Acquiring Satellites
Acquiring Satellites, Awaiting Satellite Signal, The GPS signal was lost x seconds ago… This is the time of year when we start getting lots of questions about this message with people frustrated that their GPS “doesn’t work”. So what does this error message mean, and what (if anything) can you do to your GPS to make it get a signal faster?
In order to determine your location, a GPS needs to listen to the network of GPS satellites. In order to listen to the satellites, it helps if the GPS can predict “where” to listen for the signal. And in order to know where to listen, it helps to know where you are…. a nice little catch-22. (I’m oversimplifying things a bit for the sake of not conducting a physics class when people just want their GPS to work.)
So how do you get around this catch-22?
Tips for New GPS Devices
- Make Sure the GPS has a good, clear view of the sky. “Clear” does not need to be sunny. Overcast skies have no noticeable impact on GPS performance. But buildings and trees do. So take the GPS outside where you have the biggest sky view as you can.
- Next, wait for the GPS to acquire a signal. If this is the first time you have used it, expect it to take up to 20 minutes to find a signal. Most often it will take less, but prepare for 20 minute. Now for an important step… Once it has found your location, let it continue to sit there for about 30 minutes.
While the GPS is turned on with a signal, it is downloading “almanac” data from the satellites. This information will help it find the satellites much, much faster in the future because it will be better able to predict where to listen for the satellites.
It is important that while the GPS is acquiring a signal that you not move the GPS. A few feet is fine, however if you start driving with the GPS before it has locked into a signal, it will take much, much longer to acquire a signal, if it finds one at all.
Other Signal Impacts
Rural areas don’t make a difference like they do with devices that rely on terrestrial signals like mobile phones. The GPS system was designed to work nearly any place on Earth. In fact, urban areas with tall buildings nearby are the toughest challenges for GPS systems.
GPS manufacturers are constantly working on ways to improve their products, and acquiring GPS reception is no exception. So check if there are any software updates available for your GPS. Some GPS manufacturers like TomTom also offer updates on a periodic basis that help it with that “almanac” data. TomTom calls this “QuickFix” updates and you can download them to your GPS to help it find a signal faster.
Some types of windshields (specifically athermic windshields) don’t allow the GPS signal to pass through as easily. In this case, an external antenna can help if one is available for your GPS. If you live in urban area with lots of tall buildings, an external antenna can help in that situation as well.
Taking a trip?
Note that if you move the GPS a good distance from where it was last used (say more than 100 miles) it will take longer time to initially acquire a signal. If you fly somewhere for vacation and take your GPS with you in the rental car be ready for a double whammy. Not only will it take longer to acquire a signal because the GPS has moved a large distance since it was last turned on, but you will often start at the airport in a parking garage where you don’t have an unobstructed sky view to listen in to the GPS signal.
And if you are going on a trip you might want to check out our tips on traveling through airports with GPS where we discuss x-ray machines and other transportation tips.
Have you heard about SiRFInstantFixII?
Will this not give Garmin 700 series a serious lift against Tomtom?
I have read the Garmin 760 review and people have complained about this quite a lot.
Yes, however we haven’t seen any indication that Garmin is, or will, use that feature.
Could I not apply this myself?
Or any other fix that comes along with most of the shopping for gadgets now done online, you would won’t have a dealer to take it back too to upgrade?
No, you wouldn’t be able to apply it yourself.
I think I got it right
http://www.gpsreview.net/garmin-26-nuvi-update-sirf-instantfixii/
Is your blog for the same.
Tim,
What is the difference between external Bluetooth GPS vs regular GPS navigator in term of protocol? The reason I asked, because I have HP PocketPC with TomTom Bluetooth GPS (loaded with TomTom Navigator 6 software); somehow when it acquiring satellite signal, it’s faster than my friend’s Garmin, Mio & Magellan GPS (yes, he have three GPSs). Beside that, my Bluetooth GPS has better satellite signals than my friend’s GPS navigators. Friend’s GPS keep re-position itself or tries to acquiring satellite for every 5 seconds when came to mountainous terrain. This hesitate me buying new TomTom Go 730.
George
There really isn’t any difference in protocol– they both communicate with satellites in the same manner. I’ve got four or five Bluetooth GPS devices and none of them seem to have any significant difference over the PNDs I have when it comes to acquisition time or reception.
A Bluetooth device generally will have a little more design freedom though– since they are not quite as worried about size/shape, or screen placement– therefore I suppose it is possible they could overall have better reception.
Beside the size & shape limitation, Bluetooth GPS device does have advantage of location. It can be place outside of vehicle for better reception. My TomTom Bluetooth GPS is weather resistance, so I have no worry.
Tim, thanks for the info. I just ordered TomTom Go 730 online. Quick question… can my TomTom Bluetooth GPS be use with TT Go 730 with its Bluetooth capability? This will allow better reception if been place outside of the vehicle like an external antenna.
George
No, the 730 (as with most PNDs) can only use their internal chip. You can install an external antenna however if you find you need better reception.
Got you. Thanks Tim.
Hi
We purchased our NUVI 350 1 1/2-year a go and I don’t have any problem on it. But last couple of months it’s always stock up for 30 minutes and always in Poor satellite and low satellite reception. I did follow the instruction to reset but it doesn’t help. Warranty is already over (1 year???) Please help. THANKS,
If you’ve followed those steps and reset the device I’m not sure what else you could do other than contact Garmin for repair.
Tim,
In this article on Aquiring Satellites, you said for the “first time” start up, to let it set for 20 minutes. Does updating software later have any affect on the almanac data. I guess I’m asking if this should be done after updating and at the same location.
Good question, Dave. It depends on the device. Some will wipe out the almanac data on firmware updates, while others leave it intact. If you run an update and it connects just as fast as it did before, chances are you’ve still got the ephemeris (almanac) data. If it takes longer than normal to connect, then it probably did clear the ephemeris data in which case it might be best to leave it put for a bit to download the new data.
Thanks
I read it. It takes too long to adquire satellites
I bought a TomTom 130 and used if for 10 days then it suddenly could not find a GPS signal. I returned it to the store and got another. This one has worked fine for about 20 days and now it can’t find a GPS signal. Is this a common problem with the Tom Tom 130? How can I fix it?
Pam, no, it isn’t a common problem. Are you downloading the TomTom QuickFix data? Delete the ‘ephem’ folder from your TomTom, then follow the tips in this article for new GPS devices.
Hi Pam,
I am having the same issue with my Navman S35. I bought it 7 days ago, and started this rubbish today. I was at the same location for well over an hour with the unit switched on, and it still couldn’t locate a damn satellite. Well, it finds them after you do a full reset, and gives you your location for about 20 seconds, then all the green bars disappear. I’m going to be returning this tomorrow.
Troy, that type of issue sounds like a defective device and doesn’t sound like normal operation at all.
Hi Pam, did you resolve your issue, i am experiencing exactly the same thing on my new navman S150. Can’t acquire any satellites unless i reboot the thing, then i finds satellites for 15 seconds and looses them
Hi Tim,
finding it very hard to get manual on line for our navman S35, have you any idea’s. Also we are travelling to new zealand shortly, will our navman pick up sinal out of oz??? thanks
sally
I have a nuvi 350 and am having trouble acquiring and keeping satellites. I will be driving and lose the signal and within 10 seconds it will come back. Sometimes it will be miles before it comes back. This is while driving state expressways with nothing within miles higher than a farm silo. Sometimes it takes 20-30 minutes when first starting out to get the satellites, but if i try out in my house it takes 1-2 minutes. Can the problem be with my car’s dash? I have a toyota camry and use on dash w/o the holder but use a pillow of corn to hold. Kept falling off dash so now i use this method. This is my second unit, my last one was sent back because it could not get satellites at all and this one worked for a while and started doing same thing.
Hope you can help.
Ron, some of the Nuvi 300 series devices are starting to develop aging issues where the antenna cable that runs through the hinge is breaking– that is a possibility. Otherwise, make sure when you flip up the antenna that you don’t flip it “all of the way” up– just leave the square antenna so that it is horizontal with the ground for the best reception.
I have the same problem with nuvi 255w and Camry 2007, if you take it off the dash (ej. rear seats) it works well…I’m guessing if bluetooth is conflicting and looking for taking it off in the camry but could’nt do it…
I fly and drive with quite a few different GPS units. Some are mobile, many are “built in”. A few years ago, I noted that, as I tried to depart some airports a few of the GPS units would Lose Lock “they were working on the flight in and now they just lost all signal”. After seeing this happen from time to time I noted that it happened only at some airports with some aircraft with some GPS?. I tracked the problem down to the other radios in the aircraft. When the radio was tuned to receive on ground frequencies. In this case the ground frequencies at some airports (always AM 121.xx caused the radios in some aircraft to create a 3rd Inter-modulation frequency that swamped the “computer” in the GPS. If I used the secondary radio or changed the frequency or moved the GPS antenna to a different location the GPS would work fine. I pointed this out to several friends and we all found some interference level on some frequencies if the GPS receiving antenna was close enough to the radio bodies. So try your GPS out of the CAR and away from the AM / FM radio or the car’s other computer / electronics in the dash.
Steve
I’ve been searching for a while and this is the closest post/thread/article I could find regarding my question (you guys do a great job clarifying things =p).
While my unit (60Cx) was acquiring satellites for the first time, I moved it in-and-out of the house a couple of times, and it was left indoors for the most of the time.
Is that going to affect the “calibration sequence” of my GPS , or its “accuracy” in the future?
Thanks in advance.
Mac, no– that won’t impact your device at all, it will be just fine.
I just purchased a Nuvi 750 and was talked into buying an ac charger. I have owned a Streetpilot 340 for 4 years and have always just used the car power cord to run the unit. The batteries in the streetpilot died 2 years ago. Is it better to run the unit on it’s battery or is just using the power cord ok?
i lost sat signal and never got it back even leaving it on and resteing it what do i so
Tom, you should call the support department of the manufacturer.
i wrote before about loosing satellite connection and have found out later if i try using it before i get into car to go it will work. just several times i lost connection and it came right back. also i just had antenna 1/2 way up or out and doing both things the problem has stopped. don’t know which way was problem but it is all but solved. thanx for all the help.
thanx again.
Help! I need a basic unit for a trip to Ireland, and England. I can get a garmin 205 or 750 for good prices, but the reviews I’ve read (CNET + bloggers) occasionally say that the 750 is sluggish to mention turns or acquire satellites. Any suggestions-which one to buy? I will likely not use it much once I return to the US but will use it every minute and hold onto it like a bible when I’m driving on the left and listening to my “navigator” in the seat next to me telling me where to go… Do you have any experience with either of the units for speed and reliability issues? Don’t think I care about features too much, just something that’s reliable and won’t miss a turn! Thanks for any suggestions.