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Modulation
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Definitions Amplitude: “Size” Frequency: “Rate of occurrence”
Phase: “Position or interval within a cycle” Modulation: “To vary amplitude, frequency, or phase”
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Pure Sine Wave (146 MHz, no info)
“Carrier” Pure Sine Wave (146 MHz, no info) “Magical” Voltage or Current NOT These Time or Distance
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HF and VHF Carriers Voltage or Current Slow (HF, 80 m, 3 MHz)
Fast (VHF, 2 m, 144 MHz) Time or Distance
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Carrier/CW/AM “Carrier” Modulator or speech AM CW or OOK (BW=150 Hz)
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AM vs. FM Single Audio Tone BWFM = 5 to 15 KHz
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Sidebands AM SSB USB LSB DSB 3 KHz Note break in axis 28 MHz
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SSB (BW = 3 KHz) Long Distance or Weak Signal
1. Two Tone Test Waveform 2. Single Tone Test Waveform: Just a pure RF sinewave offset from carrier by audio tone frequency!! Compression “Splatter” 3. This is how SSB speech sounds (tuned, AM detection, untuned) Sound clip: Photo:
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Amateur TV Analog fast-scan NTSC Widest BW (6 MHz) 440 MHz , 75 cm
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Modulation Video Demos
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