In this Sigfox for dummies post I will take you through the basics of what Sigfox is and where we might use it in our IoT projects.
I won’t go into the technical details too much here but rather give you an overview of the technology and show practical uses and examples where possible.
By the end of reading this post I hope that you can begin to think about utilizing Sigfox over other available technologies where the advantages would benefit you.
What Is Sigfox?
Sigfox is a worldwide cellular network designed to send minimal sensor data from remote IoT end/edge devices to servers connected to the internet.
Sigfox is one of many low powered radio WAN technologies used to target Internet of Things use cases which addresses two problems in existing technology..
And that is to offer a long range communication system over a wide area while still maintaining a low power consumption at the end device.
Sigfox is a French company that operates their network all around the world and can be found at Sigfox.com.
It’s network infrastructure is currently made up of tens of thousands of antenna’s worldwide as of 2020 with hundreds of servers in multiple data centers that deliver more than 40 million messages per day.
The system is used to send short messages from an edge device to the gateway (Comms tower) which could be many kilometers away.
Sigfox isn’t just about collecting data but providing a complete end-to-end solution for many industry sectors. This includes analyzing the data collected from the edge devices.
With Sigfox it’s not about the product, it’s about the data.
Meaning that we can use any device as the end/edge “thing” whether it’s being a proprietary product or even home built using open-source hardware and software platforms.
When we think about data collecting we usually think of the unethical practices from tech giants.
There’s no doubt that sigfox can be used for nefarious uses just like any other IoT implementation.
We’ve all heard of 4th and 5th generation cellular network technology (4G/5G) but sigfox is known to be 0G!
This is because we are not trying to transmit as much data as possible like 5G+ is intended to do, but quite the opposite.. Sigfox tries to send as little data as possible.
Would could implement an IoT solution which uses WIFI as it’s primary data connection and Sigfox as a backup for example.
A mobile app can be used to access the data from the Sigfox network/dedicated cloud infrastructure.
Comparing Sigfox With The Mobile Phone Network
Most of us have a general understanding of how a cellular mobile phone network operates in that we have a phone which transmits and receives data to and from a base station tower.
Sigfox works with this same concept yet has some very different technical differences to allow for long range with low power.
It’s all about energy efficiency by using minimal data transmission to ultimately save battery power!
Imagine that you accidentally dropped your phone in a field somewhere out in the middle of nowhere! Are you imagining..?
You get home and realize your phone is missing..! The horror right?!
How long do you suppose the battery life will last in the phone? Maybe 10 hours if it wasn’t fully charged? Maybe 10 hours if it WAS fully charged? Maybe a whole day if you never bothered to try ringing it every minute in a frantic panic while trying to find it?
Now imagine your mobile phone didn’t have a screen while it was laying in the field. The battery life would last longer as it doesn’t need to supply power to that power hungry component.
Now let’s imagine your phone had a soil sensor connected to it and it was inserted into the soil in the field and that you didn’t accidentally drop your phone, but it had been purposefully placed down in the field to act as an edge device in an IoT network.
This edge device (or “thing”) can now monitor the soil PH acidity level and soil moisture.
(This kind of information could help a farmer to select what crop would grow in optimal conditions in this field for example.)
We want this soil data to be transmitted to the cell tower every 5 minutes. Even without a screen and any other component that we could remove from the device we are still only going to get a few days maximum of data transmitted before the battery drains away and dies.
So what else can we do to make this edge device’s power last much longer?
Of course we can connect solar cells and/or wind turbines to recharge the battery and this is probably a good idea if we want the device to stay powered indefinitely.
But we now need to change some fundamental things about the technology to become much more energy efficient.
After all, sending this soil data every 5 minutes isn’t going to be anywhere near the amount of data compared to you zoom calling your aunt or streaming YouTube videos in 4K.
The device will go to sleep once data is transmitted and only wake up to transmit again.
A Mobile phone is very similar to an edge device! Edge devices can have an operating system such as Android, a mobile phone has a multitude of sensors built-in such as accelerometer, gyroscope and temperature sensors.
You could call a mobile phone an IoT device in itself!
Overhead And Control Data:
A mobile phone will establish a connection with the base tower before any data can be sent to it.
Sigfox will not.
Sigfox will blindly transmit it’s data and “hopes” the tower is listening.. Sigfox towers are always listening whereas mobile towers do not, and they need that connection established before it can accept any data.
Firstly, we need to reduce the amount of data being transmitted by this remote edge device. Mobile phone communications have lots of overhead. This is control data.
By only transmitting on a very narrow bandwidth of the frequency spectrum we can achieve a long distance transmission with minimal amount of battery power consumption.
Where Is Sigfox Used?
Sigfox is designed to solve real-world problems across many industry sectors. The official YouTube channel shows Sigfox being implemented in:
- Boat and car parking
- Monitoring wildlife and building data maps for bird species
- Prevent car theft
- Smart cities
- Optimize under-occupied office space: As more people are working from home, Sigfox can optimize physical office work space to reduce rent costs and create “flex-offices”
- Asset tracking for vehicles and pets (cats/dogs) and implanting devices into rhino horns
Advantages of using Sigfox:
- Cellular subscription fees are lower due to small data transmission
- Further coverage than 4G/5G and uses less gateways/towers
- Low cost hardware compared with other cellular technologies – as low as $2 per module
Disadvantages of using Sigfox:
- Sigfox can not be utilized in time-critical applications as it operates with multiple seconds of latency due to it’s long range and low data rate
How To Get Started With Sigfox
It’s possible to build our own IoT edge device at home and incorporate Sigfox technology into our applications.
DIY maker boards such as the Arduino MKRFOX1200 can be purchased for less than $50 from well-known suppliers.
if you’re unfamiliar with Arduino then you can read my beginner tutorial on the Arduino Uno here.
RS Components for example offers this development board for purchase and here is a more detailed description about this Arduino model on their official website.
RS Components also offer shipping to many parts of the world and host a “Getting Started” PDF guide here which is worth checking out.
And this link will take you to the RS Components “country selection” web page as they seem to segment their website across the world.
Sigfox Technical Details
Sigfox was originally developed for a pure sensor network.
Only transmission from the remote sensor devices to the gateway was originally supported as the gateway could not send reply data back to the remote device.
However this technology was improved and now data can be sent from the gateway back to the sensor/thing/edge device which can be used to acknowledge the receipt of the devices transmission.
A total of 12 bytes can be sent from the device to the gateway (uplink) at 100bps (bits per second: very low data rate), and has a downlink of 8 bytes at a speed of 600bps. (remember there are 8 bits in 1 byte).
The sensor device will only listen for a replay from the gateway in a short window of time after it has transmitted data. After 20 seconds of transmitting it will begin to listen for 25 seconds. This ensures a minimal amount of power is consumed from the edge device.
- Sigfox uses ultra narrow band modulation: 100hz in Europe, and 600hz in USA. Using this narrow band allows the transmission to reach further and is more robust against interference
- It transmits across 3 of the 320 available channels at slightly different times and uses pseudo-random frequency hopping
- Operates below the 1Ghz range (WIFI uses 2.4Ghz and 5Ghz to put this into perspective) which allows for longer range
- The whole spectrum is 192khz wide and the gateways are listening on all frequencies
- Multiple gateways can pick up a transmission from the sensor device. A backend server on the internet will select the closest gateway to the remote device to transmit a reply message if necessary.
- The modulation type from the gateway to the sensor device uses 2GFSK and for the sensor to gateway uses (D)BPSK
Hopefully this Sigfox for dummies explanation has inspired you now to use this technology in IoT projects that you may want to create now or in the future.
As you can see by the advantages that Sigfox offers, we may find uses all around IoT implementations.
By implementing this long range communications with minimal power consumption it allows devices to stay connected for a considerable amount of time.
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