초록 ▼

A network of localizers determines relative locations in three-dimensional space to within 1 cm by cooperatively measuring propagation times of pseudorandom sequences of electromagnetic impulses. Ranging transmissions may include encoded digital information to increase accuracy. The propagation time

A network of localizers determines relative locations in three-dimensional space to within 1 cm by cooperatively measuring propagation times of pseudorandom sequences of electromagnetic impulses. Ranging transmissions may include encoded digital information to increase accuracy. The propagation time is determined from a correlator circuit 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. With the impulses organized as doublets the sampled correlator output can vary considerably in shape depending on where the autocorrelation function peak falls in relation to the nearest bin. Using pattern recognition the time of arrival 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. To provide the time accuracy necessary for distancing, a high-frequency clock operates during inter-localizer communications. The high-frequency clock uses a phase-lock loop circuit to increase the clock rate and a programmable delay to provide still finer time graduations. A stage in the low-frequency clock uses low-noise circuitry during transmissions and receptions, and standard circuitry at other times.

대표청구항 ▼

[ We claim:] [1.] A receiver for reception of nonsinusoidal spread spectrum radio communications from a nonsinusoidal spread spectrum radio transmitter comprising:a spread spectrum radio antenna having an ultra-wide bandwidth for receiving a nonsinusoidal communication signal impingent thereon durin

[ We claim:] [1.] A receiver for reception of nonsinusoidal spread spectrum radio communications from a nonsinusoidal spread spectrum radio transmitter comprising:a spread spectrum radio antenna having an ultra-wide bandwidth for receiving a nonsinusoidal communication signal impingent thereon during a reception time window;a code-sequence generator to generate a digital pseudorandom sequence resembling a portion of said nonsinusoidal communication signal;a time-integrating correlator to calculate values of integrals of a product of said communication signal and delayed versions of said digital pseudorandom sequences, said communication signal being an analog waveform derived from a digital signal generated at said nonsinusoidal spread spectrum radio transmitter; anda processor for determining an arrival time of said communication signal from said values of said integrals.