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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 long delay spread with little Doppler spreading can be mitigated with a relatively long MFSK symbol period to allow the channel to "settle down" quickly at the start of each new symbol. Because a long symbol contains more energy than a short one for a given transmitter power, the detector can more easily attain a sufficiently high signal-to ...
K. Fazel and S. Kaiser, Multi-Carrier and Spread Spectrum Systems: From OFDM and MC-CDMA to LTE and WiMAX, 2nd Edition, John Wiley & Sons, 2008, ISBN 978-0-470-99821-2. Hughes Software Systems, Multi Carrier Code Division Multiple Access, March 2002.
Barker codes of length N equal to 11 and 13 are used in direct-sequence spread spectrum and pulse compression radar systems because of their low autocorrelation properties (the sidelobe level of amplitude of the Barker codes is 1/N that of the peak signal). [15]
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 a binary direct-sequence system, each chip is typically a rectangular pulse of +1 or −1 amplitude, which is multiplied by a data sequence (similarly +1 or −1 representing the message bits) and by a carrier waveform to make the transmitted signal. The chips are therefore just the bit sequence out of the code generator; they are called ...
Phase-shift keying (PSK) is a digital modulation process which conveys data by changing (modulating) the phase of a constant frequency carrier wave.The modulation is accomplished by varying the sine and cosine inputs at a precise time.
Spektrum DX6i six-channel spread spectrum computerized aircraft radio which may be used for both helicopters and fixed-wing models. Spektrum is a brand of radio control systems designed for use with hobby radio-controlled cars and aircraft. Spektrum is a division of Horizon Hobby.