The Department of Agricultural and Food Sciences, University of Bologna, Italy has been looking into CANBUS-enabled activity-based costing for leveraging farm management. They have created a methodology that helps farmers to make operational decisions and create data that can be used for input into farm management information systems (FMIS).
As an example, a study showing a tractor active for 59% of the time was idling for 25% of the time. Fuel and labour costs represented from 63% to 71% of the total cost per hectare. The tractor was equipped with a CANBUS logger and Bluetooth beacons on several tractor implements to automatically recognise agricultural operations. The data was processed to classify jobs by position (field, farm, or road) and operating state (moving, fieldwork, or idling).
With such systems, farmers can determine the economic impact of farm activities and compare historical data with previous farm practices or competitors’ activities. This helps farmers make more intelligent decisions regarding crop, land and farm operations management.
The Bluetooth SIG has a new Bluetooth Technology for Linux Developers Study Guide. It explains how Bluetooth is implemented in hardware as part of the main board or added using a USB dongle. The Bluetooth stack runs as a system service using BlueZ. BlueZ is accessed via inter-process communication (IPC) via D-Bus, a message-based system service. Applications use D-Bus and hence BlueZ.
While the study guide is helpful, we suggest you also explore the Bluetooth APIs available from your chosen programming language. We have never had to program at the D-Bus level. Take a look at the Node, Javascript, Arduino, c, c++, Rust, Python and Java Bluetooth APIs and libraries.
The paper first discusses the main causes of error in AoA systems. This includes signal path length mismatches as avoided by the CoreHW AoA Hardware printed circuit board (PCB) tracks and mutual RF coupling effects that act on the antenna array.
The researchers devised and proved a technique to process IQ data to reduce systematic errors and first-order (linear) coupling effects. After a calibration phase they manged to reduce average absolute errors by more than a half in one test case more than a quarter in a second case.
Research on techniques such as this will make Bluetooth direction finding even more accurate.
Many people come to us asking for “programmable beacons” when in fact they want beacons with configurable iBeacon UUID, major and minor. All beacons allow the UUID, major and minor to be changed, usually via an iOS and/or Android app and sometimes via USB/UART for changing the values, over time, via a program. This is changing the settings rather than programming.
Truly programmable beacons are those where the internal software can be updated. The beacon contains a system on a chip that’s small computer running code to implement the beacon functionality. In most cases, the software can be updated via pads on the PCB:
Programming pads in the centre
Programming requires use of a programmer:
Segger J-Link Programmer
It can be difficult to program larger numbers so a custom-made jig is used:
BeaconZone Programming jig
It’s not possible to see and update the existing code in a beacon. Any newly uploaded program has to be created from scratch using c/c++ code. This is called embedded programming, is non-trivial and takes of the order of months.
Our BeaconRTLS™ and PrecisionRTLS™ produce a lot of historical data. How this data is used varies considerably from project to project. One use of the data is for determining human behaviour. For example, consumer behaviour, workplace safety behaviour, developmental child behaviour or other health-based analysis.
There’s recent research into Indoor Location Data for Tracking Human Behaviours: A Scoping Review that’s meta research in that it’s an analysis of past RTLS-based human behaviour research. The Canadian researchers looked into the varied ways behaviour can be extracted from RTLS data and the features that can extracted. They examined 79 studies using RTLS data to describe aspects of human behaviour. The most common use was to monitor health status, followed by analysing consumer behaviours, increasing safety, operational efficiency and investigating developmental child behaviours.
The main behaviour features were found to be dwell time, trajectory and proximity. While many papers were able to detect features and hence behaviours, few continued to clinically validate their findings. Beyond activity recognition, few took the opportunity to create models for use in their respective fields, for example, “detecting abnormal behaviours in older adults”. Such models might be used to provide useable baselines for behaviour and health monitoring.
The paper mentions using different locating technologies for different granularity. More specifically, RFID and IR technologies provide too low a level of granularity in location tracking that can prevent extraction of behaviours or continuous movement patterns. Conversely, UWB needs constant battery changing or recharging that can make data collection difficult.
The researchers conclude that while RTLS technologies provide a valuable tool to analyse patterns of human behaviours, future studies should use more complex feature analysis methods to make more of the richness of location-based data.
Bluetooth LE advertising congestion happens when there are too many Bluetooth devices in an area. As we will show, this rarely happens but with new Bluetooth technologies this situation is becoming more likely. We provide some ways to mitigate congestion.
Bluetooth LE advertising transmits periodically the period of which is configurable from typically 100ms to about 10 seconds.
If two Bluetooth devices happen to transmit at the same time, it’s like two people shouting at the same time. The signal is corrupted, the receiver can’t make sense of the signal and it is lost. This usually doesn’t matter because it’s likely the signal is seen the next time it is sent. The random advDelay in the above diagram ensures that the two sends don’t clash again. It’s very unlikely advertisers clash in the first instance because the transmit duration is very small compared to the advertising period. The above diagram isn’t to scale. Here’s an oscilloscope trace showing some real timing:
The advertising duration is very small, of the order of 1 to 2 ms (milliseconds). Advertising is also sent three times, on three different radio frequencies, so that if one is blocked, the radio signal might be heard on one of the others. All this means that advertising collisions rarely occur.
However, there are some newer Bluetooth protocols that as they are starting to roll out, are making collisisons more likely:
Bluetooth 5 advertising extensions – This allows advertising of more data, that takes longer than the typical 1 to 2 ms and hence increases congestion.
Bluetooth longer range – This transmits further thus effectively increasing the number of beacons advertising in a given area.
Bluetooth Mesh – This works by having relay beacons listen and re-transmit advertising, usually several times, to improve reliability.
Bluetooth direction finding – This also has longer advertising to send a constant tone extension (CTE) that is received by AoA hardware. However, of more affect is advertising more frequently. While beacons on assets used to advertise typically every second or longer, direction finding tends to use faster advertising to improve latency.
You can check how many devices are advertising by using a scanning app on Android. We recommend Nordic Semiconductor’s nRF Connect because it can decode the latest Bluetooth protocols. Use Android for full visibility because Apple made the poor design decision to obfuscate iBeacon advertising to coerce developers to only use the Apple iBeacon-specific APIs. Apple also hides devices’ MAC addresses making them more difficult to physically identify.
If you have a problem with congestion you might be tempted to increase the transmission power or advertise more often to increase the chances of being seen. However, this is counter-productive because you will be increasing congestion, especially if your devices are the main contributor to the congestion.
Instead:
Lower the transmit power so that beacons cover a smaller area. You can fine tune this using nRF Connect to measure the distance you need rather than needlessly advertising further. This will also conserve battery life.
Increase the advertising period to make collisions less likely.
Increase the receiver scanning period to make detections more likely.
Seek out and remove unwanted devices advertising too frequently, such as fitness devices, smartphones, displays and even cars.
Today’s just-in-time and busy manufacturing processes means that manual tracking of pallets for inbound and outbound shipments often can’t keep pace with the speed of production. Production and assembly requires the quick locating of components. Delays and inaccuracies due to lost components lead to increased costs, employee frustration and ultimately customer disappointment.
Competitive pressures are also driving the need to reduce labour thus reducing the capacity to manually search for items. Customisation using configured options and demand-driven production is also increasing the degree of inbound component searching that exacerbates the problems.
Even those companies using legacy tracking solutions find that location is only as good as the last barcode or RFID scan. Humans get lazy, make mistakes and don’t scan, causing pallets, crates and boxes to get lost. Many RFID readers don’t work reliably near metal components. Relying on a system that can’t find just a few items can be worse that a manual system that works but is slower. Bluetooth asset tracking solves these problems because the location is automatically collected in real-time and is continually updated.
Asset tracking can be applied to items such as components, pallets, cases, tools, returnable assets such as racks and cages as well as items on loan to ensure they are returned on time. It can improve worker safety and provide alerts in cases of congestion, perimeter deviation and lone worker distress. It can ensure forklifts are being fully utilised, are taking an optimum route, haven’t crashed into racking and haven’t gone out of an area.
The real-time visibility allows connected systems to generate confirmation and exception alerts and automatically trigger shipping processes, replacing costly manual workflows. Tracking outputs also allows confirmation that the correct things are loaded on the correct transport.
A Bluetooth-based real time location system (RTLS) increases visibility and allows the manufacturing process to adapt in real-time to short term business needs. It provides cost savings, greater efficiency and business intelligence that can be used to derive larger scale changes based on data rather than gut instinct. Overall reporting of input and outputs provides input to management reporting to monitor the business.
Some of the first uses of beacons was on buses. For example, in 2015 in London, 500 buses sent targeted in-app messages to passengers. It didn’t work, Proxama ceased to be in business and thankfully the use of beacons for spamming went away. Today, the use of beacons has matured as has their use on buses.
There’s a useful presentation by Texas A&M Transportation Institute and Houston METRO on Bus Stop Beacons: Transit Wayfinding for People with Visual Impairments (pdf). They classify accessibility challenges as locating stops, knowing which routes serve stops, obtaining real-time information and boarding the vehicle. They conclude that multiple location sources, using Bluetooth with GPS, work better than a single source alone. Also, sound shouldn’t be the only way riders receive information from an app because noisy environments make listening difficult. Vibrations can be used to provide additional notifications.
The current state of the art is using beacons with ticketless payment and automatic boarding and un-boarding detection. The pioneer in this area is one of our consultancy clients, UrbanThings, who has an article on Increase ridership through mobile ticketing and case studies.
Another one of our customers, Lothian buses, uses beacons to aid accessibility:
Next Stop Announcements: when on a bus, the customer can select which bus route they are on and the app will announce the name of the next stop as the bus approaches (with buses fitted with Bluetooth beacons, the customer doesn’t even need to select which bus route they are on – the app knows automatically)
CoreHW in Finland is a new entrant in the Bluetooth direction finding ecosystem. Their main product is the CHW10x0 chip that supports switching of complex antenna arrays needed for Bluetooth direction finding. It allows designs with only one component where three to five are usually required. The switch has a fast settling time for RF signals and a good phase balance between antenna ports providing better position accuracy.
CoreHW also has reference antenna arrays and 2D software for angle and position estimation to shorten time-to-market for AoA locator and AoD beacon manufacturers. They have a demo kit including 4 locators, 2 tags, a CorePatch antenna array board with CHW1010 chip, a Bluetooth T5.1 chip for IQ sampling and a USB interface (Ethernet) to connect locators with a Windows PC.
The CoreHW reference boards have some intriguing Medusa-type printed circuit board (PCB) tracks, presumably to keep the track length the same to each antenna to normalise RF signal delays.
We look forward to seeing CoreHW components in their customers’ production devices.
TRBOnet is Motorola MOTOTRBO 2-way radio control room software. The system uses GPS outside and beacons indoors. The handsets detect iBeacon advertising that shows on TRBOnet plans or maps in the control room.
Here are some tips for setting up beacons for TRBOnet:
Each beacon has a unique UUID, major and minor values. Change the UUID from the default to prevent overlap with someone else’s iBeacon network. The actual values you should use are ‘invented’ by you. We have an article on Choosing UUID, Major, Minor and Eddystone-UID For Beacons.
Set the beacons to ONLY send out iBeacon advertising. This shows in the manufacturer configuration app as using just one channel for iBeacon. If extra channels such as Eddystone or ‘info’ are enabled, the beacon will still be detected but the beacon battery will be depleted much sooner.
Motorola has a useful table that specifies the recommended beacon advertising interval based on the handset scan interval. See our post on Why Bluetooth LE Scanning Doesn’t Always See Devices to better understand this mechanism.
When the beacon device is configured for a lower advertising interval it consumes more power. There is a roughly 1:1 correlation between beacon advertising interval and battery life. Longer scan interval ON times increase the probability of beacons being detected but increase the time (latency) to detect beacons and report new positions in the control room.
Some radio vendor guides mention a specific to-the-millisecond advertising period so as to prevent beacon advertising and handset scanning from being permanently out of sync. This is a misleading information. All Bluetooth advertising includes a small randomisation in time between successive advertising to prevent this situation.
Use standard 0dbm transmit power unless you have special need to boost or reduce the beacon range. We have an article on Choosing the Transmitted Power. See our post on Testing if a Beacon is Working that shows how to measure the received signal strength (RSSI). This allows you to determine the area covered by a beacon and detect areas that are not covered.
