초록 ▼

A spread spectrum signal detector for sampling a modulated carrier employing a zero-crossing detection means having two independent control loops, a first loop for a zero-mean threshold control and a second loop for AGC control. An IF sampler quantizes the received spread spectrum signals at IF and

A spread spectrum signal detector for sampling a modulated carrier employing a zero-crossing detection means having two independent control loops, a first loop for a zero-mean threshold control and a second loop for AGC control. An IF sampler quantizes the received spread spectrum signals at IF and provides high immunity to interference or jamming. The IF signal is sampled at a number of quarter cycle intervals to allow sampling in sequence of the in-phase (I) and quadrature-phase (Q) components. The output of the IF sampler is two bits, a sign bit and a magnitude bit. The zero-mean threshold control loop using only the sign bit of the I and Q samples sets a threshold level (T0) to detect the zero-crossings of a received waveform. Two magnitude threshold levels are set at fixed offsets from the T0 threshold level. A normalized statistical accumulator using the magnitude bits of the I and Q samples determines the AGC control level for a fixed percentage of outside threshold crossings of the most significant magnitude bit. The I and Q samples are aligned in time, and every other pair of I and Q samples are inverted for digital demodulation of the IF samples to baseband. The baseband samples are provided to a signal processor for generating range and range rate information.

대표청구항 ▼

A spread spectrum signal detector comprising: means for receiving a spread spectrum signal; means, coupled to said receiving means, for sampling in time sequence an IF modulated carrier at quarter-cycle intervals of said received signal in order to generate in-phase (I) and quadrature-phase (Q) samp

A spread spectrum signal detector comprising: means for receiving a spread spectrum signal; means, coupled to said receiving means, for sampling in time sequence an IF modulated carrier at quarter-cycle intervals of said received signal in order to generate in-phase (I) and quadrature-phase (Q) samples with threshold signals; means, coupled to the outputs of said sampling means, for aligning in time each sequential pair of said in-phase (I) and quadrature-phase (Q) samples of said modulated carrier in order to process said I and Q samples at the same time for threshold level control and AGC level control; means, coupled to said outputs of said I and Q samples aligning means, for generating said threshold signals for coupling to said sampling means; and means, coupled to said outputs of said I and Q samples aligning means, for generating an automatic gain control (AGC) signal for coupling to said receiving means, said AGC setting said AGC signal level wherein said statistical accumulator comprises: means for setting the level of said AGC based on the number of time a peak amplitude of said modulated carrier of said received signal exceeds the offset threshold signals T0+D2 and T0-D2.