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17 terms

com 374 radio ch. 10

STUDY
PLAY
edwin armstrong
regenerative and super heterodyne circuits vastly improved receiver efficiency-less static, almost free of
electromagnetic waves carry
transmitter-
broadcast transmissions from station to receiver
-generates and shapes the radio waves to conform to the frequency the station has been assigned to by the FCC
-receivers pick up the transmissions, converting the incoming radio frequency into sound waves
AM (amplitude modulation)
assigned frequencies between 540 and 1700 khz
-10 kilocycles seperates am
- sidebands 5 kc
-thousands of cycles per second(frequency)
-travel across the ground much further then FM
FM
located between 88.1 and 107.9 mhz
-200 kilocycles between fm frequency
-sidebands 15kc three times wider then am
-millions of cycles per second(frequency)
Static free
-Travel above ground and therefore cannot reach as far as AM-HIGHER ANTENNA, FURTHER SIGNAL
amplitude modulation
changes the height of the wave-only for AM and static has an effect on the height of waves though has none on FM
frequency modulation
changes the frequency of wave-makes closer together or further apart-wider channels
How static free?
lightning effects the Amplitude or height of the wave and therefore has no effect on the frequency (FM)
why can u hear far away stations on AM but not on FM
signals can bounce off the ionosphere and travel but, fm does not bounce off the ionosphere and therefore generally is only as far as the eye can see
digital converts sound waves into
1 s and 0 s for processing into a low bandwidth
station engineers
usually require a restricted operator permit or a general radiotelephone license-communication overall may be even better to have P.287
engineer's duties
keep the station in line with FCC rules-keep station within the assigned operating parameters-power, antenna phase, modulation, etc.
-training techs, monitoring radiation levels, handling a budget
station log
holds information about tower light malfunctions, emergency alert system tests, am directional antenna systems
EAS
Emergency alert system-replaced old EBS-emergency broadcast system-each station is required to install and operate an EAS monitor
simulcast
to broadcast simultaneously through am and fm or radio and tv
fully automated
computer driven
satellite radio employs both
synchronous (former xm) and elliptical (sirius)
digital provides
superior frequency response and greater dynamic range