GPS with Map Software Question

[onedash]

Ok I finally got a laptop. I also have a megellan Platinum and am wondering if it can be used with a computer and streets and trips or another variant of software. I havent seen a cable that will connect my GPS to my computer. Its gonna have to be USB I think.
Can this be done or do I have to buy the sofware with a GPS antenna?

[Texas splinter]

I don't know, but I know where you can find out. This forum: http://escapees.infopop.cc/groupee/f...rm/f/127600761 is the Excapee's RV site's Computers and Software forum and if someone there can't answer your question, then nobody can.
Many RV'ers use GPS and maping software all the time, mostly with a laptop.

[jwaterdawg]

I dont have the magellan but I have a Garmin GPSMAP76S. I use it with both Mapsource (from Garmin) and TopoUSA (from Delorme) running on my laptop. I had to buy a serial to USB connector but other than that it works dandy.

Those particular software won't due street routing on the fly because that is not what they were designed for, but that's okay I mainly use it for finding fishing holes anyway. I would assume that the street routing software would work similarly.


PS: If you haven't already come across it, the following is a really cool website. You can enter street addresses and it spits back lat/lon. I've used it a lot.

http://www.gpsvisualizer.com/convert?form=address

[jziegler]

I don't have a GPS receiver, so I've never tried this, but my laptop came with MS streets and trips (part of MS Works now), and it shows an option to connect with a GPS and follow your position. It offers route finding and all that stuff, a decent program overall. But I don't know how good the interface to GPS is, and what devices it supports.

If the GPS only supports serial and your laptop is only USB, the inexpensive USB to serial converters work very well for most applications.

Jim

[LCHIEN]

most of the map programs like street atlas will take GPS position information and display the current position on the map. The standard for GPS information is NMEA0183 serial data over a serial port at 4800 bps default.
The map program will have a communications setup where you specify which COM port and can also select different rates.

Most handheld GPS receivers have a serial port from which they, BY DEFAULT, continuously transmit position information in the NMEA0183 format at 4800 bps.

The only thing, if you have a new laptop, most laptop manufacturers are deleting COM ports and putting in four USB ports. You'll have to go to COMPUSA or BestBuy and get a RS232 to USB converter for less than $25. When installed, this will appear as a port COM5 through COM8, I haven't figured out how the actual number is chosen, but you will need to make a note of the number and choose it on your map program setup which should now show this number as being available.

Older GPS receivers (like my Garmin GPS12) only have serial ports. Newer GPS receivers may already have USB ports (like my Garmin MAP 60CS) but still have the serial port. Cable connectors for the serial port vary on the GPS end so you probably have to buy one from the manufacturer.

HTH

[onedash]

I found a COM to USB cable at Radio shack for $40. ohh...I c the one at COMPUSA for $23.99.
Sweet. Now I can buy the streets and trips without the GPS.
@ $40 for the adapter I was almost ready to buy the one with GPS.
Although that would be powered by the laptop I think.

[brumere]

There's a version of MS Streets and Trips 2006 that includes the software and a USB port GPS device. It works well. I bought mine at Costco for $99.00

[gjbivin]

You may have to go into your GPS receiver's setup menu to turn on the NMEA output. In my GPSmap 76, it's at MENU | SETUP | INTERFACE, where there is a choice of several I/O formats, including NMEA.

If you are using the laptop & GPS in your car (um, where else would you use it? ), be careful and try to keep your eye on the road. It's too easy to get distracted by the map display. In fact, AFAIR, it may actually be illegal to have a computer screen visible to the driver while moving in some states. That's never stopped me , but I have caught myself drifting off-center a time or two while "field testing" moving-map systems I've designed. The GPSmap 76 is a bit better, because I can pick it up off of the dash and hold it where I can glance at the map while still -- theoretically -- having the road in my field of view.

You'll also find out that GPS is easily blocked by buildings and even thick folaige. Driving around downtown areas or in forests may result in spotty GPS coverage.

I get a laugh out of the misconceptions about GPS that crop up in TV programs. A CSI: Miami episode last week had them scanning for the one GPS receiver in the Atlantic that "was transmitting instead of receiving" -- and they had a display of all of the GPS's positions in real-time. First of all, GPS receivers are just receivers, they don't transmit to the satellite or anywhere else -- you have to add an external transmitter if you want to broadcast your position info, and that can be on any radio frequency. Second, I doubt you could detect a GPS receiver more than a few feet away (by listening for its IF frequency or something like that). If you are using a GPS, you know where you are, but no one else will -- this is why the military can use the system in combat.

[onedash]

I can jam my meridian between the widshield and dash pretty well. But its so small and I dont have the street level detail. But for the money i'd rather get it on my laptop than in the GPS.
I strap the GPS on my bike sometimes just to check distances. I dont rely on it to find new routes. Again no street level data.And I hate falling off my bike. But when ever we drive by DC we exit at the first sign of traffic jam and grab the map to find our way past it. THis should make it easier.

[onedash]

Got the USB/COM port adapter and streets and trips 06. Updated my GPS software and tested it in the back yard. Pretty Cool..... I didnt drive around yet but I will play with it on the way to work tomorrow. you can click oon it for a birds eye view from microsoft too. I think that only works in select cities so far and the pics are around three years old but its the best pics ive seen on the internet.
Got a new Thumb drive too.It has the new U3 softwareso you can run programs off it. I got the pass2go and that seems pretty neat.

[onedash]

plugged it in for the drive to work today and once I started moving it drew a path in the wrong direction. Not just on the laptop but the GPS itself.
It also have trouble staying locked on.
Once I disconnected it from the PC it was good to go.
Not sure what to do now?
I put the primary and secondary map datum to WGS-84. No idea if that could have caused the problem.

S&T also says if not using a MS GPS then a driver must be loaded. I can not find a driver at Magellan for any of their GPS's.

[gjbivin]

I wonder if you're getting interference from the laptop, possibly down the cable. You might try clamping a ferrite interference blocker (Radio Shack?) around the cable to see if that helps (if you can find one). Those are the cylindrical "blocks" you see on some computer cables. The fact that the GPS seems to work OK when you disconnect the cable makes me suspicious that that's the problem.

The GPS position will "drift" a little from natural errors, even when standing still. Accuracy these days, now that the government has turned the SA degredation off, is about 15 meters (50 feet).

WGS-84 is the standard datum these days, so that's correct. A lot of the USGS topo maps use NAD-27, which uses slightly different values for the size and oblateness of the Earth, and which can differ up to a couple hundred meters from WGS-84 positions. Normally you use WGS-84.

The map datum wouldn't make it move in the wrong direction, however.

[onedash]

ok. not sure what actually fixed it but I set primary and secondary datum to WGS-84. NAD-27 was the secondary.
I also plugged in the GPS before I booted up and the mouse pointer was hopping all over. So I disconnected an reconnected and everything worked great. It told me when to turn on which exit in how many miles...pretty cool but I had to make sure I didnt get to occupied with it while driving.

We should be getting an updated map datum one of these days. The space shuttle supposedly remapped the earth a few years ago. I thought we would have had it by now.

WGS84 to NAD 27 can be tens of thousands of meters off. In california the milgrid on both maps was nearly identical on both maps for our shop but if you plug in the 100,000 sq id and grid zone desigantor one was right on at Camp Pendleton and the other was almost in San Fransisco.
I guess that was quite a problem for pilots/ bombs in Desert Storm at first.

[gjbivin]

Glad to hear that you got your system working. When both the computer and the GPS are operating in the GHz range, funny things can happen when you hook them together.

Here's a page with some info on GPS coordinates and datums:
http://education.usgs.gov/common/les...d_answers.html

From the article

Why don't USGS map coordinates agree with those I obtain with my GPS receiver?

There are two main reasons why this may occur. First, be sure your GPS receiver is set to the correct horizontal datum. Experience has shown that the position differences between NAD27 and NAD83 (WGS84) can vary by as much as 100 meters in easting and several hundred meters in northing. In latitude/longitude the maximum error may approach 200 meters.

If you do some searching, you should be able to find software that converts between NAD-27 and WGS-84 if you are taking coordinates from older topo maps.

I'm not familiar with the Mil grid system; could the problem you mention be that the maps you are using have different grid origins, similar to the way that UTM coordinates work?

Some of the ground forces GPS receivers had reliability issues at the start of Desert Storm; I understand a lot of soldiers were using commercial receivers until more military units could be supplied.

AFAIK, the Shuttle Radar Topography Mission data was recorded relative to WGS-84 coordinates. See http://www.metrokc.gov/gis/sdc/raste...alMetadata.htm
I would confidently predict that if a new datum is defined, it will be within a few meters of the current ones.

[Jeffrey Schronce]

You are gonna love this technology. I used Laptop/GPS receiver for 3 months to get around the hurricane areas last year. Something a lot of folks don't think about is that the street signs are gone. There is a post left there (at best). The GPS, along with NOAA images helped me get around with 95% confidence (which is REAL good in these conditions).