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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 ...
1886: Heinrich Hertz succeeds in proving the existence of electromagnetic waves for the first time – now the groundwork for wireless telegraphy and radio broadcasting in physical science is laid. 1887: Unaware of Charles Sumner Tainter's experiments, German-American Emil Berliner has his phonograph patented. He used a disk instead of a ...
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Sir Robert Alexander Watson-Watt KCB FRS FRAeS (13 April 1892 – 5 December 1973) was a Scottish radio engineer and pioneer of radio direction finding and radar technology. [2] Watt began his career in radio physics with a job at the Met Office, where he began looking for accurate ways to track thunderstorms using the radio waves given off by ...
The desire to turn his garage invention into a viable business took him to reality show Shark Tank in 2013. Desperate for funds, he used the company’s last $20,000 to build an elaborate set to ...