My goal is to use multiple android devices to achieve a more accurate GPS position, but from the research I've done around the net, it looks daunting. In order to do the differential calculations, I'd need to be able to access each phone's raw gps data, specifically the pseudorange of each satellite, in real time. Unfortunately, the Android API doesn't have any hooks for this data, only the processed resulting data. I did see, on another forum, that GPSmaster, who hangs out around here, claims to have pulled it off.
So two questions really: First, since I'm a total noob here, is there a way to send users private messages, ie, can I get GPSmaster's attention somehow? Second, does anyone know of a way to get access to the raw GPS output with going way below the API layer and having to recompile the OS?
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I would like to figure out how to locate a device by its connection strenght(dBm). Even if this don't give me a direct location, it could give me a radius of the device to the phone or the other way around. So far i've been able to gather the device name and RSSI "strenght" however, its a dynamic data i'm getting. I would like an continuously update of how good the strenght is. So the part I'm stuck on is getting the correct values(ive got -72dbm and -342654dbm form the tests) and i need updates every 3 second.
What you should really do is use the Android Beacon Library, it will work the distance out for you.
The actual calculation is very complex and this Library has been used by a lot of people since Radius Networks created it. The link is for the website downloads, but you can use gradle too.
It's easy to use and probably exactly what you're looking for
I've been doing a bit of research on a problem we are trying to solve. I think this is the best approach but please add in your opinions
We are trying to calculate reaction times in a real world driving scenario and would like to use a mobile phone as the data collection device. What we are trying to accomplish is how much acceleration and more importantly deceleration a driver exerts when exposed to certain prompts.
I found this paper that has allot of useful information Accelerometer physics
The problem is that we most likely will not have a calibration time to start at zero.. however it is assumed that the driver is starting at 0. We will use GPS positioning to locate the vehicle, tracking the time stamped location data we should calculate the time when the prompt took place then using the time stamped accelerometer data we should be able to calculate their reaction to the prompt.
This is the best way I have found to solve the problem however I'm not sure if the accelerometer data will be rendered useless because of not being able to calibrate it and also the noise seen from vibrations may be too great to use the data... Has anyone tried or used these types of methods before?
Interesting application.
You are missing an important point. You either have to implement the so-called sensor fusion yourself or use the sensor fusion provided on the platform you are using. Both Android and iPhone have one.
The TYPE_LINEAR_ACCELERATION (Android, SensorManager) or userAcceleration (iPhone) should be sufficient for you.
As for the linked PDF, don't try integrating the acceleration, you will get very poor results. Even though that answer is about position, the velocity will already be inaccurate. I would try the GPS instead.
I know it's very old question but since I am recently working on a similar project let me share what we did in our company. We simply used OBD-II dongle to get velocity of car. There are many API's that return information about vehicle.
PID010D returns speed of vehicle. I'm using this PID to calculate distance between points A and B since there is no PID to return Odometer :(
There are few libraries on github that you can find easily by search. This mine. This is not library but after run on your device you can see how it works.
I've been doing a bit of research on a problem we are trying to solve. I think this is the best approach but please add in your opinions
We are trying to calculate reaction times in a real world driving scenario and would like to use a mobile phone as the data collection device. What we are trying to accomplish is how much acceleration and more importantly deceleration a driver exerts when exposed to certain prompts.
I found this paper that has allot of useful information Accelerometer physics
The problem is that we most likely will not have a calibration time to start at zero.. however it is assumed that the driver is starting at 0. We will use GPS positioning to locate the vehicle, tracking the time stamped location data we should calculate the time when the prompt took place then using the time stamped accelerometer data we should be able to calculate their reaction to the prompt.
This is the best way I have found to solve the problem however I'm not sure if the accelerometer data will be rendered useless because of not being able to calibrate it and also the noise seen from vibrations may be too great to use the data... Has anyone tried or used these types of methods before?
Interesting application.
You are missing an important point. You either have to implement the so-called sensor fusion yourself or use the sensor fusion provided on the platform you are using. Both Android and iPhone have one.
The TYPE_LINEAR_ACCELERATION (Android, SensorManager) or userAcceleration (iPhone) should be sufficient for you.
As for the linked PDF, don't try integrating the acceleration, you will get very poor results. Even though that answer is about position, the velocity will already be inaccurate. I would try the GPS instead.
I know it's very old question but since I am recently working on a similar project let me share what we did in our company. We simply used OBD-II dongle to get velocity of car. There are many API's that return information about vehicle.
PID010D returns speed of vehicle. I'm using this PID to calculate distance between points A and B since there is no PID to return Odometer :(
There are few libraries on github that you can find easily by search. This mine. This is not library but after run on your device you can see how it works.
To read the sensor's data on an Android platform (i.e. Accelerometer, Gyroscope, Magnetometer, Barometer, GPS ), people over the internet are talking about two ways to acquire such data
Primary way: reading the data using the Android SDK via JAVA.
The 2nd way is related to reading the data using the Android NDK.
What about communicating with the sensors directly via SPI,I2C, or UART without the use of the SDK or the NDK ? I understand that I'll be burdened by understanding the communication protocol with the sensors and reading specific registers from which I can acquire the data in a more efficient way. Is this possible ?
In theory it is possible, Walid. If you throw enough time and money at most technical problems, solutions become possible. But I would have to ask why anyone would want to do it that way?
It would be like saying "I'm pretty sure I can drive my car, inverted. I'll operate the accelerator and brake with my hands, and I'll add a couple of extra mirrors to reflect the windshield view down to me. And I'll steer with my legs. Don't ask me how I'll operate the horn!" It's just doing it at a goofy level.
You'd surely need details of the individual chips, which means you'd need to tear your XOOM apart - that kind of implementation info is not published. Not because it's a big secret, but because it keeps costs down if manufacturers don't publish info that 100% of consumers don't need.
Bottom line: there are more productive uses of your energy and brainpower.
Peter
I would like to log sensor data (Accelerometer, Gyro, Magnetometer, GPS, etc.) and record a time history which can be accessed for future plotting and analysis (as well as some real time calculations). I am a MATLAB programmer, so .csv files came to mind, but I've also seen a little about MySql, which I'm not too familiar with.
My question is, which datalogging method is most appropriate? I'm not limited to the two mentioned above, they're simply what I've seen so far. Any suggestions/ example codes?
PS, I've also run across MicroLog4Android (http://code.google.com/p/microlog4android/) but there are not any examples which I have come across, and being new to Android, I cannot tell if its meant for logging higher speed data (10-20 Hz) or if it's simply a program errorlog. It has some cool features (SMS sending, network storage, etc.) which make it attractive if this is indeed an appropriate tool.