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Moreover, for a given noise power spectral density (PSD), spread-spectrum systems require the same amount of energy per bit before spreading as narrowband systems and therefore the same amount of power if the bitrate before spreading is the same, but since the signal power is spread over a large bandwidth, the signal PSD is much lower — often ...
Frequency-hopping spread spectrum (FHSS) is a method of transmitting radio signals by rapidly changing the carrier frequency among many frequencies occupying a large spectral band. The changes are controlled by a code known to both transmitter and receiver .
CDMA is a spread-spectrum multiple-access technique. A spread-spectrum technique spreads the bandwidth of the data uniformly for the same transmitted power. A spreading code is a pseudo-random code in the time domain that has a narrow ambiguity function in the frequency domain, unlike other narrow pulse codes. In CDMA a locally generated code ...
Direct-sequence spread-spectrum transmissions multiply the symbol sequence being transmitted with a spreading sequence that has a higher rate than the original message rate. Usually, sequences are chosen such that the resulting spectrum is spectrally white. Knowledge of the same sequence is used to reconstruct the original data at the receiving ...
He finished high school in 1929, studied electrical engineering at the Swiss Federal Institute of Technology in Zurich and graduated in 1933. There, he became assistant to Professor Fritz Fischer , known as the inventor of the Eidophor large-screen video projection system, at the Institute of Technical Physics until 1937, followed by a few ...
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Robert Arno Scholtz (born c. 1936) is a distinguished professor of electrical engineering at University of Southern California, known for ultra-wideband and spread spectrum communications. [1] [2] A 1958 graduate and distinguished alumnus from University of Cincinnati, he obtained his PhD at Stanford University in 1964. [3]
In digital communications, chirp spread spectrum (CSS) is a spread spectrum technique that uses wideband linear frequency modulated chirp pulses to encode information. [1] A chirp is a sinusoidal signal whose frequency increases or decreases over time (often with a polynomial expression for the relationship between time and frequency).