Digital Radio in 1994, John Battison in 1931
Mar 1, 2003 12:00 PM, By Kari Taylor, associate editor
Do you remember?
In1994, the Electronic Industries Association's DAR Subcommittee and theNational Radio Systems Committee's Digital Audio Broadcast Subcommitteebegan testing seven DAR systems at the National Aeronautics and SpaceAdministration's Lewis Research Center in Cleveland. Following the labstests, the committee made its recommendations to the FCC. This was thefirst time that several DAR systems had been subjected to laboratorytesting.
Testing addressed the issues of sound quality, immunity tointerference, transmission problems and IBOC compatibility withexisting services.
The seven systems tested were: AT&T (in-band, adjacent-channel),AT&T/Amati Communications (IBOC), Thomson Consumer Electronics forEureka-147/DAB (new band), USA Digital Radio FM Implementation No. 1(IBOC), USA Digital Radio FM Implementation No. 2 (IBOC), USA DigitalRadio AM (IBOC), and Voice of America/Jet Propulsion Lab (new band,direct broadcast satellite). Amati, Thomson/Eureka and VOA/JPS actuallysubmitted two variants of their formats, so testing was administered on10 systems.
In the end, the test results were inconclusive. USA Digital Radio,AT&T and the VOA filed protests with the EIA over the IBOC testingprocedures because of the EIA's findings that IBOC showed poorperformance. Due to these circumstances, follow-up field testing wasconducted in San Francisco.
That was then
Thisphoto was taken in 1931 in a wooden shack outside the house ofTechnical Editor John Battison. The transmitter had an oscillator,audio stage, RF stage and P.A. plate modulation. The tube filamentsoperated at 4Vdc with a B-plus supply of about 200V. The main supplywas 230Vdc so no filament or power transformers could be used. Theentire transmitter was 230V hot to ground. Battison, W8KUC and formerlyG2AMC, built the transmitter himself, and operated it in the 180m band(160kHz).
In those days, engineers metered every conceivable tube electrode.The antenna was horizontal and about 50-feet long, using ceramiccrossover spacers in the transmission line and was attached to atelephone pole and Battison's house. Ten watts was the maximum powerallowed in those days without special dispensation. It was not stableand frequently broke into self-oscillation on the slightestprovocation.
Sample and Hold
A look at the state of radio today
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Generally speakig, are you satisfied or unsatisfied in the job yourlocal radio stations are doing in providing you news, information andentertainment programming?
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