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s MSK (t) =

s MSK (t) =.  k = 0 or  depending on whether m I (t) = +1 to -1 s MSK (t) has constant amplitude to ensure phase continuity at bit interval  select f c = ; n integer. f c -. and. f c +. MSK waveform - as a special case of CPFSK.

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s MSK (t) =

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  1. sMSK(t) = • k= 0 or depending on whether mI(t) = +1 to -1 • sMSK(t) has constant amplitude • to ensure phase continuity at bit interval  selectfc = ; n integer • fc - and • fc + MSK waveform - as a special case of CPFSK MSK is FSK signal with binary signaling frequencies given by • phase of MSK varies linearly over Tb

  2. sMSK(t) = • Let mI(t) mQ(t) = dk • Possible values for dk ? • k(t) = k - dk t/ 2T • For phase continuity from kT to (k+1)T,  = k+1(t) - k(t) = k+1 – dk+1 t/ 2T – [ k - dk t/ 2T ] = k+1 – k - (t/ 2T).[ dk+1 - dk ] • [ dk+1 - dk ]  0, +2, -2

  3. Phase Continuity of MSK h = ½ θ(t) = θ(0) ± 0 ≤ t ≤ T θ(t) can take on only 2 values at odd or even multiples of T t =even multiple of T θ(T) - θ(0)= πor 0 t = odd multiple of Tθ(T) - θ(0)= ± π/2 assuming θ(0) = 0

  4. π π/2 0 -π/2 -π θ(t) - (0) 1 0 0 1 1 1 0 0 2T 4T 6T t Phase Trellis: path depicts θ(t) corresponding to a binary sequence • for h = ½ ΔF = Rb/4 • minimum ΔF for two binary FSK signals • to be coherently orthogonal • e.g. if Rb = 100Mbps  = ΔF = 25MHz

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