where radio has to go

The primative radios in use everywhere today place severe limits on their use - we see this in mobile phones (although there are other issue involved  - things like limited network connections to the cell sites).  A likely way around this is sometimes called cognitive or agile radio.  This may be an area of explosive growth five or ten years out...

Here is a neat box and inexpensive for testing - I've been to the facility at Rutgers several times - it is a very impresive place.  Much more on the box here.  A couple of us used to joke that we wanted a radio that tuned from "dc to red" - this is a radio that operates simultaneously from 100 MHz to 7.5 GHz ... wow...

 

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[Roger]

Back in the 1950s I had an old 1940s vintage vacuum tube multiband radio with huge condenser cans. I stretched an antenna wire across my room and listened to skip from halfway around the world at night. I was intrigued by the strange sounds of digital data being transmitted across the airways. The radio wasn't equipped to properly demodulate single sideband, so many of the conversations were a mite distorted, but often still intelligible.

"Amateur radio operators began serious experimentation with SSB after World War II."

"In conventional (double sideband) AM the carrier signal is considered to represent a waste of transmission power and therefore SSB transmission generally attempts to reduce the (amplitude) level of the carrier signal to as close as possible to zero. This is known as suppressed carrier SSB.

"However to ensure that the transmitted audio is resolved at the correct pitch it is essential that the receiver is tuned to exactly the same frequency as the transmitter is operating on and it is often difficult to achieve the necessary level of precision. As a result audio transmitted by SSB can sound unnatural (or in severe cases suffer from poor intelligibility), which is why it is considered more suited for speech than music transmission."

So without my radio's ability to synchronize with the carrier signal and to properly demodulate SSB, its frequency would slowly drift, or the carrier frequency would slowly drift due to atmospheric effects, and the audio signal's frequencies would slowly drift and become garbled, so I would have to continually tweak the tuning knob. A distraction, but still exciting, nonetheless.

Maybe this fascination with my old radio was why I went on to get a Communications Electronics degree in Electrical Engineering, and later to become a Communications Electronics or Radar Maintenance Officer in the Air Force.