2011. Eimac 4CX20000C data sheet: www.cpii.com/docs/datasheets/75/4CX20,000C1.p...
A REAL Evolution and History of the Emergency Alert SystemA REAL Evolution and History of the Emergency Alert System
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Переглядів 8 тис.Рік тому
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КОМЕНТАРІ

  • @ChaplainDaveSparks
    @ChaplainDaveSparks День тому

    _”Jesus Stick”?_ Is that because if you don’t use it, you might *MEET* Him? Personally? At His place? Or just because you might scream His name when you get zapped? Also, what is in those gas cylinders I saw earlier? Nitrogen or argon, perhaps? And for what purpose? *73 de AF6AS*

    • @BroadcastBlueprint
      @BroadcastBlueprint День тому

      Yes and yes. The worst part is, you don’t know which one until it’s too late! The gas bottles have nitrogen in them. We run the gas through a dehydrator and fill our transmission lines with it to keep moisture out and prevent the center conductor from arcing over to the outer shield.

  • @vic.joe.lee06
    @vic.joe.lee06 День тому

    So on those little Bluetooth fm transmitters you put in your car, why aren’t they able to take your stereo Bluetooth signal and create that combined signal with left and right, then your stereo fm receiver in your car can separate them? I’ve looked for stereo Bluetooth transmitters but it’s like they don’t exist

  • @cliffrhames3023
    @cliffrhames3023 2 дні тому

    Hi, seems back in the 70’s night time AM radio was full of distant stations I could receive clearly. Now I can hardly hear the same stations, did solid state transmitters make that much difference? Did stations reduce their power? Just wondering.

    • @BroadcastBlueprint
      @BroadcastBlueprint 2 дні тому

      These days, modern electronic devices introduce a lot of noise and interference. Switched mode power supplies are one of the biggest offenders. So it’s not a matter of transmit power or the type of power amplifier in the transmitter, it’s just that there are a lot of noisy things close to you!

  • @ProductionOperationsAssistant

    This is a field I'm actively trying to learn the ins and outs of for my job; this video provided such a great reinforcement of the tiny bit of basics I know. I'm very excited to continue to explore your channel.

  • @WrvrUgoThrUR
    @WrvrUgoThrUR 4 дні тому

    Hey, cool insight, thx. I found your video looking for a history of tv broadcast play out. I’m in non-broadcast media production, but have always been intrigued by broadcast playout and knowing that once upon a time it was essentially a human being cueing physical media for live playback. Still looking for a history of that here on the UA-cams.

    • @BroadcastBlueprint
      @BroadcastBlueprint 2 дні тому

      Thanks for watching! Someone on the TikTok version of this video commented and said NexGen had a version once that was for TV and it didn’t work out so well. I’m not sure what software would be used these days.

  • @nullIvan
    @nullIvan 4 дні тому

    GSM900 sound is the same

  • @christophergreen3809
    @christophergreen3809 8 днів тому

    I understand AM and FM a little better because I worked with analog music synthesizers in college. I also remember FM's ascendance in the 1970s, and how crisp and clear it was compared to AM stations.

  • @robertblake7145
    @robertblake7145 8 днів тому

    Worked at a few am 1 kilowatt stations years ago…one at 1350 kcs. And the other 1590. This explains the 300 ft tower for 1350 and the shorter one at 1590. Great explanations. Thanks! Bob

  • @jerrysinclair3771
    @jerrysinclair3771 10 днів тому

    Good stuff. I am into ham radio and especially enjoy antenna theory. 73 de WA4CIF

  • @rexoliver7780
    @rexoliver7780 10 днів тому

    Used to work on commercial AM,FM, and analog TV transmitters. What I see here is very familiar to me. For the past 35 yrs and ongoing work on 250kw and 500 kw SW transmitters for VOA and Radio Marti( they broadcast to Cuba) The site is the only remaining Greenville,NC.plants A site and C site are closed C plant building is used by ECU and is their property(state,county) B plant where I am now is Radio Marti. The hv for the tubes is actually similar to what this commercial transmitter has-but VOA tubes run at much higher current.25A 12kv 250kw 16kv 55A for 500kw. As I typed this “don’t bypass interlocks on transmitters” years ago an engineer was KILLED from the bypass. The tubes used at our plant are water and vapor cooled. In older 250kw GE SW transmitters the RF driver feeding the PA is 50kw. Newer transmitters here have 2 power stages-not 3 as the older GE uses. Also SW transmitters are variable frequency. At the SW plant you tune transmitters several times a shift-each frequency change. This does cause mechanical wear on components. And of course the ground hook is your friend! USE THEM! Filament voltage on one of the VOA tubes is 14v-but over2000A-rectified filament supply! Rectifier diodes mounted on water cooled heatsinks.

  • @joewoodchuck3824
    @joewoodchuck3824 12 днів тому

    I missed part of the video and dont have time to go back and check what you said about the Diamond NR770 antenna. I just want to make sure that everyone knows that this particular antenna is ground independent and needs no ground plane to operate correctly.

  • @CPUTests
    @CPUTests 12 днів тому

    Yeah. Interlocks. Disabled would permit 2 transmitters on same antenna against each other... Kkk...

  • @CPUTests
    @CPUTests 12 днів тому

    That's an enterprise VPN that computer catches it's IP I presume...

  • @CPUTests
    @CPUTests 12 днів тому

    I presuma that computer is a part of an intranet network because if it accessible for all may be a little problematic... Kkk...

  • @gordonsmith8440
    @gordonsmith8440 17 днів тому

    I’ve been trying to get over the broad-strokes understanding of FM stereo radio hump for like 5 years and this video finally did it. I was just looking for something to watch while I made coffee. You’re making the internet a better place, thanks!

  • @Dratchev241
    @Dratchev241 18 днів тому

    i have always wanted to experiment with a cp antenna stack on a 440 repeater just to see what it would really do.

  • @nicholaskalogris9985
    @nicholaskalogris9985 19 днів тому

    Awesome information!

  • @jamesmatheson4746
    @jamesmatheson4746 19 днів тому

    Explain HD AM and FM. Most broadcasters have given up on HD AM

  • @redthepost
    @redthepost 22 дні тому

    Thank you for helping me resurrect my interest in broadcasting technology. Fun stuff.

  • @redthepost
    @redthepost 22 дні тому

    I am hooked. Thanks for the matchless overview. Seriously, you are good teacher. 73s.

  • @voiceofjeff
    @voiceofjeff Місяць тому

    I was looking at how close the back of that transmitter was to the wall. They're usually installed so there's just enough space to swing the back door open. That causes a major problem; you will have one injury turn into three. If you're in back of the transmitter and touch something that's still slightly energized, you'll burn the tips of your fingers. When you do that, you'll jerk your arm back and slam your elbow into the wall behind you. Immediately after that, you'll pull your arm forward again sharply and slam your nuckles into something inside the transmitter. Thus, one injury turns quickly into three! Our station engineer told me this story one night when I was in my late teens and working my first job (weekends) in radio. He and I were at the transmitter one night while he was repairing something. We both had a good laugh at it, but in my experiences, it's turned out to be nearly true! That engineer is in his late 80's now and we still laugh about it.

  • @W4BIN
    @W4BIN Місяць тому

    Trust me that antenna is nothing like a "turnstile" antenna. Turnstile antennas are horizontally polarized "slot" antennas usually with broad-banding wings. The slots are between the mounting pole and the bar of the wing that is closest to the pole, this at the feedpoint. Ron W4BIN (retired broadcast engineer)

  • @danielpereira8584
    @danielpereira8584 Місяць тому

    So kool man

  • @aligator9552
    @aligator9552 Місяць тому

    Hello. I just found your channel and subscribed. I have a question please. There is a FM station a few miles from me that the local university operates. I looked up the specs, and it says its running at 250 watts. The antenna it is broadcasting from is a few hundred feet and I noticed the radiators are placed halfway up the antenna. Why not mount them at the top for better coverage? Thank you

    • @BroadcastBlueprint
      @BroadcastBlueprint Місяць тому

      In many countries, radio station licenses are also categorized into classes. In the United States, for example, a station of a certain license class is given exclusive use of their channel to a defined geographic area, generally a number of kilometers from the transmitter where the signal strength must be a certain value. Since FM uses VHF and is typically line-of-sight, it’s possible that using more power or mounting the antenna higher on the tower will cause the station’s signal to be too strong outside their defined contour area, so lots of stations cannot use the maximum antenna height or transmit power for their license class! Stations can trade antenna height for transmit power or vice versa, but what remains the same is the signal strength contour distance. Hope that helps!

    • @aligator9552
      @aligator9552 Місяць тому

      @@BroadcastBlueprint Thank you! That helps a lot! Although I never got into the field, I have always had a love of radio. I got into short-wave back in the early 1980's and wanted to know the in's and out's of how radio waves propagate, etc.

  • @UQRXD
    @UQRXD Місяць тому

    Jerky camera mode?

  • @JoeSee
    @JoeSee Місяць тому

    Most of this is way over my head, but I absolutely love your videos! Please don't stop sharing this kind of thing!

    • @BroadcastBlueprint
      @BroadcastBlueprint Місяць тому

      Thank you!! Hopefully if you keep watching nerdy stuff, it becomes not so far over your head!

  • @minibikemadman
    @minibikemadman Місяць тому

    I knew a few people with 2 of these tubes in a mono banded amplifer.

  • @charleshunziker7416
    @charleshunziker7416 Місяць тому

    Uhf stations use mega watts, please explain

    • @BroadcastBlueprint
      @BroadcastBlueprint Місяць тому

      Since TV stations frequently use UHF (higher frequency) signals, their antenna elements are smaller and the propagation isn’t as good. Thanks to that, they also use many more antenna elements to increase the gain of their antenna arrays, resulting in an effective radiated power (ERP) approaching or exceeding 1000 kW.

  • @charleshunziker7416
    @charleshunziker7416 Місяць тому

    W about TV stations

  • @sourlemoneee
    @sourlemoneee Місяць тому

    so much country lmao

  • @światstarychnokii
    @światstarychnokii 2 місяці тому

    i use nokia 6310 (really)

  • @MountainMan7.62x39
    @MountainMan7.62x39 2 місяці тому

    I have always wondered how this worked. Great video, thank you!

  • @shaynecashman5591
    @shaynecashman5591 2 місяці тому

    I wonder how this is going to change with the shift to streaming.

  • @DavidTeerTheBackyardUfologist
    @DavidTeerTheBackyardUfologist 2 місяці тому

    Wow you are me of the past cool engineers. I miss those guys. I am a radio personality retired. I'm in a community and started a cheap LpFM community radio station. 15 watts with a ground plain antenna. I'm no engineer but did help over the years when they did work. I had no idea what was going on they usually used me to do DJing... like a day timer AM at night after midnight old army surplus tx and almost 700' antenna with transmission line going across the field like 5 copper wires on small telephone poles. I've seen ready kilowatt several times back then especially when it iced over. It was awesome so much respect fur you guys. My room mate was chief engineer back in the 70's at two radio stations he got me my job at several different stations across the country back in my day. Big stations 50,000 watt AM and 100,000 FM and one in Ciudad Juárez Chihuahua licensed to operate with a power of 150,000 watts on a carrier frequency of 800 kHz at night in 1979. I lived in El Paso was 18 years old. Man I was in heaven. 50,000 day 150,000 at night. Clear channel. I think it was CKLW in Canada that fought back and forth in between. Lol:) But ended up on FM after that AM was over for us rocking jocks. I have stories. My roommates were Mr. Leonard, Bg Brad Edwards (KISs Fm LA. Lee master ls WNBC well yes I was big time at one time. Lee just retired as CEO at NPR. Great guy. Back then anyway. We cooked. Anyway enough about me. I am listening to as an engineer. I know there are SWRs and lengths of coaxial cable and going through my limiter and compressor... lol:) nit much. But it sounds good not much noise n the carrier FM 102.7. Can you give sone pointers? I only have the antenna on side of house clearing the top of roof. I get out about a mile and a half but I go further and it comes back at 3 miles then gone. Antenna about 20' high. Hardly any wind load on it. So light. I should get out a little further with 15 watts. I know something is wrong. There are like 3 communities I want you to serve just announcements another HOA the Pool the club house the lake the skiing trail, list dogs, cats, yard sales the whole community takes part in. A lot of fun. And I play a lot of music you don't hear on the radio anymore. I rock it, I country it, I worked every format so knowledgeable music, songs to play fur our age group demographics. I'm 64 now. Old. lol:) so can you give me some pointers? I mean I just gave the small transmitter and it a few electronic equipment. I do have a radio station a board all that but won't fit where so am. I divorced after 30 years moved from Connecticut back to Alabama. All my engineers I worked with are dead or long retired and gone. I been gone from Birmingham 30 years. Anyway no more 1st class licensed engineers... if I understand it's a general class license now. I have my 3rd class elements 1,2 & 9 and can read plate current, plate voltage and amps lol:) ship to shore. I had a provisional when I was 17. I go way back they took thus very seri auxiliary back then so did FCC. Which we got visited a little until my friend came in cleaned it up. He was like you a real engineer. Liked what he did. Like me a radio personality I liked what I did. I'm having fun with this. I want to automate it and go live when I want. 24/7 but yet to come. Thanks & subscribed....

  • @FRANKMUSIKOFFICIAL
    @FRANKMUSIKOFFICIAL 2 місяці тому

    Lost me at 00:23

  • @farmerdave33
    @farmerdave33 2 місяці тому

    "I'll keep the math to minimum" Crams more math into any two minutes I've ever experienced 😂

    • @BroadcastBlueprint
      @BroadcastBlueprint Місяць тому

      Well, I never said what it would be a minimum of… minimum of math or minimum of time? 🙃

  • @barrygeary1890
    @barrygeary1890 2 місяці тому

    Has pre emphasis on fm anything to do with reducing high frequencys?

    • @BroadcastBlueprint
      @BroadcastBlueprint Місяць тому

      Sort of… since there’s more noise at higher audio frequencies in the demodulated signal, pre-emphasis helps reduce that high frequency noise while trying to keep the modulating signal intact.

  • @DoomTape1981
    @DoomTape1981 2 місяці тому

    Looking for people familiar with national control point procedures and NIC. Meaning at network master controls. FCC has little of this material in National Archives.

  • @billfargo9616
    @billfargo9616 3 місяці тому

    Leave it to Harris to put screws where speedclips belong.

  • @ocsrc
    @ocsrc 3 місяці тому

    No Safety Officer ? It's a good practice to have a Safety Officer who is on scene of any potentially dangerous work. They observe and tell you if they notice something but also stay out of the danger zone and are there to call for help if someone becomes downed. They also take readings of RF radiation during the work and log reports for each employee and their radiation exposure. At NL Industries the Safety Officer kept the logs for each piece of equipment and the total radiation daily and over time for the equipment and each employee. If an employee was nearing their legal limit of exposure the Safety Officer would put in a request for transfer for the employee so they would not receive any more radiation for the year. In real bad cases they had people who were given desk jobs or even paid time off.

    • @kenthatfield
      @kenthatfield 10 днів тому

      All the radiation, with very minor exceptions, is non-izoning. The transmitter manufacturer has responsibility for the inherent safety of the device. As far as a safety officer, the chief is there and is hands-on supervising the process.

  • @ocsrc
    @ocsrc 3 місяці тому

    Dry nitrogen to keep moisture out of the feed lines ?

    • @BroadcastBlueprint
      @BroadcastBlueprint Місяць тому

      Precisely! Since nitrogen is also a strong dielectric gas, it helps prevent arcing within the transmission line as well.

  • @barrygeary1890
    @barrygeary1890 3 місяці тому

    Love your vidios but i would put the onmia 9 at the studio side especially if you have more than one trasnmitter on the air and the onmia 9 as webstreaming encorders which means you can do fm and hd or online feed and the texture of the sound for fm would be like the online the difference would be fm would be pre emphasis 75

  • @jaredbater6229
    @jaredbater6229 3 місяці тому

    What an absolutely fantastic video. Amazing explanations!

  • @ABCEasyas--
    @ABCEasyas-- 3 місяці тому

    The Oddity Archive did it first in 2012, now there are others who made videos about the EAS

  • @hugh007
    @hugh007 3 місяці тому

    The best description of AM and FM I've seen. 100 years of radio in 34 minutes: quite a feat. I had the privilege of meeting Tom Lewis when his book was released and the film was in production. Thanks for all your work. K4XBC

  • @michaelcox436
    @michaelcox436 3 місяці тому

    Excellent, thank you

  • @ChrisGoosman
    @ChrisGoosman 3 місяці тому

    Fantastic video! Pre- and De- emphasis, as well as the curves used in various noise reductions schemes, is also somewhat analogous to the RIAA curve used when cutting and then playing back vinyl. I've been involved in disc cutting in my lifetime, and like FM, it's magic and a wonder that it works as well as it does, ha!

    • @BroadcastBlueprint
      @BroadcastBlueprint 3 місяці тому

      When I want the challenge of not knowing why something works when it clearly shouldn’t, I go straight to audio and RF electronics!

  • @TVJAY
    @TVJAY 3 місяці тому

    This is an amazing video. Thank you for making it. I will share this with a lot of people.

  • @christopherjones2283
    @christopherjones2283 3 місяці тому

    bravo! well done professor

  • @StringerNews1
    @StringerNews1 3 місяці тому

    We should remember that radio broadcasting didn't commence until ~1920 because amplitude modulation needed the enabling technology of the triode tube, for amplification and mixing. Also, while Lee De Forest's name is on the patent, he didn't invent it really. De Forest was the first at the patent office, but his understanding of how it worked was non-existent. It took the work of others to discover uses for the triode tube that De Forest simply couldn't conceive himself. Today we'd call De Forest a patent troll. I remember learning the mathematical relationships between the baseband audio signal and the modulated AM and FM signals, and marveling that someone had the insight to figure that out. The people who actually did suss out the math deserve the credit far more than De Forest.

    • @BroadcastBlueprint
      @BroadcastBlueprint 3 місяці тому

      That's a really important point - Lee de Forest didn't really understand the triode and it wasn't until other people like Armstrong started picking it apart that it found real usefulness. Of course, his personality would not stand for such a thing, so he took all these people to court and spent the rest of his life trying to convince everyone that he deserved all the credit. His autobiography is called "The Father of Radio" for crying out loud. The segments of the "This Is Your Life" television program with Lee de Forest featured in the Ken Burns documentary were nothing less than cringeworthy. The letter de Forest wrote to Carl Dreher after Dreher *dared* to pay tribute to Armstrong in Harper's Magazine after his death was dripping with pettiness. History has thankfully not shown Lee de Forest in the most favorable light, and it really is a shame that Armstrong didn't live to see his full vindication and how popular his creation ended up becoming.

    • @StringerNews1
      @StringerNews1 3 місяці тому

      @@BroadcastBlueprint yes, also noteworthy is that De Forest was a contemporary of Nikola Tesla, a person who has been deified of late by the woo-woo pseudoscience crowd. As with De Forest, Tesla's self-cultivated image doesn't really jibe with his actual body of work, that peaked with two patents for AC induction motors that look nearly identical to what Galileo Ferraris published in Turin, Italy just a year before Tesla got onto a boat to the US, and headed straight to the patent office. After that, Tesla's alleged genius never produced any working science or technology. I think that in both cases, the personality cults were created to wishcast a reality that they wanted for themselves, but which they didn't actually achieve. That's why I admire great ideas more so than great men.