Events in room K.3.601

This talk introduces ElemRV, a lightweight open-source RISC-V microcontroller designed for accessibility and adaptability. We'll trace the project's origins and its first tape-outs using IHP's Open PDK, demonstrating how open-source silicon can move from concept to fabrication. The presentation covers ElemRV's architecture and key components, highlighting the design choices that shaped the microcontroller. We'll walk through the complete ASIC flow - from RTL source code to tape-out-ready GDSII files - demystifying the process of creating custom silicon with open-source tools. The session concludes with the roadmap for future tape-outs and planned enhancements, inviting community collaboration on this libre hardware project.

The f8 is an architecture for small embedded systems optimized for memory efficiency - regarding both code and data memory. We present the current state of the architecture (including the f8l variant for reduced core area), reference implementation, and the toolchain, which is based on the Small Device C Compiler (SDCC). https://github.com/f8-arch https://sdcc.sourceforge.net/

I have been working hands-on with FPGAs for open-source projects in distributed storage and networking. More recently, I have been interested to FPGA applications in finance and ultra–low-latency systems. Along the way, I found out that several open-source projects were immensely helpful, which made me realize that engineers and developers who want to get started could benefit from the same resources. This talk will cover the fundamentals of how, why, and where FPGAs are used in financial applications. Naturally, this talk will also highlight key open-source projects that can help the community build FPGA-based projects in this domain.

We will explore version 2.0 of the FABulous embedded FPGA (eFPGA) Framework and show how to design, implement, and simulate an embedded FPGA fabric. Starting from a high-level specification, we work towards a tiled and optimised, tapeout-ready physical layout (GDSII), in just a few steps.

FABulous is an easy-to-use, free and open-source eFPGA framework covering all aspects of what an FPGA ecosystem requires, from high-level design and layout to simulation and CAD tool integration. Version 2.0 introduces the ability to automatically generate a tiled and optimised physical layout, simplifying chip-level integration significantly.

The framework supports extensive customisation, including user-defined primitives, I/O cells, and integrating complex blocks such as CPU cores or ADCs. It has demonstrated superior area density in both standard-cell and custom-cell-based flows and has been validated across more than 15 manufactured chips, spanning 28 nm to 180 nm, including open (SKY130, IHP130, GF180) and industry (TSMC 180, 130, 28) PDKs. This demonstrates its practicality and adaptability across a wide range of design contexts.

GitHub: https://github.com/FPGA-Research/FABulous Docs: https://fabulous.readthedocs.io/en/latest/

The use of programmable logic devices, such as FPGAs, requires a range of software tools, from editors for HDL design to the place and route software that maps the design to the physical device and the software that handles the actual configuration process. These are often combined into a coherent IDE to improve efficiency and ease the learning process by offering smooth transitions between the different stages of development, from writing HDL via synthesis, simulation and implementation to the configuration of the device. In the world of FPGAs, these IDEs are mostly proprietary software, developed and owned by the few big FPGA vendors, that only support their own hardware. This means that once design flows are established around one vendor’s software suite, switching to a different vendor’s hardware becomes a tedious or even entirely unworkable task. For years now, pioneers in the open-source community have been steadily working to bridge the gap between commercial and open design tools, to the point that competitive solutions now exist for many aspects of FPGA design. With all the building blocks now available we in the FEntwumS project are now working to integrate a whole range of these tools into one coherent IDE that is as vendor-agnostic as possible and, most importantly, free and open-source. As a representative case study to validate and benchmark this platform, we integrate OpenEye, an open-source and fully FPGA-compatible neural network accelerator developed within the consortium. Its scalable architecture enables us to evaluate the robustness of the toolchain across different device classes and design configurations, testing synthesis behavior, implementation quality and runtime characteristics. By using OpenEye as a practical test vehicle, we ensure transparent evaluation, reproducibility and alignment with the open-source philosophy that underpins the entire project. In this talk, we will present our approach, our current progress, issues we have encountered and our future plans.

The organizing team of the Devroom welcomes you to the Railways and Open Transport room. Exciting content lies ahead.

The public transport sector is mostly a traditional sector with an oligopolistic market situation for system solutions for travel planning and ticketing. The lock-in and dependency to few system vendors in Europe stifles innovation and impedes initiatives to make public transport more attractive. But in the Nordic countries, public transport agencies (PTA) choose an alternative path to overcome system vendor dependency through open source and by engaging in community development. Our qualitative study interviewed 13 persons from 5 different PTAs in the Nordics entails an alternative pathway where they digitally disrupted the regional or national public transport market. They choose to utilise open source for central components and engage in community development to achieve political ambitions to make public transportation an attractive alternative to car travelling.

Our study presents a model on how organisations can co-evolve with the open source community through long-term engagement to access state-of-the-art digital technology and foster innovation. The model depicts a cumulative process that yields better opportunities the longer and deeper the engagement becomes. This enables digital transformation outcomes such as access to a global pool of knowledge, agile and adaptive value-creation, open innovations processes, partnership and synergy opportunities. The talk will present the findings from the study and how the model can be used as a tool to better understand and depicts the organisational alignment process, the inner mechanism and the possible transformative outcome of engaging in open source community development. Our findings demonstrate that also large traditional organisation within the transport sector can partially foster digital transformation capabilities through departmental engagement in community development which can radiate to other parts of the organisation. This entails alternative pathways for traditional organisation that are under demand to digitally transform. But this requires sustained resource investment and loyalty to community objectives to gain influence and trust, to access deeper collaboration and innovation opportunities. The talk will discuss both obstacles, possibilities and strategies that organisations can adopt when engaging in open source community development.

2025 marks a turning point for European mobility data. A significant update to the Multimodal Travel Information Services (MMTIS) regulation takes effect in March 2025. In parallel, ERA and DG MOVE have initiated a coordinated overhaul of all Transmodel-based standards, and a newly agreed TSI Telematics revision (November 2025) sets the direction for railway digitalisation from 2026 onward.

This talk brings together Yann Seimandi (DG MOVE) and Stefan Jugelt (ERA) to give developers and open-source contributors a clear picture of the new regulatory and technical landscape. We will cover:

What’s new in MMTIS 2.0 - How NAPCORE supports harmonised, cross-border mobility data - Upgrading Transmodel-based standards to European Norms - Specification of EUDIT, the new Transmodel-based Booking API - Development of EFIP, a unified European NeTEx Fares Profile - Alignment of TSI Telematics with the broader multimodal ecosystem

Participants will gain insight into the impact on APIs and data models and how open-source communities can contribute to Europe’s mobility infrastructure.

European transport systems are adopting standards such as DATEX II, NeTEx and SIRI, but developers struggle to discover existing tools, validators, converters, and libraries. We're launching Awesome NAPCORE Tools (awesome.napcore.eu) - a community-curated registry of open source tools for European mobility data. This talk introduces the platform and invites the open source community to contribute. We'll cover:

• The European mobility data landscape and key standards
• Current challenges in tool discovery
• How the registry works and the contribution process
• Inclusion criteria and governance approach
• Vision for community ownership

Whether you maintain a DATEX II validator, a NeTEx library, or build transport applications, we want to showcase your work and connect you with users and fellow developers.

We deserve open-source transit technology that is both beautifully designed and easy to use. The Mobility Database is a free, open-source platform for global transit data in the General Transit Feed Specification (GTFS) and General Bikeshare Feed Specification (GBFS) formats. These global specifications make it easier for public transport agencies, operators, and shared mobility providers (bike-share, scooter-share, car-share) to publish accurate, high-quality transit data, enabling them to share their services efficiently with the public.

Why are we building this at MobilityData? 1️⃣ Easy access & maximum reuse of open data: Because open data should not feel like a scavenger hunt, we make it easy to find and access global mobility data for free, and with a barrier-free API.

2️⃣ High quality of open data: We provide simple quality evaluation reports that can guide precious resources of the industry where they matter most, guaranteeing that hard work translates into the high-quality, reliable information public transport riders deserve.

3️⃣ Strengthen the open data community by boosting the international visibility of feeds. This turns the platform into the trusted meeting ground where analysts can easily cross-reference global best practices and collaborate worldwide.

We recently released map visualizations, the ultimate tool for the data detective 🕵: on the platform, we can now instantly see the modes, routes, stops, and coverage of any data source, making it simple to spot a rogue stop or understand a feed's architecture at a glance.

In Europe, the Mobility Database relies on the National Access Points (NAPs) across multiple countries (France, Norway, Switzerland, Spain, Denmark, Sweden, Finland, and more). And because good open source is a two-way street we also contribute back by providing free open-source tools for our partners and making sure producers coming our way find their way to their local National Access Point (NAP). This way, no stakeholder will have to browse the entire digital continent just to get comprehensive data from their region of choice.

This talk will explore how the Mobility Database fosters a vibrant open-source ecosystem, gives transit data the attention it deserves, and supports sustainable transport.

Despite EU-level initiatives, the availability and quality of open data on public transport differs wildly between member states. I'll talk about the situation in the Czech Republic from the perspective of someone who's been fighting for data availability for the last 5 years.

We'll focus mostly on timetables, briefly covering the history of the Czech Republic's centralised system, the current state of affairs after multiple lawsuits, and the (hopefully) rosy future. I'll also talk about other datasets, like real-time positions and train composition, and also about my experience trying to fit Czech data into existing open standards and software.

In this talk, I will present why and how I started writing Bimba, a public transport application for my city back in 2017. The talk will show major turning points in the journey: when the city started providing open data, when Bimba no longer worked in single place, when Transitous was integrated enabling not only global coverage but also global routing, and meeting people and ideas during last year's RaOT track at FOSDEM and the first Open Transport unconference. I will also present how—with crowdsourcing—Bimba is now also a part of the community and finally, I will hint to what may come in the future.

Not every public transport agency publishes real-time delay information, and some do not even have it. Some of the proprietary transit apps have used user-submitted data to bridge this gap for some time now.

This talk explores how we can do the same in open-source apps, based on Transitous. It covers the steps from collecting the vehicle positions from people's phones in an ethical way, to deriving the delay and to integrating the results with existing routing services and apps.

In addition to allowing for the independent collection of real-time information, the components written for this project (gps-collector and gtfs-delay-tracker) could potentially be useful for community buses, heritage railways and smaller public transport agencies with limited budgets.

In late 2025, DB InfraGO - Germany's state owned operator of railway infrastructure - released its “OpenStation“ API, the new single source of truth for train station data. The API (or as some users have put it: "glorified collection of XML files") is based on the european NeTEx and SIRI standards, and its contents are released as CC0 (public domain), a first for Deutsche Bahn.

In this talk, we want to share our experiences with NeTEx and SIRI from a data producer's perspective, highlight some benefits and challenges of our new API, explain its intended role within the transport data ecosystem, and discuss our future plans for OpenStation. Last but not least, we would like to hear your thoughts and feedback on our new API.

OpenTripPlanner is a mature, open-source engine for multimodal journey planning across public transport, walking, cycling, micromobility, and driving/park and ride.

It supports datasources on multiple different format (NeTEx, GTFS), consumes hundreds of realtime updates per second to timetable data while delivering fast response times.

With all these capabilities it is important to map real world as accurate as possible.

How do you manage time-traveling trains, ghost buses, levitating trains, and how long is a staircase?

Inconsistent data, outliers and quirky rules go head to head with configuration and algorithms in a battle to answer the questions, what is the best journey from A to B.

With a smartphone, users nowadays can plan public transport journeys spontaneously and react to incidents in real-time by changing itineraries on the fly, even proactively. Algorithms and UIs however are still clinging to the notion of an upfront query and journey plan that the user is blindly following as long as is physically possible.

Similar to turn-by-turn directions for car drivers, we propose to focus on showing the user only the next best step they should take according to the real-time situation in order to eventually get to their destination, and not an entire, fixed journey plan. Instead of just the destination arrival time, we compute the probability distribution of destination arrival of the user, taking into account reliability of transfers and alternative continuations. Simulations show that on average, a user will arrive earlier than when following a classical journey planner, not only in the case of delays.

A prototype can be used at https://tespace.traines.eu/ with source code available at https://github.com/traines-source/time-space-train-planner. TeSpace relies on https://transitous.org/ and the https://github.com/motis-project/motis API for global public transport timetable coverage (where available). Let's also talk about how to advance these two beyond classical pareto-optimal journeys!

Long ago I wanted to build an app for the local bike sharing system in my city, only to realize open data was not publicly available. Out of frustration, I built a free and open API for others to create applications, visualizations and research using bike sharing data.

Fast forward today and thanks to the community, the CityBikes project supports more than 800 cities all around the world and our API powers bike sharing transportation apps across all platforms.

"open" data

Even with the introduction of open data standards like GBFS (at this time, approx 60% of our feeds) there's a fair amount of systems that are not accessible outside of their apps. The reality of open data shatters once you look too close into it: cursed APIs, broken feeds and HTML tables.

Our mission is to change that by providing developers, researchers and organizations the tools and resources to bridge this gap.

In this talk, I’ll share the motivations behind the project, what it’s like to maintain it after more than a decade, and dive into the new tools and historical data systems we’re building.

Visualizing origin-destination (OD) mobility data—commuter flows, transit ridership, freight traffic—is essential for transport planning, but datasets can contain millions of flows that overwhelm traditional mapping approaches. In this talk, I'll present open-source tools for preparing and visualizing large-scale OD data interactively in the browser.

I'll introduce flowmap.gl, a WebGL-based flow map layer for deck.gl that renders geographic movements with adaptive clustering and filtering. To handle large datasets, I'll demonstrate sqlrooms-flowmap, a Python tool that uses DuckDB with spatial extensions to prepare OD data for tiled serving:

• Hierarchical clustering: locations are grouped at each zoom level using pixel-radius clustering, creating a hierarchy where clusters merge as users zoom out
• Nested Hilbert indexing: OD pairs are indexed using a space-filling curve that preserves locality, enabling efficient range queries for tile-based serving
• Spatio-temporal aggregation: flows are aggregated to match zoom-based clustering, with optional temporal bucketing by hour/day/week

The prepared data can be visualized using a demo app built with SQLRooms, a browser-based analytics framework powered by DuckDB, where users can query and explore flows using SQL alongside interactive maps.

I'll show a live demo using Switzerland's National Passenger Transport Model (NPVM)—an open dataset of passenger flows across the Swiss transport network—demonstrating the full pipeline from raw data to interactive visualization, all using open-source tools that can run locally without cloud dependencies.

In the past two years the Open Source Railway Designer (OSRD) has been presented at FOSDEM. The integrations shown there sparked our interest in testing OSRD ourselves in a practical context. In initial studies we used OSRD to evaluate capacity effects on highly congested corridors, including a scenario with a speed increase in rail freight transport. These studies show that OSRD provides a solid basis for open, reproducible capacity studies.

However, the next crucial step in the planning process is microscopic operational simulation, which can be used to evaluate the effect of timetables and operating procedures over time and during disrupted operations. This component is not yet part of the OSRD workflow. To address precisely this gap, we have investigated how the agent-based tool SUMO (Simulation of Urban MObility) can be applied for railway operational issues. SUMO enables a detailed representation of vehicle movements along an infrastructure under a given timetable and allows delays and different operating modes to be modelled.

In a case study on the Frankfurt underground, we used SUMO to analyse various operational concepts. This included simulations in fixed-block and moving-block operation as well as the modelling of a driverless shunting. The results show that SUMO delivers precise insights into the dynamic system behaviour and provides relevant key figures for operational evaluation - while also exposing the framework conditions and limitations of the current approach.

Finally, we discuss the potential of linking OSRD and SUMO: from open infrastructure modelling and timetable mapping to microscopic operational simulation. We would like to outline how a consistent open source workflow for railway and light rail systems could be created and invite the community to develop it further together.

Open Source Railway Designe (OSRD) https://osrd.fr/en/ Simulation of Urban MObility (SUMO) https://eclipse.dev/sumo/

You're a railway infrastructure manager. A train operator calls up, and would like to fit a new train in the existing schedule. It should leave at 10am, and it's 8am. How do you make sure this new train won't cause any traffic jams?

Three years ago, we made a proof of concept for this complex problem (I've already talked about it in this track). Since then, we've successfully made it production-ready, and we've had users for a year now.

We have faced new challenges, both expected and unexpected. We have made some mistakes and learned from them. We have stories to tell.

OSRD website GitHub

After a successful beta run, the HackerTrain to FOSDEM is back! This time we are going distributed.

In this talk we will present:

• how we organized a train trip for an unknown number of groups of unknown people that travel on different dates and on different routes to the same event
• lessons learnt on how to manage such chaos on a zero budget
• how the actual train rides went (hopefully with pictures!) – we expect several lines from all corners of Europe
• lessons learnt on those routes
• what are the next steps and the long-term goals for the HackerTrain

Through this beta run of the HackerTrain to FOSDEM we hope to uncover also the potential for (massive) group travel to (FOSS) events, as well as the hurdles that we still need to overcome to make affordable, easy, comfortable and engaging cross-border public travel possible.

Welcome and introduction to the SDR/DSP devroom, some personal highlights of the past year and program description.

Abstract: The Opulent Voice Protocol (OVP) is an open-source digital voice protocol designed for bandwidth-constrained radio communications, including satellite and terrestrial amateur radio links. Developed through the peer-reviewed research and development process at Open Research Institute, OVP addresses the critical need for high-quality voice communication protocols that are freely implementable without licensing restrictions.

Built around the 16 kbps Opus voice codec, OVP delivers superior voice quality that exceeds existing amateur digital voice modes while seamlessly integrating voice, keyboard chat, and data in a unified protocol. This eliminates the need for separate, clunky packet data modes. This talk will explore OVP's architecture, performance characteristics, and design trade-offs. The first implementation target for the modem is the PLUTO SDR and can be found here https://github.com/OpenResearchInstitute/pluto_msk

Key Technical Features in the Reference Implementation: Minimum shift keying modulation has constant envelope and no phase discontinuities. Optimized for low SNR conditions, with forward error correction and flywheel synchronization. Efficient bandwidth utilization suitable for 70 cm and above amateur bands. Current hardware implementation on FPGA enables a future open source ASIC design.

We'll cover: The architectural decisions behind OVP's design, showing how domain modeling of the radio channel shaped protocol choices. Audio quality comparisons between OVP and legacy digital voice modes. The integrated communication model, which allows voice, chat, and data to coexist in a single protocol. Performance analyses. Integration with existing SDR platforms and open-source radio stacks. Lessons learned from deploying OVP over the air. The peer-review process and how open collaboration improved the protocol.

Human-radio interface project is here: https://github.com/OpenResearchInstitute/interlocutor Processor-side codebase (Xilinx/AMD 7010 Zynq) is here: https://github.com/OpenResearchInstitute/dialogus Satellite simulator is here: https://github.com/OpenResearchInstitute/locus

This talk is relevant to anyone interested in software-defined radio, open hardware communications systems, space technology, or building robust protocols for constrained environments.

At a time when Global Navigation Satellite System (GNSS) signal spoofing and jamming has never been easier, time and frequency has become an ubiquitous commodity most distributed communication infrastructures rely on. Returning to the pre-space era of long range communication using very low frequency (VLF) signals, we investigate some of the remaining VLF time and frequency transfer signals. Despite their long communication range, the need for bulky antennas and low VLF noise environment makes the direct reception of these signals impractical. In this presentation, we collect timestamped records of VLF signals collected throughout the world from the KiwiSDR network, and assess the performance of the broadcast signals and the receivers.

WSDR is a web-based platform for real-time signal processing, application development, and custom workflow creation—all in a plug-and-play environment. Built on WebAssembly, WebUSB, and WebSockets, it supports even demanding workloads, including running a full open-source cellular network directly in the browser with all DSP executed on the frontend. In this session, we’ll show how WSDR simplifies building and deploying custom applications.

The Parks-McClellan (Remez) algorithm is a filter design algorithm that is optimal in the sense that it minimizes the maximum error between the desired and realized transfer functions. Many implementations of this algorithm exist, including in GNU Radio and SciPy. However, some of these have issues such as numerical stability for some filter design problems. I will give a summary of the Remez algorithm, why there are different possible implementations, and why some may be better than others. I will also explain how to use this algorithm for some practical filter design problems. The talk is intended partly as publicity for the pm-remez Python/Rust modern implementation by the speaker and partly as a tutorial on filter design.

ZigRadio is a lightweight flow graph signal processing framework built with Zig that features ergonomic syntax, minimal dependencies, easy cross-compilation, and seamless integration into host applications. This talk introduces the project, discusses aspects of the Zig language leveraged by the framework, provides examples of standalone radio receivers as well as integrated applications, and outlines the future roadmap.

Since 2022, CERN uses White Rabbit to distribute the radio frequency signal in the SPS accelerator and the LHC accelerator is planned to also use White Rabbit for the next run (2030).

This talk will give a short overview of the CERN accelerator complex, how RF is used to accelerate protons and what is White Rabbit. It will then discuss why the RF phase is very important for an accelerator, how clocks are synchronized, how RF is computed, digitally distributed and locally regenerated using dedicated electronics.

Module developed for this project: https://gitlab.cern.ch/be-cem-edl/chronos/wr2rf-vme/-/wikis/home

White Rabbit (WR) is a digital synchronization protocol over Gb Ethernet whose development is centralized by CERN with contributions from high energy physics communities including accelerators and detectors. The sub-ns synchronization capability provided by WR makes it well suited for distributed-SDR system synchronization, but the phase detection mechanism requires two tunable oscillators hardly found in generic FPGA boards. Thanks to the advances of FPGA internal clocking circuitry, WR has been demonstrated to run on generic boards not fitted with these peripherals: we demonstrate WR synchronization of the (low cost) AcornCLE215 board and Enjoy Digital's M2SDR board with some limitations over the dedicated hardware and induced by the AD936x RF frontent.

For the past decade, artificial Intelligence (AI) and machine learning (ML) have revolutionized numerous research fields and industries. The machine learning community has not left out software-defined Radio (SDR) and digital signal processing (DSP).

Thankfully, this development has not been done behind closed doors, and plenty of frameworks have been released by research laboratories and industry with an open-source license. To name a few (in no particular order): Sionna (https://github.com/NVlabs/sionna), Commplax (https://github.com/remifan/commplax), MOKka (https://github.com/kit-cel/mokka), scikit-learn & numpy, and maybe some more.

The goal of this talk is to give an overview of existing frameworks combining DSP and ML, and present a short tutorial on some aspects of what is already possible.

PlutoSDR is running a minimal Linux distribution as the flash memory is limited to 32MB. Recent clones support SD card booting which extends these capabilities to several Gigabytes. The purpose of the presentation is to show how to take advantage of this extra storage to use the platform in a new way. - Debian 12 based - Software pre-installed (Python, GNU Radio, gpredict, maia-sdr api...) - Toolchain to achieve it : - Buildroot : https://github.com/F5OEO/tezuka_fw - rootfs : https://github.com/F5OEO/adi-kuiper-gen - FPGA : https://github.com/F5OEO/maia-sdr/tree/sweep - Web interface to use it, no need to install software on PC - FPGA DSP support (FFT, decimation...) - Optimizing GNU Radio flows for smoother performance - Use case: Web transceiver https://github.com/F5OEO/Remote-SDR-Tezuka

At the Dwingeloo Radio Telescope, we've developed a suite of tools that stream IQ data from SDRs using VRT (VITA 49.0 Radio Transport) over ZeroMQ to multiple clients simultaneously. This architecture enables us to run various applications—including SigMF recording, spectral analysis, pulsar dedispersion, correlation, and more—on the same data stream in real time.

Using this setup, we have successfully received signals from Voyager 1, conducted lunar radar experiments in a bi-static configuration with Astropeiler Stockert, and even achieved a Venus radar bounce.

These tools are highly generic and have found applications beyond radio astronomy. In this talk, we'll provide an overview of the design philosophy and practical usage of these tools, illustrated with examples from our work at the Dwingeloo Radio Telescope.

https://github.com/tftelkamp/vrt-iq-tools/

The MAX2771 chip provides broadband (<44 MHz) signal processing and digitization in the lower (1.1-1.3 GHz) and upper (1.5-1.65 GHz) L-band. Initially dedicated to GNSS signal reception, two such chips clocked by a common frequency reference can be used for passive radar or direction of arrival measurements. In this presentation, we tackle the challenges of PLL setpoint drift leading to phase variations despite the common clock, the impact of low ADC resolution on the recorded signal characteristics, and on correlation calculation. These results are not confined to this particular chip, but valid for any low SNR recordings, including for radioastronomical measurement systems. We demonstrate the use of this setup on passive radar measurements using various ground based and spaceborne sources of opportunity.