GPS technology to be used to help abuse victims

OKLAHOMA CITY (AP) - The Oklahoma Senate has voted 47-0 to permit the use Global Positioning System technology to protect victims of domestic violence.

The measure, by Sen. Debbe Leftwich, now goes to Gov. Brad Henry.

Under the legislation, court-issued GPS devices will notify both the victim and law enforcement if an offender violates geographic boundaries set by the court.

Leftwich, an Oklahoma City Democrat, says offenders must pay for the GPS bracelet at a cost of about $4.50 a day.

The Oklahoma Coalition Against Domestic Violence and Sexual Assault says there are about 25,000 domestic abuse calls to authorities every year.

Copyright 2008 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

Using the waypoint list

GPS receivers have an information page that lists all the waypoints that you’ve created and stored. (Again, check your user manual for information on how to access and use this list.) The waypoints can be listed by name or those closest to your current location. By selecting a waypoint, no matter where you are, you can find your way to it.

• The distance to the waypoint, such as a parking lot or trailhead.
• The compass direction in degrees that you’ll need to head to get to the waypoint.

Any of the waypoints in the list can be deleted or edited. See your user manual for specific instructions.
If you roam around the Internet searching for information about GPS, you’ll come across handy collections of waypoints that you can enter into your GPS receiver. There are all manner of waypoint lists, from fishing spots to pubs in England. If you’re planning a vacation, consider doing a Web search ahead of time to see whether there are any waypoints associated with your destination. Then bring your GPS receiver along with you as a personal tour guide. GPS receivers designed for outdoor use always assume a straight line as the route between two points. That might be convenient for airplanes and boats, but it doesn’t take into account cliffs, rivers, streams, fences, and other obstacles on land. GPS receivers designed for automobile navigation are a bit smarter, having built-in databases of road information that’s used in suggesting and measuring appropriate routes from Point A to Point B. Depending on the GPS receiver model, other waypoint-related information that you may be able to display includes

• Travel time: The amount of time it will take you to reach the waypoint based on your current speed.
• Compass: A picture of a compass that displays the waypoint direction heading.
• Directional arrow: An arrow that points in the correct direction that you should be heading.
• Navigational hints: A picture of a road that moves as you travel. If the road is centered onscreen, your destination is straight ahead. If the road veers to the right or the left, you need to correct your course so that the road is centered. A symbol associated with the waypoint will grow larger as you get closer to it.

Some GPS receivers come with databases of cities, highways, airports, landmarks, and other geographic features. These are just waypoints stored in memory that you can’t edit or delete to free up memory for new waypoints.
Most GPS receivers support mapping. At the very least, a GPS receiver has a simple plot display, a map page that shows waypoints, tracks (see the upcoming section, “Making Tracks”), and your current position. More advanced (and expensive) GPS receivers support more sophisticated maps; your waypoints and tracks appear along with roads, rivers, bodies of water, and whatever built-in features the map has. When the map page is displayed, you can zoom in, zoom out, and move around the map with an onscreen cursor that you control with buttons on the GPS receiver.
A map page can be orientated two ways: so either the top of the screen always faces north or the top of the screen faces the direction you’re traveling. Orientating the screen to the north is probably the easiest if you’re used to working with maps, which usually are orientated with their tops to the north.

How to Save Waypoints?

The two types of waypoints you can enter and save to your GPS receiver are

• Current location: GPS receivers have a button on the case or an onscreen command for marking the current location as a waypoint. (Check your user manual for details.) After the waypoint is marked, the GPS receiver screen displays a waypoint information page where you can name the waypoint and associate an icon with it.
• Known location: If you know the coordinates of a location that you want to save as a waypoint, you can manually enter it in the GPS receiver. Most GPS receivers also allow you to mark wherever the cursor is on the map page as a waypoint. A known location could be a good fishing spot that a friend saved to his GPS receiver or perhaps a lake you want to visit that you got the coordinates from a digital map. Again, check your user manual for directions on how to manually enter a waypoint.

Always use meaningful names when you save a waypoint. GPS receivers typically assign a sequential number as the default waypoint name. Although numbers and cryptic codes might make sense when you enter them, I guarantee you that you probably won’t remember what they mean a couple of weeks down the road.
Some GPS units have a MOB function, which has nothing whatever to do with tommy guns or cement shoes. MOB stands for Man Overboard and was designed for boaters to use in case someone fell into the water. (Go figure.) After seeing or hearing the splash, the captain can press a button (that creates a waypoint appropriately named MOB) and then turn around and head back to the exact location of the unlucky sailor.
Although a GPS receiver is good for letting you know where you are, waypoints are important for helping you get somewhere you’d like to go. GPS receivers have a number of features that can help you navigate to a waypoint that you’ve entered.
Maybe you decide to go for a hike. Before you leave the trailhead, you save the location of the parking lot as a waypoint, naming it PRKLOT.
Note: Some GPS receivers support waypoint names only in uppercase characters; others allow you to use both uppercase and lowercase characters. As you hike down the trail, you hear the call of a rare ivory-billed woodpecker and head off into the brush, intent on getting a sighting of the very elusive bird. After an hour of tromping around in the dense woods, you discover two things. First, the bird was just a robin; second, you’re totally turned around and are somewhat lost. But fortunately, because you have a GPS receiver with you (and have read this book), you know that you’ll be able to easily find your way back to the car and be home in time for dinner. The following sections show you how.

Endangered zebra life caught on GPS

(CNN) -- If you were a zebra, how would you spend your days?
Daniel Rubenstein, director of the Department of Ecology and Evolutionary Biology at Princeton University, has been pursuing this question for years.

He and collaborators spend their summers in Kenya trying to figure out how endangered zebras form social networks, avoid predators, and interact with the livestock and herders in the area.

ZebraNet, a collaborative project that Rubenstein co-founded with Princeton engineering professor Margaret Martonosi, studies zebra behavior through data from GPS locators on collars around zebras' necks. Photo See photos of ZebraNet in action »

Just like the positioning systems in cars, the collars collect information about the whereabouts of the zebras, as well as their velocities and turning angles.

The team is particularly interested in the Grevy's zebra, an endangered species whose numbers have dropped to only about 2,000. Data from the GPS collars have given Rubenstein and associates an unprecedented view of how Grevy's zebras balance the opportunities for acquiring food and water with the risks of being killed by lions.

The ability to gather data about nocturnal animals has always been limited, but with GPS collars recording data every eight minutes, the researchers learned a lot about zebra behavior at night.

The team, which includes several graduate students, found that zebras graze in the open plains during the day, moving slowly in straight lines, while lions rest under trees in wooded areas.

"They're like grass vacuum cleaners, chip-clipping away at the vegetation as they move," Rubenstein said of the zebras.

When night falls, the lions leave the woodlands to go hunting in the plains, and the zebras move into the woodlands, moving deliberately and quietly. They spend about 60 percent of the night in the woodlands, and the rest of the time in the plains, moving quickly and erratically while the lions hunt there.

"By using this remote sensing ability, we've been able to show the zebras change behavior markedly when they use the plains at night to minimize the risk of being preyed upon by lions," Rubenstein said.

In the past, when collared zebras got close to one another, ZebraNet's GPS technology transferred data between them. Eventually, all the data percolated back to the researchers' cars, which serve as mobile base stations. First getting information about interacting zebras was a thrill for Rubenstein.

"It was way cool to see the location and movements of many individuals from the data downloaded from only one!" he said.

Now, the project uses a similar technology that was recently developed by a German startup company. The new collars have improved battery power, but they don't have the peer-to-peer data swapping feature. They also sample every 15 minutes to an hour instead of every eight minutes, but can collect information over a longer period of time.

With these more power-efficient collars, researchers must track down each individual zebra and download its data. The second generation of these collars will debut this summer.

As a doctoral student at Duke University, Rubenstein was fascinated with how animals make decisions and why their societies form the way they do. He started studying equids -- a family of mammals that includes horses, donkeys, and zebras -- because they form associations among strangers.

He has also examined how the Grevy's zebra social network -- and he doesn't mean Facebook or MySpace -- may contribute to its endangerment. Associations between Grevy's zebras are less close-knit than those of the Plains zebra, whose core societies consist of closed-membership harem-groups and bachelor groups.

In a harem, several females choose to live with one male that protects them against harassment in exchange for sex. Female Grevy's zebras, on the other hand, don't stay with one male for long periods of time, meaning they don't have the benefit of a larger male watching out for them.

With food and water so scattered, female Grevy's zebras with young foals must stay near water to drink every day, while females without young foals wander more. Males, in turn, set up territories on access routes to water to gain mating opportunities with both the wandering females and ones that stay near water.

Lions, which prefer to eat Grevy's zebras, are a major source of endangerment as well. Rubenstein also plans to put collars on them to better understand their interactions with zebras and learn how best to intervene for the sake of zebra conservation.

ZebraNet also pays locals to gather data, which generates income for the communities, Rubenstein said. They put collars on livestock so researchers can examine the relationships between herds and herders, a topic that they will further investigate this summer.
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The project also increases awareness, as people come to understand that wildlife and livestock are not necessarily antagonistic.

"No longer are [zebras] necessarily vermin that are viewed negatively by the community," Rubenstein said. "They now have some economic worth."

Setting Waypoints

A waypoint is GPS lingo for a location or point that you store in your GPS receiver. Some manufacturers also call them marks or landmarks. A waypoint consists of the following information:

• Location: The location of the waypoint in whichever coordinate system the GPS receiver is currently using. Some receivers also store the elevation of the location.
• Name: The name of the waypoint. You get to choose your own name; the length varies between GPS receiver models from six characters on up.
  
• Date and time: The date and time the waypoint was created.
  
• Optional icon or symbol: An optional icon or symbol associated with the waypoint that appears on the GPS receiver’s map page when the area around the waypoint is displayed.

This could be a tent for a campground, a boat for a boat launch, or a fish for a favorite fishing spot. All GPS receivers can store waypoints, but the maximum number that you can save varies from model to model. As a general rule, as the price of a GPS receiver goes up, so does the number of waypoints that can be stored. Lower-end consumer GPS receivers store 100–250 waypoints, and top-of-theline models can store 1,000 or more.

Datum lessons learned

Here’s a quick story from my Forest Service firefighting days that illustrates the importance of being aware of datums. A fire was reported in a mountainous area of eastern Oregon, and my partner and I helicopter-rappelled in to put out the fire. Because the fire was bigger than expected, we requested some smokejumpers to assist. They were down from Alaska, helping out during the lower 48’s fire season, and they all had new handheld GPS receivers, which were pretty state of the art back then (1998). The fire continued to grow, and we called in a small air tanker to stop the fire’s spread. One of the Alaska jumpers pulled out his GPS unit, and we called in an exact set of coordinates for the pilot to hit. As the tanker approached, the pilot radioed us, asking whether we were sure that was where we wanted the retardant to go. Turns out that the jumper still had his GPS unit set with an Alaska map datum (that didn’t match the local datum on the pilot’s GPS receiver), and the coordinates that the Bureau of Land Management (BLM) jumper gave were on the other side of the ridge, nowhere near the fire. Fortunately, the pilot used his own initiative and dumped his load right where it needed to go.

Bill Would Require GPS For Some Sex Offenders

COLUMBUS, Ohio -- Tier 3 sex offenders could be monitored for life.

House Bill 538 would require tier 3 sex offenders to wear a GPS tracking device for the rest of their lives, once released from prison.

Earlier in 2008, sex offenders were broken into tiers -- as part of the Adam Walsh law.

Tier 1 offenders must register once a year, tier 2 offenders register every six months and tier 3 offenders register every 90 days.

A group of sex offenders is suing, claiming the law is unconstitutional because it reclassified 26,000 offenders without a new hearing.

GPS not a license to turn off your brain

By ROBERT L. JAMIESON Jr.
There's an episode of NBC's hit show "The Office" where Michael, played by Steve Carell, follows his Global Positioning System device -- and drives right into a lake.

Art imitated life in a serious way Wednesday, when a bus carrying a Seattle high school softball team plowed into a brick-and-concrete footbridge.

The impact sheared the roof off the bus. The driver reported that he was simply following the route provided by his GPS.

I suppose that in a country that already has given us the "Twinkie Defense," we shouldn't be surprised by what's coming down the road -- The GPS Defense.

Even though car navigation systems are godsends for the terminally lost and eternally map-challenged, they are popping up on the radar of blame.

Last May, the BBC reported that a British university student got in a wreck after she followed her satellite navigation system onto a railway track.

A train smashed into her car.

"I put my complete trust in the sat nav," Paula Ceely said, using British shorthand for satellite navigation. "It led me right into the path of a speeding train."

It would be nice if such antics were isolated. They're not. Vince Yearley, spokesman for the Institute for Advanced Motorists, told a blogger for Computerworld.com: "We've heard some very hilarious stories where people just blindly follow (GPS) instructions. Like if the (GPS) says, 'Drive into this muddy field,' they think, 'That's weird,' but they do it anyway."

Wednesday's bus accident in the Washington Park Arboretum had a happy ending. Members of the girls softball team from Garfield High were shaken up, but no one was seriously hurt. One thing died at the scene, however: common sense.

The footbridge clearance is 9 feet.

The bus was nearly 12 feet tall.

Do the math.

The president of the bus company blamed the GPS for routing the bus into danger's way. "We just thought it would be a safe route," Steve Abegg, president of Lynnwood-based Journey Lines, told reporters.

Abegg's way of thinking hints at the underlying problem linked to GPS dependency -- people being so reliant on all kinds of technological doodads that they become stuck on stupid.

They stop thinking. GPS devices are driving aids -- not excuses to turn off the brain.

A mild confession: I was a GPS virgin until recently.

When a night news assignment beckoned in a hard-to-find neighborhood near Sea-Tac Airport, Seattle P-I reporter Casey McNerthney lent me his hand-held navigator.

Heading south on state Route 99, an authoritative female GPS voice guided me.

Right turn coming up, the voice cooed.

I was going a bit too fast, and flew into the turn only to see potential trouble a hundred yards away -- concrete abutments that marked a detour. Hitting the brakes, I stopped the car in time.

That's when the GPS piped up: Make a safe U-turn as soon as possible, it said, after "reconfiguring."

Had I been distracted, the GPS warning would have come too late. That experience gave me a bit of perspective on Wednesday's bus wreck.

Yes, the bus driver may have been unfamiliar with the road. And, yes, he may have failed to see the hard-to-miss flashing lights or the sign -- in black letters against blazing yellow -- that mentions the bridge height.

But a professional driver is supposed to be an expert, whether that means negotiating a passenger bus in rain or snow, or realizing if a road is washed out or a footbridge clearance is too low.

So, don't blame the GPS. Do take personal responsibility. A GPS device is helpful; it got me to my destination the other night. But it isn't a magic box.

People should not exercise less awareness or caution driving with a GPS than they would without one. Traffic experts say drivers need to realize that rules of the road and signs have priority over GPS commands.

After all, the siren call of the GPS voice may be reassuring, even alluring. But you never quite know where it might lead you.

How much latitude?

GPS units can display latitude and longitude in several different formats. Take the location at the top of Mt. Bachelor (some great skiing in Central Oregon if you’re ever in the neighborhood) and see how it can be expressed.

• Degrees, minutes, decimal seconds (D° M’ S”): 43° 58’ 46.94” N, 121° 41’ 14.73” W
• Degrees, decimal minutes (D° M.M’): 43° 58.7824’ N, 121° 41.2455’ W
• Decimal degrees (D.D°): 43.9797069° N, 121.6874253°W

And just for fun, here are the UTM coordinates for that same location: 10T 0605273E, 48 70240N. Ouch! Is this confusing or what? Although it doesn’t seem like it, all these coordinates refer to the exact same location. Remember, just like converting locations from one coordinate system to another, you can also use your GPS receiver as a calculator to convert from different latitude and longitude formats. Suppose you have some coordinates in decimal degrees and need them in degrees, minutes, and seconds:

1. Change the coordinate settings in your GPS receiver to decimal degrees.
2. Manually enter the coordinates as a waypoint.
3. Change the coordinate settings in your GPS receiver to degrees, minutes, and seconds.

When you look at the coordinates of the waypoint that you entered, they’re now displayed in degrees, minutes, and seconds. (Note: Because changing coordinate systems varies from model to model, check your user manual for specific instructions.)

Land navigation

Discovering how to effectively use paper maps and compasses for land navigation is both an art and a science, with complete books written on the subject. Here are two excellent, free online resources if you want to find out more.

• Map and Compass for Firefighters (NFES 2554) is a self-study course developed by the U.S. government for wildland firefighters. The course is available at www.nwcg.gov/pms/training/map_comp.pdf.
• Map Reading and Land Navigation (FM 3-25.26) is the U.S. Army field manual on the subject, available at www.army.mil/usapa/doctrine/DR_pubs/dr_a/pdf/fm3_25x26.pdf.

Another great way to become a pro land navigator is through the sport of orienteering. Orienteering involves using a map and compass to find control points (small flags) in the shortest amount of time as possible. Do a Web search for orienteering to find more about the sport and how you can participate in clubs and events in your local area.

Understanding GPS and Datums

A datum is a frame of reference for mapping. Because the earth isn’t flat, geographic coordinate systems use ellipsoids (think of a sphere that’s not perfectly spherical, much like the shape of the Earth) to calculate positions on our third planet from the sun. A datum is the position of the ellipsoid relative to the center of the earth.
Unless you’re a cartographer or geographer, that probably hurts just thinking about it. Sparing you a long and detailed technical description, here are the two important things that you need to know:

• All maps have a datum. Hundreds of different datums are in use. Most good maps used for navigation — and highway maps don’t count —usually state which datum was used in making the map.
• You can set what datum your GPS receiver uses. The default datum for GPS receivers is WGS 84, more formally known as the World Geodetic System 1984. WGS 84 was adopted as a world standard and is derived from a datum called the North American Datum of 1983. Most USGS topographic maps that you use for hiking are based on an earlier datum called the North American Datum of 1927, or NAD 27. This datum is divided into different geographic areas, so if you’re in the United States — at least in the lower 48 states — use a version of NAD 27 that mentions the continental U.S.

So why is all this datum stuff so important? In the United States, if a position is saved in a GPS receiver by using the WGS 84 datum and the same coordinates are plotted on a map that uses the NAD 27 datum, the location can be off as much as 200 meters. That’s more than a couple of football fields off. The latitude and longitude coordinates will be identical, but the location is going to end up in two different spots.
The moral of the story is to make sure that the datums on your GPS receiver and maps are the same. Or, if you’re with a group of people using GPS receivers, make sure that all your datums match.
Not having the map datum match the GPS receiver datum is one of the biggest errors that new users of GPS receivers make. I can’t emphasize this point strongly enough: Make sure that the two match!

Linking GPS, Maps, and Coordinate Systems

Some people think that after they have a GPS receiver, they really don’t need a map, especially if the receiver has built-in mapping capabilities. This isn’t necessarily true. GPS receivers are best used in conjunction with maps, whether those maps are paper or digital. Here are some of the reasons why:

• Detail: Most maps on handheld GPS receivers don’t offer the detail of full-size paper or digital maps, especially topographic maps and nautical charts.
• Size: A GPS receiver’s screen is pretty darn small, and it’s just about impossible to get the big picture that a full-size map can give you.
• Backup: If you have a paper map with you and know how to use it, the map becomes an important backup if your GPS receiver’s batteries fail or if you encounter poor satellite coverage. Gadget lovers might consider a paper map and magnetic compasses primitive, but they don’t require batteries — and both are lightweight and cheap, to boot.
• Complementary: After you get back home or to the office, you might want to see where you’ve been on a map, based on the locations that you’ve stored in the GPS receiver.

With a digital map, you can easily plot the exact route that you took or identify the places you visited. All maps and GPS receivers use coordinate systems, which are grids on maps that enable you to find locations on a map. Because GPS receivers are designed for use with maps, they support a number of coordinate systems that correspond to those commonly found on maps. Thus, you can take a location that you recorded on your GPS receiver and precisely locate it on a map. By default, your GPS receiver displays positions in latitude and longitude. But you can change the settings to display locations in exotic-sounding coordinate systems such as the Finnish KKJ27 grid, the Qatar grid, or the W Malaysian R grid. You probably won’t need to switch to some of these obscure coordinate systems, so you can stick with latitude and longitude or Universal Transverse Mercator (UTM), which are used pretty much everywhere.

If you’re fuzzy on what latitude and longitude or UTM are, which gives an overview of the two coordinate systems. Suppose you have your GPS receiver set to latitude and longitude, and you record some locations. When you get home, you find out that your paper map doesn’t have latitude and longitude marks but uses only the UTM coordinate system. Not a problem. Look in your GPS receiver user manual for information on changing the coordinate system from latitude and longitude to UTM. Location points that you store in latitude and longitude appear as UTM coordinates. This is a quick and easy way of converting data between coordinate systems. Or you can visit the Graphical Locator Home Page at Montana State University (www.esg.montana.edu/gl/index.html) to perform online conversions of latitude and longitude and Township and Range. Although Township and Range is a popular coordinate system used on many maps in the United States, don’t expect your GPS receiver to support this system.

Unlike the latitude and longitude and UTM grid systems, which were mathematically derived, grids in the Township and Range system may not always be the same size, thus making it difficult for a GPS receiver to determine coordinates in this system. Most maps that have Township and Range information also have latitude and longitude or UTM marks. If you have a location reported in Township and Range, you’ll need to spend a bit of time looking at a map, manually figuring out the position that the coordinates point to, and then plot that position by using a different coordinate system.

The Future of GPS

Modern technology rapidly evolves, and the same holds true for GPS. Since consumer GPS receivers first became available in the mid-1990s, the market has grown tremendously because of cheaper receiver prices and new ways to use GPS. A peek into a crystal ball shows what the future may hold for GPS.

• More accurate: The United States has started planning the next generation of GPS, dubbed GPS III. Driving factors are better accuracy and reliability, improved resistance to signal jamming, and the looming European Galileo system. Increasing the number of WAAS satellites in orbit is also planned. The first GPS III satellite is tentatively planned for launch in 2012. The U.S. government budget will have an impact on plans to improve the present GPS system; the Iraq invasion delayed the launch of several satellites.
• Smaller: GPS receivers will continue to shrink. GPS units already are integrated into wristwatches, and PC Card GPS receivers can plug into a laptop or PDA. The three limiting factors that prevent a consumer receiver from shrinking are antenna size, screen size, and power source size
• Cheaper: Prices will continue to decline as manufacturing costs decrease and production quantities increase.
• Easier to use: Simplified and less technical user interfaces will become more of a priority as GPS receivers become more appliancelike to meet the needs of specialized markets. An example is Garmin’s Forerunner product, which is targeted to runners and lacks a number of features typically found in traditional GPS receivers.
• Easier to view: Improved screen technology will make GPS receiver screens brighter and easier to read.
• More integrated: GPS receivers are being integrated into cars and trucks, cellphones, PDAs, Family Radio Service (FRS) radios, and other consumer electronic devices. Expect some new products and services that take advantage of location-aware data.
• Thriftier: User-replaceable AA and AAA batteries have long powered portable GPS receivers, but expect some changes in power sources.
• Built-in Lithium ion (Li-Ion) and nickel metal-hydride (NiMH) batteries, popular in cellphones and laptops, make sense for GPS receivers. Garmin started releasing rechargeable GPS receivers at the end of 2003.
• Further on the horizon, miniature fuel cell technology will keep GPS units going and going without frequent battery changes.
• Less wired: Most GPS receivers transfer data from personal computers through a cable. Wireless technologies such as Bluetooth (www.bluetooth.com) and wireless USB are well suited for fast and easy data transfers to GPS receivers without using cables.

GPS monopoly

The U.S. has had a monopoly on satellite-based location systems over the years (the Russian GLONASS, Global Orbiting Navigation Satellite System, has really never been a viable player), but that may soon change.

The European Union is moving toward deploying its own positioning system called Galileo. If everything goes as planned, Galileo will be operational by 2008 with a constellation of 30 stationary satellites. Position accuracy is touted as within a meter, which is ten times more precise than what GPS currently provides to civilians. The United States isn’t happy about this; as an alternative, GPS prevents the U.S. government and military from selectively degrading signals and blocking use elsewhere in the world. China, Israel, and India have expressed interest in becoming involved with Galileo. As of early 2004, after a number of negotiation sessions, the U.S. and European Union had reached a number of compromises that met both parties’ needs.
http://europa.eu.int/comm/dgs/energy_transport/galileo/index_en.htm

Synthesized voice

Some models of GPS receiver, designed primarily for automotive use, have a synthesized voice that provides you with route-finding information. Although this feature has been available as an option in some luxury cars for many years (for example, in the OnStar system), portable GPS units that talk to you are available. You don’t have to pay monthly subscription fees for them, and you can easily move them from car to car. (Ah, progress.)

If you’re using your GPS receiver primarily for navigation in your vehicle, mount it securely so that it doesn’t slide around the dashboard.

• GPS receiver manufacturers make mounting brackets for in-vehicle use.
• Do-it-yourself solutions can include Velcro, Silly Putty, small beanbags, or modeling clay (the nonhardening type).

Never mount your GPS unit where an airbag deploys during a crash.

External storage

Some GPS receivers aren’t limited to internal memory for storage, using support memory cards that can be plugged into the receiver to store data.
External memory can be either

• Manufacturer proprietary data cards
• Generic (and less expensive) storage, such as
• MultiMediaCard (MMC; www.mmca.org)
• Secure Digital (SD; www.sandisk.com)

Internal memory

A receiver’s internal memory holds such data as waypoints, track logs, routes, and uploadable digital maps (if the model supports them). The more memory the receiver has, the more data you can store in it. All the data that’s been stored in the GPS receiver is retained when the device is turned off. GPS receivers have different amounts of memory. Unlike personal computers, you can’t add memory chips to a GPS unit to expand its internal memory.

GPS Antennas

Well, yes, a GPS unit has to have an antenna to receive radio signals to do you any good. Several types are available, each with its advantages.

Internal antennas
All GPS receivers have one of two kinds of built-in antennas. One antenna design isn’t superior to the other; performance is related to the receiver’s antenna size. (Cough . . . bigger is better.)

Patch
An internal patch antenna is a square conductor mounted over a groundplane (another square piece of metal). Patch antenna models reacquire satellites faster after losing the signal.
For best performance with an internal patch antenna, hold the receiver face up and parallel with the ground.

Quad helix
An internal quadrifilar helix antenna (or quad helix) is a circular tube wrapped with wire. Quad helix antennas are more sensitive and work better under tree cover than the other types.
For best performance with an internal quad helix antenna, hold the receiver so that the top is pointing up to the sky.

External antennas
Some GPS receivers have connectors for attaching external antennas. An external antenna is useful if the GPS receiver’s view of the sky is otherwise blocked, like in a boat, a car, an airplane, or a backpack.

Reradiating antennas
If a GPS receiver doesn’t have a jack for connecting an external antenna, you can improve the reception with a reradiating antenna. These antennas work just as well as conventional external antennas that plug into a GPS receiver.
A reradiating antenna combines two GPS antennas:

• One antenna receives the GPS signal from the satellites.
  
• The other antenna is connected to the first and positioned next to the GPS unit’s internal antenna. Here are a couple of sources for reradiating antennas:
• Roll your own: If you’re handy with a soldering iron, search Google for reradiating antenna GPS for tips on how to make one yourself.
• Buy one: Purchase an assembled reradiating antenna from Pc-Mobile at www.pc-mobile.net/gpsant.htm.