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Unformatted text preview: EE455/591 EE455/591 Binary or Antipodal Signaling Binary or Antipodal Signaling Reading: Section 7.1, 7.2 Reading: Section 7.1, 7.2 Review: 2PAM and 2PPM Review: 2PAM and 2PPM Topics: Topics: 1. 1. The Problem of Digital Decision at Receiver The Problem of Digital Decision at Receiver 2. 2. Optimal Decision for Binary Signal Transmission Optimal Decision for Binary Signal Transmission 3. Error Events for Binary Transmission 3. Error Events for Binary Transmission 4. Computing Probability of Error 4. Computing Probability of Error Review: Antipodal Signaling (or 2PAM) Antipodal signaling: – Suppose we transmit “01101”, a sequence of a n with a =1, a 1 =a 2 =1, etc. – Each bit is sent as a baud/symbol consecutively (spaced T apart) – The symbol is represented by the impulse response h(t) • E.g. Rectangular h(t)=A for 0<t<T, h(t)=0 otherwise (time limited) • E.g. sinc function with zero crossing at nT for n 0 (band limited) ≠ – Signal represented by x(t) = ∑ n a n h(tnT) – Pictorial representation x(t) = convolution of impulse train and h(t): A T TT A 2T T 4T 3T 5T 1 1 1 2T T 4T 3T 1 1 1 System with impulse response h(t) Impulse train of a n Review: Pulse Position Modulation 2PPM (Example of Binary Orthogonal Signaling) • PPM Information carried by position of pulses – Time T divided into 2 time slots – Bit a n sent in interval [nT, (n+1)T] – If a n =0, pulse in first half of interval – If a n =1, pulse in second half of interval • PPM is a kind of orthogonal signaling (Orthogonal meaning they don’t overlap in time) • Another orthogonal signaling is Frequency Shift Keying FSK (i.e. 2FSK when a tone is sent in one of two frequency slots) 2T T 4T 3T 5T 1 1 1 1. General Problem of Digital Receiver1....
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 Spring '09
 Hui

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