This post is a VLOG entry, as usual in French, you will find the english text version in the next part of the post.
Basically, I’m explaining how the two LPWAN technologies : Sigfox and LoRa use the radio frequency to communicate with a low power consumption in a wide area environment.
In this video you will find a mix of demonstration with voice to highlight how it works with day-to-day life example and spectrum capture of both technology to visualize how it looks like.
I recently bought an AirSpy mini SDR (Software defined radio) dongle. Understand, it is a radio scanner you connect on your computer able to analyze radio communications on a large frequency range from 24MHz to 1,7HGz. The main difference between this SDR and the low cost one based on RTL 2832 + R820T is the spectrum view up to 6Mhz, the TCXO working with 0,5ppm and globally the quality of the solution and the availability of libraries. What is presented here is also valid for RTL based dongle.
With this tool you can see what is happening on the radio frequencies in real time, compare power, listen radio … This post is presenting how to install it and use it on windows & Mac Os X.
I just got them at home ! The new Sigfox module with a low cost approach based on the OnSemi AX-Sigfox-D chip is now ready and available for being delivered. With a price less than $3 per module for a quantity of 10 this module offer a low cost access to the Sigfox network.
In this post I’ll describe the first step with this module.
Since a long to time I did not post about MQTT … The main reason was I uses MQTT as a protocol to publish data directly from a device but in a centralized environment like SigFox / LoraWan you can’t use it directly on the device. Actually I have some devices communicating with a backend and the question about how to provide these information to the customers of my service are raising. To match this pattern I have to ways : providing and API where the information are pulled by the customer and MQTT where the information are pushed to the customer.
One choice is not against the other one, I had the two kind of customers. For this reason I will describe how we can implement a MQTT server (mosquitto) to push Sigfox data device as json content.
I’m using different GPS antennas with different price, size and gain and I had never compared the result in a real live test. So now it is done and the result are good to share.
My test condition are quite bad and we can’t really consider this as a scientific bench but, experimentally it sounds like a real life test.
So the test is to connect an antenna to a TD1204 with a GPS code on it and test the time it makes to fix the position and get some note about signal level, satellites in view… I used in fact 2 TD1204 : one with a reference antenna to ensure we have equivalent condition from one test to the others. The tests are made indoor where the sensitivity is an important factor. This post detail the results.
I have recently discovered the smartEverything prototyping board for Sigfox. This board was used during the SigFox maker tour and It is really nice for creating some prototypes and evaluate the technology.
The board is an Arduino board based on an Atmel SAM D21 MCU (Cortex M0) with 256KB of flash and 32K SRAM running @48Mhz
The most important part is concerning the sensors available on the card and this is clearly the best point about this board : you have a lot of them available : crypto authentication chip, BLE module, GPS, NFC, Accelerometer / gyroscope / magnetometer, Pressure / Humidity / Temperature sensor, proximity light / sensor, RGB Led, Led & push button. It can be powered by USB or external 2xAA batteries.
The board cost is about 106€ and can be found at RS. It is provided with a sigfox network access to the backend.
This post detail how to get start with the board
After making my kit on my own, I finally got the official Telecom Design TD1204 kit (thank you TD) There is no big issues to use it once you have the right entry point, but as I had some email exchange with support to be fully ready for using it, I’m prefer to share some words with you on what to do and how it works.
Basically, the TD kit is an EFM32 Tiny Gecko Starter kit (STK3300) with some little modifications. The EFM kit have two interesting functions : in own a Jlink JTAG/SWD programming and debugging interface and its EFM32 MCU can be use to monitor power consumption with precision.
I needed to access a mongodb instance to manage my collections. I was looking for something like phpmyadmin for mongo but the first tool I found was mongoclient.
This tool is an application for desktop provided for many OS including mac OsX. The quality of the tool is really good.
The mongodb was installed on my server remotely and protected by a firewall so the easiest way to access it was to open a ssh tunnel. Mongoclient is supposed to manage the ssh tunnel in the application but it was not working for me so I had to manually connect the tunnel :
# ssh -L 27017:localhost:27017 -p 22 user@mongodb.server.com
Once connected it is possible to create a localhost connection with mongoclient.