Faraday Bags for Bluetooth

One of the most useful tools when deploying beacons is the Faraday Bag. A Faraday bag allows you purposely block beacons you haven’t yet placed so that they don’t affect testing. During development, it also allows you to simulate beacons or scanning devices going out of range without you even moving.

Faraday bags work by having a very thin gauze layer that block radio signals. Not all types of Faraday bag are the same. For BeaconZone Faraday bags, we had the manufacturer use two layers of gauze to block even the strongest Bluetooth beacons.

For any Faraday bag, the radio signal can leak through any larger holes in the gauze. This includes the opening that should be folded over and attached onto itself using the hook and loop fastening.

Faraday Bags

Detecting Moving Beacons

There’s a new question at GrindSkills on Can Bluetooth beacon be detected while it’s in motion? This deals with similar issues to our previous post on Using Bluetooth to Measure Travel Time.

Both scenarios don’t consider the scanning and advertising periods. Our previous post on Why Bluetooth LE Scanning Doesn’t Always See Devices (the First Time) explains the relationship between these timings.

In order to reliably detect moving beacons it’s necessary to scan more often and have smaller gaps between scanning. Also, if you have control over the advertising device, more frequent advertising will make detection more reliable.

BeaconZone Consultancy

Forest Modelling Using Beacons

Researchers from the University of Manouba, Tunisia have been looking into the analysis of individual forest trees to monitor the state of the forest. This is needed for forestry tasks such as characterisation, inventory, management of forest and fire behaviour modelling.

Airborne Laser Scanning (ALS) derived methods were applied for individual tree detection (ITD) based on a canopy height model (CHM). A Bluetooth beacon was used to collect trees coordinates.

View iBeacons

Bluetooth Aiding Accessibility

We recently came across RightHear, an app that assists people with orientation difficulties or vision impairments. It provides navigation information in indoor and outdoor settings.

The app acts as a virtual directory for users, directing them through locations with audio cues (such as ‘reception is 20 feet ahead to the left’ or ‘exit is 50 feet ahead’). Users can point their phone in a specific direction to learn what’s in front of them.

For companies, the app improves accessibility compliance, aids corporate responsibility and improves a brand’s narrative regarding inclusion. It works using Bluetooth beacons that are picked up by the app. The app creates auditory descriptions and notifications. There’s also a dashboard for companies/admin to control and track the solution.

View Bluetooth Beacons

Beacons with Location-Based Games

We often go out to a local park to test the range of beacons. As we are regularly looking at our phones and moving about, people sometimes ask us if we are playing some sort of location-based game.

Location based games involve solving puzzles and finding clues via a location-enabled smartphone app. Examples include Ingress Prime, Minecraft Earth and Pokemon Go. While most only use GPS, beacons allow greater precision and use indoors. The user’s location and sometimes the location of other players is commonly shown on a map or plan. It’s also possible to use beacons with Augmented Reality (AR) to show the location of people or things on top of the camera image.

Location-based gaming isn’t restricted to pure gaming but can also be used to gamify other situations such as visitor spaces. The principles are the same except that simpler information is usually displayed, with clues and directions, rather than use from a gaming engine. Retailers such as Macy’s have also used gamification in retail.

View iBeacons

Using Bluetooth to Measure Travel Time

There’s recent research from Thailand on Evaluation of Bluetooth Detectors in Travel Time Estimation. The researchers looked into the feasibility of using detected Bluetooth devices to estimate travel time and assess the affect of vehicle speed on Bluetooth detection performance.

Bluetooth provides a compelling method because it’s already transmitting from smartphones, car stereo speakers, wireless headphones and other devices such that dedicated transmitters are not required. Bluetooth devices are also non-intrusive and more affordable compared to other types of traffic sensors and don’t suffer from low light and inclement weather as with the case with automatic license-plate recognition.

A 28 km toll section in Bangkok was used for the study. Bluetooth detectors and microwave radar devices, for comparison, were installed to collect traffic data. The data for 20-days, with 2 million Bluetooth trips, was processed in 5 ways to estimate the travel time.

The resulting Bluetooth trip data was compared with the traffic counts recorded by microwave sensors. For inbound traffic, the detection rates for the study area were in the range of 50–90 percent during the day and 20–50 percent during the night. Slower traffic during peak periods made it more likely for the Bluetooth detectors to detect MAC addresses.

New Nordic Wireless Quarter Magazine

Nordic Semiconductor, the manufacturer of the System on a Chip (SoC) in many beacons, has published the latest online issue of Wireless Quarter Magazine. It showcases the many uses of Nordic SoCs.

The latest issue of the magazine highlights the use of the SoC in the following Bluetooth solutions:

  • Leak detectors that harvest energy from water
  • A smart lock that can be retrofitted to most doors
  • Future wearables that can detect Alzheimer’s disease

There are also articles on how IoT is forecast to save eight times more energy than it consumes, a piece on smart homes and an in-depth explanation how advanced wearables are moving beyond fitness to provide better health outcomes.

Read Nordic Semiconductor Wireless Quarter

Beacon Battery Size, Type, Capacity and Life

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. All our 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 intervalbeacon 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, for example, 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)

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.