Wireless location and direction indicator for multiple devices

Details Wireless location and direction indicator for multiple devices Wireless location and direction indicator for multiple devices

2000-06-28

2001-06-12

Ho, Tan (Department: 2821)

Communications: radio wave antennas

Antennas

With means for moving directive antenna for scanning,...

C342S357490

Reexamination Certificate

active

06246376

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to wireless communications, and more particularly to a wireless system and method for locating positions of multiple wireless devices relative to one another.
2. Description of the Prior Art
Today there are handheld global positioning system (GPS) devices available that display the position of the device (longitude and latitude). These devices do not communicate with each other and cannot indicate to each other their positions relative to one another. Further, these devices have undesirable limited accuracy since they make use of non-military GPS systems inhibiting the devices from providing location data having accuracy necessary to locate objects such as a car in a big parking lot, a child in a crowd, child in a theme park, or even a fixed known location (such as a shop in a mall or a booth in an expo).
In view of the foregoing discussion, a need exists in the wireless communications art for a device capable of communicating with other like devices for the purpose of direction finding intended to overcome the absence of GPS data or inaccuracies in such GPS data.
SUMMARY OF THE INVENTION
The present invention is directed to a wireless communications device, e.g. cellular and/or “BLUETOOTH” (see www.bluetooth.com), capable of communicating with like communication devices to transfer identification data and either fixed or variable location data, and analyzing an identified “BLUETOOTH” signal, in combination with indications from an electronic compass, for the purpose of direction finding intended to overcome the absence of GPS data or inaccuracies in such GPS data. Present telecommunication system technology includes a wide variety of wireless networking systems associated with both voice and data communications. One exemplary system is named “BLUETOOTH” after a 10
th
century Scandinavian king who united several Danish kingdoms. This system operates in the 2.4 GHz band and advantageously offers short-range wireless communication between “BLUETOOTH” devices without the need for a central network.
The “BLUETOOTH” system provides a 1 Mb/sec data rate with low energy consumption for battery powered devices operating in the 2.4 GHz ISM (industrial, scientific, medical) band. The current “BLUETOOTH” system provides up to 100-meter range capability and an asymmetric data transfer rate of 721 kb/sec. The protocol supports a maximum of three voice channels for synchronous, CVSD-encoded transmission at 64 kb/sec. The “BLUETOOTH” protocol treats all radios as peer units identified by unique 48-bit addresses. At the start of any connection, the initiating unit is a temporary master. This temporary assignment, however, may change after initial communications are established. Each master may have active connections of up to seven slaves. Such a connection between a master and one or more slaves forms a “piconet.” Link management allows communication between piconets, thereby forming “scattemets.” Typical “BLUETOOTH” master devices include cordless phone base stations, local area network (LAN) access points, laptop computers, or bridges to other networks. “BLUETOOTH” slave devices may include cordless handsets, cell phones, headsets, personal digital assistants, digital cameras, or computer peripherals such as printers, scanners, fax machines and other devices.
The “BLUETOOTH” protocol uses time-division duplex (TDD) to support bi-directional communication. Frequency hopping spread-spectrum technology accommodating frequency diversity permits operation in noisy environments and permits multiple piconets to exist in close proximity. This is so since frequency diversity is inherent in frequency hopping, especially when it is wide, as in the case of “BLUETOOTH” (spread over a band of about 80 MHz). The frequency hopping transmission hops at a rate of 1600 hops per second over 791-MHz channels between 2402 MHz and 2480 MHz. Various error-correcting schemes permit data packet protection by ⅓- and ⅔-rate forward error correction. Further, “BLUETOOTH” uses retransmission of packets for guaranteed reception. These schemes help correct data errors, but at the expense of throughput.
A wireless location and direction indicator device in one embodiment of the present invention is equipped with a cell phone having a micro controller unit (MCU), a GPS receiver, a “BLUETOOTH” unit and a ‘Northfinder’. The device protocol communicates its present location to a trusted device such as another like device having GPS capability. When a user activates a specific protocol on device A, it pages device B and requests location data specific to device B. Device B transmits the requested location data and device A then uses the information transmitted by device B in combination with the angle (0) between the axis of device A and North that is provided by the Northfinder, as well as device A's own position to display the direction and distance to device B on the display of device A. The direction indication on the screen of device A is most preferably updated continuously since device B may have moved along with its user. Radio communication between device A and device B is implemented using “BLUETOOTH” techniques or by alternative cellular techniques when an extended communication range is required.
GPS is an accurate three-dimensional global positioning satellite system which provides radio positioning and navigation needs. A GPS receiver and data processor is hosted by the present portable location and direction indicator. Generally, the GPS is initiated when the receiver starts to track pseudo-random noise from a plurality of satellites and generates time-of-arrival values. Thereafter, the GPS data processor takes over. The GPS data processor first samples the time-of-arrival values from the GPS constellation for each of the aforesaid plurality of satellites and multiplies the sample data by the speed of light to produce a plurality of pseudo-range measurements. The data processor then adjusts these pseudo-range measurements to compensate for deterministic errors such as the difference between each satellite's clock and GPS system time, atmospheric distortion of the signals and other considerations such as relativity factors. The GPS receiver includes an instruction set which gathers the information necessary to compute adjustments to the pseudo-range measurements from a 50 Hz digital data stream which the satellites broadcast along with their precision and coarse acquisition code. After the data processor makes all the necessary adjustments to the pseudo-range measurements, it then performs the position/time solution process to determine the present GPS receiver antenna position. The data processor computes its X, Y, Z position fix in terms of the World Geodetic System adapted in 1984, which is the basis on which the GPS develops its worldwide common grid references. Generally, the X, Y, Z coordinates are converted to latitude, longitude and altitude map datum prior to output or display. The GPS position solution is intrinsically referenced to the electrical phase center of the antenna. Finally, the data processor computes clock bias results which are one of the parameters to be considered in addition to the X, Y, Z coordinates. The clock bias is computed in terms of the time offset of the clock in the GPS receiver versus GPS system time. Accordingly, the present portable location and direction indicator receives the GPS position data which information is processed via the host processor such as a digital signal processor (DSP) to establish the present position.
As used herein, the following words have the following meanings. The words “algorithmic software” mean an algorithmic program used to direct the processing of data by a computer or data processing device. The words “data processor” and “data processing device” as used herein refer to a CPU, DSP, microprocessor, micro-controller, or other like device and an interface system. The interface system provides access to the data processing device such

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