TAG FREQUENCY CONTROL

• US 20110039591A1
• Filed: 10/29/2010
• Published: 02/17/2011
• Est. Priority Date: 06/02/2004
• Status: Active Grant

• Current Assignee: Ubisense Incorporated (IQGeo Group Plc)
• Original Assignee: Ubisense Incorporated (IQGeo Group Plc)
• Inventors: WARD, Andrew Martin Robert
• Granted Patent: US 8,301,162 B2
• Time in Patent Office: Days
• US Class Current: 455/509
• CPC Class Codes: H04B 1/7183 Synchronisation
• CPC Class Codes: H04W 56/001 Synchronization between nodes
• CPC Class Codes: H04W 56/0015 one node acting as a reference for the others
• CPC Class Codes: H04W 56/0035 detecting errors in frequency or phase

Abstract

A communication system comprising one or more transceiver units of a first type and one or more transceiver units of a second type capable of communicating with the transceiver units of the first type; each transceiver unit of the first type comprising: a frequency comparison unit for comparing the frequency of a signal received from a transceiver unit of the second type with a reference frequency; a feedback signal generator for generating a feedback signal dependent on the result of that comparison; and a transmitter for transmitting that signal to the transceiver unit of the second type; and each transceiver unit of the second type comprising: a local frequency reference unit on which the frequency of signals transmitted by it are dependent; and a frequency adjustment unit for receiving the feedback signal and adjusting the local frequency reference unit in dependence on the feedback signal.

Claims

1. A communication system comprising:

one or more transceiver units of a first type;

a data store accessible to the or each transceiver unit of the first type;

two or more transceiver units of a second type, the transceiver units of a second type being capable of communicating with the transceiver units of the first type, and each transceiver unit of the second type comprising a local frequency reference unit on which the frequency of signals transmitted by it are dependent;

wherein;

at least one transceiver unit of the first type comprises a frequency comparison unit for comparing the frequency of a signal received from a transceiver unit of the second type with a reference frequency, and a feedback data storage unit for storing data representative of the result of that comparison in respect of that transceiver unit of the second type; and

the or each transceiver unit of the first type comprises a frequency adjustment unit for adjusting the transmit and/or receive frequency of the transceiver unit of the first type for communication with one of the transceiver units of the second type in accordance with feedback data stored in respect of that transceiver unit of the second type.

2. A communication system as claimed in claim 1, wherein the or each transceiver unit of the first type is arranged to communicate with a single one of the transceiver units of the second type at any one time.

3. A communication system as claimed in claim 1, wherein each transceiver unit of the first type is a base station.

4. A communication system as claimed in claim 1, wherein each transceiver unit of the second type is an identification unit.

5. A communication system as claimed in claim 4, wherein each transceiver unit of the second type has a unique identity within the system.

6. A communication system as claimed in claim 5, wherein each transceiver unit of the second type is a mobile transceiver.

7. A communication system as claimed in claim 6, wherein each transceiver unit of the second type is a radio tag.

8. A communication system as claimed in claim 1 wherein each transceiver unit of the second type comprises a power source.

9. A communication system as claimed in claim 1, wherein the system is a locationing system and is capable of determining the location of a transceiver unit of the second type relative to the or each transceiver unit of the first type.

10. A communication system as claimed in claim 1, wherein communication between the transceiver units of the first type and the transceiver units of the second system is by ultrawideband radio.

11. A communication system as claimed in claim 1, wherein the communication system is such that each transceiver unit of the second type can establish communication with each transceiver unit of the first type only if the operating frequencies of those transceiver units are synchronised to better than 2 ppm.

12. A communication system as claimed in claim 1, wherein the or each local frequency reference unit is an oscillator and the or each frequency adjustment unit is capable of altering the oscillation frequency of the oscillator.

13. A communication system comprising:

one or more transceiver units of a first type;

two or more transceiver units of a second type, the transceiver units of a second type being capable of communicating with the transceiver units of the first type, and each transceiver unit of the second type comprising a local frequency reference unit on which the frequency of signals transmitted by it are dependent;

wherein at least one transceiver unit of the first type comprises;

a frequency comparison unit for comparing the frequency of signals received from transceiver units of the second type with a reference frequency and forming an offset signal representative of the average offset between the frequency of the received signals and the reference frequency;

a frequency adjustment unit for adjusting the reference frequency in accordance with the offset signal.

14. A communication system as claimed in claim 13, wherein each transceiver unit of the first type is a base station.

15. A communication system as claimed in claim 13, wherein each transceiver unit of the second type is an identification unit.

16. A communication system as claimed in claim 15, wherein each transceiver unit of the second type has a unique identity within the system.

17. A communication system as claimed in claim 16, wherein each transceiver unit of the second type is a mobile transceiver.

18. A communication system as claimed in claim 17, wherein each transceiver unit of the second type is a radio tag.

19. A communication system as claimed in claim 13 wherein each transceiver unit of the second type comprises a power source.

20. A communication system as claimed in claim 13, wherein the system is a locationing system and is capable of determining the location of a transceiver unit of the second type relative to the or each transceiver unit of the first type.

21. A communication system as claimed in claim 13, wherein communication between the transceiver units of the first type and the transceiver units of the second system is by ultrawideband radio.

22. A communication system as claimed in claim 13, wherein the communication system is such that each transceiver unit of the second type can establish communication with each transceiver unit of the first type only if the operating frequencies of those transceiver units are synchronised to better than 2 ppm.

23. A communication system as claimed in claim 13, wherein the or each local frequency reference unit is an oscillator and the or each frequency adjustment unit is capable of altering the oscillation frequency of the oscillator.

24. A method for adjusting the transmit and/or receive frequency of a transceiver unit in a communication system comprising one or more transceiver units of a first type, the transceiver units of a second type being capable of communicating with the transceiver units of the first type;

the method comprising;

comparing the frequency of a signal received by a transceiver of the first type from a transceiver unit of the second type with a reference frequency;

storing feedback data representative of the result of that comparison in respect of that transceiver unit of the second type; and

adjusting the transmit and/or receive frequency of the transceiver unit of the first type for communication with one of the transceiver units of the second type in accordance with feedback data stored in respect of that transceiver unit of the second type.

25. A method for adjusting a reference frequency of a transceiver unit in a communication system comprising one or more transceiver units of a first type, and two or more transceiver units of a second type, the transceiver units of the second type being capable of communicating with the transceiver units of the first type, each transceiver unit of the second type comprising a local frequency reference unit on which the frequency of signals transmitted by it are dependent;

the method comprising;

comparing the frequency of signals received from transceiver units of the second type with a reference frequency;

forming an offset signal representative of the average offset between the frequency of the received signals and the reference frequency; and

adjusting the reference frequency in accordance with the offset signal.