Transmission, reception, and processing of information with the use of electronic circuits

Defined as knowledge or intelligence that is communicated between two or more points.

Transmittal of digitally modulated analog signals (carriers) between two or more points in a communication system.

Sometimes called Digital Radio Digitally modulated signals can be

propagated through Earths atmosphere and used in wireless communications system.

Ease of processing Ease of multiplexing Noise immunity

Include systems where relatively high-frequency analog carriers are modulated by relatively low-frequency digital information signals (digital radio) and systems involving the transmission of digital pulses (digital transmission).

v(t) = V sin (2 ft + )

ASK FSK PSK

QAM

Relatively low-speed voice-band data communications modems

High-speed data transmission system Broadband digital subscriber lines (DSL)

Digital microwave and satellite communications systems

Cellular telephone Personal Communications Systems (PCS)

Theoretical study of the efficient use of bandwidth to propagate information through electronic communications systems.

Measure of how much information can be propagated through a communications system.

Function of bandwidth and transmission time.

Expressed as a bit rate Bit rate

number of bits transmitted during one second

Expressed in bits per second (bps)

I B x t Where: I = information capacity (bps)

B = bandwidth (Hertz) t = transmission time (sec)

Where: I = information capacity (bps) B = bandwidth (Hz) S/N = signal-to-noise power ratio (unitless)

For a standard telephone circuit with a S/N of 1000 (30 dB) and a bandwidth of 2.7 kHz, what is its Shannon Limit for information capacity? I = 26.9 kbps

Is a term derived from the word binary.

M simply represents a digit corresponds to the number of conditions, levels or combination possible for a given number of binary variables.

It is often advantageous to encode at a level higher than binary (beyond binary or higher-than-binary encoding) where there are more than two conditions possible.

N = log 2 M Where: N = number of bits necessary

M = number of conditions, levels or combinations possible with N bits

2N = M

I = 2 B log 2 M Where: I = information capacity (bps)

B = bandwidth (Hz) M = number of conditions

A radio channel has a bandwidth of 10 kHz and a signal-to-noise ratio of 15 dB. What is the maximum data rate than can be transmitted: (a) Using any system? (b) Using a code with four possible

states?

I = 50.24 kbps

I = 40 kbps

Refers to the rate of change of a signal on the transmission medium after encoding and modulation have occurred.

Is a unit of transmission rate, modulation rate, or symbol rate

Symbols per second or baud

Where: baud = symbol rate (baud per second) ts = time of one signaling element (seconds)

Minimum Nyquist Frequency Minimum theoretical bandwidth

necessary to propagate a signal.

fb = 2B Where: fb = bit rate (bps)

B = ideal Nyquist Bandwidth

fb = B log2 M Where: fb = channel capacity (bps)

B = minimum Nyquist bandwidth (Hz)

M = number of discrete signal or voltage levels

Where: N = number of bits encoded into each signaling element

A modulator transmits symbols, each of which has 64 different possible states, 10,000 times per second. Calculate the baud rate and bit rate.