Navigation reference system

• US 4,070,671 A
• Filed: 09/18/1975
• Issued: 01/24/1978
• Est. Priority Date: 09/18/1975
• Status: Expired due to Term

• Current Assignee: Rockwell International Corporation
• Original Assignee: Rockwell International Corporation
• Inventors: Morrow, James A.
• Primary Examiner(s): Hubler, Malcolm F.
• Application Number:
  US05/614,456
• Time in Patent Office: 859 Days
• Field of Search: 343/6.5 R, 343/6.5 LC
• US Class Current: 367/6
• CPC Class Codes: G01S 15/74 Systems using reradiation of acoustic waves, e.g. IFF, i.e. identification of friend or foe
• CPC Class Codes: G01S 15/874 Combination of several spaced transponders or reflectors of known location for determining the position of a receiver G01S15/872 takes precedence
• CPC Class Codes: G01S 5/26 Position of receiver fixed by co-ordinating a plurality of position lines defined by path-difference measurements G01S5/28 takes precedence

Abstract

A set of three or more acoustic transponders positioned below the surface of the ocean is provided with logic circuitry that enables location of transponder positions merely by listening to transponder signals and also enables location of an unknown receiving station merely by listening to transponder signals. The transponders are self-synchronizing to eliminate the need for precision timing over long periods. In a first mode, each transponder transmits a signal to the surface and retransmits upon receipt of its echo to thereby provide depth data. In a second mode the transponders transmit to each other and retransmit an acknowledge signal upon receipt of a reply from one of the other transponders. This provides data to enable a remote station to calculate distances between the respective transponders. In a third mode, geographic location of the transponders is determined and the transponders continue to transmit, each resetting itself upon each transmission, and each transmitting in a master or slave relation with respect to the others thereby to enable a receiving station to determine its position with respect of the transponders by conventional methods of hyperbolic navigation.

Claims

1. The machine method of establishing a navigation reference system comprising the steps of

emplacing a plurality of pairs of transponders at fixed positions, transmitting an interrogation signal from a first transponder of each pair to a second transponder of each pair,

receiving at the second transponder of each pair the signal transmitted thereto from the first transponder of such pair and in response thereto sending a reply signal from said second transponder back to said first transponder of each pair,

transmitting an acknowledgement signal from the first transponder of each pair in response to receipt thereat of the reply signal from the second transponder of such pair,

receiving at a remote station both the interrogation and acknowledgement signals from the first transponder of each said pair,

repetitively transmitting master interrogation signals from one of said transponders,

receiving each of said master interrogation signals at transponders of a group of slave transponders, transmitting a reply signal from each of said slave transponders upon receipt of each of said master interrogation signals from said one transponder, repetitively transmitting second master interrogation signals from a second transponder, said second master signals being transmitted in a predetermined chronological relation with respect to the transmission of said first named master interrogation signals, receiving said second master interrogation signals at the transponders of a second group of slave transponders,

transmitting a reply signal from the transponders of each of said second group of slave transponders upon receipt of each said second master interrogation signal, whereby a plurality of said transponders are caused to act as master transponders to thereby provide a measure of redundancy,

said first named and second master interrogation signals being each uniquely identified and including the steps of setting and resetting said transponders to selectively respond to uniquely identified master interrogation signals from each of said first and second transponders at different times.

2. The method of claim 1 including independently timing the operation of each of a group of said transponders and synchronizing said timing in response to receipt of at least some of said signals.