GPS Certainly Not a Perfect Science

[mr__ed]

I'm new to this particular area in Albuquerque. My Garmin GPS generally does a good job, but when I tried to locate a nearby Starbucks, it couldn't find any at all. It didn't seem to recognize the name "Starbucks". Next, I used my smart phone and it found several in the area, the closest being less than 1/2 mile away (using Google).

A little later, I tried finding a Verizon store and the Garmin couldn't find any. The smart phone located several. Now, I still like my Garmin since it's been pretty reliable on long trips and generally reliable in locating places nearby. Kinda strange it couldn't locate two major businesses close by!

[fj12ryder]

Just curious why you wouldn't check the address before you left home, rather than depend on a device you have admitted doesn't work very well. I look up the address beforehand and then check the GPS to make sure it has the address/location correct.

[mr__ed]

Well, my Garmin did it again. Yesterday, I punched in a local Albertsons supermarket. I was put on the correct street and Garmin told me the store is on my right. I pulled into a group of businesses and couldn't locate the store. It turned out to be on the left side of the street. It would have been a dangerous maneuver in Albuquerque traffic to move into the far left lane to get to the store. I've had this Garmin unit for many years and it had always proved reliable. It was updated only a few days ago, too. The unit still "gets it right" most of the time, but it appears Google maps is the better app, especially around town.

[mr__ed]

You make good points, Bill Satellite, but I'm not concerned about having unneeded data on my phone. For only #35/month I get unlimited talk, text, plus 3 GB data. That should be good for me for a long time, especially if I keep using my Garmin, since it works well most of the time. And yes, I'm aware of all the hotspots that may be used to save data usage. Right now, I'm at a Days Inn motel that supplies excellent in room Wi-Fi.

[Bill_Satellite]

mr. ed wrote:
Good explanation, wa8yxm. I just added more data to my cell plan (only had 500MB to begin with). Cost $5 extra/month for extra 500 MB. Since I mainly use the phone as a GPS device if the Garmin doesn't work, that may be sufficient. I can always add more if necessary.

Well, I have 3 GB now ($5/mo) after negotiating at the Verizon store

You do not need ANY data to make your phone work with Google Maps. All you need is free wifi at home or at McDonald's or your RV park before you lave on your trip. You can download maps for the entire area you plan to travel before the trip begins and then just use Maps to get you to your destination. It will work even if you turn off mobile data!
You will not get live traffic updates if you do this but that's all you lose as far as the GPS portion is concerned. Even if you run mobile data the entire trip, Google Maps only uses about 150MB (0.15GB) during a 250 mile trip. You don't need a huge data plan to take care of that! WAZE uses about 2X that amount as it uploads information about your speeds and any helpful hints you choose to add while driving (accidents, police, road hazards, etc.)

[bob_nestor]

wa8yxm wrote:
Actually you are not describing a failure of your GPS. it was working perfectly.
You are describing a failure of the Cartographers who wrote the map for the GPS.

The gps has basically one duty. To properly report your geographical location in 4 dimensions (Altitude, Latitude. Longitude and Time) It may also carry "optional information" to your receiver (Weather. Alerts, Traffic) but that is just "Radio" not GPS.

Translating 2 (or even all 3) of the GEO varibles (Lat, Long, Alt) to a spot on a map or represention of a building.. Well that is the job of the map maker. and the map software.. Locating a nearby "Attraction" (Target destination) is yet other optional software... And part of the map package. NOT THE GPS. it just runs the map program.

Your smart phone has another advantage. IF a new store opens. it will knwo about it almost before the ribbon is cut.

Actually it isn't all the cartographers fault. The GPS solution can be very precise but isn't always because of the implementation. The US array adds fuzz to the signal that makes getting a precise solution impossible unless the receiver has the ability to remove the fuzz. That ability is contained in a classified piece of HW not available to the public. Some of this can be circumvented to an extent if the WAAS option is enabled in the receiver and it detects WAAS signals. I suspect the Russian GPS uses a similar method (without WAAS) in their system, but not sure about the EU or the Japanese systems.

It generally takes a solid lock on four signals or satellites to obtain a solution. But satellite signals get masked by terrain, buildings and such. Also the GPS software will mask any satellite signal coming from a bird that is too close to the horizon, or in some cases it it's more or less in-line with the sun's position. And for the US array one needs to remember that it was designed for the military and the birds are positioned to give better signals over Europe, not the US. I suspect the Russian array is designed to offer better solutions over the US so nowdays when I'm looking for a new GPS I look for one that can handle both US and Russian arrays.

Another issue with GPS systems is they are designed to continue to offer solutions even when they haven't got a solid lock on enough signals. This is called "coast mode" and it projects your position based on your last known good position, your direction of travel and your speed. The amount of time the GPS remains in "coast" telling you where you are (even when it has no good idea) is somewhat indeterminate and depends on the GPS unit. I have some units that tell me pretty quickly, others that might tell me when I'm in the next State.

[2oldman]

lynndiwagon wrote:
It may not be perfect but man...

Yeah, gps is amazing, but right now I'd settle for just excellent, let alone perfect. I swear my unit from 8 years ago never made all these mistakes. I can't trust it in a city much at all, anymore.

[mr__ed]

lynndiwagon wrote:
It may not be perfect but man it's amazing how these things work. Sometime when you're not doing much look into how GPS really works. Amazing.....

Agreed. I'm fascinated with technology in general. I love my computers. Not too many years ago a person would think this was all magic.;)

[lynndiwagon]

It may not be perfect but man it's amazing how these things work. Sometime when you're not doing much look into how GPS really works. Amazing.....

[mr__ed]

Good explanation, wa8yxm. I just added more data to my cell plan (only had 500MB to begin with). Cost $5 extra/month for extra 500 MB. Since I mainly use the phone as a GPS device if the Garmin doesn't work, that may be sufficient. I can always add more if necessary.

Well, I have 3 GB now ($5/mo) after negotiating at the Verizon store

[fj12ryder]

2oldman wrote:

Edd505 wrote:
Hate burned coffee, and lattes, that's not coffee. Folgers or Maxwell House, that's coffee.

Can't wait to hear what you think music is.

wa8yxm wrote:
Your smart phone has another advantage. IF a new store opens. it will knwo about it almost before the ribbon is cut.

It also knows what hours the store is open.

And how much money you have to spend. 🙂

[2oldman]

Edd505 wrote:
Hate burned coffee, and lattes, that's not coffee. Folgers or Maxwell House, that's coffee.

Can't wait to hear what you think music is.

wa8yxm wrote:
Your smart phone has another advantage. IF a new store opens. it will knwo about it almost before the ribbon is cut.

It also knows what hours the store is open.

[philh]

traveling down a 2 track in my car thanks to garmin...

[wa8yxm]

Actually you are not describing a failure of your GPS. it was working perfectly.
You are describing a failure of the Cartographers who wrote the map for the GPS.

The gps has basically one duty. To properly report your geographical location in 4 dimensions (Altitude, Latitude. Longitude and Time) It may also carry "optional information" to your receiver (Weather. Alerts, Traffic) but that is just "Radio" not GPS.

Translating 2 (or even all 3) of the GEO varibles (Lat, Long, Alt) to a spot on a map or represention of a building.. Well that is the job of the map maker. and the map software.. Locating a nearby "Attraction" (Target destination) is yet other optional software... And part of the map package. NOT THE GPS. it just runs the map program.

Your smart phone has another advantage. IF a new store opens. it will knwo about it almost before the ribbon is cut.

[mr__ed]

Well, I just updated my Garmin yesterday and it hasn't solved anything. However, it does get me back to my original location, so it's likely I'll be using my Samsung Galaxy J3 (with Google) more and more around town. I also like the way instructions are given by the "lady" on Google. I think she's easier to follow than the "lady" on Garmin. That's important for me since I only have use of my right hand (vehicle has been modified for right hand driving), so easier to follow, more explicit instructions are safer both for me and others on the road.