New AllStarLink3 - Mumble Bridge (Additions / Extensions) to the ZS1I HUB Network in Mossel Bay (Part 2)

When working or setting up any amateur radio addition or extension, I believe to do it in a structured manner.  I have therefor compiled a list of the sequence on how I installed all the firmware needed for the AllStarLink3 (ASL3) / Mumble Bridge.  I have said it before that articles on this Blog is not to brag or boast and therefor it is also used as a "library" or reference / storage facility should I want to revert back to a project I undertook.

I need to inform readers that this listed method worked for me and the equipment I used.  I can therefor not guarantee that it will work for your setup. 

Herewith the sequence list:

Install the following firmware on the Raspberry Pi 4 

1.  Use a new clean SD Card to write the firmware on.  I only use SanDisk Ultra Class 10 cards in all of my projects.  Never had a card fail on me.

2.  Write AllStarLink3 (ASL3) Bookworm firmware to the SD Card using Raspberry Pi Imager.

3.  Install and run ASL3 Raspberry Pi.  I use a Raspberry Pi 4 Model B Rev 1.5 4 Gig Ram.  I am sure one can run the firmware of a Raspberry Pi Zero 2 W.  I opted to install the Mumble Server  and Mumble Client on one of my Dell Optiplex PC's.

4.  Setup a Public Node using the asl-menu command.  In my instance the public node number is 467650.

5.  Setup a Private Node using the asl-menu command.  In my instance the private node number is 1977. 

For assistance on how to setup the above two nodes and DVSwitch, do a search on Youtube for videos by Ham Radio Crusader.  Link:  https://www.youtube.com/@HamRadioCrusader  

6.  Connect the following 3 x Nodes permanently together:  467650, 1977 and 49355 (ZS1I Hub Node)  I used a script to connect all three nodes together permanently.  

7.  Install the ASL3 Check Connection Script to connect the above three nodes permanently together.

8.  Install DVSwitch on the Raspberry Pi.  No setup needed. I used the Analog_Bridge folder to store the bridge files and firmware.  When you install DVSwitch the Analog_Bridge directory will be amongst other directories that were installed in "/ " under the opt directory.  $ /opt/Analog_Bridge  This is the directory I used to work out and run the mumble_bridge.py script.

9.  Install pymumble on the Raspberry Pi.  I used the system wide installation.  Run:  $ pip3 install pymumble from the cursor in the /home/pi main root directory.

10.  It is now time to install the AI created Mumble_Bridge.py script file in the Analog_Bridge directory.  Name of file = mumble_bridge.py (6.6 kb python file 8 June 2026 18:38:09)  Copy this file to the Analog_Bridge folder using FileZilla.

11.  Install the tcpdump network packet analysis utility program.  This program will assist you if you have any audio packet issues.

Install the following firmware on the Dell Optiplex PC running Linux Mint 22.3

1.  Install the Mumble Client (PC) version.  This is your main control program where you will see all the clients, channels, servers etc.  Mumble uses a client–server architecture which allows users to talk to each other via the same server.

2.  Install the Mumble Server. Also called Murmur.  Murmur is the VoIP server component for Mumble. Murmur is installed in a system-wide fashion, but can also be run by individual users. Each murmur process supports multiple virtual servers, each with their own user base and channel list.

Installed the following application on my Oppo Phone

Plumble Free Ver 3.2.0 nowadays called Mumla - Mumble VoIP and available via PlayStore. 

Note:  I would advise that the Mumble PC Client and the Murmur (Mumble) Server be installed completely separate from ASL3 / DVSwitch/Mumble_Bridge on the Raspberry Pi.  I found that the performance is just better and faster and here is no clashing/fighting between the firmware.

  

Breathtaking sunrise this morning in Mossel Bay situated along the Garden Route of South Africa!

The images below were taken this morning (11 June 2026 @ 07:27) from my QTH in Mossel Bay, South Africa.  The images really do not capture the complete beauty of the sun rise because a two-dimensional photograph cannot convey lived experience, movement, atmospheric lighting, or the emotional depth of a moment. Real-world beauty engages all the senses, whereas an image flattens reality into a simple static frame.  None the less the images are better than no images at all.  

Garden Route was officially crowned the best road trip in the world.

South Africa's Garden Route was officially crowned the best road trip in the world by a global study. It achieved an impressive score of 90.6 out of 100, outperforming iconic drives like Route 66 and the Pacific Coast Highway due to its stellar visibility, low winds, and perfect driving weather. 

🗺️ The Route at a Glance

• The Stretch: Roughly 300km (about 185 miles) along the N2 highway.
• The Path: Runs directly through your area—stretching from Mossel Bay eastward to the Storms River Mouth.
• Key Highlights: The route is celebrated for seamlessly blending towering mountains, ancient indigenous forests, lagoons, and the rugged Indian Ocean coastline.

🌲 Core Attractions

At the heart of this global champion is the Garden Route National Park, which is divided into three main, unmissable sections: 

1. Wilderness Section: Famous for calm waterways, birdwatching, and outdoor activities like canoeing and mountain biking.
2. Knysna Section: Known for its lush forests, estuarine environments, and the chance to spot the endangered Knysna seahorse.
3. Tsitsikamma Section: Offers rugged coastal scenery, dramatic hiking trails, and the iconic suspension bridge at Storms River Mouth. 

🚗 Popular Towns to Stop and Explore

You don't just drive through this route; the stops are what make it special. Some of the top towns and villages along the way include: 

• Mossel Bay: The official starting/end point for the drive.
• Wilderness: Quiet, sweeping beaches and river estuaries.
• Sedgefield: Famous for its bustling Wild Oats Community Farmers' Market (go early to beat the crowds).
• Knysna: Great for oysters, lagoon cruises, and forest walks.
• Plettenberg Bay: Beautiful beaches, marine safaris, and upscale eaterie

Why not explore this world-renowned coastal drive over 3 to 7 days, discovering hidden gems and local wildlife along the way and as a bonus you might experience sun rises as seen in the image below.

Enjoy!

(Click in images for larger view.) 

 

Sad to see a decline in Amateur Radio during the Winter in South Africa?

Image:   AI  (Click on the image for larger view.) 

Having been in amateur radio for more than 30 years it is sad to notice that there is nowadays an enormous decline of amateur radio activities during the winter times.  Having said that let me just point out that this was not the case in the days gone by.  I have noticed that on-air activity is very low and in some instances exceed to exist during winter times.  Looks like radio amateurs move into hibernation.   Why this topic and what does it have to do with me? Well firstly it is just an observation on my part and secondly the decline in activity is not good for amateur radio.  I hear you say but there are ongoing activity.  Yep you correct and I did not say that in general nothing is happening in amateur radio but definitely on-air activity has declined. 

Image:   AI  (Click on the image for larger view.) 

Now tell us what was it like in the olden days during the winter.  Man-o-Man now you are talking.  Winter time was the time when radio amateurs get together on the air literally in their droves.  "Foot-warmers" nick name for tube amplifiers  and tubes of valve radios were working overtime in the Shack.  Another benefit was that the heat coming from the old valve equipment also heated the inside of the Shack.  You did not need an electric heater to heat the Shack.  With valve radios you kill two flies in the Shack at once.  O! ...  now I see what the problem is nowadays.  All the new transistor- and chip radios are cold and you need an external heater to warm the Shack if you lucky to have electrical power.

Enough!  I am not trying to say that things were better in the olden days.  I just found that there are less activity in the winter nowadays.  Are the days of spending times in a warm cosy Shack in winter now forever gone?  I hope I am wrong about all of this.

Hope to hear of more on the air and off the air (home brewing) activity during the long winter months.  If you do not want to sit in the Shack then sneak a radio into your bedroom but for Pete's Sake just be more active during the winter.  We have a saying here in the Southern Cape if nothing is heard on the air that -  "Dit is net dooie kole!"   In other words the coals that keep the "fire burning" (amateur radio going) is dead. 

To assist some of my fellow radio amateurs read more here:

Winter hibernation for your rig is a common choice, but you don't have to stay off the air! Discover warm-weather and cold-weather operating tips in the Winter Ham Radio Tips OH8STN video, or browse community perspectives on the Hibernating until spring due to cold weather - Facebook

Let's keep those "coals burning" and stop the radio hibernation!

BREAKING: New AllStarLink3 - Mumble Bridge (Additions / Extensions) to the ZS1I HUB Network in Mossel Bay (Part 1)

Some might have noticed that the editor of this article was not very active on the ZS Link Group Nets the past three week. Well there was good reason for this.  I in collaboration with AI have been working on a project relating to create a analog to digital bridge network between AllStarLink3 (ASL3) and Mumble.  I now do have the pleasure to announce a new addition  / extension to the ZS1I Hub Network in Mossel Bay:  

The new "KID" = The ZS1I AllStarLink3 (ASL3) to ZS1I Mumble Bridge now incorporated into the ZS1I Hub Network in Mossel Bay.  

Before I tell you more about the new "KID" on the block, it is important to first provide some information on Mumble.

Background: 

Now why on earth would one want to use Mumble, firstly in general and amateur radio and secondly use a commercial software application when there are more than enough amateur radio software applications available and thirdly build a bridge between ASL3 and Mumble?

Firstly:

Mumble is fundamentally a digital voice application.

It uses AREDN, your computer or phone's internet connection to transmit compressed, digital voice data, unlike the analog streams typically processed by AllStarLink (ASL3). However, in amateur radio, I used software like DVSwitch and Analog_Bridge as well as a Mumble_Bridge.py script to bridge Mumble and other digital networks into analog ASL3 nodes.  

    • ASL3: Connects via analog radios and repeaters (FM), though the system relies on digital servers, the internet and AREDN to link nodes together.
    • Mumble: Transmits over Voice over IP (VoIP), capturing and compressing your voice into digital packets right from the start. 

Let's look further at Mumble: 

Mumble is a free, open-source, and highly secure Voice over Internet Protocol (VoIP) application primarily designed for real-time voice communication.  It is celebrated for its incredibly low audio latency and high sound clarity, offering a self-hosted alternative to platforms like Discord or TeamSpeak.

Because it relies on a decentralized, client-server model rather than centralized corporate servers, Mumble offers a unique set of features and capabilities for its users: 

Key Features

• Extremely Low Latency: Mumble was engineered to transmit voice packets with virtually zero delay, making it vital for fast-paced, competitive applications where split-second communication matters. 
• High-Quality Audio: It utilizes advanced, royalty-free audio codecs (like Opus and CELT) to ensure crystal clear, wide-band voice communication without heavy resource usage. 
• Positional (Spatial) Audio: In certain supported applications, Mumble uses 3D listening technology that simulates a 360-degree soundscape.
• Privacy and Security: All Mumble communications are encrypted by default. Because the software is open-source, it contains no ads or user-tracking mechanics. 

How It Works

Mumble uses a two-part architecture: 

• The Client (Mumble): The desktop or mobile application you use to log in and talk.
• The Server (Murmur): The back-end software that routes the voice data. 

Unlike Discord, where you hop into a server hosted by a single company, anyone can download the Murmur server software and host their own private Mumble server on their own hardware. This gives server administrators complete control over user data, privacy, permissions, and complex channel setups. 

Who Uses It?

While originally built for gamers, Mumble's reliability and self-hosting capabilities have made it popular in other fields: 

• Podcast Recording: Its high fidelity and multi-channel audio recording make it a popular tool for podcasters recording remote interviews.
• Radio Enthusiasts: Amateur radio operators use it to bridge internet-based communications with physical radio nodes and AREDN.
• Workplaces: Teams requiring highly secure, self-hosted, or on-premises voice communication networks.

Now that we know a little bit more about Mumble let's move on to the second part as stated in the the background heading above.

 

Secondly:

 

Why use a "commercial" software application when there are more than enough amateur radio software applications available out there?

 

In the early 2000's I started to create a HSMM and later a AREDN Mesh Network in the Mossel Bay area.  I decided to use Mumble over the mesh network and it is important to mention it here as Mumble plays an important roll in AREDN. I therefor wanted to use Mumble as an ASL3 / Mumble bridge and to conform to software already in use.  

 

Here are the reasons for using Mumble in Amateur Radio: 

• Extremely low latency - Important if you run any amateur radio network.
• High-Quality Audio  - Need I say anything?  Maybe just that Mumble uses advanced audio codecs to transmit pristine, natural sounding voice.
• Privacy and Security: Mumble communications are safe and open source. It contains no ads or user-tracking mechanics. 
• Mumble channels function like isolated virtual rooms where connected users can speak to one another.  Creating of different channels for different uses in amateur radio.  In my AREDN setup I also use Mumble and I created several channels (chat-rooms) for different services like Amateur Radio Emergency Coms Channel, Citadel Email and Client Channel, Digital Radio Mode Channel, Echolink Relay/Listen Channel, Emergency JOC Channel, General Voice Chat Channel etc.
• Remote Audio Bridging - Amateurs use Mumble to stream audio directly from remove transceivers of Software-Defined Radios (SDR's)
• Bandwidth Efficiency - It allows remote multi-operator teams to listen to or control stations without needing heavy, complicated port forwarding on routers.
• Repeater and Cross Band Linking - Mumble acts as a central hub or "rendezvous server" to bridge analog repeaters, AllStar nodes and Digital modes via the Internet, AREDN and interconnected networks.
• Cross-linking - It handles multiple users speaking simultaneously without Garbling, which is ideal for broad group communications or net check-ins. 
• Emergency Communications - During a disaster or emergency responses or power grid outages, radio amateurs can set up self-hosted local servers that auto-reconnect reliably.  (Author's AREDN Network a good example of this.)
• Low CPU usage - One can use a Raspberry Pi to host the software.
• Highly Reliable Application Software - Been using it for years!
• Can be used for remote station Control/Audio  - HF Remote Control Station
• Can be used for multi-operator contesting - Setup and win contests!
• Can be used for multi-channel operations in Amateur Radio - Already discussed above.  Definitely a big plus point! 

I only mention a few uses for Mumble in Amateur Radio but am sure there are many uses not mentioned above that Mumble can be used with.  As mentioned before I had to once again incorporate Mumble into the ZS1I AllStar3 Hub Network in Mossel Bay having used it very successfully in the ZS1I AREDN Mesh Network.

 

Thirdly:

I in collaboration with AI has successfully created a  Mumble_Bridge.py script that establish a bridge between ASL3 and Mumble.   I am not going to provide more detail in this part but will provide full information in future parts of this article.

An ASL3/Mumble bridge script (often utilizing the Analog_Bridge software from the DVSwitch project) is a utility that connects your amateur radio system to a Mumble VoIP server. It allows you to relay audio seamlessly both ways between physical radio nodes and internet-linked computers or mobile devices. 

The ASL3 (AllStarLink 3) environment connects amateur radio repeaters, nodes, and hotspots. By adding a Mumble bridge, the script performs several key functions: 

Two-Way Audio Relaying: It encodes and decodes audio so that when someone speaks into a radio connected to your ASL3 node, the audio is streamed into Mumble. Conversely, when a Mumble user talks, it is pushed out over your RF node. 

Protocol Translation: The script translates between the VoIP protocols used by Mumble and the audio formats (like ULAW) that Asterisk (which powers ASL3) natively uses. 

User Accessibility: It allows radio amateurs and other operators who might not be near a radio to participate in local net check-ins or general conversations using a simple Mumble client on their PC, Mac, or Android device. 

Bridging Software: These integration scripts utilize tools developed by the DVSwitch ecosystem to link different digital modes together, creating a unified communication space.

Short Overview of the script:  This script successfully handles bidirectional audio streaming. It processes incoming 352-byte DVSwitch frames from Asterisk, strips the 32-byte header, up-samples the audio to 48kHz, and packs it into 20ms blocks for Mumble  For outbound audio (phone/PC to radio), it down-samples to 8kHz and constructs a valid big-endian sequential DVSwitch header to trip the Asterisk TX gate.

Well this is enough for Part 1.  In future parts I will describe the working components and configurations that successfully established the ZS1I AllStarLink3 (ASL3) to Mumble Bridge.  

The ZS1I ASL3 to Mumble Bridge is currently fully operational on the ZS1I Hub Network in the Mossel Bay area.  Fine tuning the set-up and audio loudness will be an ongoing task until optimal results are achieved, but so far reports indicate that the setup is working great.

Plans are already underway to expand the radio stack even further by adding: 

•       Configure automated backups for the system.
•       Set up real-time system alerts if the bridge drops offline.
•       Integrate additional digital modes to the network.

In the mean time enjoy the crisp audio on the air and feel free to use the ZS1I HUB Network! 

Images (Click on images for larger view.)