FM- Frequency Modulation PM - Phase Modulation

← Back to document page

11FM- Frequency ModulationPM - Phase ModulationEELE445-14Lecture 30DSB-SC, AM, FM and PM()[] == =+==tfpdmjDctmjDcccceAtgeAtgtmjtmAtgtmAt gtmAtg )()()()()( )()()(1)()()( :EnvelopeComplex FM :EnvelopeComplex PM :EnvelopeComplex SC-SSB :EnvelopeComplex AM :EnvelopeComplex SC-DSB2FM and PM[][])(cos)(Re)()()()()()()(ttAetgtsAtg tReAetRtgcctjctjctjc +== ====:signal modulated-angle dTransmitteconstantis power constant ais envelope real the EnvelopeComplex FM and PM[][]voltHzDvoltradDdmDtvoltradDtmDtttA etgtsfftfppcctjc 2sec)()()()()(cos)(Re)(= = =+== constant Modulation or deviation Frequency :FM for constant Modulation or ysensitivit Phase :PM for:signal modulated-angle dTransmitte3FM and PMRelationship between mf(t) and mp(t): dmDDtm

where 2 is the pk-pk phase change in one symbol duration, T For Digital signals the modulation index: FM signals have the same peak frequency deviation, then when m(t) is a sinusoidal signal set such that the PM and note: phase modulation index peakphasedeviation phase deviation θ π θ β β β θ θ θ θ Δ Δ ≡ = = ≡ 2 max ( ) max ...

  Phases, Change, Phase change