Too many potential customers contact us asking what’s the least expensive beacon that provides the best range, the best battery life and the smallest size. Unfortunately, all these things are related. You need a larger battery to provide enough power for a longer range. A large battery implies a larger beacon size. A larger battery and case implies a more expensive beacon. The choice of ‘best’ beacon usually involves some sort of compromise.
It’s also often the case that customers focus on price, range, battery life and size without considering other factors such as:
Visual appearance – Good-looking beacons can sometimes be counter-productive as they can be attractive to thieves.
App – Some manufacturer configuration apps are easier to use than others.
Waterproofing – Some unexpected scenarios need waterproofing due to high humidity.
Motion triggering – Some beacons provide motion triggering to significantly increase battery life.
On-off button – It’s sometimes desirable to be able to turn the beacon on and off without having to remove the battery.
Attachment options – Some beacons include strong double sided stickers, tabs for screws or holes for fastening.
We get many questions regarding setting the distance a beacon can transmit. This might be to save battery power or to limit the distance at which a beacon can be detected.
Despite some 3rd party platforms and SDKs having settings to set distance, having such a setting is misleading. You can’t set the distance. You can set the transmitted power that affects the transmitted distance. However, as it’s radio and is susceptible to reflections and interference, there’s no way that a particular power can accuratelycorrespond to a particular distance.
If you are detecting beacons in an app you can also use the Received Signal Strength Indicator (RSSI) to filter only those within a particular range. However, again, there’s no way to accurately map RSSI to the actual distance.
Some people ask if it’s possible to set the distance to the order of centimetres rather than metres, much like NFC. This usually isn’t possible as most beacons still transmit of the order of a metre when set to the minimum power. However, an exception to this is the Sensoro range that have two antennas that provide for what they call micro location. Their app allows you to choose between 12 power levels, the lowest of which indicates a 5cm range. However, as mentioned above, as it’s radio, such things can’t be determined accurately and our tests reported a 10cm range.
Instead if framing the questions as to whether the transmitter can be set to a minimum distance, instead consider setting the receiver to ignore longer range detections. It’s possible to use the RSSI value at the receiving app or other Bluetooth scanning device to filter out beacons that are far away. More specifically, you can ignore detections that have an RSSI less than a specific value. This can be used to only process detections of the order of centimetres.
Beacons allow you to set the transmit power to levels such as -30dBm, -20dBm, -16dBm, -12dBm, -8dBm, -4dBm, 0dBm and +4dBm. The number of actual setting values depends on the beacon. 0dbm is the default power recommended for normal use. Our article on Choosing the Transmitted Power explains these values and how they relate to distance.
We are often asked ‘What are the Estimated Distance/s for Tx Powers?’. This depends on the beacon, the environment and the receiver. An analogy is someone shouting a word. How loud does someone have to shout to be heard a certain distance? It depends on how clear the person shouts, how much noise there is and how well the person listening can hear. With beacons it depends on the beacon (mainly antenna) design, how much radio frequency (RF) noise there is, the degree of RF reflections, the receiving ability of the device (smartphone or gateway) you are using and even the weather.
The only way to determine the relationship between distance and power is experimentally and it will likely change over time as the environment changes.
Most beacons’ configuration app have a setting for iBeacon ‘measured power’ or ‘RSSI at 1m’. This doesn’t change the power output by the beacon. Instead, it’s a value that’s put into the advertising data that declares to receiving devices what the power should be at a distance of 1 meter from the beacon. Receiving devices such as smartphones and gateways can use this to help calibrate a calculation to determine the rough distance from the beacon.
You don’t usually change this value and it’s actually rarely used. In most cases the value is irrelevant and can be ignored. However, if your app or receiving device does use this value, it’s best to first do some tests to see what the power level is in your particular situation. Things like the physical environment, blocking and beacon orientation can affect the actual power level at 1m. Set the value according to your particular scenario.
Beacons are often placed in shops, offices and other buildings for detection in smartphone apps. Battery powered beacons last from months to years depending on the size of the battery and the transmission power (adjustable). The compromise between battery life and physical range can be avoided if USB beacons are used instead.
USB beacons are powered from an available wallsocket, laptop, desktop or other standard USB socket. Alternatively, they can be powered using an inexpensive mains charger used to charge a smartphone or other device. Powering from the mains allows the beacon to be permanently set to full power with no worry about checking or changing the battery.
The use of mains power also allows for use of specialist beacons that output the maximium legally allowed (Class 1) power that wouldn’t be feasible using battery power.
The FSC-BP109 can be received up to 1000m on Android and 4000m on iOS.
It’s an electronic component to be used at the SoC output to amplify the signal prior to being sent to the antenna. We expect this to be included in some future long range beacon designs. However, note that it uses more current (115 mA at +20 dBm) so is less suitable for use in coin-cell based battery powered designs.
Our ultra long range beacons already use RF amplifiers but from different component manufacturers. For example the iB003N-PA uses a RFAXIS X2401C chip to achieve up to 300m range. The FSC-BP109 also uses an output amplifier to reach up to 1000m on Android and 4000m on iOS but this beacon requires USB power.
Unseen Tech has a recent whitepaper on Bluetooth 5 range. It describes some tests that were performed to assess Bluetooth 5 to see the improvements in range compared to Bluetooth 4’s typical 30m to 100m. The tests used development boards from Texas Instruments and Nordic that, used outside, achieved about 650m and 750m respectively.
While some companies are claiming Bluetooth 5 support in products, many don’t actually use Bluetooth 5 yet but instead offer an upgrade path to Bluetooth 5. Other’s do offer Bluetooth 5 but downgrade to Bluetooth 4 when communicating with Bluetooth 4 devices (e.g. smartphones) which are still the large majority of devices.
The iB003N-PA has a range up to 300m because it uses the RFAXIS X2401C 2.4GHz amplifier to increase the range.
When you use the manufacturer app to change the power output by a beacon, you are changing the power output by the Nordic nRF51 System on a Chip (SoC) that is usually fed to the antenna. In the case of the iB003N-PA, the RFAXIS X2401C instead receives the signal, amplifies it and sends it to the antenna. The resultant change in output is:
20dBm is the maximum allowable output for class 1 Bluetooth. There’s no difference whether you set to 0dBm or 4dBm, the output will be 20dBm. Even at a low power setting, -10dbm, the amplified output is 10dBm which is relatively high compared to the nominal 0dBm for most beacons. That’s just over 3x the power (3dBm change is a doubling of power) of a normal beacon. You can see that this beacon is primarily designed for long distance and there’s no need to change the SoC power from the default 0dBm = 20dBm.
The Wiki includes information about Bluetooth LE idioms such as advertising, MAC address, Bluetooth name, GATT, transmit power, measured power, range, RSSI, mesh and the new direction finding feature. It also has links to hardware and programming information.
We coincidentally had two customers last week with the same query and the same resolution. They wanted to know why their ultra long range beacons weren’t achieving the expected range.
It turns out both customers where expecting the beacons to transmit through obstacles. It’s important to understand what can block signals. When a signal gets blocked, there’s no point trying beacons with longer ranges in the hope they will push the signal through the physical obstructions. Longer range beacons only work long range when there is unobstructed line of sight such as in a large warehouse or event space.