摘要:
An intrusion detection system of the type using cables arranged along a perimeter to be protected and sensing changes in the electrical field around the cables caused by the presence of an intruder. The cables are divided into sections or blocks and typically only one of the sections is energized at any time. The variations caused by an intruder at the selected sections are transmitted through the intervening section to the receiver portion of a transceiver located at one end of the cables. This indicates in which section intrusion has occurred. The system uses continuous wave excitation whereby the expense and complexity of high speed switching and timing of r.f. signals are avoided.
摘要:
An intrusion detection system using waves guided by the conductive outer sheath of a coaxial cable. An r.f. signal from a transmitter is supplied between the inner conductor and outer conductor or shield in conventional fashion. Coupled wave devices are spaced along the cable; each coupled wave device transferring r.f. energy between a transmission mode within the cable and a guided mode propagated along the exterior of the conductive outer shield. In one embodiment a second coaxial cable similarly provided with coupled wave devices is spaced from the transmitter cable and has one end connected to a receiver. The change in r.f. coupling between the cables caused by an intruder produces variations in the r.f. energy coupled to the second cable which is detected at the receiver. Alternative embodiments include the use of a single cable with coupled wave devices adapted for both transmission and reception. Further alternative configurations include the use of a leaky coaxial cable, preferably buried, operating in combination with a cable provided with coupled wave devices. In some circumstances a single elongated conductor can support the guided mode. The guided mode can be established in the outer shield or single conductor by an external source and need not always be coupled from the cable interior.
摘要:
A multi-antenna GNSS system and method provide earth-referenced GNSS heading and position solutions. The system and method compensate for partial blocking of the antennas by using a known attitude or orientation of the structure, which can be determined by an orientation device or with GNSS measurements. Multiple receiver units can optionally be provided and can share a common clock signal for processing multiple GNSS signals in unison. The system can optionally be installed on fixed or slow-moving structures, such as dams and marine vessels, and on mobile structures such as terrestrial vehicles and aircraft.
摘要:
A system for ascertaining the range from an interrogator to one or more transponders comprises an interrogator that transmits an RF carrier that is received by each transponder, the energy in the received carrier being used to charge up a storage capacitor in each senses the termination of the received carrier and initiates a known delay interval different from those of the other transponders. At the end of the delay interval, the transponder transmits an RF signal which is received by the interrogator. The interrogator then calculates the range to the transponder by subtracting the known delay interval from the round trip time registered in the timer.
摘要:
Apparatus and process for determining the position and heading or attitude of an antenna array are described based on radiating sources, preferably GNSS or other such satellite positioning systems. An optimum satellite is selected and the antenna array is “null steered” by combining the phase of the received signals to calculate a null or null angle that points toward the optimum satellite. The null will determine angle for elevation toward the optimum satellite and azimuth or heading. The heading is the azimuth of the (which may be actual or calculated) projection of the null vector to the satellite onto the Earth's surface. The actual location on Earth of the antenna array can be found and the antenna array azimuth with respect to the satellite can be determined. The null angle may be measured more precisely by dithering on either side to average out noise and then averaging the angle deviations to calculate the null angle. If the attitude of the antenna array with respect to the Earth's surface is desired, a null vector to a second satellite may be generated and the intersection of the two nulls will allow the attitude of the antenna array, with respect to one or both of the satellites, to be determined. The difference between the measured attitude of the antenna array with respect to the null vector and the calculated attitude of the satellite from the GNSS signals, is the attitude of the array with respect to the Earth's surface. All viewable satellites may be used, tracked, and nulls determined for each, and many antennas if in a known pattern relative to each other can be used to make the determinations more accurate and reliable.
摘要:
A multi-frequency GNSS antenna is provided which can be manufactured from PCB materials and exhibits good multipath rejection. The antenna is capable of receiving RHCP signals from all visible GNSS satellites across a wide beamwidth. A multi-frequency GNSS antenna manufacturing method includes the steps of providing PCB base and support assemblies, first and second feed networks and connecting said first and second feed networks to first and second hybrid connector outputs.
摘要:
A multi-frequency GNSS antenna is provided which can be manufactured from PCB materials and exhibits good multipath rejection. The antenna is capable of receiving RHCP signals from all visible GNSS satellites across a wide beamwidth. A multi-frequency GNSS antenna manufacturing method includes the steps of providing PCB base and support assemblies, first and second feed networks and connecting said first and second feed networks to first and second hybrid connector outputs.
摘要:
A global navigation satellite sensor system (GNSS) and gyroscope control system for vehicle steering control comprising a GNSS receiver and antennas at a fixed spacing to determine a vehicle position, velocity and at least one of a heading angle, a pitch angle and a roll angle based on carrier phase position differences. The roll angle facilitates correction of the lateral motion induced position errors resultant from motion of the antennae as the vehicle moves based on an offset to ground and the roll angle. Alternative aspects include multiple-antenna GNSS guidance methods for high-dynamic roll compensation, real-time kinematic (RTK) using single-frequency (L1) receivers, fixed and moving baselines between antennas, multi-position GNSS tail guidance (“breadcrumb following”) for crosstrack error correction, guiding multiple vehicles and pieces of equipment relative to each other, and snow grooming equipment and method applications.
摘要:
An RF/digital signal-separating receiver is provided for GNSS and other RF signals. The receiver includes a first master antenna and a second slave antenna, which are positioned in spaced relation for directional, radio compass applications. First and second downconverters and first and second ADCs are located under the first and second antennas in analog signal areas, which configuration minimizes cross-coupling RF signals from the antennas and reduces noise. The first and second ADSs are connected to respective first and second correlators in a digital signal location, which is centrally located relative to the antennas. The correlators are connected to a microprocessor for computing distances for the received signals, from which the receiver's orientation or attitude is determined. A method of manufacturing receivers with this configuration is also disclosed.
摘要:
The present disclosure provides a system for converting differential-GPS signals to a format suitable for input to a conventional GPS receiver and combining the converted signal with GPS ranging signals. The combined signals are provided to a conventional GPS receiver via a cable. Circuitry for converting the augmentation signal and combining it with a GPS signal are co-located in a housing which supports both a standard GPS antenna and a differential GPS augmenting signal antenna.