The SmartONE[157] is a tracker designed for both asset and vehicle tracking, and — like the SPOT tracker — transmits positions via satellite, using the Globalstar network. It sends information either by text or by email. It runs off a power supply or four AA batteries, giving up to 3 years of battery life with infrequent position readings. It contains motion sensors and supports other, custom configured sensors, with a serial connection to interface with sensors and deliver messages from the user. The tracker measures 3.25x6.5x1”, and weighs 385g.
5.5. Comparison with commercial trackers 141
5.5.5 MeiTrack MVT-600
MeiTrack[158] make a large number of trackers, including vehicle, asset and personal. One example is the MVT-600 vehicle tracker, which includes inputs (mainly as triggers for sending positions, for example when connected to a car door switch, but also analogue sensor inputs whose values are reported when uploading positions). It also has a built in camera and remote audio feed. The tracker weighs 220g and measures 103x98x32mm.
5.5.6 MeiTrack VT-400
The VT-400[159] is another tracker from MeiTrack. It is a ruggedised tracker de- signed for heavy machinery, and it includes outputs as well as similar inputs to the MVT-600. These outputs are triggered by a remote request from the user, and are designed for things such as cutting out the engine. It measures 123x83x37mm and weighs 350g.
5.5.7 CelloTrack Solar
Part of the CelloTrack family, from Pointer Telocation. These are highly rugged asset trackers designed to be strapped to items such as shipping containers. They include movement sensors, and will report the position of a moving item more often than a stationary one, although they are designed to give extremely infrequent readings (once per day, although this is configurable to a small extent). The CelloTrack Solar[160] is notable because it is powered by a solar panel, charging an internal battery. This means that it can be attached to the outside of something like a shipping container or a train and left there indefinitely. As this tracker requires a solar panel and is designed to be attached to a large item it is larger than some of the other trackers mentioned here, measuring 585x130x30mm.
5.5.8 ATrack AY5i
This vehicle tracker[161] is unusual, in that instead of using GPRS to transmit data it uses 802.11b/g wifi. This means that it must be within range of an available wireless
142 Chapter 5. GPS tracking network in order to be able to report; however, as it contains a 8MB internal memory it is also able to log positions while out of range. It supports a 1-Wire interface, which is a similar protocol to the I2C supported by the Durham Tracker, and has a built in accelerometer for crash detection as well as analogue sensor inputs and digital trigger inputs. It measures 100x65x26mm, and weighs 161g.
5.5.9 UAV trackers
There are several trackers designed for attaching to model aircraft. These tend to be small and lightweight, but with a lower range method of transmitting and often no logging.
One example is the TinyTelemetry GPS tracker from Immersion RC.[162] This sends position data and sensor inputs back to the user using the audio stream of a video transmitter, but requires the user to be in radio range. It is extremely small at 55x15x10mm, and weighs 12g.
A similar device is the EagleEyes FPV Station, from EagleTree Systems.[163] This is a system for providing a camera for a model aircraft, with an on screen display. Position data and inputs from a range of sensors both overlay a video feed and are transmitted to a proprietary receiver attached to a computer to allow for graphing of data and plotting routes.
The TinyTrak SMT[164] from Byonics is slightly different. It’s a surface mount version of the TinyTrak APRS GPS position encoder. APRS (Automatic Packet Reporting System) is a worldwide amateur radio protocol for transmitting positions. Each transmitter periodically transmits a packet containing its ID, GPS position, and the local timestamp. This is then propagated by other units, either by repeating the packet’s transmission or via the internet. The data can then be viewed to give current or historical positions. The TinyTrak SMT is a particularly small APRS encoder, measuring only 1” x 0.925” x 0.16” (a separate power supply, radio and serial based GPS receiver are also required). The APRS protocol allows for a ‘comments’ field in the packet, which could be used for including any sensor data. It should be noted that using APRS can cause potential difficulties when away from urban areas as there is no guarantee that the transmitted signal is received
5.5. Comparison with commercial trackers 143 and forwarded; however, a series of UAVs would be able to repeat signals between themselves to form a chain back to a longer range repeater, and the UK has a number of automated wide area VHF repeaters which give a wide coverage. Another potential issue is that there is no aspect of privacy — any information transmitted by this means becomes public and is distributed worldwide.17
Complete autopilot systems will also usually include a GPS receiver for calcu- lating positions, and several have capabilities for reporting back flight data to the user, usually by radio.
5.5.10 Animal trackers
There are many questions that biologists have about the behaviour of wild animals, such as foxes, which are difficult to answer due to lack of unbiased data. Wild animals are almost by definition elusive and difficult to accurately observe. One means of obtaining data is to remotely monitor the animals using animal attached transmitters. These can be GPS based, or can be radio transmitters which are then triangulated by teams of observers.
Most wildlife GPS receivers are prone to error due to their use case (they will often be transmitting either under heavy undergrowth, in underground dens, or in urban canyons, and will need to have an extremely long battery life). There has been interest in developing the Durham tracker for tracking foxes in Bristol,[144] due to its GPS capability and ability to transmit positions over GPRS.
Animal trackers share a number of similarities to UAV trackers — they need to be small, light, low powered devices with a long battery life, capable of relatively high speed tracking and tracking in difficult situations. Despite the problems associated with animal trackers there are a number of devices commercially available.
Vectronic’s GPS Plus Telemetry Collars[165] take regular GPS readings as well as other sensor inputs (temperature, movement, etc.), log them locally, and can then report them via several different means — by satellite (ARGOS, IRIDIUM or GLOBALSTAR), by GSM, by radio (UHF or VHF), or by detaching from the animal for later retrieval. While many of their collars are designed for larger, heavier
17
Including via satellite; the International Space Station, amongst others, will relay APRS data signals.
144 Chapter 5. GPS tracking animals, their smallest is designed for tracking birds. It weighs from 100g and offers VHF or GSM for data transmission.
Another example is the Quantum 4000 Advanced GPS Collars from Telemetry Solutions. These include temperature and mortality sensors and can store 60,000 readings on internal memory. Readings can be taken as often as every 5 seconds, and transferred over UHF. They offer a customised collar for any animal specification, with their smallest weighing from 30g. This smallest uses UHF for data transfer with a two way connection — or alternatively can be set to fall off the animal after a set period, with a VHF beacon for locating the collar and recovering the stored data. Battery life is quoted as being up to 270 days with infrequent (twice daily) readings.