Communication Systems
How information travels over wires and through the air: modulation, noise, antennas and wireless standards.
A communication system has a transmitter, a channel and a receiver. The channel attenuates the signal and adds noise; modulation and coding techniques make communication reliable despite them.
Sub-topics (6)
Shannon Capacity
The maximum error-free data rate of a channel depends on its bandwidth and signal-to-noise ratio.
Amplitude Modulation
AM varies the carrier's amplitude with the message signal.
Frequency Modulation
FM varies the carrier's frequency, giving better noise immunity at the cost of more bandwidth.
Digital Modulation
ASK, FSK, PSK and QAM map bits onto carrier amplitude, frequency and phase.
Antennas
Antennas convert electrical signals to radio waves and back — length, gain and radiation pattern.
Wireless Standards for IoT
Wi-Fi, Bluetooth LE, Zigbee, LoRa and cellular IoT compared.
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