Continuous time chaos dithering
First Claim
1. A method for further reducing cyclostationary content in a chaotic spread spectrum data communication channel, comprising:
- digitally generating a first chaotic sequence of values to form a spreading code;
using said spreading code to form a digital intermediate frequency (IF) spread spectrum signal having a uniform sampling interval;
converting said digital IF spread spectrum signal to a sampled analog IF spread spectrum signal at a conversion rate;
selectively varying a duration of said uniform sampling interval in said sampled analog IF spread spectrum signal in accordance with a first pseudo-random sequence to introduce a known dither in said sampled analog IF spread spectrum signal; and
subsequent to introducing said known dither, converting the sampled analog IF spread spectrum signal to a continuous IF signal, upconverting said continuous IF signal to an analog RF spread spectrum signal.
1 Assignment
0 Petitions
Accused Products
Abstract
Embodiments of the present invention provide a system and method for further reducing cyclostationarity and correspondingly energy density in a chaotic spread spectrum data communication channel, by digitally generating a first chaotic sequence of values to form a spreading code. The spreading code is then used to form a digital IF spread spectrum signal having a uniform sampling interval. The digital IF spread spectrum signal is converted to a sampled analog IF spread spectrum signal at a conversion rate substantially equal to the uniform sampling interval. The duration of the sampling interval is then selectively varied in accordance with a first pseudo-random sequence, thereby introducing a known dither in the analog IF spread spectrum signal. After introducing the known dither, the analog IF spread spectrum signal is upconverted to an analog RF spread spectrum signal. The first pseudo-random sequences may be designed to be a chaotic sequence.
211 Citations
15 Claims
-
1. A method for further reducing cyclostationary content in a chaotic spread spectrum data communication channel, comprising:
-
digitally generating a first chaotic sequence of values to form a spreading code; using said spreading code to form a digital intermediate frequency (IF) spread spectrum signal having a uniform sampling interval; converting said digital IF spread spectrum signal to a sampled analog IF spread spectrum signal at a conversion rate; selectively varying a duration of said uniform sampling interval in said sampled analog IF spread spectrum signal in accordance with a first pseudo-random sequence to introduce a known dither in said sampled analog IF spread spectrum signal; and subsequent to introducing said known dither, converting the sampled analog IF spread spectrum signal to a continuous IF signal, upconverting said continuous IF signal to an analog RF spread spectrum signal. - View Dependent Claims (2, 3, 4, 5, 6, 7)
-
-
8. A system for further 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 defined by a sampling rate; a digital-to-analog converter configured for accepting said digital IF spread spectrum signal, and producing a sampled analog IF spread spectrum signal at a conversion rate substantially equal to said uniform sampling interval; a timing variation apparatus configured for selectively varying a duration of said uniform sampling interval in accordance with a first pseudo-random sequence to introduce a known dither in said analog IF spread spectrum signal; and an anti image filter to convert the sampled analog IF signal to a continuous analog signal and an upconverter configured for accepting said analog IF spread spectrum signal, and producing an analog RF spread spectrum signal. - View Dependent Claims (9, 10, 11, 12, 13)
-
-
14. An apparatus for further reducing cyclostationarity in a chaotic spread spectrum data
communication channel, comprising: -
a first digital chaos 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 digital to analog converter configured for accepting said digital IF spread spectrum signal, and producing a sampled analog IF spread spectrum signal at a conversion rate; and 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 sampled analog IF spread spectrum signal. - View Dependent Claims (15)
-
Specification