I'm wanting to know if what I want to do is even possible and if there is a good practise that I should follow.
For my experiment I have a collection bluetooth low energy beacons laid on the ground with each projecting out their own BLE signal. Each of these signals is getting read in by a fourth device that takes the corresponding RSSI value and uses it to determine it's position within the area.
Following this I now want each of my beacons that are laid on the ground to know the distances that separate them from each other. So my questions are as follows:
Is it possible to have the beacons on the ground broadcast different signals using two different UUID values?
Can a beacons both read and broadcast a signal at the same time? By that I mean the beacons will still be sending out their initial signal being read in by my fourth device whilst also reading in the distance value from their fellow broadcasting beacons on the ground.
I'm not sure if I've done a good job at describing what it is I'm wanting so I've (terribly) drew a picture in order to show what I want do and describe what I've got so far.
Key:
Black dots are my beacons on the floor
Green dot is my reader that finds its distance from the floor beacons. On the green dot is another app that is projecting out a BLE signal which the floor beacons are reading.
Purple line is the BLE signal being sent out from my reader device.
Yellow line is the RSSI value showing the beacons distance from the BLE signal being projected
Blue line (this is the key to this post) is meant to represent the beacons projecting and reading their own BLE signal so they can find their distance from each other.
Green line is then each beacon sending its distance from the other beacons to the reader.
At this point Bluetooth Smart-only devices currently do not support simultaneous peripheral/central mode.
What I would suggest is using the nRF51922 which supports concurrent BLE/ANT.
ANT is fully capable of doing this functionality for you as it supports all kinds of topologies, and you can relay your final information over BLE, or go with an nRF51422 and stay ANT only, I believe all latest Sony and Samsung devices support ANT anyway so it might be enough for you.
You can read more about it at http://www.thisisant.com
Related
I am working on app which used to detect beacons in iOS device using objective c. I have successfully done the scanning of beacons using core bluetooth and core location framework i.e did range beacons which provides an array of scanned beacons.
Case - I have to discard beacon scanned which are of distance more than 10 meters. So I have used RSSI value for that and calculated distance using formula and not considering beacons above that distance.
Problem - did range beacon is not providing the beacons distance more than 5-6 meters sometimes it provide around 8 meter beacon also.
Question - is there any specific range after that iOS discard the scanned beacons automatically?
It is not unusual for mobile devices to not be able to detect beacons beyond 8-10 meters. This has nothing to do with the operating system and is caused by the radio signal level falling below the noise floor as detected by the receiver.
The maximum distance a beacon can be detected is typically 40-50 meters in ideal clear line of sight conditions, but this also relies on the bluetooth transmitter being set to the maximum radio signal level allowed by international regulations, and the transmitter's antenna being directed generally toward the receiver.
It also relies on the receiving mobile device having it's antenna oriented toward the beacon transmitter and not blocked by a case or other radio obstruction.
Typically conditions you describe are caused by a beacon transmitting a signal far weaker than allowed by law. This may be adjusted on some models. Check the instructions from the beacon manufacturer.
Some mobile device.models have poor Bluetooth receiver antennas, although Apple devices are generally good. (Huawei Android devices are notoriously poor receivers.). If in doubt, try another device.
is there a way to show the beacon direction as an arrow point the direction to the beacon? I know it is possible to change the color according to the proximity of the beacon but what I need is a direction to find the beacon.
You can't do this just with one beacon as all you have is the received signal strength (RSSI). The Determining Location Using Bluetooth Beacons article explains more and references a paper that shows a workaround that might help when using just one beacon.
Sorry, you cannot get direction to a Bluetooth beacon. A Bluetooth receiver on a mobile phone is omni-directional. It works much like an old-fashioned AM radio. You can get some idea how far away a radio station is by how much static you hear, but there is no way to know which way the transmitter is by standing still and listening.
The paper that #Simon-Judge mentions in his answer basically suggests it could be possible to figure out roughly which way the transmitter is by spinning around in place and measuring signal. To take the AM radio analogy, this is similar to pointing the antenna in each direction in 180 degrees to see where it picks up the signal best. While this might work with some degree of success, it certainly isn't going to plot an arrow on the screen for the direction of the beacon.
I am doing an Indoor Navigation using I Beacon. I want to know the current location of the user. Is there any property for beacon like proximity or accuracy where i will get the distance of the beacon from the userLocation. Please help me to get the distance of the beacon from the userLocation. According to my knowledge beacons have accuracy, proximity and Received Signal Strength (RSSI). So it will be helpful if i get a clear idea of what these accuracy, proximity and RSSI means and how i can calculate or get the distance of the beacon from the userlocation.
Thanks in advance.
The CLBeacon class contains three properties which are related to the distance between the beacon transmitter and the receiving device:
rssi: The Received Signal Strength Indicator, measured in dBm, tells how strong the beacon signal was as averaged over the last one second ranging cycle. It originates from the radio receiver on the Bluetooth LE chip, and has a large amount of variation due to radio noise.
accuracy: This field provides a distance estimate in meters between the beacon and the receiving device. It is calculated using a mathematical formula from a running average of the rssi over 20 seconds, combined with a reference measurement of what the rssi is expected to be for the beacon at a distance of 1 meter. This reference measurement is transmitted inside every iBeacon packet. The field also has quite a bit of variance and error due to radio noise, signal multipath and reflections.
proximity: This field is derived from accuracy, and puts that value into one of three "buckets" depending on a range of values. "Immediate" is for an accuracy under 0.5 meters, "Far" is for an accuracy of 3 meters or more, and "Near" is for any value in between.
None of these fields can be used by themselves for indoor positioning, which is a much more complex subject. However, the first two fields can be useful inputs depending on the technique used.
More details are available here: http://developer.radiusnetworks.com/2014/12/04/fundamentals-of-beacon-ranging.html
I am working on indoorpin, which is a ready to use framework for iBeacon management. You can integrate it to your mobile app (IOS or Android) and use it with any iBeacon device. It consists of a web based CMS and SDK for mobile app. In CMS, you can see the real-time location of the mobile app user or you can get a report for historical data as heat-map or bubble map.
I want to locate an object position inside a house( one floor).
The object will have a iBeacon on it.
What are the best approach.
With api, i can get distance from the iBeacon, but this doesn't reflect position.
One idea was to have 4 fixed iBeacon on the floor, but seem's i can't get the distance from the moving iBeacon to a fixed.
Any idea?
iBeacon isn't the right technology for this - at least not with a single receiver.
iBeacon only gives you an approximate distance. If you have multiple beacons in known locations then you can try and triangulate the receiver's position but you can't use this information to determine the location of another transmitter in an unknown location - only estimate its distance from the receiver.
Even using known, fixed transmitters it is difficult to locate the receiver with any accuracy due to the nature of the Bluetooth signals.
If you had multiple iBeacon receivers on the floor at known locations then it might be possible to determine the location of the transmitter.
We are having a issue with iBeacons.
App makes wrong guess sometimes as to which proximity region its in before eventually correcting itself. It sometimes shows Far when the Proximity is Near. And then later it flips back to Near.
The problem actually occurs when we need to fire an event when we are in the Near/Far/Immediate region. This doest happen in that way. App is likely to lose range of beacons for brief instances.
Are there any other way to solve this Issue.
It is normal for the Proximity estimate to fluctuate with radio noise, but your experience sounds extreme. What iBeacon brand are you using?
Make sure you are using an iBeacon with as fast enough transmission rate. Different iBeacons transmit advertisements at different frequencies from 30 times per second to once per second or less. Generally, faster transmission rates give you less noisy distance estimates because they give iOS more radio signal strength measurements to work with.
If an iBeacon transmits less than once per sec, you may get intermittent exit/entry events.
For your testing, Try an iOS-based iBeacon like Locate for iBeacon or EZBeacon to see if it helps. It is known to transmit 30x per second.
The proximity issue can be effected by advertising frequency as David has already said. The reason for this is that iOS takes an average of the RSSI readings overtime and uses these to find a final value, if you hold an iOS device in an ideal location, (i.e. clear line of site to the beacon) the result settles down over a few seconds of holding the device still. Apple describes the averaging as: "This value is the average RSSI value of the samples received since the range of the beacon was last reported to your app."
However a bigger factor can be fluctuations in the environment, the RSSI will change dramatically if an obstruction appears between the iBeacon and the iOS device, if the iBeacon and iOS device are both at a low level, this could be a person walking past. I have published some initial results using Estimote iBeacons that show changes in distance based on the device operator rotating 360 degrees. A distance change of +/- 2m is not an uncommon change in this circumstance and could result in the behaviour you observed if the iOS device is near the proximity region boundary.
This is Wojtek Borowicz, I'm a community evangelist at Estimote.
Calculating the exact proximity of a Beacon is based solely on the radio waves it’s broadcasting an is really hard. You encounter factors like multipath propagation, wave diffraction, absorption or interference. That’s exactly why iBeacon standard does not try to calculate the exact distance between a Beacon and the receiving device. Instead, it uses a value called RSSI (received signal strength indicator), which allows to estimate the proximity based on signal power. For calibration purposes, there’s also included a metric called Measured Power - but it’s nothing more than just RSSI measured 1 meter away from the Beacon. Even calibrated, RSSI might fluctuate heavily, due to the factors mentioned above.
The stability of the Beacon’s signal is also based on two main factors. One of them is advertising interval (frequency - the lower, the better signal) and broadcasting power (the higher the better signal). Improving them will allow for much better proximity reading, but will also strongly affect battery life.