I and a couple of friends have got a list of requirements for a new project. This project, basically asks us to synchronize a specific directory in a laptop with the user's phone (just like dropbox does) but using BLE for the communication.
Everything is working as expected. We're using Android on the phones and a BlueGiga USB dongle on the laptop side. The only problem we're facing is that we cannot limit the distance in which the phone is detected.
We do know that we can modify the TX Power and also the Advertising mode as it's explained here (https://developer.android.com/reference/android/bluetooth/le/AdvertiseSettings.html). The real problem is that we cannot get the same max distance on every phone because of differences with the chipsets, antennas, etc throughout all the Android devices in the market.
How could we do to limit the connection distance to 1 meter for all the devices running Android? We'd need to rely on the RSSI values but I'm open to different approaches anyway.
Thank you very much in advance guys and remember that everything is working perfectly. We just need to adjust the max distance.
Thanks.
Max.
Simple answer: You can't get an absolutely exact range limitation because of the physical properties of electromagnetic radiation. There are so many things you have to take into account, which makes it a quite difficult and complex task.
What you can do is very sophisticated calculations based ony many different factors to get an approximation. As already mentioned in the comments, you might find helpful libraries with algorithms and formulas for well known devices, chipsets antennas etc. so you don't have to do all the calculations on your own.
With the help of some libraries and tools, you may be able to quite safely determine if the device is within a range of between 1 and 3 meters.
Related
Now many Android phones have already support 2*2 mimo which means there are 2 wifi modules inside the phone. I wanna separately control these modules, one for sending signals and the other for receiving signals. How to directly control the hardware? I do not find relevant information in google documents.
As far as I know, there is no official way / API interface to control the WIFI modules or the antennas directly.
In my opinion, it does not make sense to do so. With MIMO, the best antenna is automatically calculated and used based on the quality of the input signal.
Here is a good explanation from Intel:
MIMO technology uses a natural radio-wave phenomenon called multipath. With multipath, transmitted information bounces off walls, ceilings, and other objects, reaching the receiving antenna multiple times at different angles and slightly different times. In the past, multipath caused interference and slowed down wireless signals. With multipath, MIMO technology uses multiple, smart transmitters and receivers with an added spatial dimension, increasing performance and range.
https://www.intel.com/content/www/us/en/support/articles/000005714/wireless/legacy-intel-wireless-products.html
What you are planning to do, however, would go against this principle and turn the MIMO antennas into two SISO (Single Input Single Output) antennas.
This would only be possible with a rooted smartphone or an XPOSED module.
If you want to find out how many antennas are built into a smartphone, I would recommend the WIFI Alliance website. Here you can find detailed information about all certified smartphones.
Website WIFI Alliance
For Example the Spec Sheet of the Oneplus 6t
Oneplus 6t WIFI Specs
I've done some experiments on different devices and I made each of the scanner and receiver at the same time and saved RSSI get from other nearby devices but the result was strange. first, there was a Huawei p6 that could scan other devices signal but nobody could see its transmit signal. second, the RSSI was completely device-dependent although beacons setting was the same for all of them inside the application and I want these signals to approximate their distance from each other.
question is that is this library reliable for my purpose which is getting approximately distance of devices from each other? I should mention that these results have gotten from android devices and I think that iPhones are another problem
The fragmentation in Android devices means that there is a huge variation in not just bluetooth chips, but in the external bluetooth antennas and phone cases that affect the strength of the signal Android devices receive and transmit.
While the distance estimates provided by the Android Beacon Library are useful for finding the relative distances to different beacons, using the value as an absolute distance estimate will not be consistent across different Android devices. The library does provide a way to tune its distance estimates to a specific hardware model, but unless you are targeting only a small number of devices this approach is not practical to tune for thousands of Android models out there.
I'm contemplating the development of an Android app that detects all or most nearby mobile devices (iPhone, Android, etc) in the immediate neighborhood that are turned on. I don't need to interact with these devices, just detect them, and a requirement is that the detected devices can't need to have any special / unusual apps installed on them. The app only needs to work for typical U.S. devices and networks.
I've thought about a few ways to do this (somehow detecting bluetooth, wifi, or cellular transmissions / identifiers), but I'm looking for specific implementation methods for a way to detect a relatively large proportion of nearby devices. I'm not sure which of these methods is possible / feasible or how to put them into practice...
Perhaps using Bluetooth: Is there a way using the Android SDK to detect non-discoverable Bluetooth devices (not in discoverable mode)? The Nokia Developer site seems to suggest this is possible using Service Discovery Protocol (SDP), but I'm not sure if this is possible more generally in Android.
Perhaps using cell tower mast switching simulation? Ok, this is almost certainly beyond the reach of Android, but this article suggests that there may be a way to "mimic cell mast switching process to trigger quiescent phones into transmitting. Phones respond with their ID and authentication signals...".
I think you should see this, it is a paper, and you cannot view it for free, but in the summary, it clearly states:
Concerns about Bluetooth device security have led the specification of the “non-discoverable” mode, which prevents devices from being listed during a Bluetooth device search process. However, a nondiscoverable Bluetooth device is visible to devices that know its address or can discover its address. This paper discusses the detection of non-discoverable Bluetooth devices using an enhanced brute force search attack. Our results indicate that the average time to attack a non-discoverable Bluetooth device using multiple search devices and condensed packet timing can be reduced to well under 24 hours.
But for an android application, you need the detection time to be well under a few seconds instead of less than 24 hours, so a practical solution may not yet be available.
I want to facilitate video-calling from the android device to another android device. My question is that can i connect the android WiFi device with the android WiFi device without any use of internet connection. I want to use it just like the Skype. is this possible or not? if it is possible then how can i implement it...can i get some code snippets as well???? Please give me link to download that app
First, your idea works completely different from Skype, which is completely dependent on a functional Internet connection for its core functionality.
Second, while you could create an ad-hoc WiFi network betweeen two Android devices, their range will be the limiting factor:
WiFi is intended as a short-range wireless medium. There's a reason nobody wanted the 2.4 GHz band (and therefore it is unlicensed): there's a significant noise and signal loss on these frequencies, noticeable even at short range.
Moreover, wireless equipment in mobile devices is engineered for power efficiency - which translates to lower broadcast power when compared to on-the-grid devices.
Also, the antennae in such devices are omnidirectional - this is rather useful for normal use, but again lowers your available broadcast power
Even if you had huge, high-quality directional external antennae connected to each device, pointing very precisely at each other (btw that also means each of them is stuck in one place; see e.g. this for a dish size calculator), you'd need to make some pretty drastic changes to their networking stack, as the latency inherent in long-distance comms will screw up TCP/IP pretty badly.
Even so, the setup would be very brittle, dependent even on the weather (water vapour absorbs significant amount of power in that part of the spectrum).
I want to programmatically measure the phone signal strength in a mobile phone. I don't actually care about the mobile phone or the programming environment: It can be based on android or windows mobile or even J2ME and can be from any manufacturer (please no iPhone). However, it needs to be a real, commercial mobile phone and not a special measurement device.
This problem is not as easy as it seems with a first look. I am aware that there already exist a number of methods that claim to return the phone signal strength. Some of these
are:
SystemState.PhoneSignalStrength for WM6
RIL_GetCellTowerInfo for WinCe (dwRxLevel member of returned RILCELLTOWERINFO struct)
android.telephony.NeighboringCellInfo.getRssi() for android
The problem with the above is that they only return a few (under 10) discrete values, meaning that, for instance, the return values of SystemState.PhoneSignalStrength can only be translated to (for instance) -100 dbm, -90 dbm, -80 dbm, -70 dbm and -60 dbm, something that is not useful for my application, since I'd like to have as much precision as possible.
It doesn't matter if there is an undocumented solution that only works on only one phone, if you can tell me a way I'd be grateful.
Thanks in advance
Please check about JSR-256 Mobile Sensor API for Java ME. Nokia S60 5th edition devices support this API. You can check about network signal intensity by using this API. But, it might be good to ask it's granularity from Nokia Forum first.
Here's a solution I found for people who are still looking for an answer:
Some windows mobile HTC mobile phones have a program called fieldtest.exe which contains the information I need (probably other phones also have that, I've only tested with a specific HTC but from search on google I understand that most HTC WM phones it). The fieldtest program not only has the exact signal strength for the phone, but also a big amount of other very useful telephony information not accessible otherwise.
The only problem is how can you use the data of that program in your process since all the values are stored in a ListView.
Well, that was the point of another question I had posted.
So, the solution is to run the fieldtest program and extract / steal the required values from there !
There is a good tutorial that explains how to get the Real GSM signal measured by your phone
Try this tutorial:
http://www.firstdroid.com/2010/05/12/get-provider-gsm-signal-strength/
Hope it help,
Adrian.
On WindowsCE platforms this might be tough. The last platform I worked on used a Siemens modem which I could directly access and get their own information from. However since their last firmware update they've now closed this off and forced me to go via RIL.
I'm guessing you might have to find a particular unit with a particular modem. However I don't know of any in particular. Sorry. :(