I quit! Due to burnout and other factors, my benchmark hunting activity
came to a stop on November 1, 2003. One of the problems is that I work during almost all the daylight
hours during the week, and my weekends are occupied by other interests. Also I realized that I was
wearing out my car (which already has almost 225,000 miles) looking for more and more remote benchmarks out
in the suburbs. All this, coupled with endlessly having to explain myself to relatives, onlookers,
property owners and overzealous security guards, has led me to the decision to pull the plug on this
hobby. That's it. I'm giving it up.|
In the hotter
months of 2003, I undertook the hobby of benchmark hunting. After enjoying
it for a while, I tired of it quickly, but I have left this page on line for the
benefit of those who still have not heard of this activity, and those who still
Many people asked me what benchmark hunting is all about — usually while I was
walking around in circles on a street corner, alternately looking at a data sheet
and a GPS navigator, as I tried to find a metal marker buried under years of accumulated
grass and dirt. Benchmarks typically are small metal discs embedded in
sidewalks or bridges. Some qualify
stations. They are used by surveyors as reference
points; and their latitude, longitude, and altitude has been determined with great
precision, in some cases several decades ago. Many benchmark discs in the Dallas
area are dated 1934, 1947, or 1986. Apparently those were three good years for
surveyors. The newer style (1986 and later) consists of a metal rod, usually
driven 20 feet or more into the ground, which is surrounded at the top by a
protective cover and is flush with the ground.
The position of a benchmark is determined with great accuracy, as previously stated,
however there are some which have had their coordinates "adjusted" to more precise figures,
apparently after someone has made GPS measurements at the site. Benchmarks
were used as reference points long before anyone imagined a satellite
navigation system like GPS.
and science of benchmark hunting is a mixture of GPS navigation, urban archaeology
and digital photography. Benchmarks are often covered with dirt and weeds and
can be difficult to find. It helps if the marker is accompanied by
a "witness post", which is a warning sign usually posted about a foot
from the mark, urging people to leave it alone. (See illustration.) Each
benchmark also has
a data sheet available,
which gives a description of its location, but in many cases the descriptions are fifty
years old, and some descriptions refer to buildings, airports or water towers which are long
gone. A hand-held GPS navigator is an essential tool for the serious benchmark
hunter, since buildings and trees come and go but latitude and longitude are here
Hobbyists who locate a benchmark usually take a picture of it and its
surroundings and upload the pictures to
the Geocaching web site. Close-up
pictures are great for proving that you were there, but overview pictures help
the next hunter find the mark. Quite often it is possible to find exactly
the right location only to find that the marker has been destroyed, but this
information is very helpful to others, and is posted so other people
don't waste time looking for a marker that is no longer there. In
any event, when a benchmark is located, it is left alone, aside from
brushing off the dirt to get a better picture.
Personally, I think finding water towers and church steeples is too easy, but I did
not hesitate to use them to run up my score. My final total
of 172 benchmarks does not include 79 others for which I hunted, but was
unable to locate, 20 places where I just visited the area and posted notes about the site,
for one reason or another, and 12 marks which I have reported as
destroyed. (For example, I have been to five places where, in each case, there
was supposed to have been a water tower, but it was obviously no longer
there. These I reported as "destroyed".)
Once I went digging
in a public park with a spoon, looking for the MIDLOTHIAN marker, which was three inches
underground. That was probably my most difficult "find."
If you're interested, here is
a list of
the benchmarks I found.
If you're really interested, here is
the complete list of
all the benchmarks I found, tried to find, or didn't find, and the ones about
which I posted other information.
If you look into the possibility of hunting for benchmarks in your area, you will find
that some marks are listed in the
government database but
have been destroyed years ago by farm machinery, vandals, landscaping, or
widening highways. Some are exactly where they are supposed to be, but
they're covered with dirt or weeds or tall grass, or they may have been
painted over! Others are in place but are accompanied by fire ants,
stray dogs, poison ivy, heavy traffic or unfriendly neighbors.
more information about benchmarks, see
"What is a benchmark?" at the
Geocaching web site.
Turns Deadly. Police say it looks like 64-year-old
James Max Chamberlain fell off a small cliff at Eisenhauer Park in
San Antonio. Chamberlain went on the scavenger hunt Saturday
morning [12/11/2004] using a hi-tech GPS system he had just bought.
Even if you know where something is, you can't necessarily get to it. Be
careful out there!
A word about photography near federal buildings:
In the current political climate, with all the talk of terror alerts and
homeland security, there are a lot of security guards at federal buildings
who are rather touchy about allowing photography. Recently (9/3/2003) I ran
into one such security guard who intercepted me just as I had located a
benchmark at the Fort Worth Federal Building. He told me that "photography
of all federal facilities is prohibited." This was rather discouraging,
because I thought there was a chance that he could have been correct in his rash
assertion, and perhaps this was a feature of the new Patriot Act of which I was
unaware. So the next day (9/4/2003) I went back to Fort Worth and talked to the
security people at the Federal Building, including one very cooperative
who explained that photography of public buildings is not prohibited,
nor could it ever be, as long as the Constitution is still in effect. I was
told instead that photography at any federal building is permissible as long as (1) you
talk to the building manager first, and explain what you're doing, and (2) you
don't take pictures of the guards, cameras, barriers, or any other components
of the building security system.
Let's face it... if I were a spy or a terrorist, the security guards
would never have known I was taking pictures.
this discussion among a bunch of other photographers who have
experienced the same treatment, just for taking pictures!
See also The
Photographer's Right - A Downloadable Flyer. An explanation of your
rights when stopped or confronted for photography.
Legal Rights of
Photographers: A clear explanation of what is legal to shoot and publish.
The Ultimate Legal Guide for Photographers.
Photographers are often confronted when they're taking photos. The confrontation may take place between the
photographer and private citizens or even with law enforcement. You may be told to stop taking photos or you may be
told that you have no rights to photograph the area or the people. You do have rights as a photographer that you should
know about. Read this guide and keep it for future reference to protect yourself as a photographer.
I'm sure this looks like so much fun, you'll be tempted to take up this hobby
yourself. Before you do, let me offer a few words of caution: When
hunting for benchmarks, you are advised to observe the limits of private
property, government property, restricted access areas, unsafe inner city
neighborhoods, highway traffic lanes, and other hazardous areas. This activity
may also expose you to other risks, including (for example) inclement weather, exertion
beyond your physical fitness level, adverse terrain, overzealous security
guards (as explained above), insect bites, snake bites, dog bites, or exposure
to poison ivy. You assume the entire risk as to your use of the
information on this page or any other page on this web site. In no way
shall anyone connected with ae5d.com be liable for any direct, indirect,
punitive or consequential damages arising out of, or in any way connected
with the use of this website, especially this page, or use of the information
contained herein. Read
my disclaimer carefully. Any
actions you take based on whatever you saw, or think you saw, on this site are entirely
your own responsibility.
I have put together a new page about the
Camp Wisdom Triangulation Station,
located at 32° 40' 20.38" N., 96° 55' 50.06" W., at
an altitude of 761 feet.
Search of ARL5: My field trip to the
Arlington CORS station! Be
sure to see the latest pictures on the update page, Return
My search for Benchmark BN0594
at Longhorn Caverns, near Burnet, Texas.
The City of Cedar Hill, Texas, has its own benchmarks. For example,
Cedar Hill Benchmark #2009 (shown below) is located
at 32° 36' 19.24328" N., 96° 56' 42.39458" W., at
an altitude of 667.536 feet, and appears to be
a Berntsen Model C1 marker.
Photos of Cedar Hill Benchmark #2009:
When I took these pictures, Cedar Hill benchmark 2009 was in the middle of nowhere, just off a lonely
road near some railroad tracks. Right after these pictures were taken, a new neighborhood sprang up
across the street!
Benchmark hunting is a spin-off of a hobby
called Geocaching, in
which people use GPS navigators to find a cache of goodies at some spot and
sign the guestbook. (Here is
a brief explanation.) This
is obviously a great way to sell GPS navigation gear; however, Geocaching is potentially
a way to get into a lot of trouble. In most cases, the "hidden treasure" is on
private property, or in areas which are off limits to the
public, or in places where law-abiding people do not ordinarily go. In any event,
if you remove anything from someone else's cache, like GeoCoins for example (see below),
it is suspicious behavior at best, and technically it is petty theft. And
you're at the mercy of everyone else who has visited that site, since anyone
could stash illegal drugs or explosives or anything else in a GeoCache, and if
you're caught with it in your hands, it's yours! All I'm saying is that if
you undertake this hobby, be prepared to spend the day explaining yourself
to "badge happy" police officers, many of whom are a little too eager to take
a bite out of crime.*
Signing the log book
at a Geocache. It was only about 100° that day.
Travis says, "You
pick the strangest
hobbies." He's right.
Some Geocaches contain GeoCoins
or Travel Bugs.
Various styles of Geocaching coins exist,
or you could design your own! Several
companies make custom tokens and medallions.
Geocaching: A GPS
Receiver is a Radio Too! There's an Amateur Radio angle to this rapidly
Related hobby: The Degree
Confluence Project: The goal of the project is to visit
each of the latitude and longitude integer degree intersections
in the world, and to take pictures at each location. So, for example, you might
take your new hand-held GPS navigator out into the boonies and try to find exactly
30°N., 94°W. (This
spot is in a swamp southeast of Beaumont, and has only recently been
photographed. Maybe that's because there are probably at least three spiders per square
foot in an area like that, not to mention the snakes.) What fun!
Hunting Terminology explained at
dot com. A very professional-looking web site dedicated to this hobby.
Other benchmark hunting enthusiasts:
Photos of Survey markers and Witness Posts.
your own benchmarks. The markers aren't very expensive.
Geodetic mark recovery
Maintenance and preservation of these marks is of utmost importance to users of the net
and to NGSD [the National Geodetic Survey Division], recognizing that many valuable
geodetic marks are destroyed by construction, new roads, erosion, or for other causes.
Back to the top of the page
Other material related to geography, latitude/longitude, GPS applications, etc.:
Find latitude and longitude of any spot on a map.
Convert latitude and longitude to bearing and distance.
TopoGrafix - Power Tools for your GPS!
Wormley's Waypoints: Numerous interesting links
National Geodetic Survey
NGS Datasheet Retrieval Page for benchmark data sheets.
database with numerous links.
GPS Web Tools : Latitude-Longitude
of US Cities.
The Australian National Public Toilet Map.
Computing Azimuth and Elevation
Difference Between GPS and GIS. Most people are familiar with the global positioning
system (GPS). After all, it is a technology that has become increasingly prevalent in day-to-day
life, from navigation systems in cars to tracking the movement of wildlife in research programs. The
geographic information system (GIS) is less well-known, but without GIS, GPS could not possibly be
used to its full potential. GPS is a satellite-based navigation system, and GIS is a software
program designed to store and manipulate the data that GPS accumulates.
devices on sale. Navigating devices using Russian [Glonass] satellites will appear in the shops
this year as the first alternative to the widely used GPS network of the United States, officials said
GPS helps cities catch goof-offs.
GPS tracking devices installed on government-issue vehicles are helping communities around the country reduce
waste and abuse, in part by catching employees shopping, working out at the gym or otherwise loafing while on
the clock. The use of GPS has led to firings, stoking complaints from employees and unions that the
devices are intrusive, Big Brother technology. But city officials say that monitoring employees'
movements has deterred abuses, saving the taxpayers money in gasoline and lost productivity.
A homemade receiver for GPS and GLONASS
satellites by Matjaz Vidmar, S53MV. This ham operator in Slovenia (?) went to a lot of trouble
to build this equipment, and to prepare the documentation. He has also undertaken many other experiments
with UHF equipment.
GPS jamming incident in San Diego
harbor in January 2007. The U.S. Navy was conducting a scheduled communications jamming training
exercise in the Port of San Diego. Two Navy ships participated in the exercise for approximately two
[Along with numerous other services, GPS was jammed] — unintentionally of
course — and the jamming continued for approximately two hours.
Why 70 Miles Per
Hour Is the New 55: Left to their own devices, American drivers confronted with an open stretch
of interstate highway tend to drive at about 70 miles per hour — whatever the legal speed limit
happens to be. That's the finding of an analysis of speed data gathered by TomTom Inc., a marketer
of GPS navigation devices.
The Editor asks...
And how did they find out? Is TomTom harvesting data from units in the field?
Why your trusty GPS sometimes
fails you: GPS navigation systems aren't perfect. Most of them are pretty good, but
blind acceptance of their advice can become a traveler's nightmare.
Homeland Security Control the GPS Network? Americans have become accustomed to the presence of Global
Positioning System (or GPS) technology embedded in everything from the GPS on their dash to their cell phones and
iPads. In fact, GPS is nearly taken for granted for everything from locating a restaurant to navigating
a fishing boat through the fog. But now it appears that GPS, which was developed primarily for its
military applications, is rather overtly returning to its "national security" roots, as NASA plans to turn
the security of the GPS system over to the Department of Homeland Security.
House Pressure for a Donor? The Pentagon has worried for months that a project backed
by a prominent Democratic donor might interfere with military GPS. Now Congress wants to know
if the White House pressured a general to change his testimony.
LightSquared: The Next Big Obama Scandal.
The new Obama scandal is huge, but it's also nice and simple. LightSquared is a satellite broadband
company, based out of Virginia. It received heavy investments from a fund run by a big-money Democrat
donor named Phillip Falcone, a billionaire who "became wealthy shorting subprime debt," according to The
Daily Beast. The company's biggest investors, according to the Huffington Post, include Obama donor
and current U.S. ambassador to South Africa Donald Gips, Obama friend and investment manager George
Haywood... and Barack Obama himself...
Air Force general tells secret Congressional hearing,
House forced me to back project funded by Obama donor. A four-star Air Force general
told a classified Congressional hearing he was pressured by the White House into changing a political
briefing to favour a Democratic-backed firm. Air Force Space Commander General William Shelton
was speaking about a wireless project by Virginia satellite broadband company LightSquared. The
Pentagon believes it could interfere with GPS — but the firm's majority owner happens to be
Democratic donor Philip Falcone's hedge fund.
House Pressure for a Donor? The Pentagon has worried for months that a project backed by a
prominent Democratic donor might interfere with military GPS. Now Congress wants to know if the White
House pressured a general to change his testimony.
Board: LightSquared, GPS Can't Coexist. On Friday [1/13/2012], two Deputy Secretaries, one at the
Department of Transportation and the other at Defense, in their capacities as co-chairs of the National Space-Based
Positioning, Navigation and Timing (PNT) Executive Committee, released a one page letter concluding that the modified
broadband deployment plan of LightSquared could not coexist with current GPS devices and their spectrum.
FCC moves to kill
LightSquared over GPS interference concerns. The Federal Communications Commission (FCC) moved to reject
LightSquared's planned wireless network on Tuesday [2/14/2012] after the president's top adviser on telecom issues said
there is "no practical way" to prevent the network from disrupting GPS devices. Philip Falcone and his investment
firm Harbinger Capital invested billions of dollars in LightSquared's plan to build a nationwide high-speed cellphone
network, which now appears dead.
to fight FCC decision. Wireless start-up LightSquared plans to fight the Federal Communications Commission's
(FCC) move to reject its proposed nationwide 4G network, a company official told The Hill. Jeff Carlisle, LightSquared's
vice president for regulatory affairs, said the company will file a formal comment with the FCC urging the agency not to follow
through on its proposal to "indefinitely suspend" LightSquared's authority to operate cell towers.
Court: Police Need Warrant for GPS Tracker. The government argued that attaching the tiny device
to a car's undercarriage was too trivial a violation of property rights to matter, and that no one who drove in
public streets could expect his movements to go unmonitored. Thus, the technique was "reasonable," meaning
that police were free to employ it for any reason without first justifying it to a magistrate, the government
said. The justices seemed troubled by that position at arguments in November, where the government acknowledged
it would also allow attaching such trackers to the justices' own cars without obtaining a warrant.
Hail Samuel Alito, Privacy Champion Extraordinaire! Yesterday [1/23/2012] the Supreme Court handed
down the most important privacy case of the Roberts era, U.S. v. Jones. The unanimous decision
is an occasion for dancing in the chat rooms. In holding that the government needs a warrant before
attaching a GPS device to a suspect's car to track his movements 24/7 for a month, all the justices rejected
the Obama administration's extreme and unnecessary position that we have no expectations of privacy when it
comes to the virtual surveillance of our movements in public places.
Tests found major flaws in parolee GPS
monitoring devices. A little more than a year ago, California quietly began conducting tests on the GPS monitoring
devices that track the movements of thousands of sex offenders. The results were alarming. Corrections officials found the
devices used in half the state were so inaccurate and unreliable that the public was "in imminent danger." Batteries died early,
cases cracked, reported locations were off by as much as three miles. Officials also found that tampering alerts failed and
offenders were able to disappear by covering the devices with foil, deploying illegal GPS jammers or ducking into cars or buildings.
GPS Was Off Because the Whole Country Moved. Australia is moving. This isn't so surprising —
all the continents are on the move, and Australia drifts 70 millimeters to the northeast every year. But that journey
is starting to mess with systems that rely on pinpoint accuracy, specifically GPS. The country its currently updating its
very longitude and latitude to correct a divergence with global satellite navigation systems. Geoscience Australia, a
part of the Australian government, is behind the project of getting the Geocentric Datum of Australia, the country's national
coordinate system, up to code and bring it in line with international data.
The Editor says...
The GPS systems available to the general public do not offer the level of precision performance with which one would
notice a movement (of everything!) of 70 mm per year. If you're in a self-driving car, or you are landing an
airplane or using GPS in any other application, you can only rely on it for relatively coarse positioning.
gets stranded on North Carolina beach after GPS gives wrong directions. A truck driver took a ride on the wild
side after his GPS apparently led him onto a North Carolina beach. The driver of the Interstate Van Lines truck told
WVEC-TV he was supposed to be driving south on Route 12 Monday [7/2/2018] but somehow ended up travelling north.
He tried to find a place to turn around but instead reached the end of the road — quite literally — and
ended up stuck on the beach in Corolla, North Carolina, a small village in the Outer Banks.
$225 GPS spoofer can send sat-nav-guided vehicles into oncoming traffic. Billions of people — and a
growing number of autonomous vehicles — rely on mobile navigation services from Google, Uber, and others to
provide real-time driving directions. A new proof-of-concept attack demonstrates how hackers could inconspicuously
steer a targeted automobile to the wrong destination or, worse, endanger passengers by sending them down the wrong way of a
one-way road. The attack starts with a $225 piece of hardware that's planted in or underneath the targeted vehicle that
spoofs the radio signals used by civilian GPS services. It then uses algorithms to plot a fake "ghost route" that
mimics the turn-by-turn navigation directions contained in the original route. Depending on the hackers' ultimate
motivations, the attack can be used to divert an emergency vehicle or a specific passenger to an unintended location or to
follow an unsafe route. The attack works best in urban areas the driver doesn't know well, and it assumes hackers have
a general idea of the vehicle's intended destination.
More information about GPS as a potential threat to privacy can be
GPS background material and GPS-related web sites:
Joe Mehaffey and Jack Yeazel's GPS Information Website
Wormley's Global Positioning System (GPS) Resources (Excellent web site!)
David L. Wilson's GPS Accuracy Web Page
GPS Nuts is a web site for GPS navigation enthusiasts.
GPS Enthusiasts Web Ring - Evidently there
are several such web sites.
How GPS works
Definitions of GPS Terms
Another GPS overview
GIS File Library
and theory of operation
Current GPS Satellite Data from
the little-known National Imagery and Mapping Agency.
Stanford University Testbed Master Station has something to do with WAAS.
Discussion of Selective Availability
NGS FAQ page Explains the difference between NAD27, NAD83 and WGS84.
on GPS, Geodetic Datums, and Grid/Lat-Lon Conversions
and Practice of GPS Surveying.
To see the current GPS week, among other things, go here.
GPS Technology and Cars.
Rino 110: A walkie-talkie with built-in GPS.
Garmin GPS sensors and boards.
Garmin GPS35PC TracPak,
GPS to get Time and Frequency
GPS receiver as a NIST traceable frequency reference
US Coast Guard GPS page
Trimble Thunderbolt is used
in precisely locating cell phones
using Time Differential Of Arrival.
The 12 Channel Lassen IQ
GPS Receiver with DGPS looks like fun
... and for only a few dollars more you can get
the Evaluation Board.
This isn't the news page, but here are a couple of news items with a GPS twist:
Brother rides shotgun: Rental-car company
uses GPS to track customer, fines him $450 for speeding.
An Introduction to GNSS. What has most significantly changed navigation
techniques is the advent of GNSS (Global Navigation Satellite Systems) which started with the launch of the U.S. Department of Defense Global Positioning
System (GPS) in the late 1970's. Early applications of GNSS were developed for the military, and in the fields of surveying and mapping.
Now, commercial operators of planes, trains and automobiles can know their position and heading quickly and accurately.
GPS. Galileo will be Europe's own global navigation satellite system,
providing a highly accurate, guaranteed global positioning service under civilian
control. It will be inter-operable with GPS and GLONASS, the two other global
satellite navigation systems. Galileo will deliver real-time positioning accuracy
down to the metre range, which is unprecedented for a publicly available system.
EU Considers Running Galileo GPS Project.
The European Union is to consider taking over the Galileo satellite system as it is faced with demands for more
time and extra public funds from the project's private builders, officials said.
satellite launch challenges GPS. The European Union launched its first Galileo navigation
satellite on Wednesday [12/28/2005], moving to challenge the United States' Global Positioning System
(GPS). … Galileo's accuracy in positioning is to be 3 feet or less, while GPS's precision is more
than 15 feet. EU officials also say Galileo would never be switched off for strategic reasons,
which could sometimes be the case with GPS.
Europe still keen on
Japan joining Galileo GPS project. In just four years, Europe will bring about a sea change in
the world of car and man navigation, which has long depended on a single service source, the American global
EU's satellite project, Galileo,
funded at last. After hours of haggling, the European Union on Friday [11/30/2007] salvaged its
highest profile investment project, agreeing to divert €2.4 billion of public money to bail out its
struggling satellite navigation project, Galileo. Designed to rival the American GPS system, Galileo
has been beset by funding difficulties and hit by lengthy delays after a consortium that was supposed to get
the satellite network off the ground failed to agree on financial terms.
How GPS Is Killing
Lighthouses: The popularity of the satellite-based global positioning system has led to the
closure of lighthouses along the German coast. Many more may soon be extinguished. But critics
question whether the new system is reliable and safe enough to warrant the closure of these
historical beacons of safety.
Announcement of the end of
GPS degradation through Selective Availability 5/1/2000.
Standard Positioning Service Performance Standard (PDF)
Military GPS news: U.S.
Could Deny GPS to Taliban The Defense Department could take steps to limit the
usefulness of GPS receivers in the hands of Taliban forces
without affecting North American users.
The Pentagon is probably jamming GPS in Afghanistan: The
U.S. Defense Department has probably been selectively jamming signals from the Global Positioning System (GPS) in Afghanistan since the start of the air campaign
[October 2001], according to nonmilitary GPS experts.
GPS flaw could let terrorists hijack
ships, planes. The world's GPS system is vulnerable to hackers or terrorists who could use it to hijack ships — even commercial
airliners, according to a frightening new study that exposes a huge potential hole in national security. Using a laptop, a small antenna and an
electronic GPS "spoofer" built for $3,000, GPS expert Todd Humphreys and his team at the University of Texas took control of the sophisticated navigation
system aboard an $80 million, 210-foot super-yacht in the Mediterranean Sea.
The Editor says...
"Pardon Me, Soldier, but
Would You Happen to Have the Atomic Time?" "If GPS is disrupted or jammed, a CSAC could provide precise time to the GPS
receiver to enable rapid recovery or to protect receivers from GPS spoofing, a condition where false GPS signals are broadcast to fool
GPS receivers with erroneous information. The hope is that the Soldier wouldn't even know that his GPS is being jammed."
It is highly unlikely that the Muslim terrorists, who live day to day in the 7th century, would suddenly acquire the 21st-century skills and equipment
to pull off such a stunt. (If the Muslim terrorists know anything about GPS navigation, it is probably from the standpoint of the end user.)
It is far more likely that the technique of locally spoofing GPS could be (and probably is already) used by the military against our enemies.
into space; carries satellite to guide weapons. A rocket carrying a GPS satellite to better
guide military weapons was launched into space Thursday. The Delta 2 rocket lifted off from Cape
Canaveral at 3:04 p.m. (2004 GMT) with the modernized NAVSTAR Global Positioning System Block 2R
military navigation satellite aboard for the U.S. Air Force.
The satellite is expected to circle the Earth
for up to a decade before becoming obsolete.
[The article includes no mention of the price tag for ten years of service.]
Would You Track Your
Kid by GPS? Question: if you had the ability to track your child's every movement
during the day, would you do so? Or is this an example of helicopter parenting taken to extremes?
How about tucking a portable GPS unit in her backpack?
Surfing the internet, you may find people who believe that GPS navigation is degraded or unusable in cities
where there is a TV station on Channel 23 or Channel 66. This is because Channel 23's
third harmonic and Channel 66's second harmonic are in the neighborhood of the GPS downlink
frequency. Some tech writers seem to be especially concerned because the signals from digital TV stations have the
same noise-like characteristics as the GPS signals. I haven't been to such a location to check it out,
but keep in mind that spurious and harmonic signals from DTV stations are supposed to be 110 dB below the
power level of the station's primary output, and even at a station with a megawatt of average power, that would
only leave a maximum of 10 microwatts of power in the GPS band. That's not much power, but then
again, the GPS signals are very weak, too.
Is GPS reliable? Yes.
The news media thrive on crises and stories of impending doom. Pay no attention when they
come up with sensational predictions such as the following:
GPS System Could Fail Next Year, Report
Warns. Mismanagement and underinvestment by the U.S. Air Force could possibly lead to the
failure and blackout of the Global Positioning System (GPS), a federal watchdog agency says. The
risk of failure starts in 2010, according to the Government Accountability Office (GAO) report quoted
by PC World.
System Could Begin To Fail Within a Year. The Global Positioning System faces the possibility
of failures and blackouts, a federal watchdog agency has warned the U.S. Congress. Mismanagement by and
underinvestment by the U.S. Air Force places the GPS at risk of failure in 2010 and beyond. The
problem: Delays in launching replacement satellites, among other things.
Here is the "all clear" message to end this "crisis" ...
Tax GPS to save GPS?
For starters, how big a crisis is this? Not so bad. We really only need 24 satellites working in
order to have assured accuracy, and there are 31 operational in the current constellation, with more launches
planned. The odds of seven or more failing before replacements get into orbit is rather low. The
satellites may be reaching the end of their expected lifespans, but military equipment often lasts much longer
than its expected lifespan.
Don't rely too heavily on GPS -- or any computer system!
GPS mistakenly leads
woman into flash floods in Catalonia, where she drowns. A woman was swept away during flash floods in a village
45 kilometers from the Catalan capital of Barcelona in Spain after her GPS device sent her driving across a riverbed through
the village of Sant Llorenç d'Hortons. The 20-year-old woman, who was not named, was traveling with her partner
to reach a caravan site where they would meet family members when the incident happened, the Local reports.
Woman Killed After GPS Takes
Her to Wrong Street. GPS directions might at times drive you insane, but one woman was actually driven to her death in Brazil. Travel
agent Regina Murmura, 70, and her husband Francisco, 69, were aiming for a Niteroi beach on Avenue Quintino Bocaiuva on Saturday [10/10/2015] when their
Waze GPS app directed them to Quintino Bocaiuva Street, home to one of the city's most notorious favelas or slums, Caramujo, where drug gangs run rampant,
report the Telegraph and Sky News. There, Regina Murmura was shot as someone fired 20 bullets into the couple's car, police say.
bicyclists in 2 days on I-94, 1 said smartphone GPS took her there. In the last two
days, bicyclists have pedaled their way onto Interstate 94, prompting calls from concerned motorists
and potentially, a hefty fine — or worse. [...] On Tuesday [6/16/2015] in St. Paul, a
14-year-old bicyclist told police she followed her smartphone GPS to eastbound I-94. Just
after 8 a.m., she was near Highway 280 when several drivers called 911.
follows GPS off demolished bridge, killing wife, police say. A Chicago woman was
killed after her husband followed their car's GPS navigation off a partially demolished bridge that
has been closed since 2009, according to reports. Zohra Hussain, 51, died after their Nissan
Sentra fell more than 37 feet off the old bridge and burst into flames.
Woman drives 900 miles out of her way after GPS error. Put too much faith in technology
and you may wind up in Croatia. [...] The woman only wanted to go about 90 miles from her hometown of Hainault Erquelinnes, Belgium, to
pick up a friend at the Brussels train station. Her GPS device sent her about 900 miles to the south before (during the second day of
driving) she realized that something was amiss.
discourage use of Apple maps app after rescues. Police say they have rescued a half-dozen motorists in recent weeks who were using
the app to navigate to a city only to find themselves stranded in the wilderness of a national park.
Alderman Suggests Requiring
GPS Devices On All Guns. A South Side alderman is asking for City Council hearings on an unorthodox gun control measure
that would allow for GPS tracking of firearms. WBBM Newsradio Political Editor Craig Dellimore reports Ald. Willie Cochran (20th), a
former police officer, has suggested that global positioning system chips be embedded in new guns, and retrofitted on existing firearms,
so they could be located if they go missing.
The Editor says...
drivers led astray by the lights. British motorists left frustrated when their expensive satellite
navigation systems do not work now have a culprit to blame — the northern lights. The aurora
borealis, which produces colourful light displays in the sky above northern Europe, disrupts the satellite
signals that satellite navigation devices rely on to pinpoint their location.
This is a remarkable display of ignorance on the part of the Alderman. If the police wanted to locate a specific gun, the "GPS"
device would have to include a cell phone, and the criminal would have to be dumb enough to leave the device on the gun, and the device
would have to be in contact with a cell tower, which is easy enough for a gun owner to prevent.
after GPS led them to Utah cliff. A GPS device led a convoy of tourists astray, finally
stranding them on the edge of a sheer cliff. With little food or water, the group of 10 children
and 16 adults from California had to spend a night in their cars deep inside the Grand Staircase-Escalante
A tip of the hat
to Peter G. Neumann
Homeowner Says Crews Demolished Wrong House.
A Sandy Springs [Georgia] man got a phone call Monday [6/8/2009] that his family home in Carroll County was
gone. Torn down. Demolished. ... Channel 2 Action News reporter Jovita Moore asked Byrd if
the demolition company had an address. I said, "What address did you have?" and he said, "They sent
me some GPS coordinates." I said, "Don't you have an address?" (and) he said, "Yes, my GPS
coordinates led me right to this address here and this house was described." said Byrd.
Woman drives into
marsh on GPS advice. The driver and her two female passengers were returning to the hotel from
dinner in the Mercedes rental when they became lost and tried to use the Hertz-provided GPS. The woman
told police she was following the satellite navigator's instructions but must have made a wrong turn just
after midnight on Wednesday [6/15/2011].
Tracking Disaster: Japanese Tourists Drive Straight into the Pacific. Three Japanese tourists in
Australia found themselves in an embarrassing situation after their GPS navigation system lured them down the
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