Methods and system to assist search for lost and submerged objects

Abstract

Devices and methods for aiding a large area search for submerged objects such as aircraft. A searcher transmits interrogation signals to be received by a device at the target object. The interrogation signals have a long range relative to that of returned signals. The target device responds with a ping signal modified to be more easily found by means of information contained in the interrogation signal. The information may be inherent in the nature of the received signal or data encoded and embedded by the searching device. The target device may use a microprocessor to do complex operations using the information from the interrogation signal and other information. Detection of a weak ping is facilitated by such means as being beamed in the direction of the interrogation, arriving at a predictable time, or having parameters adapted to values requested by the searcher.

I claim: 
     
         1 . A first device configured to be located at an object to aid in the location of the object when the object is lost comprising:
 a receiver at the first device configured to receive information when sent from a search second device located at a distance from the first device greater than the range of a ping signal from the first device to the search second device comprising encoded information encoded in an interrogation signal; and   a transmitter at the first device configured to transmit a ping signal to the search second device in response to the interrogation signal from the search second device; wherein:   a parameter of the ping signal is modified as a function of at least one of the parameters of the interrogation signal to substantially increase the distance between the search second-device and the transmitter across which the search second device can detect the ping signal from the distance between the search second device and the transmitter across which than the search second device can detect a ping signal from the transmitter using the parameter without the modification.   
     
     
         2 . The first device of  claim 1  wherein:
 a parameter of the ping signal is modified by scheduling a ping signal to be transmitted to arrive at the search second device at a predetermined delay from the time of transmission of the interrogation signal that increases the probability of ping detection at the search second device. 
 
     
     
         3 . The first device of  claim 1  wherein:
 the ping signal is at least one of an optical and a radio signal. 
 
     
     
         4 . The first device of  claim 1  wherein:
 a parameter of the ping signal is modified to direct a ping signal in a direction that increases the probability of ping detection at the search second device so that the search second device can detect the ping signal at an increased distance between the device 
 
     
     
         5 . A first device configured to be located at an object to aid in the location of the object when the object is lost comprising:
 a receiver at the first device configured to receive information when sent from a search second device located at a distance from the first device greater than the range of a ping signal from the first device to the search second device comprising encoded information encoded in an interrogation signal; and   a transmitter at the first device configured to transmit a ping signal to the search second device in response to the interrogation signal from the search second device; wherein:   a parameter of the ping signal is modified as a function of the encoded information to substantially increase the distance between the search second device and the transmitter across which the search second device can detect the ping signal from the distance between the search second device and the transmitter across which than the search second device can detect a ping signal from the transmitter using the parameter without the modification.   
     
     
         6 . The first device of  claim 5  wherein:
 a parameter of the ping signal is modified by scheduling a ping signal to be transmitted to arrive at the search second device at a predetermined delay from the time of transmission of the interrogation signal that increases the probability of ping detection at the search second device. 
 
     
     
         7 . The first device of  claim 6  wherein:
 the ping signal is at least one of an optical and a radio signal. 
 
     
     
         8 . The first device of  claim 1  further comprising:
 a microprocessor; and 
 a multi-element sensor array wherein: 
 the microprocessor calculates a direction of arrival of the interrogation signal and employs the direction as a determinate of the modification of the parameter of the ping signal. 
 
     
     
         9 . The first device of  claim 8  wherein:
 the device directs the ping signal toward the search second device. 
 
     
     
         10 . The first device of  claim 5  wherein:
 the information is encoded in an interrogation signal; further comprising: 
 a microprocessor. 
 
     
     
         11 . The first device of  claim 10 ; wherein:
 the ping signal is modified by applying ping signal parameters that are determined as a function of a request by a search second device.   
     
     
         12 . The first device of  claim 10 ; further comprising:
 an absolute time clock.   
     
     
         13 . The first device of  claim 10  wherein:
 the microprocessor employs the encoded information to calculate a time for transmission of the ping signal; whereby 
 a search second device is enabled to predict a time of arrival of the ping signal. 
 
     
     
         14 . The first device of  claim 10 ; wherein:
 the microprocessor employs the encoded information to calculate a relative location of the search second device to the device.   
     
     
         15 . A device comprising:
 a transmitter to transmit an interrogation signal wherein:   information is encoded and transmitted configured to be used by the first device of  claim 5  to modify a ping signal so that a search second device can detect the ping signal at an increased distance between the device and the search second device as a function of said encoded information.   
     
     
         16 . A device comprising:
 a receiver to receive a ping signal located at a search second device; and   a means to predict the arrival time of a ping signal transmitted by the first device of  claim 5  wherein:   the prediction is based on a modification to a parameter of a ping signal made by the target device as a function of the information encoded and embedded in an interrogation signal.   
     
     
         17 . A search device for facilitating location of a target device located at an object; comprising:
 a transmitter to transmit an interrogation signal with encoded information to aid the target device to transmit from a transmitter at the target device a ping signal to the search device in response to the interrogation signal from with at least one parameter of the ping signal determined at least in part by encoded information to help the search device determine the presence of the target device.   
     
     
         18 . The method of  claim 17  further comprising:
 determining the transit time of the interrogation signal from the absolute time of transmission; and 
 scheduling a ping signal to be transmitted from the target first device to arrive at the search second device at a predetermined delay from the time of transmission of the interrogation signal that increases the probability of ping detection at the search second device 
 wherein: 
 the encoded information in the interrogation signal includes an absolute time of transmission of the interrogation signal; and 
 the ping signal has a time of transmission determined at least in part by the encoded information. 
 
     
     
         19 . The method of  claim 17  further comprising:
 extracting encoded information from the interrogation signal when an interrogation signal sent from a search second device is received by the target first device; and 
 determining the location of the target first device based at least in part on information encoded in at least one interrogation signal; 
 determining the transit time of the interrogation signal from relative locations of the search second device and the target first device; and 
 scheduling a ping signal to be transmitted to arrive at the search second device at a predetermined delay that increases the probability of ping detection at the search second device.