Code in cables can be in a large frequency range {broadband}|.
Two nearby wires can exchange signals {cross talk}|.
Demagnetizing {degaussing}| randomly aligns magnetic fields.
Amplifiers can increase current or voltage {gain}|.
Sound systems can have less than 15% distortion {high fidelity}| {hi fi}.
Interfaces between metal and semiconductor have resistance {Schottky barrier}|, when voltage forces electrons into semiconductor from wire.
Code can be in a large frequency range {wideband}|. Systems {wideband code-division multiple-access} (WCDMA) can divide code into streams and send directional signals.
Wireless transmission {wi-fi}| can be digital.
Broadband information channels {wireless broadband}| can carry megabytes of information per second. Wireless uses 802.11 technology.
Signal channels can have different-wavelength signals {multiplexing, electronics}.
Two radio signals at different frequencies can mix to make a beat frequency {heterodyne}|, for amplitude modulation.
Edwin Armstrong [1918] invented a Supersonic Heterodyne Receiver to convert a selected radio frequency, for amplification and filtering {superheterodyne}| {superhet}.
Optical channels can have different-wavelength signals {wave division multiplexing}| (WDM).
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Date Modified: 2022.0225