Location System And Communication System

Abstract

A location system comprises a plurality of transponders whose locations are detectable by a base system. The base system interrogates ( 51 - 55 ) the transponders one at a time in accordance with a schedule of consecutive time slots. In response to a priority request received ( 53 ) from one of the transponders, the base system interrupts the schedule and interrogates substantially immediately ( 56, 57, 55 ) the signaling transponder so as to determine its location with minimal latency.

1 . A method for locating a plurality of devices having locations detectable by a base system, the method comprising:
 polling locations of the devices one at a time in a sequence of time slots, wherein the location of each device is repeatedly polled;   receiving from the devices ultrasonic signals transmitted by the devices in response to the polling; and   interrogating a location of a requesting device of the devices substantially immediately in response to a priority request radio signal from the requesting device.   
     
     
         2 . The method of  claim 1 , wherein the interrogating the location of the requesting device further comprises interrogating the location of the requesting device in a first time slot to start after receipt of the radio signal from the requesting device. 
     
     
         3 . The method of  claim 1 , wherein the radio signal from the requesting device is a manually actuable signal. 
     
     
         4 . The method of  claim 1 , wherein the base system comprises a plurality of fixed ultrasonic transducers and a processor for determining positions of the devices from propagation times of ultrasonic energy from the devices to at least some of the fixed ultrasonic transducers. 
     
     
         5 . The method of  claim 1 , wherein interrogating a location of a requesting device comprises transmitting an electromagnetic signal. 
     
     
         6 . The method of  claim 5 , wherein the electromagnetic signal is a radio signal. 
     
     
         7 . The method of  claim 1 , wherein the locations of the devices are detectable anywhere within a predetermined region of space. 
     
     
         8 . A method for locating a plurality of devices having locations detectable by a base system, the method comprising:
 polling locations of the devices one at a time in a sequence of time slots, wherein the location of each device is repeatedly polled; and   interrogating a location of a requesting device of the devices substantially immediately in response to a priority request signal from the requesting device, the sequence of time slots being delayed by a time slot following the substantially immediate interrogating.   
     
     
         9 . The method of  claim 8 , wherein the interrogating the location of the requesting device further comprises interrogating the location of the requesting device in a first time slot to start after receipt of the radio signal from the requesting device: 
     
     
         10 . The method of  claim 8 , wherein the radio signal from the requesting device is a manually actuable signal. 
     
     
         11 . The method of  claim 8 , wherein interrogating a location of a requesting device comprises transmitting an electromagnetic signal. 
     
     
         12 . The method of  claim 11 , wherein the electromagnetic signal is a radio signal. 
     
     
         13 . The method of  claim 8 , further comprising:
 receiving from the devices signals transmitted by the devices in response to the polling.   
     
     
         14 . The method of  claim 13 , wherein the signals transmitted by the devices in response to the polling are ultrasonic signals. 
     
     
         15 . A tangible computer-usable medium having computer readable instructions stored thereon for execution by a processor to perform a method for locating a plurality of devices having locations detectable by a base system, the method comprising:
 polling locations of the devices one at a time in a sequence of time slots, wherein the location of each device is repeatedly polled;   receiving from the devices ultrasonic signals transmitted by the devices in response to the polling; and   interrogating a location of a requesting device of the devices substantially immediately in response to a priority request radio signal from the requesting device.   
     
     
         16 . The tangible computer-usable medium of  claim 15 , wherein the interrogating the location of the requesting device further comprises interrogating the location of the requesting device in a first time slot to start after receipt of the radio signal from the requesting device. 
     
     
         17 . The tangible computer-usable medium of  claim 15 , wherein the radio signal from the requesting device is a manually actuable signal. 
     
     
         18 . The tangible computer-usable medium of  claim 15 , wherein the base system comprises a plurality of fixed ultrasonic transducers and a processor for determining positions of the devices from propagation times of ultrasonic energy from the devices to at least some of the fixed ultrasonic transducers. 
     
     
         19 . The tangible computer-usable medium of  claim 15 , wherein interrogating a location of a requesting device comprises transmitting an electromagnetic signal. 
     
     
         20 . The tangible computer-usable medium of  claim 19 , wherein the electromagnetic signal is a radio signal.