Pondering GPS
OK, I know very little about GPS (other then the excellent entries I’ve read in this group.)
I read somewhere that a survey found that GPS is more anticipated by potential users of mobile phones then mobile TV.
This doesn’t surprise me as finding ones way around the countryside strikes me as a damn useful thing to have in a phone.
I’m noting down a few thoughts, after using the GPS in the N95 a few times in the last couple of weeks…
- GPS seems to work better if I’m driving. The positioning seems to be more accurate if I’m standing in the middle of the road. Maybe trees confuse the satellite signals? That said, I had some real problems getting a fix on the satellites recently, until I slid the phone up onto the dash. Once I had a fix, my passenger wouldn’t let go of the phone as she found it fascinating to watch our progress on the screen as we drove through the countryside.
- It would be nice if the camera app in the N95 auto logged onto the GPS and geotagged photos and videos. In fact, it would be interesting if everything were geotagged such as SMS and email.
- Maps should allow an option to override the screensaver without running the backlight continuously.
- It would be nice to see the two GPS apps (the info app and Maps) combined.
- This device should be the ideal hiking phone, but the lack of protection for the screen, the strength of the plastic case, and the battery life reduce its effectiveness. What if the phone could plot a path following my movements through the bush? This data could be picked up by the Lifeblog app and mashed up with geotagged photos (including recorded sounds and video,) and finally the whole lot uploaded to Google Maps.
- There is a GPS device on sale over here that allows the user to take a photo of a place, and this becomes part of the info for tagging a location. The user can browse for the photo of where they want to go, select, and the path finder does the rest. The N95 is the idea platform for this sort of functionality.
I thought it was interesting to read in the manual that the N95 has three different ariels.
Is this why the phone is clothed in plastic fantastic?
Is it not possible to ‘time slice’ access by the phone/Wifi/GPS to a single areal?
I was bush walking on the weekend and a couple of people whipped out their GPS units.
We got to talking about something called ‘assisted GPS’ where the Cell towers are used to glean extra position data.
Since there are three ariels in the N95, Any ideas on whether the N95 can use this technique?
Comments
- GPS kind of requires direct line of sight to receive the GPS sattelites signals. Dedicated GPS systems usually can show a hemisphere diagram and the sattelites that are visible. Typical attenuators are clouds/snow/rain, trees, wet trees, snowy trees, roofs, tunnels etc. attenuate the sattelite signals reducing quality. To larger the field of view of the sky the more sattelites the GPS sees. The more sattelites you can receive (track) the higher the accuracy of your position (statistical reduction of your location error).
A lock on the signal of 3 sattelites is required to get a position fix. A lock of 4 sattelites is required to get a position and altitude fix. Note that the vertical accuracy is 3x larger than the horizontal accuracy (in general around a 100 meters.
Carroofs are usually metal and attenuate the GPS sattelite heavily/completely. Carwindows hardly attenuate unless you have one of those new metalcoated widows lik in the Citroen C5. The N95 has a better view of the sky on the dashboard. The GPS signal receiver is in the keypad, therefore, slide the screen up to increase signal reception and shorten the sattelite lock.
- refections: GPS radiosignals can be reflected from surfaces. This is effect is used on purpose in sattelite dishes i.e. Reflections can distort the sattelite signal and make it unreadable or give an error in location. The N95 can cope quite well with reflections but is less sensitive than i.e. SIRFIII. Nemerix and MTK i.e. are just as sensitive as the SIRFIII chipset but better at coping with reflections. The new GPS chipset designs are a result of GPS being more and more used in city environments.
- You can install Shozu to geotag your pictures, however since you were complaining about batterylife. Remember the battery drains in 6 hours when running the gps. Shozu also creates google earth kml files (As like sporttracker). Still I like the idea for Lifeblog to cope with gpx or kml-files for th map application.
You could encase the N95 in a shock and waterproof suit. And it can plot and track your movements. Did you read D2's review? Sadly only US and UK topographical maps (YET!). Still for the real treehugging trip (week of solohiking in Lapland) I prefere an inbuilt magnetic compas, shockproof (9 G), IPX7 waterproof (30 minutes, 50 cm deep), scratchfree (saphire glass), altimeter GPS for outdoor stuff. Preferable a GPS that floats. There is no mobile reception out there in Saamen maa (read: Lapland) anyway. Only on the Everest you can make a mobile phone call. Silly Chinese goverment ;-)
- There are multitudes of GPS-trackers/loggers that track you position . This info can be used to combine it with the time/date info of the picture. Still all these programs do this afterwards on your pc.
- To answer your last question. AGPS according to WikiPedia
It's not to technical. In short is a reason to allow GPRS/3G connection when running satnav. It quickens a location lock if the local network supports it.