Abstract: An anti-jam system for use with a normal L1 Only Global Positioning System (GPS) receiver. The anti-jam system includes a switchable L1/L2 RF downconverter for receiving L1 and L2 RF signals from an RF signal source and converting a selected one of the L1 or L2 RF signals to a low frequency analog signal. An analog-to-digital converter (ADC) converts the low frequency analog signal to a digital signal. A digital anti-jam processor processes the digital signal to enhance anti-jam performance. A digital-to-analog converter (DAC) converts the processed digital signal to an enhanced analog signal. An RF upconverter converts the enhanced analog signal to an L1-based RF signal for use by a normal L1 Only GPS receiver.

Abstract: A system and method using a multi-element digital beamformer for detection and mitigation of spoofer and repeater threats to GPS that would not be addressed by baseline signal-to-noise (SNR) maximization algorithms is disclosed. GPS correlators and processing are applied to multiple beam outputs to detect and locate spoofer and repeater threats. In the beamformer processing, detected threats can be spatially nulled, even in the presence of traditional high power jamming, by modifying the normal sample covariance matrix to introduce synthetic nulls. A digital complex weighting system multiples each input channel by a complex (gain/phase) weight and adds the weighted channels together to form beams that the GPS receiver can use to reacquire the satellites in use without knowledge of platform attitude or the antenna manifold.

Abstract: The present invention is a method and apparatus for providing anti-jam protection for GPS receivers. The anti-jam system of the present invention may require less space and less power than conventional anti-jam systems. The anti-jam circuitry of the present invention may provide anti-jam protection while reducing the number of high-power usage components and integrating the components into an overall reduced form factor. Complex signal processing may be avoided whereby hardware manipulations are handled by hardware components rather than a digital signal processor.

Abstract: A method and apparatus for mitigating multipath signal distortion using a multi-element antenna array is provided. The multi-element antenna array is used to discriminate between the desired signal and its multipath components based on spatial angle of arrival. A reference signal, provided by the positioning system receiver, is used to compute element weightings that are utilized to null out the multipath components before they reach the receiver.

Abstract: Disclosed are global navigation satellite system (GNSS) receivers, including digital spatial nulling arrays, and a method of providing antenna pattern outputs using the same. The digital spatial nulling array receives multiple antenna element inputs. A fast Fourier transform (FFT) is applied to the multiple antenna element inputs to obtain frequency domain representations of the multiple antenna element inputs. The antenna pattern outputs are provided by the spatial nulling array as a function of the frequency domain representations of the multiple antenna element inputs.

Abstract: A method of reducing jamming in a global positioning system (GPS) satellite receiving system includes the steps of: a) selecting an initial weight value corresponding to each antenna element; b) selecting a weight adjustment scheme for adjusting the weights; c) measuring a power output from the antenna array; d) obtaining navigational data representing the orientation of the array; e) calculating for a gain of the antenna array corresponding each of the GPS satellites, using the navigational data to provide an indication of the orientation of the array relative to each GPS satellite; f) estimating a power level of a received signal corresponding to each GPS satellite; g) solving for the signal to noise ratio for each GPS satellite, using the estimated power level corresponding to each GPS satellite; h) iteratively and continuously adjusting the weights to obtain a greatest value of the signal to noise ratio; and i) continuously repeating steps (c) through (h).

Abstract: An apparatus is provided for a protective shield for a stoma and a stoma collection pouch. The shield comprises a rigid thin shell portion having a convex exterior surface and a concave interior surface. A peripheral edge joins the two surfaces. A spring clip portion mounts onto a neck piece of the collection pouch and is attached to the peripheral edge of the shell portion such that the spring clip portion normally touches the concave surface of the shell portion and extends over the top of the collection pouch. The spring clip portion, when forced away from the shell portion, is urged to return toward the shell portion by spring action between the spring clip portion and the shell portion. The protective shield is positioned onto the collection pouch with the shell portion covering the outfacing external surface of that portion of the collection pouch surrounding the neck piece. The peripheral edge contacts the collection pouch surface and straddles the neck piece.