25 Oct 2025
TalkAndroid
Boba Story Lid Recipes – 2025
Look no further for all the latest Boba Story Lid Recipes. They are all right here!
25 Oct 2025 6:36pm GMT
Dice Dreams Free Rolls – Updated Daily
Get the latest Dice Dreams free rolls links, updated daily! Complete with a guide on how to redeem the links.
25 Oct 2025 6:35pm GMT
This PS game looks like Drive with Ryan Gosling and it’s getting rave reviews
If you've ever wished you could step into Ryan Gosling's scorpion jacket from Drive, the PlayStation Plus library…
25 Oct 2025 3:30pm GMT
24 Oct 2025
Android Developers Blog
5 things you need to know about publishing and distributing your app for Android XR

Posted by Jan Kleinert, Android Developer Relations Engineer
Samsung Galaxy XR is here, powered by Android XR! This blog post is part of our Android XR Spotlight Week, where we provide resources-blog posts, videos, sample code, and more-all designed to help you learn, build, and prepare your apps for Android XR.

Today, we're focusing on one of the last steps in your development journey, ensuring these experiences successfully reach your users. Publishing correctly ensures your app is packaged efficiently, discovered by the right devices, and presented in the best possible light.
Here are 5 things you need to know about publishing and distributing your app for Android XR on Google Play.
1. Uphold quality with the Android XR app quality guidelines
One of the most important steps before publishing is ensuring your app delivers a safe, comfortable, and performant user experience.
Following the Android XR App Quality Guidelines helps ensure that your app provides users with a great experience on devices like the Galaxy XR.
Why quality matters
These guidelines build upon the large screen app quality guidelines, and focus on critical XR-specific criteria including:
-
Safety and comfort: This is paramount. These guidelines help you avoid causing motion sickness by setting standards for camera movement and frame rates, and by limiting visual elements like strobing.
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Performance: Your app must hit performance metrics, such as target frame rates, to prevent lag and ensure a fluid, comfortable experience.
-
Interaction: The guidelines specify recommended minimum sizes for interactive targets (e.g., 48dp minimum, 56dp recommended) to work well with eye-tracking and hand-tracking inputs.
2. Configure your app manifest correctly
The AndroidManifest.xml file describes important information about your app. The Android build tools, Android system, and Google Play use this information to know what kind of experience you've built and which hardware features it requires. Proper configuration is vital for correct device targeting and app launch.
Specify which Android XR SDK your app uses
In your app manifest, include android.software.xr.api.spatial or android.software.xr.api.openxr to indicate whether you're building with the Jetpack XR SDK or building with OpenXR or Unity.
|
SDK used |
Manifest declaration |
|
Jetpack XR SDK |
|
|
OpenXR or Unity |
If your app is built using OpenXR or Unity, you must set the android:required attribute to true. For apps built with the Jetpack XR SDK, set android:required attribute to true if your app is published to the Android XR dedicated release track and set android:required attribute to false if your app is published to the mobile release track.
Set the activity start mode
Use the android.window.PROPERTY_XR_ACTIVITY_START_MODE property on your main activity to define the default user environment:
|
Start mode |
Purpose |
SDK |
|
XR_ACTIVITY_START_MODE_HOME_SPACE |
Launches your app in Home Space, the shared multitasking environment. |
Jetpack XR SDK |
|
XR_ACTIVITY_START_MODE_FULL_SPACE_MANAGED |
Launches in Full Space, a full-immersion, single-app environment. |
Jetpack XR SDK |
|
XR_ACTIVITY_START_MODE_FULL_SPACE_UNMANAGED |
Launches in Full Space, a full-immersion, single-app environment. Note that apps built with OpenXR or Unity always run in Full Space. |
OpenXR or Unity |
Check for optional hardware features at runtime
Avoid setting optional XR features (like hand tracking or controllers) to android:required="true" unless they are truly required for your app. If a device doesn't support a required feature, Google Play will hide your app from that device. If you have features set as required but your app could operate without them, then you could unnecessarily limit your audience.
Instead, check for advanced features dynamically at runtime using the PackageManager class with hasSystemFeature():
Kotlin
val hasHandTracking = packageManager.hasSystemFeature("android.hardware.xr.input.hand_tracking")
if (hasHandTracking) {
// Enable high-fidelity hand tracking features
} else {
// Provide a fallback experience
}
This ensures your app is broadly compatible and leverages advanced features when they're available.
3. Use Play Asset Delivery (PAD) to deliver large assets
Immersive apps and games often contain large assets that might exceed the standard size limits. Use Play Asset Delivery (PAD) to manage large, high-fidelity assets. PAD offers flexible delivery modes: install-time, fast follow, and on demand for progressive download of content. Apps that are built for Android XR are allowed to deliver additional asset packs: instead of a cumulative total of 4 GB for asset packs delivered on demand or fast follow, these apps are afforded a higher cumulative total of 30 GB.
For developers building with Unity, use Unity Addressables along with Play Asset Delivery to manage asset packs.
4. Showcase your app with spatial video previews
To capture the attention of users browsing the Play Store on their XR headsets, you can provide an immersive preview of your app using a spatial video asset. This must be a 180°, 360°, or stereoscopic video. On Android XR devices, the Play Store will automatically display this as an immersive 3D preview, allowing users to experience the depth and scale of your content before they install the app.
5. Choose your Google Play release track
Google Play provides two pathways for publishing your Android XR app, both using the same Play Console account:
Option A: Continue on the mobile release track (for spatialized mobile apps)
If you are adding spatial XR features to an existing mobile app, you can often bundle the XR features or content into your existing Android App Bundle (AAB).
This approach is ideal if your app maintains most of its core functionality across both mobile and XR devices, and you can continue publishing the same AAB to the mobile track. Review this guidance to be sure you are properly configuring your app's manifest file to support this use case.
Option B: Publish to the dedicated Android XR release track
If you are building a brand-new app for XR or if the XR version is functionally too different for a single AAB, you should publish to the Android XR dedicated release track.
Apps published to the Android XR dedicated release track are only visible to Android XR devices that support the android.software.xr.api.spatial feature or the android.software.xr.api.openxr feature, giving you control over distribution.
By following this guidance, you can help ensure your innovative Android XR apps provide a quality user experience, are packaged efficiently, are delivered smoothly using PAD, and are targeted to the devices that can run them. Happy publishing!
24 Oct 2025 4:00pm GMT
23 Oct 2025
Android Developers Blog
Set a reminder: Tune in on October 30 for our Fall episode of The Android Show, live from Droidcon London
Posted by The Android Team
In just a few days, on Thursday, October 30th at 10AM PT, we'll be dropping our Fall episode of The Android Show, on YouTube and on developer.android.com! This time, we'll be live from Droidcon London, where we'll be unpacking some of the latest agentic experiences for Gemini in Android Studio designed to help you be more productive, plus doing live demos of Jetpack Compose and more. And with the recent launch of Galaxy XR, we'll be diving into the world of Android XR plus how building adaptive lets you easily extend to XR devices as well as foldables, tablets and large screens.
Get your #AskAndroid questions answered live!
We've assembled a team of experts from across Android to answer your #AskAndroid questions live from London on building excellent apps, across devices; you can start sharing your questions now using #AskAndroid, and tune in to see if they are answered live on the show!
The Android Show is your conversation with the Android developer community, and this episode will be co-hosted by Rebecca Gutteridge and Adetunji Dahunsi. You'll hear the latest from the developers and engineers who build Android. Don't forget to tune in live on October 30 at 10AM PT, live on YouTube and on developer.android.com/events/show!
23 Oct 2025 6:50pm GMT
Getting started with Unity and Android XR

Samsung Galaxy XR is here, powered by Android XR! This blog post is part of our Android XR Spotlight Week, where we provide resources-blog posts, videos, sample code, and more-all designed to help you learn, build, and prepare your apps for Android XR.
There's never been a better time to get into XR development. Last December, we announced Android XR, Google's new Android platform built on open standards such as OpenXR and Vulkan, which makes XR development more accessible than it's ever been.
And when combined with Unity's existing XR tools, you get a powerful and mature development stack. This makes it possible to create and deploy XR apps that work across multiple devices.
No matter whether you've done XR development before or not, we want to help you get started.
This blog will get you up and running with Android XR and Unity development. We'll focus on the practical steps to configure your environment, understand the package ecosystem, and start building.
By the end of this blog, you'll have a good understanding of:
-
The package ecosystem
-
Essential setup steps
-
Input methods
-
Privacy and permissions
-
Composition layers
Unity for Android XR development
You might choose Unity for its cross-platform compatibility, allowing you to build once and deploy to Android XR and other XR devices.
When using Unity, you benefit from its mature XR ecosystem and tooling. It already has established packages such as XR Interaction Toolkit, OpenXR plugin, XR composition layers, XR Hands, an extensive asset store full of XR-ready components and templates, and XR simulation and testing tools. And since Unity 6 was released last November, you'll also benefit from its improved Universal Render Pipeline (URP) performance, better Vulkan graphics support, and enhanced build profiles.
Here are some sample projects to get an idea of what can be done:
Essential setup: your development foundation
Unity 6 requirements and installation
You'll need Unity 6 to create your app, as earlier versions don't support Android XR. Install Unity Hub first, then Unity 6 with the Android Build Support module, following these steps.Android XR build profiles: simplifying configuration
You can create your own build profiles, but for now we recommend using the dedicated Android XR build profile we created.
After these steps you can build and run your APK for Android XR devices.
Graphics API: why Vulkan matters
Once you have your Unity project set up with an Android XR build profile, we first recommend making sure you have Vulkan set as your graphics API. Android XR is built as a Vulkan-first platform. In March 2025, Google announced that Vulkan is now the official graphics API for Android. It's a modern, low-level graphics API that helps developers maximize the performance of modern GPUs and unlocks advanced features like ray-tracing and multithreading for realistic and immersive gaming visuals.
These standards provide the best compatibility for your existing applications and ease the issues and costs of porting. And it makes it possible to enable advanced Android XR features such as URP Application Space Warp and foveated rendering.
Unity 6 handles Vulkan automatically, so when you use the Android XR build profile, Unity will configure Vulkan as your graphics API. This ensures you get access to all the advanced Android XR features without any manual configuration.
You can verify your graphics API settings by going to 'Edit' >' Project Settings' > 'Player' > 'Android tab' > 'Other settings' > 'Graphics APIs'.
Understanding the package ecosystem
There are two different packages you can use for Android XR in Unity. One is by using the Android XR Extensions for Unity, and the other is using the Unity OpenXR: Android XR package.
These may sound like the same thing, but bear with me.
The Unity OpenXR: Android XR package is the official Unity package for Android XR support. It provides the majority of Android XR features, made available through OpenXR standards. It also enables AR Foundation integration for mixed reality features. The primary benefit of using the Unity OpenXR: Android XR package is that it offers a unified API for supporting XR devices.Whereas the Android XR Extensions for Unity is Google's XR package, designed specifically for developing for Android XR devices. It supplements the Unity OpenXR package with additional features such as environment blend modes, scene meshing, image tracking, and body tracking. The tradeoff is that you can only develop for Android XR devices.
Which one you choose will depend on your specific needs, but we generally recommend going with the Unity OpenXR: Android XR, as it gives you far more flexibility for the devices your app will be compatible with, and then based on your application requirements you can then add Android XR Extensions for Unity.
How to install packages
From here you can install these packages from the 'Unity Registry' tab:
Required OpenXR features
Now you have the packages you need installed, let's enable some core features in order to get our project working.Input
Android XR supports input for Hands, Voice, Eye tracking, Keyboard and Controllers. We recommend installing the XR Interaction Toolkit and XR Hands as these contain the best prefabs for getting started. By using these prefabs, you'll have everything you need to support Hands and Controllers in your app.Privacy and permissions: building user trust
Whatever you build, you'll need to capture runtime permissions from the users. That's because scene understanding, eye tracking, face tracking and hand tracking provide access to data that may be more sensitive to the user.For example, if you use the XR Hands package for custom hand gestures, you will need to request the hand tracking permission (see below) as this package needs to track a lot of information about the user's hands. This includes things like tracking hand joint poses and angular and linear velocities;
|
const string k_Permission = "android.permission.HAND_TRACKING"; #if UNITY_ANDROID void Start() { if (!Permission.HasUserAuthorizedPermission(k_Permission)) { var callbacks = new PermissionCallbacks(); callbacks.PermissionDenied += OnPermissionDenied; callbacks.PermissionGranted += OnPermissionGranted; Permission.RequestUserPermission(k_Permission, callbacks); } } void OnPermissionDenied(string permission) { // handle denied permission } void OnPermissionGranted(string permission) { // handle granted permission } #endif // UNITY_ANDROID |
Enhancing visual quality with composition layers
A Composition Layer is the recommended way to render UI elements. They make it possible to display elements at a much higher quality compared to Unity's standard rendering pipeline as everything is directly rendered to the platform's compositor.As well as text, it also renders video, images, and UI elements at a much higher quality. It does this by utilising native support for the runtime's compositor layers.
Build and Run
Now that you have your OpenXR packages installed and features enabled, a prefab setup for hand and head movement you can now build your scene and deploy directly to your headset for testing.What's next: expanding your skills
Now that you've got your Android XR development environment set up and understand the key concepts, here are the next steps to continue your XR development journey:-
Android XR developer documentation - comprehensive guides for all Android XR features
-
Unity XR development manual - Unity's official XR development resources
-
Android XR Unity samples - Google's official sample projects showcasing different Android XR features
-
Unity XR Interaction Toolkit examples - comprehensive examples of XR interactions and gameplay mechanics
-
Unity VR Template - a complete starting point for VR projects
-
VR Multiplayer Template - explore social XR experiences
23 Oct 2025 4:00pm GMT
15 Oct 2025
Planet Maemo
Dzzee 1.9.0 for N800/N810/N900/N9/Leste
15 Oct 2025 11:31am GMT
05 Jun 2025
Planet Maemo
Mobile blogging, the past and the future
This blog has been running more or less continuously since mid-nineties. The site has existed in multiple forms, and with different ways to publish. But what's common is that at almost all points there was a mechanism to publish while on the move.
Psion, documents over FTP
In the early 2000s we were into adventure motorcycling. To be able to share our adventures, we implemented a way to publish blogs while on the go. The device that enabled this was the Psion Series 5, a handheld computer that was very much a device ahead of its time.

The Psion had a reasonably sized keyboard and a good native word processing app. And battery life good for weeks of usage. Writing while underway was easy. The Psion could use a mobile phone as a modem over an infrared connection, and with that we could upload the documents to a server over FTP.
Server-side, a cron job would grab the new documents, converting them to HTML and adding them to our CMS.
In the early days of GPRS, getting this to work while roaming was quite tricky. But the system served us well for years.
If we wanted to include photos to the stories, we'd have to find an Internet cafe.
- To the Alps is a post from these times. Lots more in the motorcycling category
SMS and MMS
For an even more mobile setup, I implemented an SMS-based blogging system. We had an old phone connected to a computer back in the office, and I could write to my blog by simply sending a text. These would automatically end up as a new paragraph in the latest post. If I started the text with NEWPOST, an empty blog post would be created with the rest of that message's text as the title.
- In the Caucasus is a good example of a post from this era
As I got into neogeography, I could also send a NEWPOSITION message. This would update my position on the map, connecting weather metadata to the posts.
As camera phones became available, we wanted to do pictures too. For the Death Monkey rally where we rode minimotorcycles from Helsinki to Gibraltar, we implemented an MMS-based system. With that the entries could include both text and pictures. But for that you needed a gateway, which was really only realistic for an event with sponsors.
- Mystery of the Missing Monkey is typical. Some more in Internet Archive
Photos over email
A much easier setup than MMS was to slightly come back to the old Psion setup, but instead of word documents, sending email with picture attachments. This was something that the new breed of (pre-iPhone) smartphones were capable of. And by now the roaming question was mostly sorted.
And so my blog included a new "moblog" section. This is where I could share my daily activities as poor-quality pictures. Sort of how people would use Instagram a few years later.

- Internet Archive has some of my old moblogs but nowadays, I post similar stuff on Pixelfed
Pause
Then there was sort of a long pause in mobile blogging advancements. Modern smartphones, data roaming, and WiFi hotspots had become ubiquitous.
In the meanwhile the blog also got migrated to a Jekyll-based system hosted on AWS. That means the old Midgard-based integrations were off the table.
And I traveled off-the-grid rarely enough that it didn't make sense to develop a system.
But now that we're sailing offshore, that has changed. Time for new systems and new ideas. Or maybe just a rehash of the old ones?
Starlink, Internet from Outer Space
Most cruising boats - ours included - now run the Starlink satellite broadband system. This enables full Internet, even in the middle of an ocean, even video calls! With this, we can use normal blogging tools. The usual one for us is GitJournal, which makes it easy to write Jekyll-style Markdown posts and push them to GitHub.
However, Starlink is a complicated, energy-hungry, and fragile system on an offshore boat. The policies might change at any time preventing our way of using it, and also the dishy itself, or the way we power it may fail.
But despite what you'd think, even on a nerdy boat like ours, loss of Internet connectivity is not an emergency. And this is where the old-style mobile blogging mechanisms come handy.
- Any of the 2025 Atlantic crossing posts is a good example of this setup in action
Inreach, texting with the cloud
Our backup system to Starlink is the Garmin Inreach. This is a tiny battery-powered device that connects to the Iridium satellite constellation. It allows tracking as well as basic text messaging.
When we head offshore we always enable tracking on the Inreach. This allows both our blog and our friends ashore to follow our progress.
I also made a simple integration where text updates sent to Garmin MapShare get fetched and published on our blog. Right now this is just plain text-based entries, but one could easily implement a command system similar to what I had over SMS back in the day.
One benefit of the Inreach is that we can also take it with us when we go on land adventures. And it'd even enable rudimentary communications if we found ourselves in a liferaft.
- There are various InReach integration hacks that could be used for more sophisticated data transfer
Sailmail and email over HF radio
The other potential backup for Starlink failures would be to go seriously old-school. It is possible to get email access via a SSB radio and a Pactor (or Vara) modem.
Our boat is already equipped with an isolated aft stay that can be used as an antenna. And with the popularity of Starlink, many cruisers are offloading their old HF radios.
Licensing-wise this system could be used either as a marine HF radio (requiring a Long Range Certificate), or amateur radio. So that part is something I need to work on. Thankfully post-COVID, radio amateur license exams can be done online.
With this setup we could send and receive text-based email. The Airmail application used for this can even do some automatic templating for position reports. We'd then need a mailbox that can receive these mails, and some automation to fetch and publish.
- Sailmail and No Foreign Land support structured data via email to update position. Their formats could be useful inspiration
05 Jun 2025 12:00am GMT
16 Oct 2024
Planet Maemo
Adding buffering hysteresis to the WebKit GStreamer video player
The <video> element implementation in WebKit does its job by using a multiplatform player that relies on a platform-specific implementation. In the specific case of glib platforms, which base their multimedia on GStreamer, that's MediaPlayerPrivateGStreamer.
The player private can have 3 buffering modes:
- On-disk buffering: This is the typical mode on desktop systems, but is frequently disabled on purpose on embedded devices to avoid wearing out their flash storage memories. All the video content is downloaded to disk, and the buffering percentage refers to the total size of the video. A GstDownloader element is present in the pipeline in this case. Buffering level monitoring is done by polling the pipeline every second, using the
fillTimerFired()method. - In-memory buffering: This is the typical mode on embedded systems and on desktop systems in case of streamed (live) content. The video is downloaded progressively and only the part of it ahead of the current playback time is buffered. A GstQueue2 element is present in the pipeline in this case. Buffering level monitoring is done by listening to GST_MESSAGE_BUFFERING bus messages and using the buffering level stored on them. This is the case that motivates the refactoring described in this blog post, what we actually wanted to correct in Broadcom platforms, and what motivated the addition of hysteresis working on all the platforms.
- Local files: Files, MediaStream sources and other special origins of video don't do buffering at all (no GstDownloadBuffering nor GstQueue2 element is present on the pipeline). They work like the on-disk buffering mode in the sense that
fillTimerFired()is used, but the reported level is relative, much like in the streaming case. In the initial version of the refactoring I was unaware of this third case, and only realized about it when tests triggered the assert that I added to ensure that the on-disk buffering method was working in GST_BUFFERING_DOWNLOAD mode.
The current implementation (actually, its wpe-2.38 version) was showing some buffering problems on some Broadcom platforms when doing in-memory buffering. The buffering levels monitored by MediaPlayerPrivateGStreamer weren't accurate because the Nexus multimedia subsystem used on Broadcom platforms was doing its own internal buffering. Data wasn't being accumulated in the GstQueue2 element of playbin, because BrcmAudFilter/BrcmVidFilter was accepting all the buffers that the queue could provide. Because of that, the player private buffering logic was erratic, leading to many transitions between "buffer completely empty" and "buffer completely full". This, it turn, caused many transitions between the HaveEnoughData, HaveFutureData and HaveCurrentData readyStates in the player, leading to frequent pauses and unpauses on Broadcom platforms.

So, one of the first thing I tried to solve this issue was to ask the Nexus PlayPump (the subsystem in charge of internal buffering in Nexus) about its internal levels, and add that to the levels reported by GstQueue2. There's also a GstMultiqueue in the pipeline that can hold a significant amount of buffers, so I also asked it for its level. Still, the buffering level unstability was too high, so I added a moving average implementation to try to smooth it.
All these tweaks only make sense on Broadcom platforms, so they were guarded by ifdefs in a first version of the patch. Later, I migrated those dirty ifdefs to the new quirks abstraction added by Phil. A challenge of this migration was that I needed to store some attributes that were considered part of MediaPlayerPrivateGStreamer before. They still had to be somehow linked to the player private but only accessible by the platform specific code of the quirks. A special HashMap attribute stores those quirks attributes in an opaque way, so that only the specific quirk they belong to knows how to interpret them (using downcasting). I tried to use move semantics when storing the data, but was bitten by object slicing when trying to move instances of the superclass. In the end, moving the responsibility of creating the unique_ptr that stored the concrete subclass to the caller did the trick.
Even with all those changes, undesirable swings in the buffering level kept happening, and when doing a careful analysis of the causes I noticed that the monitoring of the buffering level was being done from different places (in different moments) and sometimes the level was regarded as "enough" and the moment right after, as "insufficient". This was because the buffering level threshold was one single value. That's something that a hysteresis mechanism (with low and high watermarks) can solve. So, a logical level change to "full" would only happen when the level goes above the high watermark, and a logical level change to "low" when it goes under the low watermark level.
For the threshold change detection to work, we need to know the previous buffering level. There's a problem, though: the current code checked the levels from several scattered places, so only one of those places (the first one that detected the threshold crossing at a given moment) would properly react. The other places would miss the detection and operate improperly, because the "previous buffering level value" had been overwritten with the new one when the evaluation had been done before. To solve this, I centralized the detection in a single place "per cycle" (in updateBufferingStatus()), and then used the detection conclusions from updateStates().
So, with all this in mind, I refactored the buffering logic as https://commits.webkit.org/284072@main, so now WebKit GStreamer has a buffering code much more robust than before. The unstabilities observed in Broadcom devices were gone and I could, at last, close Issue 1309.
16 Oct 2024 6:12am GMT
18 Sep 2022
Planet 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:
-
a rather beefy Supermicro 2U server with EPYC 7113P CPU and 4x PCIe, two of which are populated with Digium TE820 cards resulting in a total of 16 E1 ports
-
an icE1usb with RS422 interface board connected via 100m RS422 to an Ericsson GPS03 receiver. There's two layers of of over-voltage protection on the RS422 (each with gas discharge tubes and TVS) and two stages of over-voltage protection in the coaxial cable between antenna and GPS receiver.
-
a Livingston Portmaster3 RAS server
-
a Cisco AS5400 RAS server
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
Planet 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






