Right GPS reading

[I.C.D]

Hi All,
Which GPS do you trust the google maps or the phone /hand held .Google reading lat 32.51 long 151. 18 phone/handheld lat 32.31 long 151 11 .Which one is right or split the difference

Ian

[skysurfer]

Trust the phone. That contains a real GPS.
Google Maps is just a guess, based on wifi hotspots.

[glend]

Ian, i am not sure it matters much. I used my Garmin etrex GPS when setting up my CGX in the observatory, or when it has gone to the darker site. I trust it's precision, but of course GPS alone can be 'off' by whatever error factor is set into the system at any time.
In the case of phones, if Location is turned on, then yes some tuning of the position may take place, and if you read the popup detail page about Location, it is claiming better accuracy.
The difference between the etrex and the phone is pretty small in my experience. And if your in a place without mobile coverage, say a dark site like Bretti, then GPS always is the
only choice.

[skysurfer]

The latter is not true. Set your phone to 'Device only' instead of the default 'High accuracy'. The latter is not a high accuracy at all and some apps even can't handle that. Device only os only dependant on satellites and not on cell coverage at all, so it just works like an etrex.
Even on the plane above the ocean, when the phone is held near a window, the GPS works flawlessly.

[glend]

Yes, that was exactly my point, read it again. GPS is accurate, but in phones it will suck battery power pretty quickly, and thus cannot be used for very long, if you expect to use it as a phone again without recharging. I have had my Android phone hang because it is constantly searching for a tower signal, and it rapidly drains the battery. You can turn off the phone network to extend battery life, forcing it to become a GPS device. Assisted GPS, which is what the supposed high accuracy tower triangulation positioning is called, is preferred (and usually default) for phones because it uses much less battery power than pure GPS positioning. In tests I have done, Google Maps is not very accurate, it can get to say within 5 metres in areas with multiple towers in range. Which is fine if your looking for a coffee shop on a certain street. In areas where Assisted GPS cannot work, the phone is forced into pure GPS mode, and here is where accuracy improves significantly, but if it is still searching for tower signals it will usually hang.

Yada Yada, it does not really matter in relation to Ian's question and his home location.

[skysurfer]

I always use the 'device only' setting and never have battery problems. But I only use positioning on when navigating in the car.
When 'high accuracy' it has to search for both cell towers and GPS, otherwise for GPS only. The latter takes longer when there is not a fix yet, but then is is just fast and accurate.

The so-called 'high accuracy' makes it easier for Google to track you, that is why they push it.
And when using Skysafari or Stellarium and there is not a fix yet in 'high accuracy' it sets the position to (0,0).

[I.C.D]

Hi All
Thanks for your reply's both of the long , lat numbers are the same only written down differen one is written as decemial degrees and the other written as degrees, minute's and second again thanks

[sil]

having been geocaching since before i got into astrophotography I still prefer and trust my garmin gps. Finding your location is its job, phones job is to suck your bank account dry. I know early on phone didn't always have a gps chip but would use other methods (like when connection to cells it triangulates and figures your position based on known fixed positions of the towers). But when iphone came along that was very close to my garmin (within 1-2m of it), today I still use my garmin but trust my iphone6 which gives same reading using an averaging mode on both devices. current generation gps devices I would buy over a phone for accuracy, especially if you intend to travel and "go bush" with it. Phones have gotten cleverer with using different triangulation methods combined and things like navigation software often makes assumptions and "snaps" your position to the road in its map. so phone accuracy depends on using a dedicated gps app. consumer gps tech has improved little over the years, its still the same comms rate and nmea sentences it reads, but they do have better sensitivity to allow locking on to more satellites and can do so with more simultaneously. no doubt there are a few more satellites in the gps constellation too now. There are also more ground station systems. Still not worldwide, USA had the best ground station systems and while not available everywhere or standardised like "GPS" they are still being added to GPS devices and phone apps as signals to supplement the gps data so in poor weather and under cover these may take over or help calibrate/confirm your gps position. mostly its tech improvements that allow for capturing more of these signal and processing them faster to allow for better positioning accuracy and real time positioning.

I need to finish the gps I'm building with arduino and see how good it works and how to increase accuracy with multisampling.