|Reginald Fessenden telecommunication|
- Reginald Fessenden’s first AM transmission
- in December 1900 used a carbon microphone in series
- with a rotary spark-gap transmitter
- producing ten thousand sparks per second,
- but the spark-gap transmitter was too noisy
- and too spread out over over the frequency band
- to carry clear voice transmissions,
- and the Branly or Marconi coherer
- was too crude to demodulate a voice frequency.
- So Fessenden began to work to improve
- both the transmitter and the receiver.
- He invented the process of heterodyning
- to modulate and demodulate an AM signal.
- He invented the hot wire barretter and various
- electrolytic detectors to rectify the received signal.
- He contracted with GE for the Alexanderson alternator
- to produce a high frequency radio carrier signal.
- We had Morse-code telegraphy
- by radio and by telegraph,
- and telephone networks dependent on wires.
- People did not have radios
- in their homes or in their cars.
- There were no radio broadcasts.
- So people thought of AM radio
- as a wireless telephone, not as
- a broadcast to the masses.
- Ethel Merman reported that Lucille Ball reported
- receiving radio broadcasts via temporary dental fillings
- in 1942, early in World War II.
- She was able to overhear a broadcast
- of an underground radio station from a Japanese spy
- and reported it at work to MGM security officials,
- resulting in the arrest of someone’s gardener.
- Was this a fabrication of a pair of comediennes
- or, in any case, is there a case for dental receptionists?