Trimble Navigation Limited

Brian G Westfall

Kevin B Stephenson

Gary R Lennen

Per Kristian Enge

Dominic G Farmer

Charles Gilbert

Stephen K Will

Wilfred Hand

Robert A Samsel

A system and method for determining when portable devices require service. In one embodiment, the system is co-located with the portable device and includes a sensor, positioning system receiver and communication transmitter. The sensor senses when the portable device requires service. The positioning system receiver receives positioning signals, such as positioning signals issued by the Global Positioning System, (GPS), and uses the positioning system signals to determine the location of the portable device. The communications transmitter transmits a service signal to a service base station to indicate that the portable device requires service. The service signal includes the determined location of the portable device, thereby eliminating the need for service personnel to physically inspect every portable device in order to determine if any portable devices require service.

Device servicing system and method

An antenna structure has a radiating element and a ground plane. The ground plane has a central region relatively closely spaced apart from the radiating element and a peripheral region extending away from the central region. The peripheral region comprises at least one conductive layer that extends radially beyond the radiating element and provides a sheet resistivity higher than that of the radiating element. Though physically small, the ground plane simulates an infinite ground plane, and the antenna structure reduces multipath signals caused by reflection from the earth.

Antenna with stepped ground plane

An antenna structure has a radiating element and a ground plane. The ground plane has a central region relatively closely spaced apart from the radiating element and a peripheral region extending away from the central region. The peripheral region comprises at least the conductive layer that extends radially beyond the radiating element and provides a sheet resistivity higher than that of the radiating element. Though physically small, the ground plane simulates an infinite ground plane, and the antenna structure reduces multipath signals caused by reflection from the earth.

Antenna with ground plane having cutouts

An antenna structure has a radiating element and a ground plane. The ground plane has a central region relatively closely spaced apart from the radiating element and a peripheral region extending away from the central region. At least the peripheral region of the ground plane has a sheet resistivity that increases as radial distance from the central region increases. Though physically small, the ground plane simulates an infinite ground plane, and the antenna structure reduces multipath signals caused by reflection from the earth.

Antenna with R-card ground plane

An antenna system comprises a stack of elements that include a GPS patch antenna on a groundplane with an associated low-noise amplifier (LNA), a first Faraday shield of flat ribbon cable covering a first ferrite rod magnetic field antenna, a second ferrite rod magnetic field antenna separated from and orthogonal to the first ferrite rod magnetic field antenna, a second Faraday shield of flat ribbon cable covering the second ferrite rod magnetic field antenna and having a LNA for each of the ferrite rod magnetic field antennas. A third Faraday shield is positioned between the first and second ferrite rod magnetic field antennas. All the Faraday shields are connected to ground such that there are no loops that may act as shorted turns to avoid desensitizing the ferrite rod magnetic field antennas.

GPS navigation and differential-correction beacon antenna combination

Apparatus and method for eliminating the time delay variation associated with the satellite signal propagating within an antenna for a GPS receiver (or GLONASS receiver). The antenna is an n-point symmetrical feed double-frequency feed antenna which has the reduced electrical center error ellipsoid as compared with the single point antenna. The angular dependence of the time delay variation on the azimuth and the angle of elevation of the incoming satellite signal is reduced in case of n-feed point symmetrical antenna. The GPS receiver with n-point antenna can be used for differential GPS, both static and dynamic, and for absolute GPS positioning.

GPS receiver with N-point symmetrical feed double-frequency patch antenna

Method and apparatus for reducing or cancelling impulse noise from a signal containing noise. The desired noise-free signal is assumed to have a representative frequency .omega..sub.3, but may have a range of frequencies adjacent to this frequency, and is assumed to have substantially zero amplitude for all frequencies .omega.&lt;.omega..sub.1 and/or for all frequencies .omega.&gt;.omega..sub.2, where .omega..sub.1 &lt;.omega..sub.3 &lt;.omega..sub.2 or .omega..sub.1 &lt;.omega..sub.2. An input (noisy) signal is filtered and analyzed in a narrow frequency region surrounding .omega.=.omega..sub.1 and/or a narrow frequency region surrounding .omega.=.omega..sub.2 to obtain one or two output signal components n.sub.1 (t) and/or n.sub.2 (t), respectively, that, ideally, contain no contribution from the desired signal. The input signal is also filtered and analyzed in a narrow frequency region surrounding .omega.=.omega..sub.3 to obtain an output signal s(t)+n.sub.3 (t) component including the desired signal s(t). A linear combination of signals, such as S(t)=s(t)+n.sub.3 (t).+-.[n.sub.1 (t)n.sub.2 (1)] .sup.1/2, or S(t)=s(t)+n.sub.3 (t)+.alpha.exp(-j.phi.) [n.sub.1 (t)n.sub.2 (1)].sup.1/2,or S(t)=s(t)+n.sub.3 (t).+-.n.sub.k (t) (k=1,2), or S(t)=s(t)+n.sub.3 (t)+exp(-j.phi.)n.sub.k (t), or S(t)=s(t)+n.sub.3 (t)+[exp(-j.psi.1)n.sub.1 (t)+exp(-j.psi.2) n.sub.2 (t)]/2, or S(t)=s(t)+n.sub.3 (t)+.alpha.[exp(-j.psi.) n.sub.1 (t)+exp(-j.psi.) n.sub.2 (t)]/2, is formed as a circuit output signal, and the .+-. sign and/or the multiplier .alpha. and/or the phase angles .phi., .psi.1, .psi.2 and .psi. are chosen to minimize the contribution of noise to S(t), according to a selected quantitative error measure. Three such error measures are the displacement of a signal from the median of a reference signal,the cumulative variation of a signal, and the least mean square value of a signal. Other combinations of the signals n.sub.1 (t) and n.sub.2 (t), replacing the (complex) arithmetic mean and geometric mean, may be used for the linear combination signal S(t). Methods for computation of the phase angles .phi. , .psi.1, .psi.2 and .psi. are also disclosed.

Growing community of inventors

Mountain View, CA, United States of America

Brian G Westfall