Chapter 6 Digital Data Communication Techniques. 1/26. Asynchronous and Synchronous Transmission. Timing problems require a mechanism to synchronize the transmitter and receiver timing (rate, duration, spacing) of the data bits must be the same at transmitter & receiver
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Digital Data Communication Techniques
Pb: probability that a bit is received in error, known as Bit Error Rate (BER)
P1: probability that a frame arrives with no bit error
P2: probability that, with an error detecting algorithm in use, a frame arrives with one or more undetected errors
P1=(1-Pb)Fwhere F is the number of bits per frame
CRC: Modulo 2 Arithmetic
FEC: Forward Error Correction
1. If there are no bit errors, the decoder produces the original data block as output.
2. For certain error patterns, it is possible for the decoder to detect and correct those errors
3. For certain error patterns, the decoder can detect but not correct the errors, the decoder simply reports an uncorrectable error.
4. For certain, typically rare, error patterns, the decoder does not detect that any errors have occurred
d(00111, 00100) =2
d(11001, 00100) =4
d(11110, 00100) =3
d(00000, 00111) =3; d(00000, 11001) =3; d(00000, 11110) =4
d(00111, 11001) =4; d(00111, 11110) =3; d(11001, 11110) =3
The minimum hamming distance = dmin=3