Abstract: A method of communicating to a RF tag having a low power mode and a scan mode with a radar and an interrogator. The method comprises the steps of alternating the RF tag between the low power mode and the scan mode and then transmitting a wake-up call to the RF tag with the radar. Next, the wake-up call is received from the radar by the RF tag when the RF tag is in the scan mode. Once the wake-up call has been received, the radar will transmit a downlink message to the RF tag. Upon receipt of the downlink message, the RF tag will send an uplinked message to the radar. After the uplink message has been sent to the radar, the RF tag will return to the low power mode. By alternating the RF tag between the low power mode and the scan mode, the power consumption of the RF tag is greatly reduced thereby increasing the battery life thereof.

Abstract: A classifier employing general frame wavelets for improving target recognition while decreasing computational intensity is disclosed. A wavelet selection means compares a portion of a time dependent input signal from a receiver with a set of sample wavelets, each wavelet being bandpass limited, locally supported, and mean zero, and selects a prototype wavelet resembling the input portion. A resolving means expands the prototype wavelet onto a basis of wavelet functions having variations in scale and delay, and resolves the input signal onto the basis of functions. A regionpass filter identifies a region from a grid of resolved coefficients that contains features of a target from the input signal and discards coefficients outside the region. A separability filter passes select coefficients from a scale band within the identified region where separability among known targets is high. A comparator compares the selected coefficients with an exemplar of known targets to indicate a recognition of the target.

Abstract: This invention is directed to an image processing arrangement used to estimate image displacement relative to a reference frame. It comprises a discrete complex correlator, an associated interpolator, and a displacement estimator. The unique nature of the system is its ability to estimate shifts of a fraction of a pixel for sparcely sampled data. This is accomplished by extracting the complex gradients from the gray scale data and in turn correlating the gradients via a discrete complex correlator. The resulting cross correlation function is then interpolated to yield an accurate estimate of the shift. The invention is particularly adapted for use in the autofocus portion of a synthetic aperture radar imaging system.