US Patent No. 6,400,754 -- Spread Spectrum Localizers
To develop these localizers which determine separation distances from each other using pseudo-random electromagnetic noise pulses (i.e., non-sinusoid based radio communications), the inventors had to develop innovative hardware, software and algorithms. The initial application eventually issued as five separate patents. A mathematical aspect of the invention is what is termed a "pseudo-autocorrelation function" (depicted on the Work Samples page) which is used to determine the time of reception of noise pulses with great accuracy.
I call this client as my "genius inventors" because they are so incredibly innovative and prolific. In many ways their inventions are years ahead of their time, and one of their greatest challenges is getting the people they work with (including the Department of Defense) to understand their inventions and its capabilities. This client came to me after attempting to work with a number of patent attorneys who didn't have the technical sophistication to understand their invention and therefore couldn't properly protect it.
A network of localizers determines relative locations in three-dimensional space to within 1 cm by measuring propagation times of pseudorandom sequences of electromagnetic impulses. The propagation time is determined from a correlator which provides an analog pseudo-autocorrelation function sampled at discrete time bins. The correlator has a number of integrators, each integrator providing a signal proportional to the time integral of the product of the expected pulse sequence delayed by one of the discrete time bins, and the non-delayed received antenna signal. Using pattern recognition the arrival time of the received signal can be determined to within a time much smaller than the separation between bins. Because operation of standard CMOS circuitry generates noise over a large frequency range, only low-noise circuitry operates during transmission and reception. A stage in the low-frequency clock uses low-noise circuitry during transmissions and receptions, and standard circuitry at other times.