Frequency coherence within a location network

• US 7,848,397 B2
• Filed: 08/16/2006
• Issued: 12/07/2010
• Est. Priority Date: 11/02/2001
• Status: Expired due to Term

• Current Assignee: Locata Corporation Pty Ltd
• Original Assignee: Locata Corporation Pty Ltd
• Inventors: Small, David
• Primary Examiner(s): Liu; Shuwang
• Assistant Examiner(s): Singh; Hirdepal
• Application Number:
  US11/504,309
• Publication Number:
  US 20070041427A1
• Time in Patent Office: 1,574 Days
• Field of Search: 375219-220, 375/354, 375/364, 375/135, 375/223, 375/245, 375/250, 375/295, 375/306, 375/316, 375/342, 375/350, 340/426.19, 342/357.06, 701/213, 370/342, 370/203, 370/335, 455/91, 455/95, 455/112, 455/118
• US Class Current: 375/220
• CPC Class Codes: G01S 1/24 the synchronised signals being pulses or equivalent modulations on carrier waves and the transit times being compared by measuring the difference in arrival time of a significant part of the modulations , e.g. LORAN systems
• CPC Class Codes: G01S 19/10 providing dedicated supplementary positioning signals
• CPC Class Codes: G01S 19/23 Testing, monitoring, correcting or calibrating of receiver elements
• CPC Class Codes: G01S 19/256 relating to timing, e.g. time of week, code phase, timing offset
• CPC Class Codes: G01S 19/43 using carrier phase measurements, e.g. kinematic positioning; using long or short baseline interferometry
• CPC Class Codes: G01S 5/0081 Transmission between base stations
• CPC Class Codes: G01S 5/021 Calibration, monitoring or correction G01S5/0252 takes precedence
• CPC Class Codes: G01S 5/0226 Transmitters
• CPC Class Codes: G01S 5/0289 of multiple transceivers, e.g. in ad hoc networks
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location
• CPC Class Codes: G01S 5/145 Using a supplementary range measurement, e.g. based on pseudo-range measurements
• CPC Class Codes: H04W 56/0015 one node acting as a reference for the others
• CPC Class Codes: H04W 56/0065 using measurement of signal travel time

Abstract

Generating frequency coherence between a received reference positioning signal carrier component transmitted by at least one reference transmitter and a unique positioning signal carrier component generated by a positioning-unit device. The positioning-unit device receives a reference positioning signal and measures a frequency offset of the reference positioning signal carrier component relative to a common oscillator. Once a frequency offset is measured, the positioning-unit device adjusts a frequency steerable clock by an amount derived from the measured frequency offset. The positioning-unit device then generates a unique positioning signal carrier component at an aligned carrier frequency with the reference positioning signal carrier component. Furthermore, the positioning-unit device continuously adjusts the unique positioning signal carrier component by applying the measured frequency offset to the frequency steerable clock, which is reference to the common oscillator. Subsequently, the frequency of the adjusted unique positioning signal carrier component is aligned with the frequency of said reference positioning signal carrier component.

Claims

1. A method of generating frequency coherence between a received reference positioning signal carrier component and a unique positioning signal carrier component, said received reference positioning signal carrier component being transmitted by at least one reference transmitter and said unique positioning signal carrier component being generated by a positioning-unit device, said positioning-unit device comprising a receiver, a frequency steerable clock connected to a transmitter and a common oscillator, said common oscillator being common to said receiver frequency steerable clock within said positioning-unit device, said method comprising the steps of:

a) receiving said reference positioning signal carrier component at said receiver within said positioning-unit device;

b) measuring a frequency offset of said received reference positioning signal carrier component relative to said common oscillator;

c) adjusting said frequency steerable clock by an amount derived from said measured frequency offset;

d) further adjusting said frequency steerable clock by applying an additional frequency offset for a predetermined time period to time slew said unique positioning signal;

e) generating said unique positioning signal carrier component at an aligned frequency with said reference positioning signal carrier component, wherein said unique positioning signal carrier component is aligned with said frequency steerable clock;

f) continuously adjusting said unique positioning signal carrier component by applying said measured frequency offset to said frequency steerable clock, said frequency steerable clock referenced to said common oscillator,

such that the frequency of said adjusted unique positioning signal carrier component is aligned with the frequency of said reference positioning signal carrier component.

2. The method according to claim 1, wherein said frequency steerable clock is adjusted in step (c) by an amount equivalent to said measured frequency offset.

3. The method according to claim 1, wherein said adjusted unique positioning signal is transmitted.

4. The method according to claim 1, wherein said adjusted unique positioning signal functions as a reference positioning signal for other positioning-unit devices.

5. The method according to claim 1, wherein said at least one reference transmitter includes positioning-unit devices, Wide Area Augmentation System satellites, Global Navigation Satellite System satellites, Pseudolites, or other devices that incorporate timing information.

6. A positioning-unit device for generating frequency coherence between a received reference positioning signal carrier component and a unique positioning signal carrier component, said received reference positioning signal carrier component being transmitted by at least one reference transmitter and said unique positioning signal carrier component being generated by said positioning-unit device, said positioning-unit device comprising:

a) a receiver for receiving said reference positioning signal carrier component;

b) a frequency steerable clock connected to a transmitter;

c) means for measuring a frequency offset of said received reference positioning signal carrier component relative to a common oscillator, said common oscillator being common to said receiver and said frequency steerable clock within said positioning-unit device;

d) means for adjusting said frequency steerable clock by an amount derived from said measured frequency offset;

e) means for further adjusting said frequency steerable clock by applying an additional frequency offset for a predetermined time period to time slew said unique positioning signal;

f) means for generating said unique positioning signal carrier component at an aligned carrier frequency with said reference positioning signal carrier component, wherein said unique positioning signal carrier component is aligned with said frequency steerable clock;

g) means for continuously adjusting said unique positioning signal carrier component by applying said measured frequency offset to said frequency steerable clock, said frequency steerable clock referenced to said common oscillator;

such that the frequency of said adjusted unique positioning signal carrier component is aligned with the frequency of said reference positioning signal carrier component.

7. The positioning-unit device according to claim 6, wherein said frequency steerable clock is adjusted in step (c) by an amount equivalent to said measured frequency offset.

8. The positioning-unit device according to claim 6, wherein said adjusted unique positioning signal is transmitted.

9. The positioning-unit device according to claim 6, wherein said adjusted unique positioning signal functions as a reference positioning signal for other positioning-unit devices.

10. The positioning-unit device according to claim 6, wherein said at least one reference transmitter includes positioning-unit devices, Wide Area Augmentation System satellites, Global Navigation Satellite System satellites, Pseudolites, or other devices that incorporate timing information.