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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 ...
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In the US, FCC part 15 on unlicensed spread spectrum systems in the 902–928 MHz and 2.4 GHz bands permits more power than is allowed for non-spread-spectrum systems. Both FHSS and direct-sequence spread-spectrum (DSSS) systems can transmit at 1 watt, a thousandfold increase from the 1 milliwatt limit on non-spread-spectrum systems.
Direct sequence spread spectrum is usually the sending of modified digital bits. For example, 1 digital bit might represent a binary '1' or a binary '0'. Applying DSSS to 1 single message bit will involve constructing some OTHER pseudo-random sequence of bits, having a bit-rate that is usually much higher than the message bit rate.
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 ...
Sound (or lattice vibration) can be described by a phonon just as light can be considered as photons, and therefore one can state that SASER is the acoustic analogue of the laser. [citation needed] In a SASER device, a source (e.g., an electric field as a pump) produces sound waves (lattice vibrations, phonons) that travel through an active medium.
The Silent Sam deal. In his role as vice chancellor, Somers was part of the group that brokered a controversial deal between the UNC System and the North Carolina chapter of the Sons of ...
Numerous individuals suffering from auditory hallucinations, delusional disorders, [18] or other mental illnesses have claimed that government agents use forms of mind control technologies based on microwave signals to transmit sounds and thoughts into their heads as a form of electronic harassment, referring to the alleged technology as "voice ...