A method for monitoring an animal with an autonomous monitoring device in close proximity to the animal, the monitoring device having a first sensor and a second sensor of higher electric power consumption. The method includes measuring a first parameter with the first sensor, the second sensor being deactivated. An estimated status of the animal is determined based on the first parameter. If the estimated status corresponds to a particular status, the second sensor is activated and measures a second parameter which is used to determine a specified estimated status of the animal.

A method for monitoring an animal with an autonomous monitoring device in close proximity to the animal, the monitoring device having a first sensor and a second sensor of higher electric power consumption. The method includes measuring a first parameter with the first sensor, the second sensor being deactivated. An estimated status of the animal is determined based on the first parameter. If the estimated status corresponds to a particular status, the second sensor is activated and measures a second parameter which is used to determine a specified estimated status of the animal.

Disclosed are techniques to compensate frequency systematic known error (FSKE) in reflector or initiator radios using a hybrid RF-digital approach in multi-carrier phase-based ranging. The hybrid RF-digital approach combines a coarse frequency compensation technique in the RF domain and a fine frequency compensation technique in the digital domain to remove the FSKE across all carrier frequencies from a device. The coarse frequency compensation performed in the RF domain may use a PLL to multiply the crystal frequency to arrive close to a target carrier frequency to compensate for a coarse portion of the known FSKE at the target frequency. The fine frequency compensation may use digital techniques to remove the remaining portion of the known FSKE not compensated by the RF. The hybrid approach reduces the number of fractional bits in the multiplier of the PLL when compared to an approach that uses only the RF-PLL to remove the FSKE.

Methods, apparatus, systems, and articles of manufacture are disclosed to locate persons based on adjustable signal strength thresholds. Example instructions cause processor circuitry to at least collect monitoring area information for a monitoring environment. Example instructions additionally cause the processor circuitry to determine, based on the monitoring area information, one or more one or more signal strength thresholds to set for one or more radio frequency (RF) beacons deployed to the monitoring environment. In some examples, example instructions cause the processor circuitry to, after reception of monitoring information from one or more devices in the monitoring environment, process the monitoring information and the one or more signal strength thresholds to determine one or more locations of the one or more devices in the monitoring environment.

An object monitoring system including a plurality of location beacons, each location beacon being configured to generate a location broadcast message indicative of a beacon location and a tag associated with a respective object in use. The includes a tag memory configured to store object rules, a tag transceiver configured to transmit or receive messages and a tag processing device configured to determine context data at least partially indicative of a tag context by at least one of determining a tag location in accordance with at least one location broadcast message received via the tag transceiver from at least one of a plurality of location beacons and using stored context data, use the object rules and the context data to identify a trigger event, determine an action associated with the trigger event and cause the action to be performed.

Collaborative local positioning techniques, such as could be used with smart phones, surveying equipment, or other mobile devices, are described. The techniques include independent techniques for distance measurement between devices, the relative positioning of devices, and an absolute orienting of the devices without use of fixed anchor points and through on-will participation of the devices to provide privacy. Distances between devices are determined by use of a sequence of positioning signals, such as a magnetic signal, each of which include an identifier of the transmitting device, the amplitude of the signal as transmitted, and the position of the signal within the sequence. The amplitude of the positioning signal as received can be compared to the amplitude as transmitted to obtain a distance.

The present disclosure generally pertains to systems and methods for providing position information to aircraft using radio-frequency signals. By providing a ground-based solution entirely independent of GPS, systems of the present disclosure can make navigation systems more accurate and robust, enhancing their effectiveness and safety. More precisely, systems of the present disclosure may employ a series of ground-based beacon transmitters to provide coverage across a defined geographic region. Primary beacon transmitters may be used to generate a radio-frequency (RF) signal pulse with a highly regular frequency. A larger number of secondary beacon transmitters may be used to re-transmit these RF signal pulses with a tightly controlled turnaround time. A locating receiver can detect the arrival times of these pulses and use this information, along with stored information about the relative positions of the beacon transmitters, to determine its location.

A device generates a first plurality of aerial vehicle (AV) constellations about a geographic area and determines respective positioning scores for each AV constellation. The respective positioning score is determined based at least in part on a measure of positioning accuracy for positioning enabled by the AV constellation at position(s) of interest within the geographic area. The device generates a second plurality of AV constellations based on the first plurality and the respective positioning scores by modifying one or more of the AV constellations of the first plurality using random location perturbations. The device determines respective positioning scores for each AV constellation of the second plurality. The device selects a preferred AV constellation from a group of selectable constellations based on the respective positioning score of the preferred AV constellation, the group of selectable constellations generated based at least in part on the first and/or second plurality of AV constellations.

In an aspect, a first network node may receive, from a second network node, one or more reference signals transmitted using one or more first polarizations known to the first network node, wherein the one or more reference signals are received having one or more second polarizations. The first network node may determine whether the one or more reference signals followed a line-of-sight (LOS) path between the first network node and the second network node based on a comparison of signal characteristics related to the one or more first polarizations and signal characteristics related to the one or more second polarizations.

Traditional “low-to-high waveform change” timing markers, in navigation or GPS signals, can be easily naturally or maliciously altered and require unshareable, high-resolution, high-capacity channels, often not government available. Whereas, message text format methods include proven error correction, redundancy, encryption, jam-resistance, concealability, spoof-resistance, multiuser, delayable messaging, channel efficiency, and downstream authentication. Herein, “virtual timing markers” exploit message format strengths and more. Because many navigating platforms also communicate voice, messages, or data, platforms and multiuser messages can simultaneously and unintrusively share the same transmission signal, which reduces onboard hardware, needed channel capacity, radio frequencies, costs, and infrastructure. FAA mandated, airliner collision avoidance broadcasts of their GPS location can unintrusively commingle navigation messages with aforementioned strengths as precise derivative GPS timing markers on existing, prolific broadcasts having 1000× greater power levels. “Relayed transmission pathways” can eliminate cumbersome traditional nanosecond synchronization of navigation transmitters or exploit inclusion of happenstance neighborhood transmitters. Additional features.