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Data Link Layer. Part I: Encoding. Network Architecture. message. segment. packet. frame. signal. What is a Data Link?. The Sine Wave. f(t) = Asin(B*t + C). A – amplitude B – frequency C – phase shift. Non-Zero Return Encoding Sender Sends:. Non-Zero Return Encoding Receiver Gets:.
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Data Link Layer Part I: Encoding
Network Architecture message segment packet frame signal
The Sine Wave f(t) = Asin(B*t + C) A – amplitude B – frequency C – phase shift
Non-Zero Return EncodingReceiver Gets: How many ones here? How many zeros here? Receiver does not know period/wavelength... Receiver can’t decode consecutive 1s or 0s
Non-Zero Return EncodingReceiver Solution -> Clock Receiver Receiver has a clock. One clock cycle = square wave period. Boundaries allow us to decode 1s and 0s. ? How do we determine clock cycle ? How do we keep clock cycle synchronized with square wave signal
Non-Zero Return EncodingReceiver Solution -> Clock End/Start Cycle End/Start Cycle End/Start Cycle End/Start Cycle Receiver • Sender/receiver know the clock cycle period. • Receiver uses square wave TRANSISTIONS to keep clock cycles • synchronized with square wave. • PROBLEM: Clock drift can occur over long period of consecutive 1s or 0s.