The following is a list of some on-line commercial sources of image files that are suitable for use as map images. 

www.unearthedoutdoors.net 

UnearthedOutdoors resells image tiles measuring 2° on a side (49,284km² at the equator).  True Marble™ is available for purchase for latitudes between N84° and S60°. The tiles are georeferenced in WGS84 Lat/Lon projection for use in all modern GIS programs. The GeoTIFF format maintains compatibility with popular image processing programs such as Adobe Photoshop™. Mercator projection and tiled JPEG format are also available. Other formats and projections are available on request.
http://www.unearthedoutdoors.net/global_data/true_marble/purchase

WMS Global Mosaic GeoTIFF Download

This page contains links for a complete set of the raw image data contained in the WMS Global Mosaic, base resolution only. The files are grayscale geotiffs, with the proper geolocation tag information for integration in GIS. These gzip compressed geotiff files are very large, between 350 and 500 Megabytes each, and will decompress to 800MB tiffs, 28800×28800 pixels, covering 4×4 arc-degrees fo the panchromatic band and 8×8 arc-degrees for the other bands.
http://collections.sdsc.edu/dac2/telascience/telascience_data/onearth/

When a Raveon GPS Transponder received an over-the-air position message from a tracked car, boat, truck, or person, it sends a message out of its serial port.  The message it outputs contains the ID of the vehicle that it received the position report from, along with the vehicle’s latitude and longitude.

A typical message would look like this:

$PRAVE,0003,0001,3308.8880,-11713.1500,155010,2,9,179,29,11.6,0,-86,19,-40,,*5B

The above message is in Raveon’s proprietary PRAVE message format. It was from vehicle 0003 whose position is at 33 8.888 north, 117 13.1500 west.  Details of the PRAVE message are in the M7 transponder user manual, and on this Tech Blog at http://ravtrack.com/GPStracking/2009/the-prave-message-format/

Raveon’s M7 series of GPS transponders have various built-in drivers enablinging them to output vehicle positions in a variety of different formats.  Some formats are in the industry standard NMEA 0183 and other message types are in proprietary formats.  The type of message that the M7 transponder sends out it serial port may be configured by the user, using the GPS x command.

Below is a list of message formats that the M7 Transponder supports.

TLL ($GPTLL) NMEA format Target Lat-Lon

WPL ($GPWPL) NMEA format Waypoint Location

GSV ($GPGSV) NMEA format Satellites in View

GGA ($GPGGA) NMEA format Essential Fix Data

PRAVE ($PRAVE) Raveon format Multi-Target Lat-Lon and More

For details on the PRAVE format please see this article http://ravtrack.com/GPStracking/the-prave-message-format/57/

In Dallas, Texas, police recently encountered an auto theft ring by tracking the GPS transponder on a stolen lawnmower:

Officers found at least 12 of the 25 vehicles have been reported stolen. Authorities are calling it a major auto theft operation.

Authorities spent most of the afternoon and evening hauling away stolen vehicles that were to be stripped and sold for parts. Authorities also seized two guard dogs that were on short chains.

In the future, we can expect that all assets of significant value will include a GPS tracking device. Not only could it help you track down your stolen property, but it might also help you remember which neighbor borrowed your tools.

One area where GPS technology will see greater improvements is in how it is used within large buildings and other interior spaces. Currently, it is difficult to receive GPS signals through walls and structures, but this reach can be improved with GPS repeaters and other ground-based systems. One can imagine how useful this might be in locating company personnel within a corporate office building, hospital, etc. In addition to fleet tracking your vehicle fleet you could also have a handle on all your staff in real time. Here is an article about how current GPS technology is being extended.

The system is being currently tested in Finland. In fact, it is not the first indoor system but the others have mostly been for specialist uses, such as helping firefighters find colleagues in smoke-filled buildings. This system, developed by Nokia, will work with existing handsets and infrastructure, according to the scientists.

One thing it does need, however, is access to maps of the inside of buildings. This may not be feasible for private homes, but many public sites such as big sports centres and universities already make maps available.

Perhaps as building information modeling becomes standard, public spaces will be able to submit mapping data to GPS mapping data providers or through a distributed system of mapping data?

I was reading this article earlier today about how a stolen ambulance was recovered using the vehicle’s GPS transponder. Obviously, this is just one more benefit to tracking your vehicle fleet with GPS-based solutions. It may even be possible that insurance companies will factor the presence of GPS tracking systems into your company’s insurance policy, which could result in discounts to damage coverage since vehicles should be easier to recover if lost or stolen. Likewise, if a vehicle is lost or stolen it can be recovered in less time and with less impact to your fleet capacity. Eventually we will see more and more equipment tracked in real time with GPS.

A recent study by C.J. Driscoll and Associates shows that fleet vehicles, construction equipment, and mobile workers account for about 3.6 million GPS devices in use in the United States. This number is expected to increase to about 6.5 million by the year 2012 as more businesses realize the benefits of GPS fleet tracking in terms of fuel savings, asset tracking, and overall efficiency. We expect these trends to continue until all commercial vehicle fleets adopt GPS fleet management as central to their logistic efforts.

One of the issues with the accelerated economic growth of the developing world is the reliability of road and mapping data. In many places like Dubai and China construction is taking place at such a rapid pace that municipal authorities cannot assign addresses fast enough to meet demand. Likewise, in other places like India, existing mapping data is simply unreliable. This is where GPS can be ideal as GPS uses your specific position and geographic coordinates, which makes it immune to problems that plague traditional mapping systems that use street names and other arbitrary assignments of position.
In places like Nagpur, India, city officials are meeting such challenges by installing fleet management systems in their ambulances and emergency vehicles in order to best respond to emergencies and disasters:

Dr Pradhan said that whenever anybody calls 102, the control room can track the ambulance nearest to the spot and direct it to the place. “OCHRI has installed the device on all its six ambulances as well as those of other private hospitals,” he said.
Dr Noorul Amin, senior medical officer and in-charge of Emergency Medical Services at OCHRI, said that GPS technology uses radio waves to calculate the distance between vehi Dr Pradhan said these ambulances would have one hospital staff capable of providing first aid at the spot itself. He also underlined the need for providing all life-saving medicines in them. He said the project was brainchild of NMC commissioner Aseem Gupta.

Fleet management using GPS is an ideal way to quickly respond and deploy your assets to react to crisis quickly. This is a trend we expect to continue.

Many companies are starting to see the benefits of tracking their fleets with GPS-based solutions in terms of fuel cost savings and more efficient route planning. With GPS, you can constantly optimize your routes, which will add directly to the bottom line over time through more efficient use of resources. American Airlines recently reported an investment of $400 million to upgrade its entire fleet with GPS navigation systems to operate more efficiently:

“I think we are going to save several thousand pounds of fuel on this one flight,” he said.
And that could mean more cost savings for American, which spent $9 billion on jet fuel in 2008, if it is allowed more trans-Atlantic flights that use the new technology. The carrier has said it wants to save 120 million gallons of fuel and reduce carbon emissions by 2.5 billion pounds this year.
Flight 63 will use an optimized route determined by GPS, not a route predetermined by air traffic controllers. GPS lets controllers track a plane all the way across the Atlantic, even when it’s out of radar range, unlike the Air France plane that disappeared from radar last week. GPS would help maintain appropriate separation among planes.

In addition to the cost savings and reduced environmental impact, GPS will help avoid tragedies like the disappearance of the Air France flight over the Atlantic.

The RavTrack system offers very good coverage in many environments with a single base station and single antenna.  However, in some circumstances this is not sufficient to cover the entire tracked area, or other factors may move you to install multiple antenna locations.

First, before you decide that one receiving antenna is insufficient, take a look at your area.  Do you have a voice UHF system of about 5 watts?  The Ravtrack system coverage is typically similar to the voice system coverage, although not necessarily identical.

Consider if you can mounting the base station antenna as high as possible to cover the desired territory.  In some cases this may mean moving the antenna away from the control room to achieve the best coverage.  A skilled RF technician familiar with your area can probably determine a good antenna location, sometimes by performing a site survey, or simply by experience.

Because you want to keep the antenna cable that links the antenna to the receiving modem as short a possible, this may mean that the receiving modem is moved from the vicinity of the tracking PC.  RS232 serial communication links have strict distance limitations.  However, if you have (or can get) Ethernet/IP communications between the base modem and the computer you can use a “terminal server” (AKA telnet server, serial-IP convertor) to place the base modem onto the Ethernet/IP backbone.  From here the position updates are carried via network telnet services from the base modem to the PC.

This approach can also be used to spread mulitple receiving base stations around your area, to improve coverage.  Again, you need an Ethernet/IP backbone linking all the antenna sites to your tracking PC.  You may check with your I.T. department if you have one, for help.  The Ethernet/IP backbone may be wired or wireless.  A number of wireless solutions exist. 

If you use this approach make sure your tracking software can acquire the telnet stream (sometimes you may use another telnet server), and/or that it can acquire multiple base station modems.  RavTrack PC currently supports up to 6 base station modems.

For much more detail on using terminal servers see application note 140 “Using an Terminal Server to expand your Ccverage area” at the following link.

http://ravtrack.com/pdf_appnotes/AN140(RavTrackTermServ).pdf

If for whatever reason this approach is impractical, one or more repeaters may be in order.  Remember that with RavTrack you don’t need to order fancy equipment to provide the repeater.  Any RavTrack transponder can easily be programmed to serve as a store-and-forward repeater.  Just ensure you make good locati0n and antenna choices.  For more information on antennas see the following tech blog “Antennas for a RavTrack vehicle tracking system”:

http://ravtrack.com/GPStracking/2009/antennas-for-a-ravtrack-vehicle-tracking-system/

One of the  advantages of using a repeater in your system is that the repeater will “repeat” any vehicle transmission it receives back out over its entire area of coverage.  Remember your vehicle transponder not only sends its own position information, but can receive the same from other fleet members, a feature fairly unique to RavTrack.  So, if you are equipping vehicles with tracking displays to do just that, those vehicles will not only receive position reports from other nearby fleet members, but those that are further away as well when using a well positioned repeater. 

On the flipside, a store-and-forward repeater does just that, it first receives and stores a transmission, then repeats out that same transmission.  While the RavTrack transponder has an extremely quick turn-around time from receiving to transmitting, it still will take time to receive then repeat.  Because of this the total duration of a transmission may need to be extended by lengthening the duration of each transmission slot in the system, and  you may want to recalculate system timing parameters and overall system performance and scalability projections.  If you have multiple repeaters they may require  further time slot expansions.  This is the prevalent case if you deploy each repeater using the same repeat frequency.  For more information on system timing with and without repeaters please refer to the techblog  “TDMA Time Slots”: 

http://ravtrack.com/GPStracking/2009/tdma-time-slots/

If your scenario will require you to install multiple repeaters, there are different methods for doing this as well, and different tradeoffs in the process. 

Whatever issues you face we encourage you to contact us so we can help you work towards the best approach for your particular system.