Here’s a look inside our smallest beacon, the iB001M. The circuit board measures only 2cm across and the height of the beacon is is only 2.6mm.
The waterproof iB001M can transmit iBeacon and Eddystone at the same time. There’s also a press switch to turn on/off and a buzzer that’s found in the top side of the beacon (not shown) together with the waterproof ring. This beacon can be set up to only transmit advertising data when motion is detected.
It weighs only 4g so is great for wearable and pet-related applications.
One of the problems with using iBeacon and Eddystone beacons is that it’s not easy to predict how long batteries are going to last. Battery life depends not just on the battery capacity but also the transmitted power, advertising interval, beacon processor chip type and whether the beacon has timed transmission. Also, beacons vary from model to model, sometimes even between revisions of the same model. It would be nice to know how much power a particular beacon is going to use and which beacon models are the most power efficient.
We have spent several months looking into how we can measure actual battery use. It’s not that simple. The majority of the power is expended in very short, few millisecond (ms) transmit pulses, inbetween which the beacon goes into low power sleep.
Nordic Bluetooth Advertising
Testing needs to integrate the current used over multiple advertising periods. The test equipment needs to capture this data at sub 1ms precision in order to catch the pulses. The testing also needs to be flexible enough to work for advertising periods from 100ms to 1 sec.
After lots of false starts we now have custom in-house designed test equipment capable of real-time battery current testing. This has enabled us to compare different manufacturers’ beacons having the same configured settings and we can now provide our consultancy clients with beacon battery use data based on their exact configuration settings.
As an example, an interesting test we did was was to compare the Sensoro AA transmitting just iBeacon vs iBeacon at the same time as the 3x Eddystone advertising packets. With only ibeacon @ 760ms, 0dBm advertising, 4 typical alkaline batteries would last 7.7 years. Transmitting all 4 iBeacon and Eddystone frames reduces the battery life to 2.9 years.
Another interesting observation has been that the beacons that have the strongest signals aren’t necessarily the ones using the most battery power. Design of aspects, such as the antenna, contribute to power efficiency.
We now offer case-by-case beacon battery use testing.
As previously mentioned, we have been doing some signal strength and stability tests across beacons. While the actual data feeds into our consultancy work, we have some high level observations that we can share here.
The following graph shows the standard deviation of the RSSI @ 1m, for our beacons and a few we don’t sell, measured over a 60 second time period:
Smaller bars are better and represent beacons
whose RSSI varied the least over time.
We found that beacons belonged to one or two groups. Firstly those with very stable RSSI and secondly those with an RSSI that had a standard deviation between about 4 and 6 dBm.
Signal stability is more important when you are using the RSSI to infer distance, either directly from the RSSI itself or indirectly via, for example, the iOS immediate, near and far indicators. RSSI varying without a change of distance might cause more spurious triggering. However, you should keep in mind that environmental factors can often cause variation much larger than the 4 to 6 dBm found in this test. Moving obstacles, for example people, will cause significant variation in RSSI.
We don’t yet know why beacons fall into these two groups. We couldn’t find any correlation between signal stability and manufacturer, antenna type, beacon size or processor chip manufacturer.
However, we found what might be some clues in the research paper An Analysis of the Accuracy of Bluetooth Low Energy for Indoor Positioning Applications by R. Faragher, University of Cambridge, UK; R. Harle, University of Cambridge, UK. The paper explains how Bluetooth LE advertising moves pseudorandomly between radio channels. The channels use different radio frequencies that, in turn, results in fading of the signal at different distances. Different radio frequencies experience constructive and destructive interference at different physical locations. Beacons that move more between channels can cause more rapidly varying received signal strength (RSSI).
After project rollout, human effort used in regularly replacing batteries can be significant and the human resource cost of doing so can dwarf the actual cost of the beacons. Hence, unless it’s a temporary scenario it’s best to specify beacons with as large a battery capacity as possible. Beacons with smaller capacity batteries are only suitable for short trials, temporary events or use during development.
While BeaconZone stocks a very large range of beacons, we purposely haven’t stocked any beacons with batteries smaller than CR2032 because the battery life of CR2025 and CR2016 beacons is usually too short. One exception is the iB003M that requires a CR2016 in order to be slim but you can set it to motion triggered to save battery power. All our other beacons use either CR2032, CR2450, CR2477 or AA batteries.
How long a battery lasts depends not just on the battery capacity but also the transmitted power, advertising interval, beacon processor chip type and whether the beacon has timed transmission. This article only considers the battery itself.
Battery capacity is measured in mAh. The mA part (without the h) is the unit of current. As an example, a CR2477 battery typically has a capacity of 1000 mAh which means it can supply 1 mA for 1000 hours or 2mA for 500 hours. However, most beacons only use tens or hundreds of µA when transmitting, where 1 µA is 1000 times smaller than a 1 mA. Also Bluetooth beacons only transmit for a few milliseconds (1 ms = 1/1000 sec) at a time so you can see how a coin battery can last a long time.
Here are the main battery sizes and their typical mAh rating:
CR2032 = 250 mAh
CR2450 = 500 mAh
CR2477 = 1000 mAh
2 x AA = 2200mAh (Alkaline), 3000 mAh (Li)
4 x AA = 4400mAh (Alkaline) or 6000 mAh (Li)
You can see that a beacon such as the SmartBeacon-AA containing 4 Lithium batteries can last 6x one with a CR2477 battery and 24x one with a CR2032 battery. This gives a battery life of up to 7 years depending on other configuration parameters.
Lithium AA batteries such as the Duracell Ultra Lithium and Energizer Ultimate don’t just last longer than Alkaline AA batteries. Their voltage also doesn’t vary so much with temperature which might be a consideration if your rollout is outdoors.
We have been doing some signal strength and stability tests to help provide data for some consultancy.
Last week, we started stocking the extremely long range TON9118 so we thought we’d compare it against our other beacons and some other popular beacons in the market:
Smaller bars represent a stronger signal
The beacon certainly delivers what it promises. Incidentally, the next beacon along is the PC62 that also performed well in our signal strength tests and is also one of the best for signal stability (low changes in signal strength over time).
We have some PL2303 USB To RS232 TTL converter adapter modules in stock that can be used to configure the HM-10 beacon from the desktop.
Eddystone-URL provides a quick, inexpensive way to allow users to view information based on physical locations. It doesn’t need a custom app and instead relies on the use of Chrome or the Physical Web app for iOS and Android.
We were recently asked the unexpected question why one might still choose to have an app with Eddystone. Here’s are some extra features that you can get if you have a custom app…
- Detection in background on Android (but not iOS)
- Better usage stats, per user, rather than per location
- Formatting the location information in a native (iOS or Android) specific way thus improving the user experience
- Favouriting the location (this can done by bookmarking the URL in Chrome but the URLs get mixed up with all other saved in Chrome)
- Sharing a location to social media (again, it’s possible to share the URL in Chrome but the user probably won’t do this)
- Including native aspects (the camera, sms etc) to interact more with the information
- Controlling what happens when a beacon is re-seen and defining the associated time periods for in and out of range
- Allowing the user to set a beacon to be ignored
- Controlling what’s shown based on the distance from the beacon
- Controlling what’s shown when there’s more than one beacon seen at a location, including someone elses beacon
- Extracting extra information from the beacon such as reporting battery level
Venture Beat has a great article by Kyle Fugere of dunnhumby Ventures on “Why indoor location tech is facing an uphill battle” where he says most beacon/platform providers have focussed on retail and consequently the:
“Refined focus has considerably shrunk the market opportunity for these companies”
He encourages companies to be
“more creative in regards to use cases”
and think about
“Banking, transportation, and live events with a potentially greater need and significantly shorter sales cycle”
We agree. Too many solutions tie beacons with a marketing platform. Also, one beacon type doesn’t fit all scenarios. One marketing platform certainly can’t fit all usecases. For example, a marketing platform isn’t suitable for security and sensing (IoT) applications.
The preponderance of beacon-based marketing platforms has obscured and confused what beacons actually are, due to over emphasis of the retail business benefits or description of proprietary server side CMS features. Many clients coming to us are actually confused.
The excessive competition in retail has caused beacon companies to have to run very lean. There’s noone to really talk to and even if you do get to talk to someone they only know about the benefits but can’t provide technical advice on how to solve your requirements.
Good business is all about listening to customers and adapting solutions. Most current platform providers can’t do that as most have trapped themselves with sparse human resources, narrow technical systems and very restricted ranges of beacon hardware.
Our site provides articles and a wide range of beacons to allow you to take advantage of beacons in scenarios outside traditional retail marketing and into new areas such as banking, security, transportation, distribution, sensing and the Internet of Things.
We have received a few enquiries how to go about setting up a Physical Web deployment and how to fine tune the maximum distance at which beacons will cause triggering.
The best place to start is the Physical Web: How to Get Started as a Developer document.
Don’t let the title frighten you. While the title suggests it’s for developers, the document is suitable for anyone who wants to learn how Eddystone beacons work and how to set them up.
Some tips from the document:
- Use a URL shortener for web addresses over 18 characters
- Set the beacon to low transmission power to prolong battery life and ensure that triggering only occurs when the beacon is close
- Use 700ms for the advertising frequency to ensure it’s reliably seen by Chrome
- Place the beacon as high as possible
- Use multiple beacons with the same URL to cover a large area – Chrome will de-duplicate them
- Use a URL shortener for redirection so you can change the URL without being being anywhere near the beacon
- For the redirection, use an error 404 page if you want to indicate to Chrome not to display your URL temporarily
We have a new inexpensive USB beacon in stock. It supports iBeacon. Please see the SmartBeacon-USB or PC-28E if you also need Eddystone.