Introduction to Communication Systems EENGR 3810 Chapter 1 Introduction to Communication Systems

No Homework for this chapter. Chapter 1 Homework No Homework for this chapter.

Communication System History 1837 Morse Transmitted What? Dots and dashes 1876 Bell transmitted voice by what method? Telephone 1894 Marconi transmitted messages by what method? Wireless

Communication System Information Input Source: originates the message Human voice (Analog signals) Computer keyboard (Digital data signals) Input transducer converts message to electrical waveform baseband signal

Communication System Transmitter Modulates baseband signal with a Carrier signal Transmits modulated signal Transmission medium (Channel) Wire Radio link

Communication System Receiver Demodulates baseband signal from modulated signal Sends demodulated signal to output transducer Output Transducer Converts electrical signal to original form

Frequency Bands.

Propagation of Radio Frequencies

Analog Communication Systems

Amplitude Modulation (AM) Double Side-band Full Carrier (DSBFC) Signal Generation

AM DSBFC Transmitter (AM Transmitters will be covered later AM DSBFC Transmitter (AM Transmitters will be covered later. This is an example.)

AM Superheterodyne Receiver (AM receivers will be covered later AM Superheterodyne Receiver (AM receivers will be covered later. This is an example.)

FM with a sinusoidal baseband modulating signal

FM Transmitter Block Diagram (FM Transmitters will be covered later FM Transmitter Block Diagram (FM Transmitters will be covered later. This is an example.)

FM Receiver Block Diagram (FM receivers will be covered later FM Receiver Block Diagram (FM receivers will be covered later. This is an example.)

Digital Communication Systems

Digital Communication Systems More rugged than analog communication systems Avoids accumulation of noise and distortion Binary system +A/2 and –A/2, where A = signal amplitude encoded as rectangular pulses Transmitting scheme Digitize the signal Use pulse-code modulation to transmit digital signals takes samples of signals quantizes samples Regenerative repeater stations along communication path cleans out noise and distortion in received signal retransmits clean signal prevents accumulation of noise and distortion

PCM Transmission System Block Diagram (PCM will be covered later.)