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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 ...
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.
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Frequency-hopping spread spectrum (FHSS) Direct-sequence spread spectrum (DSSS) Frequency and pulse-position modulation (FPPM and PPM) Multiple frequency-shift keying (MFSK) Orthogonal frequency-division multiplexing (OFDM) Continuous Phase Modulation (CPM) The following is a discussion on the different types of modulation and their utility to UAC.
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 ...
A silent speech interface is a device that allows speech communication without using the sound made when people vocalize their speech sounds. It works by the computer identifying the phonemes that an individual pronounces from nonauditory sources of information about their speech movements .
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).
Spread spectrum, for example frequency hopping or DS-CDMA. Space diversity : The signal is transmitted over several different propagation paths. In the case of wired transmission, this can be achieved by transmitting via multiple wires.