Thread: GPS

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    Default GPS on your Apparatus?

    Since we have had a few threads lately regarding technology in the fire service. I thought this would be a good place to start. Does anyone out there use GPS on their apparatus? If so, is connected to the dispatch center and automatically populated with the call information and directions? If its a stand alone GPS system ( like the handhelds you can get a at Radio Shack, Best Buy), how is it working out for you?

    Do you find it takes too much time to enter in an address? I have a GPS system (A Garmin Street Pilot 3) in my car. It takes some time to enter in the address manually. I looked on the web for some information about suppliers for emergency apparatus etc, but havent been able to find anything. Any suggestions?
    Last edited by Uncharged; 02-22-2004 at 12:27 PM.

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    how does it work
    I think there are currently 21-24 GPS satellites orbiting the earth. Each has an atomic clock and sends it's time, to within milliseconds, to earth. The GPS units we use also have an atomic clock and receive a signal from three satellites in a triangle. The time for each signal to reach the unit is computed to give your position. A fourth, or maybe the third signal is used for elevation.

    This is my best guess from what I've read.

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    E229Lt, you are correct, its a minimum of 4 satilites to get a 3-D fix, most modern units can utilize up to 12 satilites at once (the most that will normally be in view from one location) to get better resolution. If you'd like I can get into how the system actually uses spheres to estabilsh positions, but you've got the fundamentals down more than good enough.

    I routinely use GPS both in my own car and on boats (I am captain of a Sea Tow boat, sort of the AAA of the water) and unless you have your waypoints preprogrammed it is very time consuming to enter them. You can fairly quickly punch in a set of Lat-Long, but to manually enter an address or location takes too long to be useful in an emergency. One thing which does make my work quicker is the use of chart-plotters which have a built in map, point the curser where you want to go and follow the instructions there.

    The other problem with using GPS on fire apparatus to get directions to the scene is that most have a minimum warm up time to get a fix. Since most trucks are kept inside (GPS is a microwave signal, and like 800Mhz it does not penetrate well) you have to roll out to get the fix. Furthermore, GPS does not like to move when getting a fix, it can, but the more you change direction and speed the harder it is for the little computer to calculate its initial position. Sitting still most units will take about 30-60 seconds for a cold fix, I've driven miles w/o a fix to have it lock up at a stop light the second I stop rolling.

    Yet another wrinkle is the positional errors that reflections of the signal can cause. In the concrete canyons of cities the satilite signals can bounce off high rise buildings and present you with a false position. The error is not much, rarely more than a few hundred feet, but that may be enough to fool the unit into thinking you are on a different street. In a city full of one ways and tight blocks you could get into trouble this way.

    There are solutions, some already available, some theoretical, all expensive such as a data link to the truck when it is in the barn (plug in power, air, and fiber optic lines). I think GPS is great for reporting to dispatch when you are on the road, the closest unit can be dispatched automatically, and the supervisor can always find you if you fall asleep with the radio turned down in the parking lot of the 7-11. It is our future and the furute is closer than you may think.
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    Our Rescue/Service truck has an old Garmin GPS unit onboard. It is used on all medical runs so that if we have to call for Acadian Airmed to transport a patient we can give them accurate Lat/Lon and set up a proper landing zone. Since it is an older unit, it takes a while to warm up and get a fix on the sats. It is not hooked up to any mapping software and isn't used for finding addresses or transmitting location. Just for getting your Lat/Lon to send to Acadian Ambulance to relay to the choper.
    In my POV I have a Magellian GPS which is connected to my Kenwood D700 Ham radio. It sends out a data burst every 3 minutes with my location using data from the GPS. The Data is retransmitted by Digital Repeaters. I have a notebook computer attached to the system in my car and running mapping software I can see not only my position displayed but the position of other Ham Radio Operators as they broadcast their data. We can also type digital messages to each other instead of using the microphone on the radio. The system is called APRS-Automatic Position Reporting System and is simular to the professional systems used by police, fleet services and others. Since some Ham Radio Ops have connected theer APRS systems with the internet then you can locate any user in the world. For example, by going to- http://www.findu.com/cgi-bin/find.cgi?call=kc5sas you will see a icon of a car with my callsign, KC5SAS, displayed on 3 different scale maps to show my location the last time my car was in motion. There are Ham Radio Satelittes in orbit using APRS and even the Internation Space Station uses it. To learn more about APRS, go to- http://web.usna.navy.mil/~bruninga/aprs.html .
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    The PD in my home town now has built in GPS with the MDTs. The county went to a whole new computer system and it is ready with GPS for CAD. I saw it work and itís pretty neat. When the dispatch centers switch over to the CAD, whenever there is a call the screen inside of the car will show the map with the call location flagged. The city of Livonia MI FD uses this same system and their maps show the location of all the hydrants.

    I personally have a Rino 120 and love it. Iím actually considering the new 130 model. If you take the time to learn how to use them they can be fun little toys Öerr tools.
    Last edited by ffexpCP; 02-22-2004 at 04:03 PM.

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    We don't have any true GPS units, but we do have a GPS in one of the FD Nextels, but I bet there are only a handful of people who know it's there. That will only get a fix on your location. No maps or directions or anything. We don't really have a use for one. About the only thing we would use it for is to get coordinates for an air ambulance, but it's just as easy for us to give them a major intersection and they look it up in their GPS.........

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    My vollie department has a Garmin GPS12 for our rescue truck (the one which would be calling for the trauma helicopter in most cases). I keep trying to get them to get the car power source and cradle like I have for my personal 12XL, but nothing seems to be happening yet.

    My career department has installed AVL capabilities on 16 pumpers (out of 36), one rescue (out of six), three chief's vans (of four), and one fire inspector van so far. More are being installed as the RF modems become available. I work in Dispatch and our dispatch model has changed significantly because of this. Rigs are being recommended from their actual location, instead of where the computer last "saw" them (i.e. leaving a scene, in quarters, etc). This is especially worthwhile if you have rigs driving long distances, i.e. enroute to cover other stations, going to/from the central shop/headquarters, etc. I have to say I like it, but there are some that are a little (jokingly) perturbed that we know where they are now 24/7.

    Also, here's a great tutorial on GPS for those who want to know how exactly it knows where you are:

    http://electronics.howstuffworks.com/gps.htm
    Last edited by Jay911; 02-22-2004 at 05:41 PM.
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    We are in the process of putting a brand new CAD system into operation, all new lap tops in our rigs etc.... Included in this new venture is a GPS system, not for us to use to find locations, but to keep track of where companies are located. It supposedly updates every 3 seconds or so. Like I said it is not in service yet so I have no idea how it works or if it even will, just have to wait and see on that one.

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    maybe that link will help me ...............but I just dont get the machines..........I think it is great stuff but got no idea how to use it or understand what its telling me .........need GPS 101 !

    Oh ya ...............we have 2 stand alone GPS units but very few people know how to use them.
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    For my fire dept, since we are in a rural area with a lot of mountainous terrain and woods...and since we have one of the toughest portions of the appilacian trail in massachusetts running through our town, we rely very heavily on GPS units. We have 5 portable units that we assign to each crew venturing into the woods. The town next to us, who we call for mutual aid for searches/rescues, also has quite a few portable units. They also have a great mapping program where we can track each crew and tell the crews how far apart they are from each other, how far they have to go to get back, ETA, etc....My dept has recently received 4 laptops through grants, and we are looking at putting the mapping program on them so we can have a map right at the stagin area/command post, instead of just having the base computer. We are in discussion with the local AT groups to put GPS coordinates on the signs, so if a hiker who does not have a unit, calls for help anywhere near a sign, we can get a general area instead of "I'm by the old lean-to."
    The ambulance service I ride on has one of the older car navigation systems, which we use if we're doing long distance transfers. It doesn't work great around here...due to being a rural area, alot of the roads are not in the system.
    The comments made by me are my opinions only, not of the Fire and EMS services I am affiliated with.

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    A word of warning to GPS users:

    The GPS is a military system, it is not under the control of a civilian authority, and it can be shut off without warning any time (due to drill or national security). Usually sometime after the shut down the USCG will broadcast a notice to mariners advising them that the military is conducting GPS black out drills, but not always, and it does no good to you if you are away from the coast. I was at sea last year at least twice when it happened, usually for about 5 minutes. If you look at your satilite status page you'll see them there, but no positional data is coming from them so no fix. The warning sailors get is "No prudent marinier relies on one source for their position." Good rule to live by.
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    My department doesn't use them as far as I know (I am hardly ever home to know anyway). I personally own a Garmin eTrex Legend and love it. I also have some of the mapping software for it. If you go to Garmin International You may be able to find something for your department.
    Do any of you use your GPS units for mapping incidents, or is that done automatically at dispatch?
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    The department Iím on uses laptops hooked to GPS receivers mounted in the rigs which have maps of the county. Weíve been using the system for about 3 years now and are fairly happy with it. The system is made by a company (Geo Comm) that produces mapping solutions for E911 systems. It works rather well. Each computer has the capability of receiving the address from the dispatch center through an 800 MHz radio connection. The county promises, within the next year, they will transmit the address once the CAD software people are done updating (delaying) the system. In any case we enter the address manually into the computer and an arrow shows up on the map where we are to go. Itís not too difficult to enter an address, people with less keyboard skills it just takes a little longer. While moving an icon of the truck moves on the computer screen so you can see how close you are to the address. The computers have touch screens so we can do manual zooming in and out while moving. We havenít had too many problems with getting to an address. Most of the time when we get close to the address, we are looking for house address instead of looking at the computer screen.

    Our computers are setup to run all the time. They run off the A/C when the trucks are in the bay and switch over to the battery when we take off. The station has a re-radiator antennae inside so GPS receivers can lock in on the satellites.
    Jeff Drais
    Saint Stephen Fire & Rescue
    Saint Stephen MN

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    Thanks to everyone for all the input on this one. I got some great ideas on it now.

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    We just had new MCTs (laptops) installed in most of our rigs which are tied to our dispatch system. We're looking into possibly adding GPS hardware/software where the address would automatically be entered from the dispatch info.

    It's not really an issue in our town, as we're fairly small and everyone has to pass a map test before being allowed to drive any apparatus, but would be handy for mutual aid calls. We also often go out on brush strike teams, sometimes even out-of-state, and would definitely be a help there.
    Chris Gaylord
    Emergency Planner / Fire Captain, UC Santa Cruz FD

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