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Long Distance Communications. Carriers and Modems. Sending Signals Across Long Distances. Signal Loss Resistance to the electrical signal in copper wire causes small amounts of electrical energy to be converted into heat. Sending Signals Across Long Distances. Continuous Oscillating Signal
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Long Distance Communications Carriers and Modems
Sending Signals Across Long Distances • Signal Loss • Resistance to the electrical signal in copper wire causes small amounts of electrical energy to be converted into heat.
Sending Signals Across Long Distances • Continuous Oscillating Signal • The Carrier • Modifying the Carrier • Amplitude Modulation Reduced to 2/3 for “1” bit. Reduced to 1/3 for “0” bit.
Sending Signals Across Long Distances Frequency Modulation
Sending Signals Across Long Distances • Phase Shift Modulation • Used by computer networks After phase shift the carrier continues to oscillate, but … Carrier abruptly jumps to a new point in the cycle The size of section removed determines the amount of shift. Changes timing of carrier wave abruptly …starts at a new point in the cycle Hardware measures amount of shift to determine the number of bits.