Source: http://www.google.ca/patents/US6812824
Timestamp: 2015-11-27 08:24:06
Document Index: 314666393

Matched Legal Cases: ['application No. 60', 'application No. 09', 'application No. 60', 'application No. 09', 'application No. 09', 'application No. 60', 'application No. 08', 'art 15']

Patent US6812824 - Method and apparatus combining a tracking system and a wireless ... - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsSystem for tracking mobile tags. Cell controllers with multiple antenna modules generate a carrier signal which is received by the tags. Tags shift the frequency of the carrier signal, modulate an identification code onto it, and transmit the resulting tag signal at randomized intervals. The antennas...http://www.google.ca/patents/US6812824?utm_source=gb-gplus-sharePatent US6812824 - Method and apparatus combining a tracking system and a wireless communication systemAdvanced Patent SearchPublication numberUS6812824 B1Publication typeGrantApplication numberUS 09/517,606Publication date2 Nov 2004Filing date2 Mar 2000Priority date17 Oct 1996Fee statusPaidPublication number09517606, 517606, US 6812824 B1, US 6812824B1, US-B1-6812824, US6812824 B1, US6812824B1InventorsJames Goldinger, Colin Lanzl, Jay WerbOriginal AssigneeRf Technologies, Inc.Export CitationBiBTeX, EndNote, RefManPatent Citations (172), Non-Patent Citations (11), Referenced by (397), Classifications (37), Legal Events (9) External Links: USPTO, USPTO Assignment, EspacenetMethod and apparatus combining a tracking system and a wireless communication system
US 6812824 B1Abstract
System for tracking mobile tags. Cell controllers with multiple antenna modules generate a carrier signal which is received by the tags. Tags shift the frequency of the carrier signal, modulate an identification code onto it, and transmit the resulting tag signal at randomized intervals. The antennas receive and process the response, and determine the presence of the tags by proximity and triangulation. The recursive-least squares (RLS) technique is used in filtering received signals. Distance of a tag from an antenna is calculated by measuring the round trip signal time. The cell controllers send data from the antenna to a host computer. The host computer collects the data and resolves them into positional estimates. A combined infrastructure including a wireless communication system and the local positioning system is also disclosed.
a radio frequency identification tag that transmits a first signal in a first frequency range; a wireless communication system that transmits a second signal in a second frequency range that is different from the first frequency range; an antenna module used in receiving the first signal from said radio frequency identification tag, said antenna module also used in transmitting and receiving signals used in said wireless communication system for communication between devices other than radio frequency identification tags, wherein said devices are physically separate from a radio frequency identification tag, and the communication between said devices is unrelated to communication with radio frequency identification tags; and a controller coupled to said antenna module, said controller being used in communications with said radio frequency identification tag and said wireless communication system. 2. The system of claim 1, further including a first transmitter for transmitting signals to said radio frequency identification tag and a second transmitter for transmitting signals to said wireless communication system.
3. The system of claim 2, wherein said first and second transmitters transmit at different frequencies.
4. The system of claim 3, wherein said antenna module is also used in transmitting signals to said radio frequency identification tag.
5. The system of claim 2, further including a first receiver for receiving the first signal from said radio frequency identification tag and a second receiver for receiving the second signal from said wireless communication system.
6. The system of claim 5, wherein said wireless communication system operates in accordance with a DECT wireless communication standard.
7. The system of claim 5, wherein said radio frequency identification tag receives a third signal at a third frequency and transmits the first signal at the first frequency.
8. The system of claim 7, wherein said first frequency and said third frequency are different.
9. The system of claim 7, wherein said wireless communication system operating at the second frequency is non-interfering with operation of said radio frequency identification tag at said first frequency.
10. The system of claim 9, further including a tag reader for detecting a presence of said radio frequency identification tag and for use in operation of said wireless communication system.
11. The system of claim 9, wherein said wireless communication system is a cordless PBX product.
12. The system of claim 1, wherein said antenna module operates in a first mode for detecting said presence of said radio frequency identification tag and a second mode for use in said wireless communication system.
13. The system of claim 12, wherein said antenna module includes a transmitter and a receiver.
14. The system of claim 1, wherein said radio frequency identification tag is used in locating an object associated with said radio frequency identification tag.
15. The method of claim 14, wherein said antenna module is also used in transmitting signals to said radio frequency identification tag.
a radio frequency identification tag transmitting a first signal at a first frequency; a wireless communication system that transmits and receives second signals in a second frequency range; a remote antenna module for receiving said first signal at said first frequency and for transmitting and receiving said second signals in said second frequency range, said second signals being for communication between devices other than radio frequency identification tags, wherein said devices are physically separate from a radio frequency identification tag, and the communication between said devices is unrelated to communication with radio frequency identification tags; a frequency converter included in said remote antenna module for converting said first signal at said first frequency to a third signal at a third frequency that is less than said first frequency; and a cable for transmitting said third signal at said third frequency from said remote antenna module to a tag reader. 17. The radio frequency identification system of claim 16, wherein said cable is a first cable, said frequency converter is a first frequency converter, and further comprising:
a transmitter included in said tag reader for transmitting a fourth signal at a fourth frequency; a second cable for transmitting said fourth signal at said fourth frequency to said remote antenna module; a second frequency converter included in said remote antenna module for converting said fourth signal at the fourth frequency to a fifth signal at a fifth frequency that is greater than said fourth frequency; an antenna included in said remote antenna module for transmitting said fourth signal at said fourth frequency; and a receiver included in said radio frequency identification tag for receiving said fifth signal at said fifth frequency. 18. The radio frequency identification system of claim 16, wherein said tag reader transmits and receives signals from said radio frequency identification tag.
19. The radio frequency identification system of claim 16, wherein said radio frequency identification tag transmits and receives signals.
20. A method for locating objects and operating a wireless communication system comprising:
receiving first signals in a first frequency range with an antenna module from a radio frequency identification tag; transmitting and receiving second signals in a second frequency range that is different from the first frequency range with said antenna module from said wireless communication system, said second signals being for communication between devices other than radio frequency identification tags, wherein said devices are physically separate from a radio frequency identification tag, and the communication between said devices is unrelated to communication with radio frequency identification tags; and controlling, with a controller that is coupled to said antenna module, communications with said radio frequency identification tag and said wireless communication system. 21. The method of claim 20 further including:
transmitting, with a first transmitter, third signals to said radio frequency identification tag and; transmitting, with a second transmitter, said second signals to said wireless communication system. 22. The method of claim 21, wherein said first and second transmitters transmit at different frequencies.
receiving, at a first receiver, signals from said radio frequency identification tag; and receiving, at a second receiver, signals from said wireless communication system. 24. The method of claim 23, wherein said first and second receivers operate at different frequencies.
25. The method of claim 24, wherein said wireless communication system operates in accordance with a DECT wireless communication standard.
26. The method of claim 23, wherein said radio frequency identification tag receives a signal at a third frequency and transmits a first signal at a first frequency.
27. The method of claim 26, wherein said first frequency and said third frequency are different.
28. The method of claim 26, wherein said radio frequency identification tag operates at a first frequency and said wireless communication system operates at a second frequency that is non-interfering with operation of said radio frequency identification tag at said first frequency.
detecting, using a tag reader, a presence of said radio frequency identification tag wherein said tag reader is also used in operation of said wireless communication system. 30. The method of claim 28, wherein said wireless communication system is a cordless PBX product.
31. The method of claim 29, wherein said tag reader operates in a first mode for detecting said presence of said radio frequency identification tag and a second mode for use in said wireless communication system.
32. The method of claim 31, wherein said tag reader includes a transmitter and a receiver.
33. The method of claim 20, further including:
using said radio frequency identification tag to locate an object associated with said radio frequency identification tag. 34. The method of claim 33, further including:
transmitting signals from said radio frequency identification tag using said antenna module. 35. A method for locating objects comprising:
transmitting a first signal at a first frequency from a radio frequency identification tag; receiving said first signal at said first frequency at a remote antenna module; converting, by a converter included in said remote antenna module, said first signal at said first frequency to a second signal at a second frequency that is less than said first frequency; transmitting said second signal at said second frequency from said remote antenna module to a tag reader using a cable; and receiving, with the remote antenna module, a third signal at a third frequency from a wireless communication system, said third signal being for communication between devices other than radio frequency identification tags, wherein said devices are physically separate from a radio frequency identification tag, and the communication between said devices is unrelated to communication with radio frequency identification tags. 36. The method of claim 35, wherein said cable is a first cable, said converter is a first converter, and further comprising:
transmitting, using said tag reader, a fourth signal at a fourth frequency; transmitting, using a second cable, said fourth signal at said fourth frequency to said remote antenna module; converting, using a second converter included in said remote antenna module, said fourth signal at said fourth frequency to a fifth signal at a fifth frequency that is greater than said fourth frequency; transmitting said fifth signal at said fifth frequency to said remote antenna module; and receiving said fifth signal at said fifth frequency using a receiver included in said radio frequency identification tag. 37. The method of claim 35, wherein said tag reader transmits and receives signals from said radio frequency identification tag.
38. The method of claim 35, wherein said radio frequency identification tag transmits and receives signals.
This application claims the benefit of the filing date of U.S. provisional application No. 60/122,720, filed Mar. 3, 1999. This application is a continuation-in-part of U.S. non-provisional application No. 09/378,417 now abandon, filed Aug. 20, 1999, which claims the benefit of U.S. provisional application No. 60/097,370, filed Aug. 21, 1998. This application is a continuation-in-part of U.S. non-provisional application No. 09/339,740 now U.S. Pat. No. 6,353,406, filed Jun. 24, 1999, which claims the benefit of U.S. provisional application Nos. 60/090,556, filed Jun. 24, 1998 and 60/130,163, filed Apr. 20, 1999. This application is a continuation-in-part of U.S. non-provisional application No. 09/244,600, now abandon, filed Feb. 4, 1999, which claims the benefit of U.S. provisional application No. 60/102,843, filed Oct. 2, 1998. This application is a continuation-in-part of U.S. non-provisional application No. 08/953,755, filed Oct. 17, 1997, which claims the benefit of U.S. provisional application Nos. 60/028,658, filed Oct. 17, 1996; 60/044,321, filed Apr. 24, 1997; and 60/044,245, filed Apr. 24, 1997.
The invention relates to tracking systems and, more particularly, to systems designed to track articles and personnel.
Various techniques may be used to track articles and personnel. Global positioning systems and local positioning systems are examples that may be used depending on the particular items or persons being located. Included as part of these systems are various embodiments of hardware and software. The hardware may be used, for example, to collect data about the various entities being tracked or located.
Long range identification or tracking systems are designed to read large numbers of tags every few seconds, wherever they may roam in a bounded environment. For low cost and small size, these tags may be e usually low-powered, for example, emitting in the range of 1-10 mW. Under ideal conditions, read ranges up to about 100 meters can be realized. Alternatively, in a more cluttered indoor environment, read ranges more like 25 meters is typical. As a practical matter, an antenna placed every 20 meters or so is often needed for reliable coverage of a complete indoor space. In such instances, installing an antenna every 20 meters can pose a substantial installation challenge. In some cases, cable installation costs can exceed hardware costs, and the installation process can cause significant business disruption. Therefore, it is desirable to find additional uses for the same antennas such as enabling one installation to be used for several purposes.
In accordance with one aspect of the invention is a system. The system includes a radio frequency identification tag, a wireless communication system, an antenna module, and a controller. The antenna moduel is used in transmitting and receiving signals from the radio frequency identification tag. The antenna module is also used in transmitting and receiving signals used in the wireless communication system. The controller is coupled to the antenna module. The controller is used in communications with the radio frequency identification tag and the wireless communication system.
In accordance with another aspect of the invention is a method for locating objects and operating a wireless communication system. Signals are transmitted and received using an antenna module from the radio frequency identification tag and from the wireless communication system. A controller is coupled to the antenna module and used in communications with the radio frequency identification tag and the wireless communication system.
FIG. 1 shows an overview of a positioning system;
FIG. 3 is a block diagram of a tag RF design;
FIG. 15B is a flowchart depicting method steps of one embodiment of the Signal processing hard ware unit of FIG. 10;
FIG. 18 is a flowchart depicting method steps of one embodiment of the recursive-least squares (RLS) technique as used in a method step of FIG. 15B;
FIGS. 19A-19E are diagrams of sample waveforms in embodiments of the system of FIG. 1;
FIG. 20 is a flowchart depicting method steps of one embodiment of approximating a peak of the filtered tag signal;
FIG. 25 is an example of another embodiment of a position system;
FIG. 26 is an example of an architecture of a local positioning system (LPS) cell controller;
FIG. 27 is an example of an embodiment of a “fixed” portion of a digital enhanced cordless telecommunications (DECT) installation;
FIG. 28 is an example of an embodiment of a single base station supporting DECT and LPS systems;
FIG. 29 is an example of the Second IF Carrier Recovery, Demodulator, and AGC component of FIG. 21; and
FIG. 30 is an example of another embodiment of a system including integration of LPS technology.
Radio Frequency Identification (RFID) products typically have three components: (1) a tag (the item being identified), (2) an interrogator (a device which detects the presence of a tag), and (3) a system (typically including cabling, computers, and software which tie together the tags and interrogators into a useful solution). RFID products are typically designed to detect tags when they pass within range of a few fixed or handheld interrogators.
The tags in a passive RFID system do not carry on-board power. The interrogator in such systems transmits operating power for the tags. Such systems generally have a detection range of a meter or less, although somewhat longer ranges have been achieved. Typically, these systems operate in the 125-kilohertz or 13.56 megahertz radio band.
Although some passive RFID systems are read-only (that is, the tags in such system respond to a query by reading information from their memory and sending the information back to the interrogator), the tags used in other passive RFID systems have a limited ability to accept information and instructions from the interrogator, for example read/write capabilities in smart cards (electronic money) and “electronic manifests” in industrial applications.
Active RFID systems require battery-powered tags. The battery permits a longer detection range of between 3 and 100 meters. These systems are capable of locating tags with higher accuracy than passive RFID systems and typically operate in the 400, 900, 2440, or 5800 megahertz bands. Active tags tend to enable multiple tags to be within range of an interrogator by the use of “handshaking” between the tags and interrogator, so that each tag transmits its signal in turn. Communication between tag and interrogator in active RFID systems is also typically faster than with passive tags.
EAS systems are intended to deter theft in retail environments. EAS tags are fairly unreliable, very low in cost, and limited in capabilities. Although they track mobile tags, they are not generally considered to be identification products, because EAS tags are uncoded and cannot be distinguished from one another.
Tags: Inexpensive miniature radio frequency transponding tags 101 a-c are attached to people and/or items being tracked. Tags 101 a-c “wake up” periodically, and “chirp” (transmit) a radio-coded unique identity code (UID). The tags 101 a-c are designed so that their range is 50-100 meters in a typical indoor environment, the range mostly being limited by a need to conserve the life of the tag battery, and the requirement that the tag 101 a and tag battery be small and thin.
The tag 101 a does not generate its own radio signal. Rather, an antenna module, for example antenna module 104 a, continuously transmits a direct sequence spread spectrum interrogator signal 106 at a first frequency, for example 2440-megahertz. The tag 101 a receives this signal 106, modulates its UID code onto the signal 106, and immediately transmits back a frequency-shifted signal 107 at, for example, 5800-megahertz to, for example, antenna 104 a. The distance from the antenna module 104 a to the tag 101 a can then be determined by the cell controller 102 a from the round trip time of transmission, accounting for fixed and known delays in the wiring and electronics. The cell controller 102 a can quickly switch among antenna modules 104 a-d to obtain the distance from the tag 101 a to each of antenna modules 104 a-d (which receive the return signal 107), and from that information determines the tag's location by triangulation techniques.
If a user desires to locate tags by “zone,” one antenna per zone can be installed. Users wishing to track one or more tags 101 a-c moving down hallways, can install antenna modules 104 a-d every 20 or so meters along a hallway 130 a-c, and calculate the linear location of a tag 101 a by measuring the distance from the tag 101 a to those antenna modules 104 a-d. Customers wishing to triangulate upon the location of a tag 101 a may install enough antenna modules such that the tag 101 a will be in range of at least two or three of the antenna modules, depending on the coverage of the antenna modules and the geometry of the facility. A typical installation will cover a complete facility 110 with a combination of “zone” and “hallway” coverage at a relatively low cost per square foot, and, over time, upgrade certain areas with enough antenna modules to triangulate upon a tag's position.
The frequency mixer 304 translates or shifts the carrier frequency from 2440 megahertz to 5800 megahertz. The incoming signal, with a center frequency of 2440 megahertz, is mixed with the output of a phase locked oscillator (PLO) 305 with a center frequency of 3340 megahertz. This results in a sum frequency of 5800, along with a difference frequency and a variety of harmonics and subharmonics which are removed with a bandpass filter 306. In one embodiment, the PLO 305 consists of a phase locked loop (PLL) chip with three inputs: (1) a sampled output from a voltage controlled oscillator (VCO); (2) a reference tone from a 10 megahertz oscillator; and (3) a frequency programming interface to a microprocessor 308. This generates a pure tone with good phase noise at the 3340-megahertz tag LO frequency. In an alternative embodiment, the PLO 305 outputs a 1670-megahertz tone, which is then doubled to give the desired 3340-megahertz result.
The next element of the tag RF circuitry 300 is a biphase modulator 307 which, under control of the microprocessor 308, can either pass the 5800-megahertz signal unaltered, or change the phase of the signal by 180 degrees. The modulator 307 is implemented as a single pole double throw RF switch 801 that feeds a 180 degree hybrid, as shown in FIG. 8. Several forms of modulation can be used, including on-off keyed (OOK) modulation, binary phase-shift keyed (BPSK) modulation, multiple phase-shift keyed (MPK) modulation, and quadrature amplified (QAM) modulation. BPSK is the preferred form of modulation. The output from the modulator 307 is fed into an amplifier 310, then is filtered by a transmitter bandpass filter 311, and the output of filter 311 is emitted from a transmit antenna 312 as the tag signal 107. Since the amplifier 310 operates at high frequency, it consumes significant power, and alternative embodiments (such as that shown in FIG. 4) that make this amplifier 310 unnecessary are preferred. The Tx Filter 311, implemented as a 5-pole filter, is necessary to ensure tag compliance with FCC Part 15 requirements.
Not shown in FIG. 4, but desirable for some applications, is an embodiment where the transmit antenna 409 and receive antenna 401 are combined int