- •Contents at a Glance
- •Contents
- •Hardware Hacks
- •GPS Secrets
- •Hidden Secrets
- •Garmin Secret Screens
- •Hard Resets
- •Soft Resets
- •Warm Resets
- •Full GPS Resets
- •Diagnostic Screens
- •Autolocating
- •Magellan Secret Screens
- •Magellan Meridian Series
- •After a Hard or Soft Reset
- •Summary
- •Cables Demystified
- •The Data Cable
- •Power Cords
- •Combo Cables
- •Combining Cable Types
- •Multi-GPS Cables
- •Multi-Data Cables
- •Multi-Data/Power Cables
- •Multi-Data/Power/GPS Cables
- •Making Your Own Data Cables
- •Materials You Will Need
- •Don’t Want to Buy a Connector?
- •Making Power Cords
- •Power Cord Assembly
- •Testing
- •Precautions
- •GPS/iPAQ Connections
- •Cradle Modification
- •Testing the Connection
- •Making Combo Cables
- •Making Multi Cables
- •Summary
- •Power Hacks
- •GPS Power Needs
- •Alkaline Batteries
- •Lithium Batteries
- •Rechargeable (NiMH) Batteries
- •Battery Do’s and Don’ts
- •Power Hacks
- •Carrying Your Own 12-Volt Power Supply
- •Battery Packs
- •A Different Kind of Battery Pack
- •Alternative Power Supplies
- •Summary
- •Antenna Hacks
- •The GPS Antenna
- •Quad-Helix Orientation
- •Patch Antenna Orientation
- •Best Performance Summary
- •External Antennas
- •Antenna Placement
- •Other Things to Avoid
- •Reradiating Antennas
- •Personal Reradiating Antenna
- •Communal Reradiating Antenna
- •Reradiating Antenna Considerations
- •Setting Up a Reradiating Antenna in a Car
- •Testing the System
- •Making the System Permanent
- •Carrying a GPS Signal via Cable
- •How Much Signal Do You Need?
- •Cable Losses
- •Connector Losses
- •Using a Signal Repeater
- •Building Your Own Mega GPS Antenna
- •Materials
- •Building the Antenna
- •Summary
- •Screen Damage
- •Screen Protectors
- •More Screen Armoring
- •Commercial Protection for GPS and PDAs
- •Mounting GPS
- •Car Mounting
- •Mounting a GPS for Biking, Hiking, and Skiing
- •Making a Personalized Case
- •Summary
- •Software Hacks
- •Hacking the Firmware
- •Firmware
- •Updating Warnings
- •Updating the Firmware
- •Hacking GPS Firmware
- •Bypassing the Garmin eTrex Vista Startup Screen
- •Bypassing the Garmin eTrex Legend Startup Screen
- •Bypassing the Garmin eTrex Venture Startup Screen
- •MeMap Personalization
- •Manual Firmware Editing
- •Magellan GPS Firmware Modifications
- •Recovering from a Failed Firmware Load
- •Garmin
- •Magellan
- •Summary
- •Connection Types
- •Which Connection Is Best?
- •Troubleshooting Problems
- •PC Connection Trouble
- •General PDA Connection Trouble
- •General Bluetooth Connection Trouble
- •Software-Specific Issues
- •Erratic Mouse Pointer after Connecting a GPS
- •Windows XP Problem: Microsoft Ball Point
- •Microsoft MapPoint Troubleshooting
- •USB-to-Serial Converters
- •Summary
- •GPS Data Collection
- •Position, Velocity, Time
- •Waypoints
- •Working with the Data
- •EasyGPS
- •G7toWin
- •Creative Uses of GPS Data
- •Sharing Waypoints
- •Adding GPS Information to Digital Photos
- •Lightning Detector and Plotter
- •Wardriving
- •GPS in Programming
- •Summary
- •Examining the Data
- •NMEA
- •NMEA Sentences
- •NMEA Sentence Structure
- •A Closer Look at NMEA Sentences
- •Examining NMEA Sentences
- •NMEA Checksum
- •SiRF
- •Using NMEA Sentences
- •GPS NMEA LOG
- •GPS Diagnostic
- •RECSIM III
- •Using NMEA
- •GpsGate
- •Recording Actual NMEA Sentences with GpsGate
- •Recording Simulated NMEA Using GpsGate
- •Data Playback
- •Why Bother with NMEA?
- •Ensuring That Your GPS Works
- •Avoiding Data Corruption
- •Summary
- •More Data Tricks
- •Screenshots
- •G7toWin
- •G7toCE
- •Turning Your PC into a High-Precision Atomic Clock
- •Setting Up the Software
- •Setting Up the Hardware
- •Hooking Up Hardware to Software
- •Bringing a GPS Signal Indoors
- •Other Uses for GPS Data
- •Azimuth and Elevation Graphs
- •Surveying
- •Navigation
- •Signal Quality/SNR Window
- •NMEA Command Monitor
- •Experiment for Yourself
- •Summary
- •Playtime
- •Hacking Geocaching
- •GPS Accuracy
- •The Birth of Geocaching
- •Geocaching Made Simple
- •What Is Geocaching?
- •Geocaching from Beginning to End
- •The Final 20 Yards
- •Geocaching Hacks
- •Go Paper-free
- •Plan Before You Leave
- •Sort Out Cabling
- •Power for the Trip
- •Better Antennas
- •Protecting the GPS
- •Summary
- •GPS Games
- •The Dawn of GPS Games
- •Points of Confluence
- •Benchmarking/Trigpointing
- •GPS Drawing
- •Hide-and-Seek
- •Foxhunt
- •Other Games
- •Summary
- •GPS Primer
- •The GPS Network
- •How GPS Works
- •GPS Signal Errors
- •Summary
- •Glossary
- •Index
242 Part III — Data Hacking
FIGURE 10-30: Choosing how often to update the PC clock
With the software set up, it’s now time to set up the hardware that you will need.
Setting Up the Hardware
To set up the required hardware, you will need the following:
A GPS
A cable/wireless connection
A long-term power supply (a wall adapter is ideal — choose one with the appropriate input and output voltages, depending on your location and equipment) for the GPS (batteries aren’t going to last long if the GPS is on 24/7)
The type of GPS you use is important. I consider the long-term use of a handheld GPS such as the Garmin eTrex to be a bit wasteful; and depending on location, it might be vulnerable to loss, theft, or damage. I recommend investing in a small receiver such as the Leadtek GPS Smart Antenna GPS 9532 (www.leadtek.com/gps/gps9532/9532.htm). These are low-cost receiver-only setups and are designed for long-term exposure to the elements. However, if you only need to set up the time occasionally, your existing GPS receiver will suffice.
Power is important — for long-term use, you don’t want to change batteries regularly. The Leadtek receiver mentioned in the preceding paragraph draws power from the 5/12 volt supply and contains an internal backup battery in case of power failure.
Choosing a good position for your receiver is vital. The best position for the receiver is the tallest, least obstructed spot, away from trees and not overshadowed by other buildings. Figure 10-31 shows some good locations for the antenna, while Figure 10-32 indicates some bad locations for a receiver.
Chapter 10 — More Data Tricks 243
FIGURE 10-31: Good antenna locations
FIGURE 10-32: Poor choices for the antenna
Hooking Up Hardware to Software
Now all that is left to do is create the interface between the hardware and the software:
1.Make sure that the GPS is connected to the PC properly.
2.Switch the GPS on and make sure that it is getting an adequate signal (remember that a spot that provides you with good signal at one time might not do so later as the satellites move — check on it).
3.Run the NMEATime application.
4.From the NMEATime Properties screen, click the GPS Signal Quality tab (see Figure 10-33). Use this to check the signal quality being received by the software.
244 Part III — Data Hacking
FIGURE 10-33: GPS signal quality displayed
5.That’s it! Check the signal quality periodically to ensure that you’ve chosen a good location for the receiver. If the signal quality becomes poor, you might need to reconsider the placement of the receiver.
The accuracy you get from using GPS to synchronize your PC clock is truly amazing. Furthermore, you can access the signal 24/7 and it requires no connection to the Internet. It’s fast, reliable, and very, very geeky!
Bringing a GPS Signal Indoors
This atomic clock system relies on an antenna located outdoors, using this to bring the signal indoors. The signal is usually routed indoors via cable because wireless technologies such as Bluetooth don’t offer the range needed, especially when signals have to work through walls, roofs, and ceilings. In addition, leaving a GPS antenna outdoors 24/7 not only exposes it to the elements, but also to theft and damage.
Much better than leaving a GPS outdoors is to use only an antenna to bring the GPS signal indoors. The cheapest way to do with is to use what’s called a reradiating antenna. A typical reradiating antenna is shown in Figure 10-34.
These antennas consist of the following:
A power supply (usually 12V, DC)
An active antenna (that is, a powered antenna)
A transmitting antenna (this is, the antenna that retransmits, or reradiates, the GPS signal)
Connecting cables
As you can see, the active antenna is the antenna that receives the signals from the GPS satellites. After the signal is received, it is transmitted along a coaxial cable to the transmitting, reradiating antenna. This antenna, also powered by the 12-volt DC supply, transmits the signal received by the active antenna. The transmitted signal is then picked up normally by the GPS receiver.
Chapter 10 — More Data Tricks 245
FIGURE 10-34: A reradiating antenna
The same rules of placement regarding the GPS receiver apply to the antenna. Because it is an active antenna and has more power at its disposal, active antennas on reradiating kits are normally better at getting a decent signal in less than ideal conditions.
Here are some tips to help you with your reradiating set up:
Site the antenna well, firmly attaching it — if possible, use either the magnetic base on the antenna or screws.
Remember that the antenna needs power. Even though it is only drawing 12V DC, take care to waterproof all connections and joints in the cables. Do this properly and don’t rely on taped up connections. Short circuits can cause fires and damage your gear.
Be aware that the longer the cable you put between your receiving antenna and transmitting antenna, the more signal you lose through attenuation. If you need to use a cable longer than the one provided with the antenna kit, consider using cables that are low-loss and shielded. This kind of cable can be expensive, but so is buying poorer quality cable and finding it won’t work because of signal loss.
Finally, it’s vital to carefully consider placement of the transmitting antenna. If you place the transmitting antenna and the receiving GPS in a place where you can still pick up a signal directly from the GPS satellites, this can result in what is known as multi-path error (see Figure 10-35), whereby the GPS picks up a signal from the antenna and the satellites directly. This can cause quite a substantial error in position. The error in time is quite small, however, so unless you require atomic clock precision, you should be okay.