Do You Remember?
While radio undergoes its current transition to digital, there have been other transitions that were implemented to improve AM performance. During the late-1980s, the NRSC created a transmission standard that allowed AM receiver manufacturers to increase and flatten their frequency response without the risk of increased interference. To do this, broadcasters had to implement a modified 75ìs pre-emphasis specification, which is defined as NRSC-1.
Shortly thereafter Orban introduced the Optimod-AM 9100B audio processor, which expanded on the company''s success with multiband FM processing. The literature on the 9100B touted the unit''s ability to “increase coverage and improve source-to-source consistency.” The processor could be configured to operate in mono, C-Quam stereo or Kahn stereo. Mono units were field-upgraded to stereo by plugging in additional cards.
That was Then
This picture ran in the September 1969 issue of Broadcast Engineering. William S. Paley, president of the Columbia Broadcast System, is making contact for the first time on the control board that connected a regular network of 43 stations. W. T. Abbott, chief engineer of WABC, is at the controls.
The equipment was large and heavy, and it used storage batteries to heat the filaments of the amplifier tubes, and Edison cells created the 250V needed for plate voltage. The batteries had to charge every night.
Sample and Hold
Estimated MP3 Player Sales Growth
Source: In-Stat "Portable Digital Audio Players: Market Growth Exceeds Expectations," 2006.