the technology limitations are reached. A number of disparate system designs are all referred to as "real-time locating systems". Two primary system design elements are locating at choke points and locating in relative coordinates. Locating at choke points The simplest form of choke point locating is where short range ID signals from a moving tag are received by a single fixed reader in a sensory network, thus indicating the location coincidence of reader and tag. Alternately, a choke point identifier can be received by the moving tag and then relayed, usually via a second wireless channel, to a location processor. Accuracy is usually defined by the sphere spanned with the reach of the choke point transmitter or receiver. The use of directional antennas, or technologies such as infrared or ultrasound that are blocked by room partitions, can support choke points of various geometries. Locating in relative coordinates ID signals from a tag are received by a multiplicity of readers in a sensory network, and a position is estimated using one or more locating algorithms, such as trilateration, multilateration, or triangulation. Equivalently, ID signals from several RTLS reference points can be received by a tag and relayed back to a location processor. Localization with multiple reference points requires that distances between reference points in the sensory network be known in order to precisely locate a tag, and the determination of distances is called ranging. Another way to calculate relative location is via mobile tags communicating with one another. The tag(s) will then relay this information to a location processor. Location accuracy RF trilateration uses estimated ranges from multiple receivers to estimate the location of a tag. RF triangulation uses the angles at which the RF signals arrive at multiple receivers to estimate the location of a tag. Many obstructions, such as walls or furniture, can distort the estimated range and angle readings leading to varied qualities of location estimate. Estimation-based locating is often measured in accuracy for a given distance, such as 90% accurate for 10-meter range. Some systems use locating technologies that can't pass through walls, such as infrared or ultrasound. These require line of sight (or near line of sight) to communicate properly. As a result, they tend to be more accurate in indoor environments. Applications RTLS can be used in numerous logistical or operational areas to: locate and manage assets within a facility, such as finding a misplaced