Abstract: A FM-CW radar system comprises a frequency modulated continuous wave digital generator that produces both in-phase (I) and quadrature-phase (Q) outputs to orthogonally oriented transmitter antennas. A linearly polarized beam is output from a switched antenna array that allows a variety of I-and-Q pairs of bowtie antennas to be alternately connected to the transmitter and receiver. The receiver inputs I-and-Q signals from another bowtie antenna in the array and mixes these with samples from the transmitter. Such synchronous detection produces I-and-Q beat frequency products that are sampled by dual analog-to-digital converters (ADC's). The digital samples receive four kinds of compensation, including frequency-and-phase, wiring delay, and fast Fourier transform (FFT). The compensated samples are then digitally converted by an FFT-unit into time-domain signals. Such can then be processed conventionally for range information to the target that has returned the FM-CW echo signal.

Abstract: A FM-CW radar system comprises a frequency modulated continuous wave digital generator that produces both in-phase (I) and quadrature-phase (Q) outputs to orthogonally oriented transmitter antennas. A linearly polarized beam is output from a switched antenna array that allows a variety of I-and-Q pairs of bowtie antennas to be alternately connected to the transmitter and receiver. The receiver inputs I-and-Q signals from another bowtie antenna in the array and mixes these with samples from the transmitter. Such synchronous detection produces I-and-Q beat frequency products that are sampled by dual analog-to-digital converters (ADC's). The digital samples receive four kinds of compensation, including frequency-and-phase, wiring delay, and fast Fourier transform (FFT). The compensated samples are then digitally converted by an FFT-unit into time-domain signals. Such can then be processed conventionally for range information to the target that has returned the FM-CW echo signal.

Abstract: In a ground penetrating radar system, A-scan images of subsurface targets lying along the antenna boresight axis can be substantially improved and generated in real-time by employing a synthetic aperture, end-fire array, despite the inhomogeneous nature of the subsurface volume. The synthetic aperture, end-fire array is achieved by generating electro-magnetic (EM) ultra-wideband impulses at a number of precise locations along the antenna boresight access, shifting the returned EM signals in the time domain according to the corresponding antenna boresight location, and then integrating the shifted, returned EM signals.

Abstract: In a ground penetrating radar system, A-scan images of subsurface targets lying along the antenna boresight axis can be substantially improved and generated in real-time by employing a synthetic aperture, end-fire array, despite the inhomogeneous nature of the subsurface volume. The synthetic aperture, end-fire array is achieved by generating electro-magnetic (EM) ultra-wideband impulses at a number of precise locations along the antenna boresight access, shifting the returned EM signals in the time domain according to the corresponding antenna boresight location, and then integrating the shifted, returned EM signals. In addition, an incremental, reverse-coherent integration technique is provided. This incremental technique allows for a more rapid generation of the A-scan image. The reverse-coherent integration technique eliminates unintended, stationary targets from the A-scan image, which are caused by coherent noise/clutter sources.

Abstract: In a ground penetrating radar system, A-scan images of subsurface targets lying along the antenna boresight axis can be substantially improved and generated in real-time by employing a synthetic aperture, end-fire array, despite the inhomogeneous nature of the subsurface volume. The synthetic aperture, end-fire array is achieved by generating electromagnetic (EM) ultra-wideband impulses at a number of precise locations along the antenna boresight access, shifting the returned EM signals in the time domain according to the corresponding antenna boresight location, and then integrating the shifted, returned EM signals.

Abstract: A range finding system uses non-simultaneous measurements between two communicating and cooperating instruments such that a single carrier frequency is used to exchange information between the instruments with non-simultaneous transmission using the same transmission channel. The range finding system may be considered to be an interrogator/transponder arrangement in which the results of a phase measurement against a local clock is made at one transponder station during one time interval, and then the transponder transmits both a tone derived from the transponder's local clock and the measurement results back to the interrogator station during a second time interval. The interrogator then has everything it needs to accurately compute the range while eliminating local delays in clock differences, while permitting the interrogator and the transponder to share a single frequency intermittently.

Abstract: An apparatus and method for generating an output signal having portions thereof being linearly swept in frequency. A controller, responsive to external signals, generates a series of control signals. An oscillator, responsive to each one of the control signals, produces an output signal. The output signal includes a series of output waveforms each linearly swept in frequency and corresponding to a respective one of the control signals. A first servo, responsive to each one of the output waveforms, produces a series of first correction signals each dependent upon the linearity error in a corresponding one of the output waveforms. The first correction signals modify a corresponding control signal as applied to the oscillator so as to correct linearity errors occurring in a corresponding one of the output waveforms. A second servo, responsive to each one of the first correction signals, produces a series of second correction signals each dependent upon the correlations in the first correction signals.