Execsum

ÆTHER WIRE & LOCATION, INC.

ULTRA-WIDEBAND LOCALIZERS
Executive Summary

Knowing position location is of immense value to many military and commercial applications. The significant cost and size reduction of GPS receivers has fueled awareness of this fact in recent years. Æther Wire has developed a position location and communication system which overcomes the limitations that make other location systems unsuitable for most imagined applications. Other localization systems give absolute position on the geoid (i.e. GPS), location relative to fixed beacons (e.g. LORAN), or location relative to a starting point (i.e. inertial platforms). For most applications, what is really desired is location relative to other people or objects, whether moving or stationary, or the location within a building or an area. Moreover, the range and resolution of the position location needs to be proportionate to the scale of the objects being located. Æther Wire’s system provides relative position location within a network of RF transceivers (Localizers) distributed in the environment Our technology is capable of localization to centimeter accuracy over kilometer distances, and unlike GPS, can operate within buildings, urban areas, or forests. Also, our Localizers inherently share position location information throughout the network, while most other localization systems require a separate communication channel.

FIGURE 1. Photo of fourth generation Localizer prototype. This view shows the Receiver/control chip in its custom plastic package and the transmit antenna driver chip in its custom ceramic package. The receive antenna in the foreground and the transmit antenna behind are typical. The microprocessor, RAM, and Flash EPROM are on theback side of the PC board. The board dimensions are 2.0" x 3.6".

The most significant aspect of Æther Wire’s technology is that Localizers can be totally integrated in low-cost CMOS circuits. The combination of communication andaccurate position location capability within devices that are essentially "throw-away," opens up a host of applications. A sampling of military and commercial applications includes:.

Monitoring large numbers of sensors dispersed over an area for nuclear, biological, or chemical threats.
Geospatial registration for warfighter visualization.
Synthesis of large aperture antennas for tight beam communication, using scattered transceivers that know their precise relative location and synchronization.
Survey and construction.
Keeping track of mines, armaments, equipment, vehicles, etc.
Keeping track of personal items, such as one’s children, pets, car, purse, luggage, etc.
Inventory control in stores, warehouses, shipyards, railroad yards, etc.
Safety - Finding fire fighters in a burning building, police officers in distress, or injured skiers on a ski slope.
Sports - Arbitrating rules in a game, playback of motions for coaching, or viewing the re-creation of an event.
Home automation - Keyless locks and rooms that adjust the light, temperature, and music sound level.
Motion pictures - Automatically adjusting camera focus and motion-tracking for matching digital effects

FIGURE 2. This diagram shows a network of 5 Localizers, where each Localizer determines the range to every other Localizer and then shares the information with membersof the network. In the diagram, Localizer D is ranging between itself and A, B, C, and E. With 4 Localizers knowing all the ranges between them, a rigid tetrahedral structure is determined (assuming no 3 Localizers are collinear). Each Localizer can then be in one of two 3-dimensional locations with respect to the other 3 Localizers.Having a 5th Localizer resolves this ambiguity.

Position location is determined by sharing range information within a network of transceivers that resolve their separation by cooperatively exchanging an electromagnetic signal (Figure 2). The accuracy of this range determination is a function of the bandwidth of the exchanged signal. With conventional sinewave technology, the bandwidth of the signal relative to the carrier frequency is very small ¾ at most a few percent using spread spectrum. Ultra-wideband signals, consisting of electromagnetic impulses, have a relative bandwidth approaching 100%. Historically, ultra-wideband radiation has been used almost exclusively for anti-stealth and ground-probing radar. However, ultra-wideband radiation has unique advantages when used, at much lower power levels than radar, for communication and position location:.

Centimeter-level accuracy in determining range is possible without using expensive microwave (GaAs MMIC) technology, because gigahertz bandwidth is obtained without a carrier in the 50 GHz range.
Transceivers can be made very small (i.e. coin size), low power, low weight, and low cost because the electronics can be completely integrated in CMOS without any inductive components. MEMS can be used to integrate the resonator for the timebase on chip as well.
The antennas can be equally small, and can be driven directly by CMOS, because they are non-resonant, current-mode, and low voltage.
Ultra-wideband signals form a shadow spectrum which can coexist and does not interfere with the sinewave spectrum. The transmitted power is spread over such a large bandwidth that the amount of power in any narrow frequency band is very small.
The good features of spread spectrum are shared, including multipath immunity, tolerance of interference from other radio sources, and inherent privacy from eavesdropping (low probability of intercept).
Ultra-wideband signals have very good penetrating capabilities. Transceivers can operate within buildings, urban areas, and forests.

FIGURE 3. Current generation of Receiver chip (Aether4) on the left, and Transmitter chip (Driver2) on the right. The center photo shows both chips (on top of a dime) at roughly 3X magnification. The major structure in the bottom left quadrant of the Receiver chip is composed of 32 Time-Integrating Correlators. To the right of this is the 1GHz bandwidth RF amplifier. The PLL and Real-Time Clock occupy the top left quadrant, and to the right are the two LFSR code sequence generators. The bottom third of the Transmitter chip includes the edge delay controls and a stand-alone code sequence generator. The H-bridge Transmitter antenna driver fills the top two-thirds of the chip.

Æther Wire’s current fourth generation Localizer prototype is already pager-sized (Figure 1).

Further reduction in size, power, and cost will be achieved by increased integration of Æther Wire’s CMOS integrated circuits with functions now performed on the PC board by separate commercial chips.
Greater range and resolution will require research and development of: (a) improved receive antennas and amplifiers for ultra-wideband signals; and (b) smaller transmit antennas and drivers that radiate higher power impulses more efficiently and with greater control of the waveform. We are currently collaborating with other researchers on this task.
Higher data rates will be achieved by replication of some of the on-chip circuits, and by implementation in software of more sophisticated modulation and detection schemes..

In 1991, we realized the huge potential for small, low-cost devices capable of accurately determining 3D position location. We started an R&D effort that, unlike other researchers in the ultra-wideband field, had the long term goal of producing totally integrated transceivers. To this end, we have designed and built a series of increasingly more capable breadboard / prototype units, using our own custom chips, that implement and validate more of the complete system. With each succeeding prototype generation, we have integrated more functions which were done with commercially available chips in the previous generation. The size has shrunk from breadbox, to shoebox, to cellphone, to pager-sized for our fourth generation prototype. At the same time, the resolution and range have improved. The third generation units have about 3 centimeters resolution with 10 meters range. We expect the fourth generation units will have at least 1 centimeter resolution with 30–60 meters range. After two years of self-funded R&D, Æther Wire as incorporated and the development effort was expanded by obtaining outside funding. In the fall of 1993, Æther Wire closed a round of private investment and was awarded a DARPA grant to continue development of Localizers. In the spring of 1995, Æther Wire received a seed round of venture capital from Helix Investments, Ltd. In 1998, Æther Wire was awarded a $1.8 million DARPA grant to further develop Localizer technology. The first of several Localizer-related patents (#5748891) issued in May 1998. We anticipate that we will be able to raise additional venture capital to commercialize applications that can be served by pager-sized devices when the fourth generation software and hardware are completed, tested, and are sufficiently robust.

FIGURE 4. Æther Wire’s Volumetric Inventory System concept of operation.

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