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  1. #1
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    NYC satellite locating times

    It takes me 5 to 10 minutes - often longer - to catch a satellite with my Garmin Forerunner 305 in NYC. I've been looking into upgrading after using it for 4 or 5 years, but don't know if I need to when my main complaint is that it takes so long to locate the satellites. What's annoying about it is that I can't just ride and wait for it - after several minutes of being unable to find it, the device stops searching and asks if I'm indoors, have moved, etc.
    Does this get any better with newer GPS devices, or is it something I'll have to live with regardless of what device I get? I'm curious if others in NYC have this problem, and how they deal with it.

    I haven't used it in the States at all outside of NYC and NJ, but I've used it for bike tours in other countries. In the Netherlands it varied. Sometimes it could take as long as 10 minutes, while at other times it would catch within 2. Same in Cambodia and Vietnam. In Kenya it located the satellites within seconds every morning.

  2. #2
    Senior Member Consularrider's Avatar
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    My experience is with a Garmin Edge 500 that I bought in 2010. As the memory filled with rides it kept taking longer and longer to find satellites and download the rides. I now clear the ride memory at least once a month and the satellite locating and ride downloads are fairly quick. That said, it can take a minute or three to initially locate a satellite when I am starting next to a tall building, even with the cleared memory.

  3. #3
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    I have a Garmin 110 watch and it takes a few minutes in Brooklyn, but I've never timed it.

  4. #4
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    GPS receivers have gotten more sensitive, but there are still some inherent limitations in the startup times. When the GPS has been turned off for a few hours or more it needs to get the ephemeris data from the satellite that specifies exactly where it is in its orbit. It's not much data but the link is extremely low bandwidth (50 bps) and therefore it takes 18 seconds to send the complete message and it repeats every 30 seconds. If the signal is interrupted during that time (say you're moving and a tall building gets in the way) then the receiver has to wait for the next repetition until it finally gets the full message. So moving around while the receiver is first acquiring a signal can greatly increase the time to get the necessary data. And it needs to be receiving signals from at least 3 satellites (preferably 4 or more) to determine its position. So delays in areas with lots of tall buildings or other obstructions are not unusual. Note that GPS receivers combined with cellphones can do better since the data message with the orbit information can be sent over the cellular network.

  5. #5
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    Thanks, this has been very helpful.
    Sometimes I stand and wait for the satellites to catch, but usually I just start riding. Good to know that it's better to wait, in a clear area.

  6. #6
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    I keep my watch strapped onto the handlebars when I'm using it. When I'm getting ready to leave I just put the bike outside while I put my shoes and other stuff on and it is usually ready to go by then. Of course, if you do this in the wrong part of Brooklyn you'll be using the GPS to track down your bike!

  7. #7
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    I can't get any satellite feed on my GPS (Garmin Legend) in New York City. However, the limo drivers who are parked have no trouble getting reception at all since they are parked all day. Once you're downtown with all those buildings, it's next to impossible. I find that my cell phone (Google Maps) can get reception far better and faster than a GPS in Manhattan.

  8. #8
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    I've got an Edge, but can't speak to a Forerunner. Generally speaking, though, GPS receivers lock onto satellites faster if they were recently used. If you go for a while without using one, it's going to start from scratch in terms of locating the satellite cluster rather than assume you're near your current location and use that as a starting point.

    I've had no problem with my Edge on rides into NYC, but then again I'm normally near one of the rivers or downtown where buildings aren't quite as big an issue (literally

  9. #9
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    My Edge 500 usually isn't much of a problem, but it can vary a lot, for reasons I can't discern. Most days it can get a lock in a couple of minutes. However, some days, it can take forever. The progress bar creeps forward, then jumps back, and does that repeatedly. It is more of a problem at work, which is essentially under the Empire State Building, as opposed to home downtown. GPS accuracy can vary a lot too, from spot on, to having me careen wildly across blocks and through buildings. I just wonder why it can vary so much day to day. It doesn't seem to be related to weather, or anything else I can determine. I use my Garmin pretty much every day, so how recently it was used doesn't seem to be the determining factor either.

  10. #10
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    Quote Originally Posted by wilfried View Post
    My Edge 500 usually isn't much of a problem, but it can vary a lot, for reasons I can't discern. Most days it can get a lock in a couple of minutes. However, some days, it can take forever. The progress bar creeps forward, then jumps back, and does that repeatedly. It is more of a problem at work, which is essentially under the Empire State Building, as opposed to home downtown. GPS accuracy can vary a lot too, from spot on, to having me careen wildly across blocks and through buildings. I just wonder why it can vary so much day to day. It doesn't seem to be related to weather, or anything else I can determine. I use my Garmin pretty much every day, so how recently it was used doesn't seem to be the determining factor either.
    GPS accuracy varies depending on how many satellites you're locked on to -- the more the better. In an area like Manhattan, you're not going to get as many sometimes as you would in the outer boroughs, downtown or the 'burbs. Edge devices generally will always complete satellite synching faster if they were used recently and if you're starting your ride in the same general area where you last used it. How recently a Garmin was used definitely is a factor, as current satellite data is stored in the unit.

    The article below gives more information on this and guides you through the process of erasing your satellite data, if needed:
    https://support.garmin.com/support/searchSupport/case.faces?caseId={c8955f00-3a60-11e2-e8a7-000000000000**

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