Just got a GPS receiver, reception quesitons. (1 Viewer)

[Jeff Peake]

I moved to the Boston area a few months ago. What a horrible place to drive! I still get lost just about every time I go downtown, the streets here are very winding and confusing.
I also travel a lot for my job, so i figured it was time for a GPS.
I picked up the Garmin StreetPilot 3 .
My first problem is that the box did not contain the 32MB memory card, making the unit fairly useless. The store I bought it from stated it didnt come with any memory card....I had to go to another store and they were able to give me the card. So I finally got my maps loaded and took a trip downtown.
Everything was going fine until I got off the exit and hit downtown boston. As soon as I started driving around the sky-scrapers, I lost signal. And then i got lost!
I am just using the passive antenna that comes with the unit...I ordered a powered, external antenna that will stick on the roof of my car, hoping that will allow me to get reception with limited line of sight.
Does anyone use GPS in a big city? Do you have reception problems? What kind of antenna do you use?
I may return the unit if it doesnt work downtown....
Jeff Peake

 

[Philip_G]

GPS is going to have problems on the ground period I think. GPS is up around microwave freq's AFIK. And is pretty line of sight, so tall buildings, trees, tunnels, bridges, whatever are gonna cause you to lose some sats. Really the system is much much more suited for air navigation where there is no interference.
luckily they turned off SA about a year ago so you're accuracy is pretty good, though dependent on the accuracy of the clock chip.
Garmin builds a decent GPS. We've got mostly garmin GNS430 and a fe GNS530 GPS/NAV/COM radios in our training aircraft and I like them a lot for hat it's worth (though I think the comm radios suck in em)
[Edited last by Philip_G on November 11, 2001 at 11:31 AM]

 

[Andrew Pratt]

Unfortunatly the above poster is correct about the GPS's issues with line of sight and tall buildings. The other problem with tall buildings is they tend to scatter the signal so you might be picking up a signal directly from the satellite or one thats bounced from a nearby building etc which does nothing to help the accuracy. Now that SA is turned off though assuming you are in an open area you should expect to be within 5 - 15 feet of the actual position. We use the Garmin 3's a lot and find them to work exceptionally well but then I'm typically using them for field work where tall buildings are few and far between
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[Philip_G]

oh my other thought, they very well could have turned SA back on since we're at "war" of sorts. I think the DOD has their hand on the switch and can flip it at will

 

[Jeff Peake]

According to other GPS owners, SA is still off in the US. I heard that it was going to be turned on around afghanistan. Not sure how they selectively turn on SA...but I guess it can be done.
Accuracy has been very good so far with my Streetpilot. Plenty accurate enough for street navigation.
I am gonna give an amplified antenna a shot. It should improve things a bit, hopefully enough to at least get some signal while downtown. I dont mind if the accuracy gets off by a bit, as the software makes sure your position "sticks" to the roads...so minor innaccuracies are OK.
Jeff Peake
[Edited last by Jeff Peake on November 11, 2001 at 07:43 PM]

 

[Philip_G]

it's quite simple to turn on, they introduce a little "noise" into the stream and whammmo you get some error.

 

[Jay H]

GPS signals can be jammed quite easily, since the signal is so weak, whether the gov has SA turned on or off. Where I work, when we incorporated GPS into the Nav software, there are requirements that specify that GPS is used to enhance the current "big picture" and not to replace what we've been doing for years before GPS was prevalent.
Jay
I have a Magellan MAP 410 but the street functions is fairly useless cause it's not that detailed. I use it for hiking and stuff. Ever hear of geocaching?
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HUGGBEES!
Certified HTF bike nut and mayor of
Obscuria.

 

[Joel Mack]

Geocaching rules!

For the uninitiated.
Haven't done any in a few weeks, though. I need to get out there again...
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"The internet is a place where people from all over come together to
bitch about movies and share pornography."

 

[Ryan Wright]

Woah, Joel, thanks for the link! I may buy a GPS just for Geocaching! That looks like a hell of a lot of fun...
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-Ryan (http://www.ryanwright.com )
Before you criticize someone, walk a mile in their shoes.
That way, when you do criticize them, you'll be a mile away and you'll have their shoes.

 

[Bruce Hedtke]

Ryan,
It's a blast. As more and more people discover the sport, it has really taken off. It was tough when there wasn't many people involved...if you lived in a rural area, long drives were necessary to do any hunting. At least now, it's becoming easier to find things around ones own city...and you can always hide something if there isn't yet.
Bruce
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Welcome aboard the Satellite of Love

 

[Jay H]

I remember reading a short blurb in Outside magazine last year. I think it's also popular in Britain but they call it a different name,which escapes me at the moment. Do heed the warnings on the website about placement and storage. You want a box that is waterproof and try not to use food or perishables as they can spoil or attact wildlife (if in a woods setting). It's also cool if you get a ranger's permission cause leaving stuff in the middle of the woods can be considered litter and it's better not to piss off the rangers.
Jay
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HUGGBEES!
Certified HTF bike nut and mayor of
Obscuria.