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Radio Waves or Bluetooth? The Pros & Cons of Two Sensor Systems Used to Track Worker Movement


by dominicc | April 17, 2018 | posted in BLE, Bluetooth, Data, RFID | No Comments

John Jurewicz, Director Technology Optimization, Walbridge

If you have been watching how various sensor technologies are tracking the movement of workers at the jobsite over the last year, then you may find this article of interest.  Two competing technologies: Radio Frequency Identification (RFID) and Bluetooth Low Energy (BLE) are battling it out, to determine which one is more likely to scale in construction. We welcome input from any of you that may be testing these, as in sharing user input collectively, we can all learn from each other.

Image courtesy of Triax

In one corner, RFID:

Radio Systems[i] are offered in a variety of frequencies, from 125 khz to the higher ranges that microwaves and cordless phones use at 2.4 Ghz. Generally Radio frequency ID systems require a reader to “see” electronic tags that can be embedded on acetate or mylar tape or they can be used in a metal housing that makes it easier to read if mounted to something else that is metal (e.g. duct or a panel).

Pros

Unlike barcodes, RFID readers have improved to where:

  • Every inch of a site can be covered with pods placed every 500 ft. that can see tags behind steel and glass as well as cardboard
  • They can scan above ceilings and floors as well as behind concealed boxes
  • Readers are tracking lots of safety information, such as if a worker has fallen
  • They can also monitor equipment that vibrates – active vs idle usage
  • Environmental (temp and humidity) monitoring is possible for projects where this may be a safety concern (e.g. working in steam tunnels)
  • Tags can last 6 months or more before needing a recharge – Pods need to be powered, but relay pods do not require it

Cons

  • Horizontal Accuracy is only so-so (20 ft)
  • High deployment costs to get set up: $ 3000 (2 men full day), as well as initial costs for each tracking device ($100 per clip or per equipment tag), a monthly cost of $1500 to $2000 a month for tracking up to 500 people/devices at 10 second intervals, billed quarterly. Lease options can be worked out, but it can be more expensive for shorter duration projects

Image courtesy of beacon.ninja

In the opposite corner we have BLE challenging the radio tech:

Bluetooth systems[ii] have evolved over time, improving in terms of data throughput and range. When version 1.0 was first released in 1994 by the inventors at Ericsson, it had a 10 meter (33 ft) range has evolved to increase bandwidth to 24Mbps. The 4.0 spec (BLE), now 8 years old has a range of 200 ft. and some vendors are claiming longer ranges that come with a cost (see below). Ultra-wideband range claims a range of 400 feet.

Pros

  • Uses low power and is relatively inexpensive (1/5th of the cost per tracker compared to Radio clips per worker)
  • It is reliable and robust, capable of tracking workers and assets accurately
  • Integrations into legacy systems are possible with any number of mobile devices
  • Adopted by Apple (IOS), Google (Android) and Microsoft (Windows) operating systems, its communication means is widely recognized

Cons 

  • Bluetooth is generally known as low throughput, so it usually cannot be relied on for sending streaming video or audio longer distances
  • Inability to work effectively when it is near other wireless devices can be problematic
  • Range of Bluetooth is reduced by WiFi interference
  • Bluetooth competition is with the new standards, such as Ultra Wideband, which has higher data rates and works better alongside Wi-Fi. Ultra-wideband being tested by professional sports games to show where the players are during a game would break the bank of most cost minded contractors, but is showing more promise as it evolves

 

For further reading:

www.rfidjournal.com

Cellular fleet tracking (GPS is used to track vehicles but only works outside and not underground)

Bluetooth Interference issues (Usually can cause trouble to other WiFi but can be interrupted as well)

Ultra-wide band generally described as larger than 500 Mhz and up (short ranged and indoors)

See Yard Management Solutions by Zebra Technologies


[i] Triax Spot-r by Triax, Jovix by Atlas, Gao and Industrial Automation Group (AU)

[ii] IEE standard 802.15 such as Bluecat (Australian expanded to US), iknaia (UK)

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