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To: Sector Investor who wrote (1517)10/29/2002 10:13:09 PM
From: Sector Investor
   of 6947
 
Optics, electronics merge to provide a sense of where you are: fiber-optic-based gyroscopes can provide good accuracy at modest cost using century-old principles.
By: Bill Schweber EDN Published 05/29/02

Abstract

Although the gyro is a mechanical device and thus subject to wear and drift, designers have refined it over the last 60 years so that a gyro-based navigation system can provide extraordinary accuracy and reasonable reliability (Reference 1).

Full Text

MOST ENGINEERS ARE FAMILIAR with the mechanical gyroscope, which you can use either to maintain a fixed heading as a gyrocompass or to provide inertial navigation information when you combine it with accelerometers. Although the gyro is a mechanical device and thus subject to wear and drift, designers have refined it over the last 60 years so that a gyro-based navigation system can provide extraordinary accuracy and reasonable reliability (Reference 1). Further, unlike mostly mechanical gyro systems of the 1940s and 1950s, today's gyro-navigation units use sophisticated real-time algorithms to compensate for known errors and drifts, as well as to implement statistical models of sources of errors.

But you're wrong if you think that the gyroscope function for navigation is now obsolete due to the availability of satellite-based navigation and low-cost GPS chip sets. GPS has several major draw-backs. For example, it doesn't work in tunnels, in underground oil and gas wells, in submersible research vehicles, or outside the low orbit of the GPS satellites. Further, inadvertent interference and deliberate spoofing can corrupt the signal, and the time to deliver an initial valid position readout is approximately a minute.

For these and other reasons, GPS alone is unsuitable for many applications. However, the combination of a gyro and GPS can provide an accurate and reliable relative-motion system that tells you how much you have moved and is useful for remote-operated vehicles, submersibles, and tunnel exploration. This combination is also useful for an absolute-motion navigation-grade system that tells you exactly where you are, such as those that missile and satellite guidance need.

Yet the established mechanical gyro is meeting its match from several sources. One approach uses MEMS (microelectrical-mechanical-system) structures to provide the moving-element functions but on a much smaller mechanical scale and with new techniques to overcome traditional error sources. Long-established gyro experts, such as The Charles Stark Draper Laboratories (www.draper.com), are exploring this approach.

Another successful technique uses laser-sourced beams of light passed around a ring or an optical fiber, with interference patterns indicating any rotation of the gyro platform. These optical gyros are now available from many sources, such as KVH Industries (www. kvh.com), Sperry Marine (www.sperry-marine. com), and Honeywell (www.ais.honeywell.com).

Physicist Francis Harress in 1911 first observed the principle in the optical gyro, and physicist Georges Sagnac in 1913 also observed it. Literature now refers to it as the Sagnac Effect. This effect is an outgrowth of the work of physicist Albert Michelson and chemist Edward Morley, who won the Nobel Prize in 1907. Their 1881 interferometry experiment demonstrated that the Earth does not travel through any ether, and this experiment foreshadowed Albert Einstein's radical assumption on the constancy of the speed of light regardless of any motion of the light source or observer.

In the Sagnac demonstration, a polarized beam of light splits into two beams, and the beams move in opposite directions through a ring path--usually, triangular or square with mirrors at the corners--or an optical fiber. After their counterrotating trips around the ring or fiber, the beams emerge and interfere with each other. If the unit does not rotate, the beams travel the same distance and thus cancel each other out when they emerge. However, if the unit rotates while the beams are passing through, one beam travels a shorter distance, and the other travels a longer distance, due to relativistic effects. The differing travel times produce a shift in the interference pattern, which an optical detector can sense. A complete optical gyro requires other components, as well (Figure 1). You can find more detailed explanations of the Sagnac Effect, actual implementations, and underlying equations in references 2, 3, 4, and 5.

[FIGURE 1 OMITTED]

Although the understanding of the Sagnac Effect depends on relativity theory, the actual setup appears fairly straightforward. Don't assume, though, that building a practical optical gyro should also be straightforward. Although demonstrating the principle doesn't require even a laser as a light source, building a reasonably accurate gyro involves understanding and minimizing many of the sources of error and signal contamination, just as with any precision instrumentation. Until the 1980s, when optical gyros found use in commercial aircraft, such as the Boeing 777, they were too imprecise and non-repeatable for basic, moderate-accuracy applications.

In the first optical gyros, RLG (ring-laser-gyro) designs, the light beam travels through an evacuated path acting as a wave-guide; high-reflectance mirrors are precisely mounted at the corners of the RLG square or triangle. The RLG path can be a few meters long; higher precision applications require paths of tens of meters, but these paths are impractical for most uses.

FOG GETS YOU OUT OF THE FOG

As optical fiber technology improved, IFOGs (interferometric fiber-optic gyros), commonly called FOGs, have become practical alternatives. In this design, the light path is not a hollow-light waveguide but an optical fiber. One advantage of this approach is that it requires no corner mirrors, which mandate precise and rugged mounts. Another advantage is that you can build the light path as a compact, coiled fiber tens of meters long, which holds the potential for greater accuracy and improved low-rate-resolution performance.

The RLG design and, to a greater extent, the FOG design, offers many practical and cost advantages over mechanical gyros. One advantage of these newer designs is that you can strap them down to vehicles because they have no internal gimbals. As with other technological advances, the principle may be relatively simple, but a precise application means identifying and then eliminating or compensating for first- and second-order error sources. For example, a light-source laser must have both short--and long-term stability in its wavelength and its output power. Note that an RLG requires a more powerful light source than does an FOG because, in an RLG, the light source does not move down a thin fiber.

Any temperature change causes changes in an RLG's optical path length and thus the light wave's phase. In one precision implementation of the RLG, the device measures the relatively low rate of the earth's rotation and bores it into a block of glass-ceramic material having a near-zero temperature coefficient of expansion (Reference 6). The light path in the RLG must be a high vacuum, so that air or other molecules don't interfere with the light waves. The beams, which should be independent as they travel past each other, can sometimes lock in and synchronize with each other at low angular rotation rates due to interbeam crosstalk that arises when the corner mirrors are less than perfect and scatter some of the incident light. The designers of the implementation minimized the problem by using multilayer dielectric mirrors with 99.9999% power reflection.

The FOG has subtleties of its own. For example, any strain on the fiber and how it is supported or wound causes phase shifts, signal dispersion, or polarization changes, which translate into errors that can swamp the desired result (Reference 7). FOG manufacturer KVH Industries makes its own fiber with an elliptical cross-section, rather than the standard, widely available communications fiber, because the elliptical shape counteracts some polarization issues. The sensitivity of the FOG depends on both fiber length and diameter: Longer, thinner fiber provides a better rotation rate--but at the cost of other potential trade-offs--than shorter, wider fiber.

Nongimbaled, strap-down FOGs--especially when you combine them with a GPS system and even accelerometers to sense linear-axis motion--offer many potential advantages over gimbaled, mechanical gyros. Processor-based computational algorithms can compensate for many errors and also integrate motion data from other position and motion sources to provide an easy-to-use, calculated, highly accurate output. A compact single-axis FOG, such as the KVH DSP-5000, costs approximately $4000, provides output-scale-factor accuracy of 0.05%, and is usable at angular rates as fast as 500[degrees]/sec or as low as tens of degrees per second (Figure 2).

[FIGURE 2 OMITTED]

ACKNOWLEDGMENTS

Thanks to Jay Napoli at KVH Industries for his insight and assistance.

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To: Sector Investor who wrote (1518)10/31/2002 7:34:32 AM
From: Sector Investor
   of 6947
 
KVH Industries, Inc. (ticker: KVHI, exchange: NASDAQ) News Release - 10/31/2002
New KVH TracNet 2.0 Offers Lower-cost, Faster Mobile High-speed Internet Access

MIDDLETOWN, R.I., Oct 31, 2002 /PRNewswire-FirstCall via COMTEX/ --

Enhanced System Expands Coverage Areas, Lowers Airtime Rates, and Provides Greater Versatility via Exclusive Broadband Service

KVH Industries (Nasdaq: KVHI), the company that pioneered in-motion broadband Internet access, introduced its new, faster TracNet(TM) 2.0 Mobile High-speed Internet System today at the Ft. Lauderdale International Boat Show. TracNet 2.0 offers an expanded array of features that make it the most versatile mobile broadband Internet system available to mariners throughout North America. Among these enhancements are standard coverage that now includes Alaskan and Caribbean waters, KVH's integrated Velocity(TM) Acceleration software that significantly boosts transmission speeds, and the ability to maintain a two-way Internet connection even when the TracVision antenna is being used for satellite TV reception. In addition, KVH is reducing TracNet mobile airtime rates by 40%, making the service even more affordable.

"TracNet 2.0 is a dynamic link to the Internet, e-mail, and company networks thanks to its combination of high-powered mobile DirecPC downloads, built-in networking, and extended coverage capabilities," explained Ian Palmer, KVH vice president of satellite sales. "No other system can offer the range of capabilities built into TracNet 2.0, such as Internet downloads at speeds reaching 400 Kbps and simultaneous Internet access by up to 5 separate users. The first TracNet was a breakthrough combination of technology. We have now built on that initial success and launched an even more versatile system. Whether you need Internet access for business, pleasure, or vital information, TracNet 2.0 is your gateway to the Internet, wherever you travel."

The TracNet 2.0 system uses a powerful server/router, mobile return paths, the mobile DirecPC(R) Internet service, and a KVH TracVision(R) satellite TV antenna to provide two-way, high-speed access to the Internet even when underway. Broadband downloads are received by the TracVision antenna and are available within the mobile DirecPC coverage area, which encompasses the continental U.S., Canada, and as far as 100 miles off the coast.

TracNet 2.0's standard coverage area, which includes Caribbean waters and Alaska, provides two-way access at speeds reaching 56 Kbps when using KVH's integrated Velocity Acceleration software. In addition, the standard service can be used even when the TracVision antenna is receiving satellite TV signals, allowing passengers and crew to enjoy their favorite television programming as well as full-featured Internet connections. The powerful server-based TracNet 2.0 offers unmatched versatility that includes 802.11b (Wi-Fi) wireless and Ethernet network connections, permitting as many as 5 computers to surf the web simultaneously.

"The need for access to the Internet continues to grow among vessel owners," continued Palmer. "The variety of information that is available -- investment and business data, sports, news, entertainment, e-mail, weather and navigational information -- are all of value to our customers when they are at sea. Our system enhancements, the launch of TracNet 2.0, and the introduction of low airtime rates make two-way, broadband Internet access an affordable and powerful option for boat owners, passengers, and crew throughout North America and the Caribbean."

Complete information regarding KVH's TracVision and Tracphone systems can be found on the company's web site, kvh.com.

KVH Industries, Inc., designs and manufactures products that enable mobile communication, navigation, and precision pointing through the use of its proprietary mobile satellite antenna and fiber optic technologies. The company is developing next-generation systems with greater precision, durability, and versatility for communications, navigation, and industrial applications. An ISO 9001-registered company, KVH has headquarters in Middletown, Rhode Island, with a fiber optic manufacturing facility in Tinley Park, Illinois, and a European sales, marketing, and support office in Hoersholm, Denmark.

KVH Industries Contact:
Chris Watson, Communications Coordinator
401-847-3327
cwatson@kvh.com

Investor Relations Contact:
Phil Davidson or Jolinda Taylor
FD Morgen-Walke
617-747-3600

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To: Sector Investor who wrote (1519)10/31/2002 9:18:37 AM
From: William JH
   of 6947
 
Would you please explain to a no-tech how 400kbps compares to dial-up or DSL internet service? Thanks for all of your work here.

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To: david james who started this subject10/31/2002 9:20:33 AM
From: dvdw©
   of 6947
 
Attention Board Visitors; SI has an article from Forbes Posted as the number 1 news item OCT 29 just opposite as you look at the page face up.

This article is a YEAR OLD ( written 10-29-01), it is misleading and is just one more way attention is diverted by Omitting this fact by the hacks that spin the news.

If someone sees the Posts about TacNav dated Oct 30 and looks to the left they'll see a 10-29 date on the forbes tac nav article, when visitors read that, they might possibly not even notice that the OCT 01 QTR is what is being talked about. 02 This year turned Positive on Substantially better sales, compared to the loss of OCT 01.

Creating FUD is an art, this is but one way they do it under everyones radar, as investors,we all must dig deep and pay attention to the details.

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To: dvdw© who wrote (1521)10/31/2002 9:35:57 AM
From: Sector Investor
   of 6947
 
Could you post a link? I don't enter SI the same way you apparently do. I just go directly to this thread, so I don't see what you are seeing.

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To: Sector Investor who wrote (1522)10/31/2002 9:38:00 AM
From: dvdw©
   of 6947
 
TYPE In Quotes KVHI to see main page face up.http://www.siliconinvestor.com/research/quote.gsp?domain=Quote&s=KVHI

See what I mean, total BS.

Who at SI arranges for these things? All other news items are gone just the year old article is available. This is no coincidence.

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To: William JH who wrote (1520)10/31/2002 10:04:26 AM
From: Sector Investor
   of 6947
 
Dial-up is at best 56kbps (56 thousand BITS per second). Actually the best connection possible is only 53Kbps.

Now each character (such as a letter, number or symbol), takes an 8-bit BYTE to convey it, so the rate is about 6,600 characters per second, or about 2 pages of text.

That's pretty slow for downloading Internet graphics. DSL is usually service in the 1-2 Mbps range.

400K is between the two, and is a very acceptable rate, especially at sea or on the move.

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To: dvdw© who wrote (1523)10/31/2002 10:12:59 AM
From: Sector Investor
   of 6947
 
Seems like maybe an SI glitch to me.

Same thing for MRVC
siliconinvestor.com

but not for CSCO and JDSU.

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To: Sector Investor who wrote (1525)11/4/2002 4:57:38 PM
From: robert b furman
   of 6947
 
Hi Sector,

It appears phased array antennaes are beginning to sneak into more applications.

computerworld.com

Now we need KVHI to make theirs phase shift so it tracks when mobile and then get a bullet proof patent on it.

Encouraging to see widespread developement.

Bob

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To: robert b furman who wrote (1526)11/4/2002 6:49:19 PM
From: dvdw©
   of 6947
 
Ahhh yes; the phased array antenna, or if you will the next critical component in WLAN Applications. Beam forming and focused arrays are the new buzz words, just watch. This stuff has big legs as we'll begin to see in due course.

All this rotation forecasts the result, new technology raising the ante and shifting the benchmarks of performance across a wide ranging IP network.

The KVHI Fiber shoe is another one yet to drop,as Sector is qualified and if he's willing to present it's evolution in a way that makes it clear, he should do so.

Many iterations of MUX and transceivers can be beneficial partners with KVHI in this area. VERY exciting stuff.

Dont expect lightreading or trade rags to be honest about any of it, some big money still needs time to flee
( distribute) some areas that will be disrupted by newer and better stuff.

Wire line systems are toast ( CAPEX Wise), the 802.1 formats combined with SoftWare radios will make IP telephony the Game to be in. Look at SSPI* as a candidate for a big shift in new applications demand. BE U TI FUL!

PS>*But dont look at it before next week.

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