Discrete time chaos dithering

A system for reducing cyclostationarity in a chaotic spread spectrum data communication channel, comprising:

• a first digital generator configured for producing a first transmit-side chaotic sequence of values to form a spreading code;
• a modulator configured for using said spreading code to form a digital intermediate frequency (IF) spread spectrum signal having a uniform sampling interval;
• a timing variation apparatus configured for selectively varying a duration of said sampling interval in accordance with a first pseudo-random sequence to introduce a known dither in said digital IF spread spectrum signal;
• a digital-to-analog converter accepting said digital IF spread spectrum signal incorporating said known dither, and producing an analog IF spread spectrum signal at a conversion rate that exceeds said sampling interval of said digital IF spread spectrum signal.

An apparatus for reducing cyclostationarity in a chaotic spread spectrum data communication channel, comprising:

• a first digital generator configured for producing a first chaotic sequence of values to form a spreading code;
• a modulator configured for using said spreading code to form a digital intermediate frequency (IF) spread spectrum signal having a uniform sampling interval;
• a timing variation apparatus configured for selectively varying a duration of said sampling interval in accordance with a second chaotic sequence to introduce a known dither in said digital IF spread spectrum signal;
• a digital-to-analog converter accepting said digital IF spread spectrum signal incorporating said known dither, and producing an analog IF spread spectrum signal at a conversion rate that exceeds said sampling interval of said chaotic spread spectrum signal.

A receiver, comprising:

• an antenna configured to receive an RF spread spectrum signal having a duration of sampling intervals selectively varied in accordance with a first chaotic sequence to introduce a known dither in said RF spread spectrum signal;
• a converter configured to convert said RF spread spectrum signal to a received digital IF spread spectrum signal;
• a generator configured to produce a second chaotic sequence which is identical to said first chaotic sequence;
• and
• a dither removal circuit configured to use said second chaotic sequence to remove said known dither in said received digital IF spread spectrum signal, and thereby generate a uniform received digital IF spread spectrum signal having a uniform sampling interval.

A receiver for receiving an RF spread spectrum signal, the signal having a duration of sampling intervals selectively varied in accordance with a first pseudo-random sequence to introduce a known dither in said RF spread spectrum signal, comprising:

• a converter configured to convert said RF spread spectrum signal to a received digital IF spread spectrum signal;
• a generator configured to produce a second pseudo-random sequence which is identical to said first pseudo-random sequence;
• a dither removal circuit configured to use said second pseudo-random sequence to remove said known dither in said received digital IF spread spectrum signal and thereby generate a uniform received digital IF spread spectrum signal having a uniform sampling interval;
• a de-spreader configured to despread said digital IF spread spectrum signal using a despreading sequence;
• and
• a digital chaos generator configured to generate said de-spreading sequence.

A receiver for receiving an RF spread spectrum signal, the signal having a duration of sampling intervals selectively varied in accordance with a first pseudo-random sequence to introduce a known dither in said RF spread spectrum signal, comprising:

• a converter configured to convert said RF spread spectrum signal to a received digital IF spread spectrum signal;
• a generator configured to produce a second pseudo-random sequence which is identical to said first pseudo-random sequence;
• and
• a dither removal circuit configured to use said second pseudo-random sequence to remove said known dither in said received digital IF spread spectrum signal and thereby generate a uniform received digital IF spread spectrum signal having a uniform sampling interval;
• wherein said first and second pseudo-random number sequences comprise chaotic sequences.