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Monarch - Multizone Devices

Because of global regulations, Sigfox currently uses 7 different radio configurations. A Sigfox device will transmit properly only in the RC zone it is currently set up for - the messages will not be delivered in other zones because of the difference in transmission frequency. When leaving one RC zone and entering another, it would make sense for Sigfox devices created for global tracking to be able to switch the radio configuration they transmit in.

In order to do so, these features have to be enabled:

  1. The antenna needs to be able to transmit in the desired RC zones
  2. Switching between the RC zones has to be supported
  3. A trigger for RC zone switch has to be defined

There are several ways the RC zone change can be triggered:

  • Manual - through a switch/button, human action that’s not remote in general
  • Time - the easiest one, if you know that the device is leaving a port you can tell the device to switch to another radio zone within 2 days
  • GPS - if the device has a GPS module, you can program the device to switch the zones when it reaches a zone border
  • World Time Code emitter - you can listen to it and switch the RCZ based on location
  • WiFi beacons - if you have a predefined trajectory and are able to put managed WiFi beacons at transition points, you can use them to switch the zones
  • Monarch - a system of beacons provided by Sigfox that transmit a Monarch RCZ zone information each 5 minutes and are located at maritime ports and airports and also at the final destination - factories, warehouses etc. Beacons are integrated into all types of regular base stations.

The major issue with Monarch is that the beacon is only available at ports and not anywhere else. So it’s necessary to somehow detect that the device is at the port and start Monarch listening. Or the device has to be listening all the time.

Listening all the time can be configured based on the knowledge of how long the device stays around the beacon/port/airport. If the device stays there for at least one day it is enough to listen only once a day.

If it stays around the airport for at least two hours it is enough to listen every two hours.

With SimplePack, each Monarch listening consumes roughly the same energy as 40 messages. (So we can listen once a day for 1000 days).

Also, if you know that the device will travel overseas for extended time periods, you have an option to start listening only after a certain period of time. If you miss the beacon port, the device does not switch zones and is lost so to prevent this you must have a backup beacon in the final destination point.

If you enable Monarch listening at ports/airports only, you can detect them by:

  • GPS boundary/position
  • barometric trigger landing/taking off of the airplane
  • barometric trigger lifting by few meters and loading/unloading the containers
  • accelerometer detecting the taking off and landing of the airplane

Monarch is NOT an automatic worldwide trigger and needs complete Discovery or a very use case specific approach.