Using DME for terrestrial time transfer

• US 9,715,017 B2
• Filed: 03/04/2016
• Issued: 07/25/2017
• Est. Priority Date: 03/06/2015
• Status: Active Grant

• Current Assignee: Iposi, Inc.
• Original Assignee: Iposi, Inc.
• Inventors: Lee, Richard M., Derbez, Eric
• Primary Examiner(s): Nguyen, Chuong P
• Application Number:
  US15/061,808
• Publication Number:
  US 20160356891A1
• Time in Patent Office: 508 Days
• Field of Search: 34235748, 34235731, 34235749, 34235771
• CPC Class Codes: G01S 19/11 wherein the cooperating elements are pseudolites or satellite radio beacon positioning system signal repeaters
• CPC Class Codes: G01S 19/23 Testing, monitoring, correcting or calibrating of receiver elements
• CPC Class Codes: G01S 19/24 Acquisition or tracking or demodulation of signals transmitted by the system synchronisation aspects of direct sequence spread spectrum modulation H04B1/7073
• CPC Class Codes: G01S 19/256 relating to timing, e.g. time of week, code phase, timing offset
• CPC Class Codes: G01S 19/31 Acquisition or tracking of other signals for positioning
• CPC Class Codes: G04F 1/00 Apparatus which can be set and started to measure-off predetermined or adjustably-fixed time intervals without driving mechanisms, e.g. egg timers
• CPC Class Codes: G04R 20/02 the radio signal being sent by a satellite, e.g. GPS
• CPC Class Codes: G04R 20/26 the radio signal being a near-field communication signal

Abstract

Techniques for allowing a remote or fielded receiver to derive a precise time reference (such as Coordinated Universal Time (UTC)) when the fielded receiver is not able to derive time directly from received GPS signals. One or more fixed DME reference stations are located within range of DME beacon signals from an existing DME beacon station, the DME reference stations also having the capability to receive GPS signals and derive UTC therefrom. Based on the known distance between the DME reference station and the DME beacon station, the DME reference station can determine the time of transmission from the DME beacon station of each DME beacon signal. This time tag information is then provided to the fielded receiver, which is also within range of DME beacon signals from the DME beacon station. With this time tag information, the fielded receiver can correlate that with the received DME beacon signals and derive UTC to within an acceptably small margin.

Claims

1. A system for deriving a precise time reference with the aid of DME beacon signals from a DME beacon station, comprising:

a DME reference station located within range of the DME beacon signals from the DME beacon station, the DME reference station receiving GNSS signals and determining a precise time reference therefrom, the DME reference station also receiving DME beacon signals from the DME beacon station and determining the time of transmission of one or more of the DME beacon signals from the DME beacon station based at least in part on the distance between the DME beacon station and the DME reference station; and

a receiver also located within range of the DME beacon signals from the DME beacon station, the receiver being in communication with the DME reference station to receive from the DME reference station the time of transmission of the one or more DME beacon signals, wherein the receiver derives a precise time reference based at least in part on;

the received DME beacon signals and their time of transmission from the DME beacon station, and

the distance between the DME beacon station and the receiver.

2. A system as defined in claim 1, wherein the DME beacon signals received from the DME reference station includes time tags for each DME beacon signal received by the DME reference station from the DME beacon station, the time tag including a precise time reference for the time that the DME beacon station sent the respective DME beacon signal.

3. A system as defined in claim 1, wherein the time of transmission of DME beacon signals from the DME beacon station includes UTC time.