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بسم الله الرحمن الرحيم Relationship between data rate and bandwidth Arafat el-madhoun 120080147 engineering software. what is bandwidth?. Bandwidth - the frequency range (or spectrum) of a signal. It is measured as the difference between the highest and lowest frequencies.
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بسم الله الرحمن الرحيم Relationship between data rate and bandwidth Arafat el-madhoun 120080147 engineering software
what is bandwidth? • Bandwidth - the frequency range (orspectrum) of a signal. It is measured as thedifference between the highest and lowestfrequencies. • •The maximum rate at which the hardware • can change a signal is known as itseffective
what is bandwidth? • bandwidth. Bandwidth is measured in • cycles per second or Hertz. • •Thecapacity of the channel is related to the effective bandwidth and is measured in bits per second.
Relationship between Data Rate and Bandwidth • In the 1924 H. Nyquist discovered a fundamentalrelationship between the bandwidth of a system andthe maximum number of bits per second that can betransmitted over that system. It is called the NyquistSampling Theorem which states that:
Relationship between Data Rate and Bandwidth • the maximum data rate in bits per second that canbe achieved over a transmission system ofbandwidth B is 2B. • E.g. A voice channel is used to transmit data via modem. Assuming a bandwidth of 3100 Hz, then the transmission capacity of the channel (i.e. the maximum data rate) is 2B = 6200 bps. • The above formula is based on the assumption thatthe channel is noiseless and the transmission
Relationship between Data Rate and Bandwidth • systemuses 2 voltage levels - one bit for each signalelement. • If the system uses K possible values for voltage,instead of two, Nyquist’s theorem states that themaximum data rate possible, in bits per second is: • D = 2Blog2K
Relationship between Data Rate and Bandwidth • Nyquist’s formula provides an absolute maximumthat cannot be achieved in practice. Noise is inherentin real communication systems, making impossibleto achieve the theoretical maximum data rate.
Relationship between Data Rate and Bandwidth In 1948, Claude Shannon extended Nyquist’s workto specify the maximum data rate that can beachieved over a transmission system that introducesnoise. Shannon’s theorem states that: C = Blog2(1 + S/N) whereC is the effective channel capacity Bis the hardware bandwidth, S is the average signal