Actually, cell phones do use the GPS satellites. They use the cell signal to augment the GPS to aquire signal faster, and as a method to improve accuracy, but without GPS satellite, cell tower triangulation can at best get you within about 150 meters. You are correct that you don't need cell service for the phone to use the position augmentation from the towers.

Android phones also have electronic magnetic compasses. GPS can only give you direction if you are moving faster than 1kph. Below that, the phone will use its compass.

There are a few Android apps that can stream the sensor data, including GPS data via Udp packets to a listener. DJ wrote an ARC object that can listen to Sensor Stream, a similar app for iPhone, but the message format is different on all of the Android IME apps, so it doesn't work.

Writing a plugin for this is one of the many things on my todo list, but it has been there for about 3 years (was going to use the SDK originally), so I would not hold my breath waiting for it from me.

Alan

Right on it seems a simple way to get free navigating data that EZB could process to navigate the robot anywhere with no complex sensors to setup. My phone has no magnetic compass so it is the cell towers that can see what direction the phone is facing,just starts giving me ideas but you could be right that robot speed may need to be faster,I need to experiment and see.

What phone do you have? There hasn't been an Android phone ever sold in the US that didn't have a compass. I know you are in Canada, but I would be very surprised if yours doesn't have one.

Later today I'll send you a link to an app that can read all of your sensors to tell you what you have.

Again, the phone can not get directional information, either from GPS or towers unless it is in motion. If it tells you direction when standing still, it has a compass.

This is one of my areas of expertise. I have been studying and teaching GPS for over 20 years.

Hey good to know if I have further questions I'll let you know! My phone HTC can't use the EMF detector apps because it only works if phone has built in magnetometer sensor. I need to use my black berry tablet which does have the magnet sensor on haunted house investigations for electro magnetic field detecting.I do think EMF fields when strong can cause people to hallucinate /dizzy or sick so it is an important tool. This GPS free function is Amazing to play around with,so much possibility to aid robots if it can be tuned in properly. I know DJ does have an indoor navigation sensor coming out as well which is also very exciting.

Hmm... What model HTC? I have had several and they all have had EMF. Maybe your sensor is broken (the sensors on my Nexus 7 table keep dying and I need to reboot once or twice to get them back. I have seen a fix, but I need to open it up and deal with some very tricky cables, and it isn't worth risking for the uses I have for that tablet).

Alan

It's a HTC Desire 601 one of the best phones I ever had does everything really fast just no compass or EMF.

That's just crazy that it doesn't have it. Looks like no orientation sensor either. http://gadgets.ndtv.com/htc-desire-610-1320

If you were in the US, I would give you my old HTC OneM8 for your project, but I think the Canada customs charges would be more than it is worth.

Alan

Ha ha ya customs always sucks, a newer phone in the future should help and I use this HTC now for everything else including my car Speedo and GPS map navigator!For the robot I can still use my BlackBerry tablet for EMF and compass hacking.