The Monarch feature makes IoT devices aware of the local radio configuration (RC) to use.
A single device can thus lawfully communicate on the Sigfox network even when moving between countries with different radio regulations.
In everyday use, Monarch is transparent and simple: the device automatically chooses the appropriate radio configuration without human intervention.
Monarch relies on beacons broadcasted by some base-stations of the Sigfox Network that devices must detect, to select the applicable radio configuration.
It was designed with all values that prevail in Sigfox technology, which for the device means:
- Hardware design must be adapted but existing Sub-GHz semiconductor solutions can be reused: no need to add high-value power-hungry components.
- On Software, Monarch comes as an additional option inside the Sigfox Protocol Library but it remains simple and compact.
- Both the beacon signals and its broadcasting frequency are designed to enable devices to keep multi-year battery lifetime.
To evaluate the Monarch functionality for your PoC, end-to-end solutions (including device and its cloud application) are already available. For instance, Axible Tracker (suitable for sea and air transport).
Monarch can be supported by most semiconductor solutions that currently implement Sigfox:
- The antenna and RF front-end must support all the targeted radio configurations and corresponding frequencies,
- The Sub-GHz transceiver must provide an OOK demodulator (that will demodulate Monarch Beacons),
- The MCU on which is hosted the Monarch-enabled Protocol Library shall have enough processing bandwidth to decode the Monarch pattern sampled at 16kHz.
The complete Monarch implementation encompasses RF and SW know-how as depicted in the chart above. To develop such device, it is therefore recommended to use a Sigfox Verified solution.
- Chip-on-board design approach: please contact your preferred semiconductor vendor. A reference implementation is already available from ST.
- Use a Monarch modular design: several references are under development and will be widely available soon.
Note that even when using a Sigfox Verified Monarch solution, the triggering of the beacon search remains under the device maker duty based on multiple sensor events and possibly real-time clock.
Before going into the field, you need to validate the Monarch detection and demodulation chain in the lab. It requires the following:
- A RF I/Q Vector Generator such as for example a LitePoint IQxel-M,
- Monarch I/Q patterns, to be requested from Sigfox,
- The software Add-on “RF & Protocol” delivered with the Sigfox Protocol Library that automates all “RF & Protocol” testing.