Communications: directive radio wave systems and devices (e.g. – Directive – Including a satellite
Reexamination Certificate
1999-08-11
2001-10-16
Issing, Gregory C. (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
Directive
Including a satellite
C342S357490
Reexamination Certificate
active
06304210
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to accurate location of existing marked positions, and to generation of new marked positions, on or below the Earth's surface, corresponding to selected positions in a database, and more specifically to use of satellite communications for location and generation of position marks for survey and construction purposes.
BACKGROUND OF THE INVENTION
Survey and construction activities necessarily involve measurement of distances and/or angles, for placement of new marks or for location of marks already set down. One conventional method of performing such measurements is by use of a transit and pole, theodolite, or electronic distance measuring equipment (EDM). This requires use of cumbersome equipment, usually by at least two persons, for example, one operating the transit and the other holding the pole. If measurements are being made sequentially, an error in one distance or angle measurement will often be incorporated in all later measurements in that sequence. Workers in this field have developed other approaches that do not rely upon use of a transit and pole, theodolite or EDM for survey purposes.
A geodetic survey system using a digital phase meter is disclosed by Jaffe in U.S. Pat. No. 3,522,992. The apparatus measures distances and changes therein between a transmitter and a receiver, by combining, modulating and transmitting two laser beams having different frequencies and measuring their corresponding phase difference at the receiver. The modulated composite light beam is split by a dichroic mirror, and the phase and intensity of each of the two frequency component signals (modulated) is analyzed to determine an initial or reference modulated waveform. The reference waveform is compared with a subsequently received waveform having the same signal frequency to determine any changes in the transmitter-to-receiver optical distance or in the refractive index of the intervening transmission medium. This apparatus requires transmission of two or more light beams along a line of sight, and the apparatus does not appear to be hand-held or transportable by one person.
Davidson et al, in U.S. Pat. No. 4,225,226, disclose use of a rotating laser beam transmitter/receiver to guide an aircraft or similar vehicle that overflies a field or region in a specified pattern for a particular purpose, such as crop spraying. The rotating laser beam transmitter/receiver, which is carried by the aircraft, produces a light beam that is reflected from a sequence of reflectors on the ground that are positioned at known locations relative to each other. The reflected return signals from the ground reflectors allow the aircraft to determine its present location and to fly in the specified pattern relative to these reflectors. It appears that the pattern must be determined and entered before the aircraft begins its work.
A similar approach is disclosed in U.S. Pat. No. 4,398,195, issued to Dano, using radar signals emitted from the aircraft and received and returned by three transponders, positioned at spaced apart locations surrounding the region over which the aircraft pattern is to be flown. The aircraft carries a radar trilateralization receiver that receives and analyzes the return radar signals.
A guidance system for an earth-working vehicle, such as a tractor, is disclosed in U.S. Pat. No. 4,244,123, issued to Lazure et al. A signal transmitter, such as a rotating laser beam source, is positioned in a field to be worked, and two signal receivers are positioned at fixed, spaced apart, longitudinal locations on the vehicle, to distinguish changes by the vehicle in two horizontal directions. The receivers determine and report on the present location and bearing of the vehicle, based on what may be a phase difference of the signals received at the two receivers.
A similar approach is disclosed by Goyet in U.S. Pat. No. 4,677,555, where a rotating laser beam defines a reference plane for the earthworking vehicle. Datum points, defined by several beacons fixed in the ground and indicating the pattern (bearing, elevation) to be followed by the vehicle, are provided. A microcomputer carried on the vehicle monitors the pattern followed by the vehicle.
U.S. Pat. No. 4,309,758, issued to Halsall et al, discloses an unmanned land vehicle guided by three omni-directional light detectors carried on the vehicle. At least two spaced apart light sources must be provided off the vehicle, with each detector receiving light from two of the light sources. The vehicle bearing and location appear to be determined by signal phase differences for light from a common source arriving at the different detectors.
Stephens discloses a guidance and control system for one or more land vehicles in U.S. Pat. No. 4,647,784. Each vehicle generates and transmits a light beam that is reflected from each of two or more reflectors, each reflector having its own optical code (for example, stripes having different light reflectivities) and being oriented to reflect and return the light beam to a light detector carried by the vehicle. The returned light beams from each beam are analyzed to determine the present bearing of the vehicle.
A method of automatically steering a land vehicle, such as a tractor, along a selected course in a field is disclosed in U.S. Pat. No. 4,700,301, issued to Dyke. A rotating laser beam source and directional light detector/processor are mounted on the vehicle, and two or more reflectors are positioned at or near the boundary of the field. The laser beam is reflected from the reflectors, returns toward the vehicle, and is received by the detector/processor, which determines the present location of the vehicle and its present bearing. In another alternative, two rotating laser beam sources are positioned near the edge of the field, the the laser beams emitted by these sources are received by an omni-directional light detector carried on the vehicle.
Use of a rotating laser beam for two-dimensional navigation of a land vehicle in a specified region is also disclosed by Boultinghouse et al in U.S. Pat. No. 4,796,198. Three or more reflectors, one having a distinctive reflectivity, are positioned near the boundary of the region to reflect the laser beam back to the vehicle, where the reflected beams are received by a photoelectric cell and generate signals with associated beam arrival directions that allow determination of the present location of the vehicle. Distinctive reflection from the one mirror provides an indication of the angular position of the laser beam on each rotation.
U.S. Pat. No. 4,807,131, issued to Clegg, discloses an automated land grading system in which the position of a cutting blade is controlled automatically to provide controlled shaping of a land region being graded. A laser beam is projected in a predetermined pattern across the land region, and a laser detector carried on the grading machine receives the beam and approximately determines the location of the cutting blade and the blade angle and depth appropriate for grading that location in the land region. Information on the desired blade angle and depth is stored by a microprocessor carried on the grading machine and is compared with the actual blade angle and depth to correct the blade orientation and elevation.
Olsen et al disclose survey apparatus for collection and processing of geophysical signals, using a Global Positioning System, a GPS base station and one or more data acquisition vehicles, in U.S. Pat. No. 4,814,711. Each vehicle carries geophysical measuring instruments, a GPS signal receiver and processor to determine present location, a visual display of present location, and radio communication equipment to transmit location information to the base station. The base station periodically polls and determines the present location of each vehicle, with reference to a selected survey course that a vehicle is to follow. The base station transmits commands to each vehicle to keep that vehicle on the selected course. Each vehicle also transmits results of the geophysical data
Allison Michael Timo
Nichols Mark
Sorden James L.
Issing Gregory C.
Pelton, Esq. William E.
Trimble Navigation Limited
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