Our TTN Gateway in Rapperswil is Live!

As you could read in our last two blogposts, we are currently experimenting with LoRaWAN, specifically with The Things Network.

The LoRaWAN infrastructure is not built and provided by a single company, but can be set up by anybody without the need for any licenses. While there are a few companies that started building classical pay-per-message LoRaWAN networks (in Switzerland it’s mostly Swisscom and Loriot), there is also a company/project following a different approach: The network provided by The Things Network is entirely built and maintained by volunteers. Anyone can join it with a gateway and use it for free, no strings attached (as long as the fair use rules are followed). The backend is fully open source. While the backend architecture was initially centralized in the Netherlands, it is currently in the process of being decentralized.

At Coredump, we also wanted to become a part of the community and provide coverage for Rapperswil-Jona with a gateway. We internally crowdfunded the hardware needed to build a DIY multi-channel gateway, consisting of an IMST iC880A-SPI LoRaWAN concentrator board and a Raspberry Pi 3. Total cost including enclosure and PoE kit was around 450 CHF. This (pretty long) blogpost tells the story of how we got there. Continue reading

LoRaWAN 868MHz Antenna Test (Part 2/2)

In our previous blogpost, we talked about ways to measure and compare antennas. If you haven’t read it yet, you should probably do so, unless you already know what antenna gain and VSWR are. Also, I want to reference the great Application Note AN-00501 again, which contains a lot of resources that help interpreting the following results.

Today, we’ll take a look at the results we got from antenna measurements. Since I already had a few LoRa antennas from various sources, I wanted to know how they compare. The best way to do that is with an antenna test chamber. Luckily, the people at the Institute for Communication Systems (ICOM) at HSR built themselves such a test chamber from an old SBB freight container. Continue reading

LoRaWAN 868MHz Antenna Test (Part 1/2)

Over the last year, I started playing around with LoRaWAN, a long-range low-power wireless data transfer protocol. We internally crowdfunded a LoRaWAN gateway at Coredump and joined the Things Network. More about our gateway in a future blogpost. For a general introduction into LoRaWAN, I recommend watching this video. And this 33c3 talk is a fantastic introduction to the LoRa PHY layer.

This blogpost is not about LoRa or LoRaWAN itself though, but about a related topic: Antennas! In Europe, LoRaWAN is operated at a frequency of 868 MHz. After testing multiple antennas for LoRaWAN nodes and gateways, I wondered how these antennas can be compared. We’ll take a look at three metrics to compare antennas: Directivity, Gain and VSWR. And then – in a follow-up blogpost – I’ll present the results from a lab test of 11 different 868 MHz antennas. Continue reading

Erste Versuche mit Reflow-Ofen

Welcher Hobby-Elektroniker kennt es nicht: Man hat ein cooles PCB mit vielen SMD Bauteilen designt, welches nun bestückt werden soll. Doch ein Bestückungsservice ist teuer, und von Hand löten ist sehr aufwändig und dessen Resultat überzeugt häufig nicht wirklich. Daher haben sich ein paar Coredump Mitglieder entschlossen, einen Reflow-Ofen zu finanzieren um damit in Zukunft bequem und sauber PCBs bestücken zu können.

Continue reading