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In article , (Dennis
Ferguson) writes: Len Over 21 wrote: In article , "Jim Hampton" Hans Brakob came out of the blue with a personally insulting comment about "bad research," something that I allegedly "always do," solely about "the first voice transmission by radio." Hans claimed, but did not reference or otherwise verify that it was done with a SPARK TRANSMITTER. I quoted an Electronics magazine special edition text paragraph that stated this 1906 Christmas transmission was done with a 1 KW ALTERNATOR, probably using a water cooled microphone in the antenna line. Just to clarify, this is what the article at http://ewh.ieee.org/reg/7/millennium...fferences.html says about it: At the turn of the century Fessenden was using a spark transmitter, employing a Wehnelt interrupter operating a Ruhmkorff induction coil. In 1899 he noted, when the key was held down for a long dash, that the peculiar wailing sound of the Wehnelt interrupter could be clearly heard in the receiving telephone. He must have had a detector of some sort that was working for him, even at this early stage in the development of wireless. This suggested to him that by using a spark rate well above voice band (10,000 sparks/sec), wireless telephony could be achieved; and this he did transmitting speech over a distance of 1.5 km on 23 December 1900, between 15 metre masts on Cob Island, MD [Belrose, 1994a; 1994b]. In autumn of 1906 Fessenden had his HF alternator working adequately on frequencies up to about 100 kHz. About midnight in November, 1906 Mr. Stein at Fessenden's Brant Rock station was telling the operator at a nearby test station at Plymouth, MA how to run the HF alternator. It was usual for these two operators to use speech over this short distance. However his voice was heard by Mr. Armor at Machrihanish, Scotland with such clarity that there was no doubt about the speaker, and the station log books confirmed the report [...] Fessenden's greatest success took place on Christmas Eve 1906, when he and his colleagues presented the world's first wireless broadcast. The transmission included a speech by Fessenden and selected music for Christmas. So, while the first radio voice broadcast was made at Christmas, 1906, using an alternator, the first radio voice transmission of any sort was made 6 years earlier using a spark transmitter. I agree with what you said here but that is NOT what the brought on Hans Brakob's ranting, raving, and jellied jeremiad about "poor research." Brakob SPECIFICALLY stated that Fessenden's 1906 Christmas voice broadcast used a SPARK transmitter. Miccolis, presumably in Brakob's defense, tried to misdirect by pointing out the 1900 test by Fessenden with the 1906 broadcast. Miccolis did not correct Brakob's false statement, but attempted to misdirect into other subjects when Brakob was confronted with his error. My general source of old radio histories are several but I keep one on the bookshelf, the Electronics magazine special 50th Anniversary edition that covered ALL electronics and radio prior to 1980. Right or wrong, printed matter cannot be changed by any webmaster or website author. For Internet sources of old radio history, I prefer the excellent works of Thomas H. White, at the new address of http://earlyradiohistory.us/index.html There is a close correlation of what the 1980 Electronics magazine description of the 1906 Christmas voice broadcast and what White has in more detail on his site. The microphone for Fessenden's 1906 broadcast was not water cooled (as Electronics writers speculated) but air cooled and the picture on White's pages indicates it is robust and designed to dissipate heat (as the photo caption put it). Jack (formally John) Belrose is a familiar name to Antennex readers (www.antennex.com, a specialty site for antennas) and his recreations of early spark transmitters as they MIGHT have been made by Fessenden are interesting. However, let's face it, Fessenden's first experiment in 1900 was done with only ONE OTHER experimenter only ONE MILE distant and witnessed by no one else. Fessenden's experimental broadcasts (plural, involving several things in communication) at Brant Rock involved many persons, primarily financial backers paying for everything. Radio was a hot item and many were getting involved for a piece of the action back then. Radio in those prehistoric times involved money (few components available, nearly everyone had to build everything themselves) so it was seldom an "amateur" activity. In Thomas H. White's pages you will note that Fessenden dropped out of the radio experimentation game after that historic voice broadcast due to disagreement with his backers. That 1906 voice broadcast involved a 750 Watt alternator "RF source" at 70 KHz and the "modulator" was a carbon microphone in series with the antenna feed line. [technically that is "down modulation" of a carrier, no gain of RF power on peaks as with conventional AM] It stands to reason that the heat losses in that microphone were considerable (hence the obvious robust design in the White collection photo). Manual holding of such a microphone would be prohibitive, much the same as an American Beauty 100 W soldering iron uses an insulating wooden handle. Practical application of the Fessenden voice broadcasting experiment was an obvious no-no. There were no interested parties eager to buy rights to the system and, for the times, no one wanted to pirate the system. Yes, Reginald Fessenden is acredited with being the first to broadcast voice on radio frequencies. No argument from me on that. Hans Brakob is NOT a qualified judge of fact correction when he confuses both dates (6 years difference) and the type of transmitter and then contends that another is "guilty of poor research." The description of how the spark transmitter was used to transmit voice makes perfect sense to me. If you take a band-limited continuous waveform and transmit discrete samples of the waveform taken at a rate which is twice the maximum continuous frequency (i.e. 10,000 amplitude-modulated sparks per second for 5 kHz bandwidth audio), then low-pass filtering the received signal back to the original bandwidth will reproduce the original continuous waveform. This is from the Nyquist(-Shannon) sampling theorem, though if I recall this was done a quarter century before Nyquist's paper on digital (telegraph) signals over bandwidth-limited analog channels and a half-century before Shannon explained what this meant for discrete sampling. That's pretty neat. A lot of early papers on electricity and "radio" may "sound neat" but, despite the descriptions by learned gentlemen with many letters after their names are FAR from "neat" when seen today. Reginald Fessenden did not invent sampling theory any more than Lee deForest invented electron geometry inside vacuum tubes. Both had IDEAS, inspirations, hunches, bursts of thought or whatever and were willing to tinker and try. Some succeeded. Many did not. A Professor Langley convinced the US Navy that they should under- write his aeroplane thing and even converted an old Navy vessel to be the first aircraft carrier (or one with a landing area). Nice try. The Langley aeroplane flew...off the end of the deck and into the water. Splash. TS. Off in another place a couple of bicycle mechanics were busy tinkering with rudimentary aeronautical engineering and made the FIRST heavier-than-air powered flights...and won the first US military contract for a heavier-than-air-craft (by the Army's Signal Corps) to start the whole aircraft world. By some VERY elastic stretching of things, one can say (presumably with a straight face) that James Clerk Maxwell "invented EM radio propagation" by coming up with his equations...or that Heinrich Hertz was "the first VHF operator" or "used spark the first time for radio propagation." I wouldn't. Few would...even though, in a mighty exaggerated way, those are true. Some would go to such lengths for newsgroup message points and "getting even" with another and devote a large part of their free time absorbed in such. :-) There are MANY, many "firsts" in radio and none can claim to be THE first. Unfortunately, some folks have devoted hero-worship of certain individuals and over-emphasize their accomplishments; their righteous anger at not finding agreement leads them to outrageous statements in here. Not my problem...until they start to get personal. :-) LHA |
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