초록 ▼

A method and apparatus for detecting and identifying Doppler frequency and phase information contained within a signal of the direct sequence spread spectrum type. An incoming signal is split by a circuit and component parts mixed with first and second local oscillator signals, the frequency of the

A method and apparatus for detecting and identifying Doppler frequency and phase information contained within a signal of the direct sequence spread spectrum type. An incoming signal is split by a circuit and component parts mixed with first and second local oscillator signals, the frequency of the first local oscillator being less than that of the carrier and the second being greater than that of the carrier by the same amount, plus an amount equal to twice the maximum Doppler frequency shift. The heterodyned signals are then low pass filtered, mixed with each other to form a heterodyned output that is then low pass filtered. The resultant signal retains Doppler phase and frequency information and is independent of carrier frequency and modulating PN-code thereby providing an easily demodulated signal whose Doppler information may be readily identified.

대표청구항 ▼

A method for extracting the Doppler frequency and phase from a direct sequence spread spectrum signal of the type that include a sinusoidal carrier modulated by a psuedo-noise sequence, said method comprising the steps of: (a) splitting said signal equally into first and second signals; then (b) mix

A method for extracting the Doppler frequency and phase from a direct sequence spread spectrum signal of the type that include a sinusoidal carrier modulated by a psuedo-noise sequence, said method comprising the steps of: (a) splitting said signal equally into first and second signals; then (b) mixing said first signal with a first local oscillator to provide a first heterodyned signal, the frequency of said first local oscillator being less than the frequency of said carrier signal; and (c) mixing said second signal with a second local oscillator to provide a second heterodyned signal, the frequency of said second local oscillator exceeding the frequency of said carrier signal by twice the maximum Doppler frequency shift; then (d) filtering the sum signals from said first and second heterodyned signals to provide a first difference signal and a second difference signal; then (e) mixing said first and second difference signals to provide a heterodyned output signal; then (f) filtering the sum signal from said heterodyned output signal.