21 Aug 2026

feedTalkAndroid

TRIBIT’s 9th Anniversary Sale Brings Up to $50 Off and Free Gifts

Two weeks of tiered discounts, giveaways, and a free tote bag with every order

21 Aug 2026 1:03pm GMT

RayNeo’s iO Smart Glasses and GT Max Push AR Screens to 307 Inches

Both lines go on sale September 4, with real-time translation across 55 languages built into the iO.

21 Aug 2026 11:19am GMT

Three months after shocking fans with a cancellation, a surprise spin-off is officially happening – but the main character doesn’t even exist in the original books

Just when fans thought Netflix had closed the book on one of its most popular series, the streaming giant has tossed in a new twist: there's a spin-off in the works, but its main character wasn't part of the original books.

21 Aug 2026 6:00am GMT

19 Aug 2026

feedAndroid Developers Blog

Preparing your app for broader memory limits

Posted by Blair Harmon, Director of Product Management, Android Platform



A great user experience is central to Android's mission, and delivering on that promise requires keeping devices fast, responsive, and reliable. This is why memory optimization is more critical than ever. Across the ecosystem, new devices are maintaining or even decreasing their physical memory capacity in response to memory price increases, yet users continue to expect the same seamless, high-performance app experience.

In Android 17, we introduced per-app memory limits, starting with Pixel devices, to help protect the overall user experience from applications using excess memory and causing system-wide slowdowns. Over the coming year, an increasing number of manufacturers will leverage the Android per-app memory limits across their portfolio of device RAM configurations from 4GB to 16GB+ devices. If your app exceeds these limits, it will be slowed down and may be terminated. Optimizing your app's memory footprint is essential to preventing OS throttling and maintaining a seamless user experience.

In this post, we'll explore how these limits work under the hood, how to measure your memory footprint using new Android vitals metrics, and actionable steps to optimize your app or game.

Understanding Memory Limits

When your app exceeds its memory budget, Android takes progressive action to protect device responsiveness:

  1. zRAM Swapping: If your app reaches its allocated limit, the system forces your app's pages into zRAM (compressed RAM). While zRAM prevents immediate eviction, compressing and decompressing pages adds CPU overhead, which can result in noticeable UI jank and experience slowdowns.
  2. Process Termination: If your app continues to increase its memory usage beyond the zRAM threshold, it will be terminated by the system. To determine if your app session was impacted by these constraints in the field, you can call getDescription() within ApplicationExitInfo. If the system applied a limit, the exit reason is reported as REASON_OTHER and the description string will contain "MemoryLimiter:AnonSwap". You can also leverage trigger-based profiling using TRIGGER_TYPE_ANOMALY to automatically capture heap dumps when the memory limit is reached.

To learn more about per-app memory limits and system enforcement, review the Android 17 App Memory Limits documentation. To test your application on different device configurations use the Memory Limiter adb commands.

Monitoring and Diagnosing Memory Issues

You can't optimize what you can't measure. Identifying memory leaks, excessive heap allocations, and Out-Of-Memory (OOM) crashes across the Android ecosystem requires leveraging complementary monitoring tools:

  • Macro-level health with Android vitals: For broad, population-level visibility without additional overhead, Google Play Console's Android vitals provides essential metrics like Memory Usage (Anonymous RSS + swap) and Bitmap Memory Usage. This gives you a clear snapshot of memory distribution across different process states (foreground, background, user-perceived services, and cached) and RAM class ranges, helping you spot memory outliers.
  • Memory Limiter exits & OOM tracking with Firebase Crashlytics: To stay informed about severe memory degradation before it impacts your key metrics, Crashlytics version 20.1.0 introduces additional debug data to help you catch, prioritize, and fix Out-Of-Memory exceptions and memory limiter kills. Tracking these events alongside custom logs and key-value metadata gives you immediate context into process status when a memory failure occurs.
  • In-field traces with ProfilingManager: For teams able to maintain a performance observability framework, the ProfilingManager API introduced in Android 15 (API level 35) allows your app to programmatically request and collect detailed memory debug artifacts such as Java heap dumps and heap profiles directly from production devices. You can also trigger heap dump captures based on specific system signals, such as TRIGGER_TYPE_OOM and TRIGGER_TYPE_ANOMALY.

Read our documentation to learn more about other memory monitoring techniques.

Summary & What's Next

With Android broadening per-app memory limits across all RAM classes, now is the time to audit your memory footprint:

  1. Prioritize memory optimizations: Prevent your app from being impacted by app memory limits by using best practices.
  2. Monitor memory use: Monitor your app's memory behavior to detect and resolve anomalous behavior.
  3. Optimize your game: Follow the latest guidance for games and complex multimedia apps to maximize memory savings across process states.

Helpful Resources & References

19 Aug 2026 7:00pm GMT

18 Aug 2026

feedAndroid Developers Blog

Tinder cuts app cold starts by 47% with new R8 Configuration Analyzer

Posted by Ajesh R Pai, Developer Relations Engineer, Ulises Uriel Verduzco Diaz, Software Engineer, Tinder, and Tracy Agyemang, Product Marketing Manager


Tinder is on a mission to power and inspire real connections by making meeting easy and fun for every new generation of singles. However, as their Android application codebase grew in size, so did its complexity. Prior to their latest optimization efforts, approximately 70% of the application was not optimized, carrying 17 dex files,including three dedicated just to startup. Although they had enabled R8, much of its optimization potential was blocked due to keep rules, and the team was unable to identify which specific rules were preventing optimization. To reduce startup time and decrease user-perceived Application Not Responding (ANR) errors, Tinder turned to the new R8 Configuration Analyzer to tackle these challenges.

By utilizing the R8 Configuration Analyzer, Tinder successfully identified and removed unintentional optimization blockers. The results were immediate and impactful: Tinder achieved a 47% reduction in app cold starts, shrank their app download size by 28.98% (down to 61.5 MB), and reduced user-perceived ANRs by 28%.

Configuration analyzer

The R8 Configuration Analyzer shows R8 optimization by tracking shrinking, optimization, and obfuscation scores to show available refinement areas. It shows the broad, redundant, or obsolete keep rules, including those from external libraries so that you can analyse the keep rule impact and refine the keep rules.

Key metrics shown in Configuration Analyzer include:

  • Shrinking Score: Code percentage available for R8 shrinking.
  • Optimization Score: Code percentage open to optimization (for example, method inlining, horizontal class merging).
  • Obfuscation Score: Percentage of classes, methods and fields that can be renamed by R8 to decrease size.

Use the analyzer to audit keep rules and their impacts:

  • Find broad rules: Narrow the scope of package-wide rules that restrict R8 optimization, and identify the specific classes, methods, and fields excluded from shrinking, optimization, and obfuscation.
  • Refine rules: Target only specific classes/methods requiring reflection to unlock optimization
  • Remove redundant rules: Remove rules that match zero classes, methods, or fields in your current build.
  • Identical rules: Identical keep rules means rules that target the same classes, fields, and methods or duplicate declarations of keep rule in same or across keep rule files.
  • Find subsumed rules: Clean up specific rules already covered by broader configurations.
  • Identify problematic libraries: Check the combined optimization impact of merged consumer keep rules from all libraries.



R8 Configuration Analyzer report of a sample application

To assist you in using the R8 Configuration Analyzer with agentic tools, we have published an R8 Analyzer skill. This skill optimizes automated development workflows by summarizing the R8 Configuration Analyzer report to display key metrics: optimization, obfuscation, and shrinking scores. It also highlights the five most impactful keep rules, giving you clear insight into what blocks code optimization.

Pinpointing hidden optimization blockers



Prior to integrating the R8 Configuration Analyzer, Tinder's Android app suffered from significant technical debt due to a heavily unoptimized codebase. This lack of optimization directly degraded the user experience, leading to users experiencing slow cold starts

To resolve these issues, the Tinder team utilized the R8 Configuration Analyzer to comprehensively audit their R8 configuration. The analyzer showed the R8 optimization of the codebase was around 28% even with R8 full mode. With R8 Configuration Analyzer, Tinder identified that an in-house library was introducing a broad, unscoped keep rule.

# Prevents optimization in all public classes along with all of their public and protected members

-keep public class * {
    public protected *;
}

This "wide" rule unintentionally covered various dependencies across the entire app, preventing optimization in a large number of classes. Because the over-inclusive rule prevented runtime crashes, developers frequently missed adding new rules for new features that used reflection, allowing hidden issues to compound over time.

By leveraging the insights provided by the R8 Configuration Analyzer, the team successfully traced and analyzed the specific classes affected by the broad keep rule from the library. The team immediately discovered that optimization was being blocked in larger, non-dynamically invoked classes where R8 could do optimization. Refining this specific keep rule allowed Tinder to unlock substantial optimization capabilities, untangle their legacy configurations, and drastically improve their overall optimization numbers, with R8 scores increasing from 28% to 50%, driving immediate performance gains across the application, and the Tinder team is actively working to further improve this figure.

  • Faster Loading: The team achieved a 47% reduction on users experiencing slow cold starts of the app.
  • Smaller Footprint: The App download size went from 86.6MB down to 61.5 MB (28.98% decrease).
  • Improved Stability: User-perceived Application Not Responding (ANR) errors decreased from 0.35% to 0.28%, bringing them significantly closer to the peer median numbers
  • Reduced Complexity: The total number of DEX files was cut down from 17 to 11, including just two startup files.

Beyond these technical performance enhancements, the increased application optimization directly translated into tangible business growth and higher user engagement, particularly in resource-constrained markets.

  • Regional Engagement: Countries where Low RAM devices take a huge portion of the market, presented the largest increase in engagement, and decreasing the ANR rates was key to improving engagement in this vast market.
  • Engagement Growth: Engagement has increased 3% since the increase in app optimization.


Safeguarding future performance with continuous integration

Addressing code minification isn't just a one-time fix; it requires continuous vigilance. Inspired by the massive gains achieved through the R8 Configuration Analyzer, Tinder's Android team proactively integrated optimization monitoring into their daily workflow to prevent regressions.

Tinder's team added a new job in their CI/CD pipeline to report changes in the optimization stats so everyone can see how their contribution is affecting optimization. When advising other developers considering R8 configuration integration, the team emphasizes the importance of auditing internal dependencies. While most popular third-party libraries come with well-defined rules, internal company projects that are considered "stable" might actually be introducing wide rules that negatively impact overall optimization.

Key Takeaways

Faced with a heavily unoptimized codebase and a high volume of DEX files, Tinder needed a way to cleanly audit their app's minification rules. The R8 Configuration Analyzer provided the ideal tooling necessary to identify overly broad internal library rules, the classes affected by the keep rule, allowing the team to confidently optimize their codebase. As a result, Tinder successfully cut cold starts by nearly half, shrank their APK size by over 28%, and established a healthier, more performant foundation for their users, with the team actively working to further improve these numbers.

How to Use R8 Configuration Analyzer

The R8 Configuration Analyzer and its standalone features can be utilized based on your current Android Gradle Plugin (AGP) version:

  • AGP 9.3 Release: The R8 Configuration Analyzer is fully integrated and released with AGP 9.3. When running an R8 release build, the report will be generated in the build/outputs/mapping/release/configanalyzer.html folder.
  • Standalone Gradle Task: AGP 9.3 introduces a standalone Gradle task that allows you to generate the analyzer report without running a full release build, providing a much faster feedback loop when refining keep rules locally:
    ./gradlew :app:analyzeReleaseR8Config
    The report is generated at build/reports/r8/r8-config-analyzer-release.html.
  • Usage on Older AGP Versions: If you are using a version below AGP 9.3, you do not need to migrate your entire AGP version to analyze your configuration. You can update the R8 version independently to 9.3.7-dev or higher by following the Replacing R8 in AGP instructions. To generate the report locally, run your build with the property specified:
    ./gradlew assembleRelease  -Dcom.android.tools.r8.dumpkeepradiushtmltodirectory=<output_directory>

To learn more, see the R8 Configuration Analyzer documentation.

18 Aug 2026 6:00pm GMT

Jetpack XR SDK core libraries reach beta: The next milestone for Android XR

Posted by Amy Zeppenfeld, Developer Relations Engineer, Greg Underwood, Software Engineering Manager, Yasmine Evjen, Senior Product Manager, Android XR




Since introducing the Android XR SDK, developers have transformed their ideas into innovative, immersive experiences for XR headsets and wired XR glasses. As the ecosystem expands, you can more easily take those experiences from preview to production and reach users wherever they are.

Today, we're excited to announce that Jetpack SceneCore, ARCore for Jetpack XR, and XR Runtime have reached beta with Jetpack Compose for XR to follow soon! This means the APIs are stabilizing, making it a great time to start integrating them into your production workflows and creating for Android XR.

Why the Jetpack XR SDK?

The Jetpack XR SDK includes all the tools and libraries you need to build immersive and augmented experiences for Android XR. Whether you're porting an existing 2D app or creating a new 3D XR app from scratch, you can do so using the familiar Android development tools you already know and love.

To support your development, this release focuses on providing the fundamental building blocks across the SDK:

What's new in Beta?

Direct feedback from the developer previews helped shape these beta releases, introducing several important API refinements to ensure these libraries are ready for production.

See the full release notes for each library to check out specific details on naming and API changes.

Get started and provide feedback

To add these dependencies, include the Google Maven repository in your project and add the newest XR libraries to your build.gradle files.

dependencies {
    implementation("androidx.xr.scenecore:scenecore:1.0.0-beta02")
    implementation("androidx.xr.arcore:arcore:1.0.0-beta02")
    implementation("androidx.xr.runtime:runtime:1.0.0-beta02")
    implementation("androidx.xr.compose:compose:1.0.0-alpha17")
}

The ecosystem of Android XR devices that power immersive experiences is expanding, ranging from XR headsets to wired XR glasses. There's never been a better time to start building immersive experiences with the Jetpack XR SDK Beta. Dive in and start building and testing on Samsung Galaxy XR or Android XR Emulator today.

18 Aug 2026 5:00pm GMT

04 Jul 2026

feedPlanet Maemo

Reticulum is interesting

It all started innocently enough: sometime last summer, I ran into the blog post Start your own Internet Resiliency Club on Hacker News.

…communicate with each other across a few kilometers without any centralized infrastructure using cheap, low-power, unlicensed LoRa radios and open source Meshtastic text messaging software.

The idea of a local, infrastructure-free communications mesh sounded useful, especially as we were about to sail into the Pacific.

Meshtastic

While conflicts and natural disasters are hopefully far away, on the smaller atolls there is no cellular network. With Meshtastic we could communicate over LoRa.

Using Meshtastic on a boat

Over the hurricane season, the Meshtastic setup became quite extensive. Our boat has a Meshtastic node, plus a mast-mounted solar repeater. We both have Meshtastic cards that we carry with us. With these we can communicate with text messages over quite a long distance. And we get telemetry and alerts from the boat.

In Cartagena, Colombia we could hear the boat pretty much across the city. And since some of our buddy boats also run Meshtastic, we've even had conversations while offshore.

While the existing Meshtastic setup is serving us well, there is always room for improvement and new ideas.

Reticulum

Reticulum is a project that seeks to take this to a whole new level. It is a whole decentralized networking stack that allows anything from instant messaging and voice calls to full-on SSH sessions to be carried over a multitude of different interfaces. You can transport Reticulum over LoRa, Bluetooth, and also over regular TCP/IP networks. And if authorities didn't take a dim view on encryption in ham radio, it would also work over our HF radio. With store-and-forward mechanisms it can deal with intermittent connectivity.

Because your identity is portable, your connectivity can be fluid. You can be sitting at a desk connected to a fiber backbone one moment, and walking through a field connected only to a long-range LoRa mesh the next. To the rest of the network, nothing has changed. Your friends do not need to update your contact info. The messages they send do not bounce back. The network senses the shift in the medium and reroutes the flow of data automatically.
You are no longer a stationary node in a fixed grid. You are a wanderer in a fluid medium.
- The Zen of Reticulum

As it stands now, Reticulum is still quite an early system with rudimentary and tech-heavy user interfaces. But that seems to be about to change: the Columba app for Android seems about as user-friendly as Meshtastic or something like Signal. There's a lot of potential in that once it reaches a stable version.

Distributed development over Reticulum

In the meanwhile, there is one aspect of Reticulum we developers can benefit from immediately: Distributed development. With it, any rngit node running on Reticulum can be your "GitHub". Git history, issue tracking, release distribution is already there.

I recently switched my various programming projects over. We have rngit running on the boat NAS, and VPS running a mirror behind more consistent connectivity. And for now I also mirror the work periodically to GitHub for backwards compatibility.

Reticulum for software

What I think is worthwhile to explore is having machines interface with Reticulum. Just like we can tell our boat to switch lights on via a Meshtastic message, we should be able to do the same with Reticulum. And maybe there should be a NomadNet "site" for the boat showing status of the various systems.

Going further, maybe boats could share chart data, depth soundings, weather information with each other over this. The promise of VDES, but built from the grassroots perspective.

And maybe things like NoFlo should be able to communicate over Reticulum? Reticulum implementations exist for multiple programming languages, but for this we'd need a JavaScript port.

There's still a lot to study and to think about. Watch this space. Last time I noted that something is interesting, it took me to a ten year rabbit hole.

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04 Jul 2026 12:00am GMT

26 Jan 2026

feedPlanet Maemo

Igalia Multimedia contributions in 2025

Now that 2025 is over, it's time to look back and feel proud of the path we've walked. Last year has been really exciting in terms of contributions to GStreamer and WebKit for the Igalia Multimedia team.

With more than 459 contributions along the year, we've been one of the top contributors to the GStreamer project, in areas like Vulkan Video, GstValidate, VA, GStreamer Editing Services, WebRTC or H.266 support.

Pie chart of Igalia's contributions to different areas of the GStreamer project: other (30%) vulkan (24%) validate (7%) va (6%) ges (4%) webrtc (3%) h266parse (3%) python (3%) dots-viewer (3%) tests (2%) docs (2%) devtools (2%) webrtcbin (1%) tracers (1%) qtdemux (1%) gst (1%) ci (1%) y4menc (1%) videorate (1%) gl (1%) alsa (1%)
Igalia's contributions to the GStreamer project

In Vulkan Video we've worked on the VP9 video decoder, and cooperated with other contributors to push the AV1 decoder as well. There's now an H.264 base class for video encoding that is designed to support general hardware-accelerated processing.

GStreaming Editing Services, the framework to build video editing applications, has gained time remapping support, which now allows to include fast/slow motion effects in the videos. Video transformations (scaling, cropping, rounded corners, etc) are now hardware-accelerated thanks to the addition of new Skia-based GStreamer elements and integration with OpenGL. Buffer pool tuning and pipeline improvements have helped to optimize memory usage and performance, enabling the edition of 4K video at 60 frames per second. Much of this work to improve and ensure quality in GStreamer Editing Services has also brought improvements in the GstValidate testing framework, which will be useful for other parts of GStreamer.

Regarding H.266 (VVC), full playback support (with decoders such as vvdec and avdec_h266, demuxers and muxers for Matroska, MP4 and TS, and parsers for the vvc1 and vvi1 formats) is now available in GStreamer 1.26 thanks to Igalia's work. This allows user applications such as the WebKitGTK web browser to leverage the hardware accelerated decoding provided by VAAPI to play H.266 video using GStreamer.

Igalia has also been one of the top contributors to GStreamer Rust, with 43 contributions. Most of the commits there have been related to Vulkan Video.

Pie chart of Igalia's contributions to different areas of the GStreamer Rust project: vulkan (28%) other (26%) gstreamer (12%) ci (12%) tracer (7%) validate (5%) ges (7%) examples (5%)
Igalia's contributions to the GStreamer Rust project

In addition to GStreamer, the team also has a strong presence in WebKit, where we leverage our GStreamer knowledge to implement many features of the web engine related to multimedia. From the 1739 contributions to the WebKit project done last year by Igalia, the Multimedia team has made 323 of them. Nearly one third of those have been related to generic multimedia playback, and the rest have been on areas such as WebRTC, MediaStream, MSE, WebAudio, a new Quirks system to provide adaptations for specific hardware multimedia platforms at runtime, WebCodecs or MediaRecorder.

Pie chart of Igalia's contributions to different areas of the WebKit project: Generic Gstreamer work (33%) WebRTC (20%) Regression bugfixing (9%) Other (7%) MSE (6%) BuildStream SDK (4%) MediaStream (3%) WPE platform (3%) WebAudio (3%) WebKitGTK platform (2%) Quirks (2%) MediaRecorder (2%) EME (2%) Glib (1%) WTF (1%) WebCodecs (1%) GPUProcess (1%) Streams (1%)
Igalia Multimedia Team's contributions to different areas of the WebKit project

We're happy about what we've achieved along the year and look forward to maintaining this success and bringing even more exciting features and contributions in 2026.

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26 Jan 2026 9:34am GMT

05 Dec 2025

feedPlanet Maemo

Meow: Process log text files as if you could make cat speak

Some years ago I had mentioned some command line tools I used to analyze and find useful information on GStreamer logs. I've been using them consistently along all these years, but some weeks ago I thought about unifying them in a single tool that could provide more flexibility in the mid term, and also as an excuse to unrust my Rust knowledge a bit. That's how I wrote Meow, a tool to make cat speak (that is, to provide meaningful information).

The idea is that you can cat a file through meow and apply the filters, like this:

cat /tmp/log.txt | meow appsinknewsample n:V0 n:video ht: \
ft:-0:00:21.466607596 's:#([A-za-z][A-Za-z]*/)*#'

which means "select those lines that contain appsinknewsample (with case insensitive matching), but don't contain V0 nor video (that is, by exclusion, only that contain audio, probably because we've analyzed both and realized that we should focus on audio for our specific problem), highlight the different thread ids, only show those lines with timestamp lower than 21.46 sec, and change strings like Source/WebCore/platform/graphics/gstreamer/mse/AppendPipeline.cpp to become just AppendPipeline.cpp", to get an output as shown in this terminal screenshot:

Screenshot of a terminal output showing multiple log lines. Some of them have the word "appsinkNewSample" highlighted in red. Some lines have the hexadecimal id of the thread that printed them highlighed (purple for one thread, brown for the other)

Cool, isn't it? After all, I'm convinced that the answer to any GStreamer bug is always hidden in the logs (or will be, as soon as I add "just a couple of log lines more, bro" <span class=0 Add to favourites0 Bury

05 Dec 2025 11:16am GMT

18 Sep 2022

feedPlanet Openmoko

Harald "LaF0rge" Welte: Deployment of future community TDMoIP hub

I've mentioned some of my various retronetworking projects in some past blog posts. One of those projects is Osmocom Community TDM over IP (OCTOI). During the past 5 or so months, we have been using a number of GPS-synchronized open source icE1usb interconnected by a new, efficient but strill transparent TDMoIP protocol in order to run a distributed TDM/PDH network. This network is currently only used to provide ISDN services to retronetworking enthusiasts, but other uses like frame relay have also been validated.

So far, the central hub of this OCTOI network has been operating in the basement of my home, behind a consumer-grade DOCSIS cable modem connection. Given that TDMoIP is relatively sensitive to packet loss, this has been sub-optimal.

Luckily some of my old friends at noris.net have agreed to host a new OCTOI hub free of charge in one of their ultra-reliable co-location data centres. I'm already hosting some other machines there for 20+ years, and noris.net is a good fit given that they were - in their early days as an ISP - the driving force in the early 90s behind one of the Linux kernel ISDN stracks called u-isdn. So after many decades, ISDN returns to them in a very different way.

Side note: In case you're curious, a reconstructed partial release history of the u-isdn code can be found on gitea.osmocom.org

But I digress. So today, there was the installation of this new OCTOI hub setup. It has been prepared for several weeks in advance, and the hub contains two circuit boards designed entirely only for this use case. The most difficult challenge was the fact that this data centre has no existing GPS RF distribution, and the roof is ~ 100m of CAT5 cable (no fiber!) away from the roof. So we faced the challenge of passing the 1PPS (1 pulse per second) signal reliably through several steps of lightning/over-voltage protection into the icE1usb whose internal GPS-DO serves as a grandmaster clock for the TDM network.

The equipment deployed in this installation currently contains:

For more details, see this wiki page and this ticket

Now that the physical deployment has been made, the next steps will be to migrate all the TDMoIP links from the existing user base over to the new hub. We hope the reliability and performance will be much better than behind DOCSIS.

In any case, this new setup for sure has a lot of capacity to connect many more more users to this network. At this point we can still only offer E1 PRI interfaces. I expect that at some point during the coming winter the project for remote TDMoIP BRI (S/T, S0-Bus) connectivity will become available.

Acknowledgements

I'd like to thank anyone helping this effort, specifically * Sylvain "tnt" Munaut for his work on the RS422 interface board (+ gateware/firmware) * noris.net for sponsoring the co-location * sysmocom for sponsoring the EPYC server hardware

18 Sep 2022 10:00pm GMT

08 Sep 2022

feedPlanet Openmoko

Harald "LaF0rge" Welte: Progress on the ITU-T V5 access network front

Almost one year after my post regarding first steps towards a V5 implementation, some friends and I were finally able to visit Wobcom, a small German city carrier and pick up a lot of decommissioned POTS/ISDN/PDH/SDH equipment, primarily V5 access networks.

This means that a number of retronetworking enthusiasts now have a chance to play with Siemens Fastlink, Nokia EKSOS and DeTeWe ALIAN access networks/multiplexers.

My primary interest is in Nokia EKSOS, which looks like an rather easy, low-complexity target. As one of the first steps, I took PCB photographs of the various modules/cards in the shelf, take note of the main chip designations and started to search for the related data sheets.

The results can be found in the Osmocom retronetworking wiki, with https://osmocom.org/projects/retronetworking/wiki/Nokia_EKSOS being the main entry page, and sub-pages about

In short: Unsurprisingly, a lot of Infineon analog and digital ICs for the POTS and ISDN ports, as well as a number of Motorola M68k based QUICC32 microprocessors and several unknown ASICs.

So with V5 hardware at my disposal, I've slowly re-started my efforts to implement the LE (local exchange) side of the V5 protocol stack, with the goal of eventually being able to interface those V5 AN with the Osmocom Community TDM over IP network. Once that is in place, we should also be able to offer real ISDN Uk0 (BRI) and POTS lines at retrocomputing events or hacker camps in the coming years.

08 Sep 2022 10:00pm GMT

Harald "LaF0rge" Welte: Clock sync trouble with Digium cards and timing cables

If you have ever worked with Digium (now part of Sangoma) digital telephony interface cards such as the TE110/410/420/820 (single to octal E1/T1/J1 PRI cards), you will probably have seen that they always have a timing connector, where the timing information can be passed from one card to another.

In PDH/ISDN (or even SDH) networks, it is very important to have a synchronized clock across the network. If the clocks are drifting, there will be underruns or overruns, with associated phase jumps that are particularly dangerous when analog modem calls are transported.

In traditional ISDN use cases, the clock is always provided by the network operator, and any customer/user side equipment is expected to synchronize to that clock.

So this Digium timing cable is needed in applications where you have more PRI lines than possible with one card, but only a subset of your lines (spans) are connected to the public operator. The timing cable should make sure that the clock received on one port from the public operator should be used as transmit bit-clock on all of the other ports, no matter on which card.

Unfortunately this decades-old Digium timing cable approach seems to suffer from some problems.

bursty bit clock changes until link is up

The first problem is that downstream port transmit bit clock was jumping around in bursts every two or so seconds. You can see an oscillogram of the E1 master signal (yellow) received by one TE820 card and the transmit of the slave ports on the other card at https://people.osmocom.org/laforge/photos/te820_timingcable_problem.mp4

As you can see, for some seconds the two clocks seem to be in perfect lock/sync, but in between there are periods of immense clock drift.

What I'd have expected is the behavior that can be seen at https://people.osmocom.org/laforge/photos/te820_notimingcable_loopback.mp4 - which shows a similar setup but without the use of a timing cable: Both the master clock input and the clock output were connected on the same TE820 card.

As I found out much later, this problem only occurs until any of the downstream/slave ports is fully OK/GREEN.

This is surprising, as any other E1 equipment I've seen always transmits at a constant bit clock irrespective whether there's any signal in the opposite direction, and irrespective of whether any other ports are up/aligned or not.

But ok, once you adjust your expectations to this Digium peculiarity, you can actually proceed.

clock drift between master and slave cards

Once any of the spans of a slave card on the timing bus are fully aligned, the transmit bit clocks of all of its ports appear to be in sync/lock - yay - but unfortunately only at the very first glance.

When looking at it for more than a few seconds, one can see a slow, continuous drift of the slave bit clocks compared to the master :(

Some initial measurements show that the clock of the slave card of the timing cable is drifting at about 12.5 ppb (parts per billion) when compared against the master clock reference.

This is rather disappointing, given that the whole point of a timing cable is to ensure you have one reference clock with all signals locked to it.

The work-around

If you are willing to sacrifice one port (span) of each card, you can work around that slow-clock-drift issue by connecting an external loopback cable. So the master card is configured to use the clock provided by the upstream provider. Its other ports (spans) will transmit at the exact recovered clock rate with no drift. You can use any of those ports to provide the clock reference to a port on the slave card using an external loopback cable.

In this setup, your slave card[s] will have perfect bit clock sync/lock.

Its just rather sad that you need to sacrifice ports just for achieving proper clock sync - something that the timing connectors and cables claim to do, but in reality don't achieve, at least not in my setup with the most modern and high-end octal-port PCIe cards (TE820).

08 Sep 2022 10:00pm GMT