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#1
July 25th 03, 03:04 PM
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#2
July 25th 03, 07:03 PM
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#4
July 25th 03, 10:39 PM
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In article ,
(N2EY) writes: (Brian Kelly) wrote in message .com... "Elmer E Ing" Elmer E wrote in message news:gk0Ua.11280$ff.3485@fed1read01... Thanks Keith I'll add those to the copout list. BTW SSB is probably 30 or 40 years old. SSB first showed up in the ham bands in 1934. AT&T had SSB running around ten years before hams did. However, the AT&T operations were fixed-frequency LF systems (5000 meters). HF SSB was not used by the telephone folks until the '30s, when about a half-dozen systems were put in service. One of the reasons AT&T went with SSB for the LF transatlantic telephone was antenna bandwidth. A 6 kHz wide AM channel at 60 kHz involves an antenna bandwidth of 10%. Hmmm...self-funded basement-workshop hams were less than 10 years behind AT&T and its nearly-unlimited resources... Next year will mark the 70th anniversary of ham SSB. Gawd I love these "new, modern modes" like SSB which make Morse such an artifact mode . . . Yup - and the theoretical background for SSB goes back even further. Truly an antique mode. Truly an idiotic statement coming from a champion of a mode that is much older, 159 years since 1844! :-) Here's a timeline: 1910 - G.A. Cambell (of AT&T) develops LC filters suitable for SSB in the LF range. Except that single sideband was not yet an accepted concept either in radio or wired communications. Those were "electric wave filters" for general electronic use. 1914 - G.R Eglund (of Western Electric) sketches geometric relationship of carrier and sidebands. 1915 - J.R Carson (of Western Electric) describes mathematical foundation of modulation and shows the theoretical advantages of SSB suppressed carrier transmission. And it should be noted that John Carson also categorized FM as generally unsuitable for communications in noisy environments. :-) He would later publicly retract that statement and do more mathematical studies...one of which was "Carson's Rule" on modulation index, a standard used in FM transmitter and system design. 1915 - Carson files for patent on SSB. It would be granted in 8 years, not 17. 1917 - Experimental 3 channel SSB telephone carrier system installed between Maumee Ohio and South Bend, Indiana. 1918 - "Type A" SSB telephone carrier system installed between Pittsburgh PA and Baltimore MD. Four channels using LSB between 5 and 25 kHz. Type A was the first nonexperimental commercial use of SSB, and eventually seven Type A systems were installed, remaining in service until the 1940s 1923 - Experimental one-way LSB 60 kHz radio system demonstrated between Rocky Point, L.I.,(New York), and London. Many of the components, including tubes, for this system were developed by Western Electric. 55 KHz. 1927 - Regular transatlantic telephone service using 60 kHz LSB put in service. Transmitting stations at Rocky Point and Rugby, England. Receiving stations at Houlton, Maine and Cupar, Scotland. A three-minute call cost $75. 55 KHz. 1932 - Carsons's SSB patent granted (17 years after filing). John Carson's patent (1,449,382) was granted in 1923, not 1932. Tsk, tsk...off by 9 whole years. 1933 - Robert Moore, W6DEI, puts an amateur station on 75 meter LSB. This station was later described in detail in R/9 magazine. It used LC filtering at 10 kHz to generate the SSB signal, followed by conversion to 200 kHz and 3950 kHz. KHz, not "kHz." Are you an engineer or not? Engineers should use correct terminology for physical terms. 1934 - Several amateur SSB stations are in the air using rigs similar to W6DEI's Between 1933 and 1934 the Dutch established a regular "shortwave" (HF) radio link between the Netherlands and the Netherlands Antilles using what would come to be the standard in service - four voice channels in a 12 KHz sideband via landline carrier equipment frequency multiplexing, the "outer" two generally handling 8 to 12 TTY circuits, also frequency-multiplexed by landline carrier equipment. The American - British link across the Atlantic went to HF by 1935. 1939 - 68 kHz channel added to Rocky Point system By 1939 both the US government and US military were outfitting for HF "commercial" SSB (12 KHz bandwidth, 4 voice channel) as fast as they could get equipment. They already has some 1934 design SSB transmitters from Western Electric in use. ADA started out with three of them, were replaced with post-war models as soon as available in the early 1950s. 1946 - R.B. Dome describes "Wide Band Phase Shift Networks" in Electronics magazine. December, 1946. 1947 - O. G. "Mike" Villard, W6QYT, puts Stanford University amateur station W6YX on 75 meter LSB with a phasing type transmitter using an audio phase shift network developed from the Dome article. 1952 - Western Electric's LD-T2 SSB transmitter was available to all buyers...4 KW PEP, automatic servo motor tuning (of 12 different stages) at 10 preset frequencies. All amplifier stages (individually shielded) were Class A except the final amplifier running Class AB. Half-minute QSY, easy, fast. ADA had four of them. The term "SSSC" (Single Sideband Suppressed Carrier) was frequently used in the early days. Not in commercial or military radio services of 1952...it was just "sideband" or "single sideband" in both written and spoken language in the USA and US forces abroad. This brings us to the point where SSB began to become common in amateur communications. Numerous homebrew transmitters and receive adapters were described in the amateur literature, followed by manufactured equipment. Early SSB efforts all used separate receivers and transmitters - the first SSB transceivers and matched-pair receiver/transmitter sets for the amateur market did not appear until the late 1950s (Cosmophone 35, Collins KWM-1 & KWM-2, Collins S-Line, etc.). Ever operate an AN/FRC-93? I don't think you've ever operated an AN/ARC-58 or AN/ARC-65. Those are airborne transceivers, single channel units primarily for USAF. All of the amateur radio SSB equipment, from day one, was SINGLE channel. SSB operation concentrated on 75 and 20 meters in the post-WW2 years because: - they were the most crowded 'phone allocations - 40 had no 'phone band, and 15 wasn't a ham band, until the early 1950s. The main reasons SSB was not more widely adopted by hams in the '30s were cost and complexity. ...and "most hams" didn't know squat about real radio theory so they went back to the usual beeping, yakking, and whining. :-) Except in the amateur 11 meter band...which they would lose in 1958 and never stop whining about it for the next 45 years! :-). In those years (late '40s-early '50s), QST had a regular column called "On The Air With Single Sideband". There were "SSB Handbooks" for hams put out by several publishers. And there were gripes that QST was becoming "too technical" and that ARRL was "forcing SSB down hams' throats". Well, you were there, right? Poor baby...must have been difficult. The more things change... The more things change the more YOU want to keep the old things. You've made a number of ERRORS in your little history missive. You've been corrected. Try to accept that in good grace...not your usual spiteful attitude as a procoder knowitall. LHA |
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