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.
We just received the 210L ultra-long 200m range beacon into stock.
Most beacons tend to have a range of 30m, 50m or 100m. The normal output is 0dBm but they can be boosted to +4dBm to achieve the maximum ranges. Read our article on Choosing the Transmitted Power for more information.
The 210L beacon transmits at +10dBM which is the maximum allowable for this class of Bluetooth 4 device. This is just over 3x the power of a beacon transmitting at 0dBm. Hence, there’s respective reduction in battery life.
People will steal beacons even if they are password protected and can’t be re-used. They don’t know they are useless and steal them anyway.
We once had a strange request from the UK Police to supply our “ugliest beacons”. In some situations, the requirement is for beacons that will blend into the environment rather than advertise their presence visually. While high visibility, attractive beacons might be great for proof of concepts and demos, in the real world beacons that blend into their environment work best.
There’s often a temptation to hide beacons behind things. However, beware of blocking the radio signal and hence reducing the range. We had a client use beacons in a stadium and they painted them to camouflage them from view. Hide your beacons, but don’t block the signal.