ZS1I Mossel Bay DMR Repeater Coverage - Radio Mobile Maps

Image:  Mossel Bay Area (Click on image for larger view.) 

The ZS1I DMR Repeater in Heiderand, Mossel Bay has been running from time to  time since June 2023.  It is permanently on the air from the 1 May 2026 after several hardware and software modifications were done for optimum functioning. Several radio amateurs have provided reports and positive comments with regard to the repeater.  It is quite strange that I never plotted the coverage area using Radio Mobile since June 2023.  I have now plotted the expected coverage area of the repeater.  

Before I publish the images it is important to first publish the repeater- , equipment- , feedline- and antenna information. 

ZS1I Digital Mobile Radio (DMR) Repeater

DMR Repeater Talkgroup 65522:   This repeater is NOT located on a remote mountain site but is situated in the Shack of ZS1I in Heiderand, Mossel Bay. This allows ZS1I to monitor and control the repeater while it is on the air.  
Mossel Bay DMR Repeater Information:

Mode: DMR
Band:  70cm
TX Frequency:  438.262500 Mhz
RX Frequency:  430.662500 Mhz
Radio Mode:  Duplex
Talk Group (TG): 65522
Colour Code: 1
Time Slot:  1 or 2 
RF Power Output: 15 Watt
Logarithmic power level: 41.76 dBm
Antenna EIRP:  46.96 dBm
Antenna:  Diamond X50
Antenna Gain:  7.2 dBi
Antenna Height:  12 Meters
Coax Cable:  RG213 Mil-Spec (West Germany)

This repeater is linked to the ZS1I AllStar Hub Network (Node 49355) (Analog Repeaters / Simplex Link Radio / Echolink / SVXLink / AllStar / South Cape Reflector) via the ZS1I DMR Bridge and Repeater.  

With your system operating at 440 MHz (70cm UHF band) with an EIRP of 46.96 dBm from an antenna height of 12 metres at sea level in Mossel Bay, your real-world coverage will be highly asymmetrical.

Because UHF signals rely almost entirely on line-of-sight propagation and are easily blocked by solid earth, your coverage splits into two completely different zones: vast open coverage over the ocean, and a sharp cutoff to the north caused by the Outeniqua Mountains.

Here is how your 46.96 dBm EIRP system will perform under these specific local conditions:

Line-of-Sight Horizon Limit

The theoretical radio horizon for an antenna 12 metres above sea level is calculated using the standard RF horizon formula:

===================================================================

RADIO HORIZON CALCULATION

===================================================================

Formula:

d = √(17 × h)

Where:

d = Distance to the radio horizon (in kilometres)

h = Antenna height above the ground/sea level (in metres)

-------------------------------------------------------------------

Your Setup Calculation (12-Metre Antenna Height):

d = √(17 × 12)

d = √(204)

d ≈ 14.28 km

Result:

The theoretical radio horizon for your repeater antenna is 14.28 kilometres.

===================================================================

• To a Handheld Radio (Ground Level): If communicating with a person holding a radio at ground level (approx. 1.5 metres high), their radio horizon is about 5 km. Adding your horizons together means you will have clean, high-clarity Line-of-Sight coverage up to 19–20 km away over the flat ocean surface or open coastal flats towards Hartenbos and Klein Brak River.

2. Terrain Obstacles: The Outeniqua Mountains

To the north of Mossel Bay, the Outeniqua Mountains rise sharply to heights between 800 and over 1,500 metres (such as the Robinson Pass area).

• The Shadow Effect: At 440 MHz, radio waves behave much like light beams. When your signal hits the massive sandstone slopes of the Outeniquas, the mountains will cast a massive "radio shadow" directly behind them.

• The Cutoff: Your signal will cleanly illuminate the southern, seaward-facing slopes of the mountains. However, coverage will completely drop off on the northern side of the ridge. You will not be able to reach deeper inland areas like the Little Karoo (Oudtshoorn region) unless you bounce a signal off a mountain-top repeater.

3. Signal Penetration in Town (Urban Factor)

Because your antenna is mounted at 12 metres, it is likely sitting just above or level with standard two-story residential rooftops in Mossel Bay.

• Structural Losses: 440 MHz UHF is excellent at bouncing between buildings and penetrating walls.

• Local Range: You can expect highly reliable, punchy coverage throughout the immediate town, even over the hilly terrain of the Cape St. Blaize peninsula. The 46.96 dBm (approx. 50 W) of effective directional power is more than enough to overcome urban attenuation within a 10 to 15 km radius through town structures.

✅ Summary of Estimated Range

• Over Ocean / Flat Coastline: 20–35 km (Excellent clarity to marine traffic or coastal stations with elevated antennas).

• Urban Mossel Bay: 10–15 km (Robust signal piercing through local neighborhood obstacles).

• To the North (Mountains): Up to the ridge line (Signal stops abruptly at the mountain peaks; no coverage in valleys behind them).

   

Images: Courtesy Radio Mobile (Click on images for larger view.)

 Above image:  Mossel Bay wide coverage area

 

 Above image:  Mossel Bay close-up image 1

Above image:  Mossel Bay close-up image 2

Above image: Repeater coverage Albertinia Town.  Bad coverage!!

Above image: Repeater coverage George Area.  Good coverage!!

Above image: Repeater coverage Mossel Bay and Hartenbos Areas.  Good coverage!!

Above image: Repeater coverage West of Mossel Bay / Gouritz River Areas.  Spotted coverage!!

 Above image:  Repeater Coverage - Still Bay, Heidelberg, Riversdale, Albertinia and Herbertsdale.  Bad coverage!!

The decline in Amateur Radio during winter is neutralized by creating activity!!

Who said there is a decline in Amateur Radio during the winter months?  I said so.  Look HERE.

My OM had a saying that if a door is closed into your face, you must always find another door to open and continue with what you are doing and enjoying.  This means do not give up and you will be able to continue also in amateur radio.  So true and this saying I have been following throughout the years.  It allowed me to bounce back in life sometimes even with better results than before.

Well amateur radio activity is up here in the Mossel Bay area as well as parts of South Africa.   Let's look at some of the activity by means of illustrated images:  

Image above:  Connected nodes to the ZS1I HUB in Mossel Bay  (Click on image for larger view.)

Image Above:  Bubble Chart of stations connected to the HUB yesterday afternoon.  (Click on image for larger view.

1.  ZS1I HUB Network Activity:  I will let the images speak for themself.  The HUB is alive and active on a daily basis with stations frequently heard also via all the cross-links and connected nodes and repeaters.  A few overseas stations were also heard on the ZS1I HUB Network.  I do not take any credit for this as the network consists of many participating entities.  Great to hear all the activity taking place.

 Image: Some "useless" information? (Click on image for larger view.)

Image:  Winter playing a role in the decline? (Click on image for larger view.)

2.  ZS1I  Amateur Radio Projects / Activities Blog:  This blog is was created in April 2026 and is already being visited by many viewers on a daily basis.  Hopefully the blog is not only my place were I keep some back-up information but also a medium where young and old can learn something.  I am not a person chasing records or wanting any attention in amateur radio.  I am to old for that nonsense.  The Blog for me is like a amateur radio "diary".  Many article might also be bored and not of interest to others.  None the less thank you to all the visitors for visiting the ZS1I Blog.   I hope to keep up rolling articles out that might be of interest to the general amateur radio community. 

Image:  Brandmeister Hoseline  (Click in image for larger view.) 

3.  DMR Activity still on the increase World Wide!  - Need I say anything about the increase in the use of DMR World Wide and in South Africa?   This is great news for amateur radio operators and the future of digital radio modes.  With the cross-linking of analogue systems to digital systems nobody is left out in the cold even if you only have a analogue HT radio.  At times the ZS1I HUB Network is linked to various DMR Talk Groups which resulted in an increase in activity.  The audio is good and the linked systems work great.  Yesterday operators were heard from Germany, Australia, UK, USA, Japan on Hoseline which was cross linked to the ZS1I DMR Bridge and DMR Repeater in Mossel Bay.  And no it was all country talk groups and not the World Wide Talk Group (91).  Great conversations and activity on DMR.  I do have a few ideas and changes that I would like to make to even better the current cross linked system.   Stay tuned!!

 

 

Image: 40 m WSPR Map South Africa (Click in image for larger view.) 

Image:  Stations that spotted the ZS1I 40m WSPR Beacon recently,  thanks to all.  (Click on image for larger view.)

4.  40m WSPR Activity:  WSPR is a great amateur radio propagation tool.  I am amazed on how propagation changes on the 40m band from time to time.  At one stage only a few stations received the 40m ZS1I WSPR Beacon.  Then all of a sudden there was a increase in spotted stations.  I must admit that I have lots to learn about WSPR.  Sure this will come with time.  In the mean time many thanks to all who regularly spot the Mossel Bay WSPR Beacon.  More interesting developments to come relating to WSPR Beacons in the future. 

5.  ZA-Net Network Activity:  For the past few days I have connected the HUB to the ZA-Net Network up in Gauteng.  At times there were activity even from abroad.  The audio quality was good and the network is working great.  Herewith more information about the network:

ZA-Net Network Web-Site:  Click HERE

• ZA-Net Repeaters & Network
  • Linked Repeater Sites
  • ZA-Net Bubble Network
  • ZA-Net Map of Repeaters
  • ZA-Net Etiquette
  • System Statuses
• Scheduled Bulletins & Talks
  • ZA-Net Schedules
• Participating Clubs
  • Sandton Amateur Radio Club (SARC)
  • Antique Wireless Association
  • West Rand Amateur Radio Club
  • Kempton Park Amateur Radio Technical Society
   

2 x Images above:  Orania AllStar Expansion - Zayn ZR3VO  (Click on images for larger view.)

 

6.  AllStar Connect and Disconnect - Orania:  Zayn ZR3VO took it to hart to create more on air activity in his part of the world by setting up a AllStar Hub that will automatically connect and disconnect to dedicated nodes in parts of South Africa.  More on this in a future article.  I assisted Zayn ZR3VO to setup his node by using 2 scripts and the crontab scheduler to automate his connections and disconnections.  This setup will provide coverage in the Free State and Northern Cape. Well done Zayn!! 

 

 

Above image:  Mumble client reflecting the Mumble Server and AllStar3 Mumble Bridge with connected Dell PC and the 467650 Bot (Click on image for larger view.) 

Image above:  The ZS1I HUB and Simplex Link reflecting the ZS1I ASL3 Mumble Bridge Node (467650) connected and ready to relay any traffic.  (Click on image for larger view.) 

 

7.  Mumble Bridge Node Relays: - Relay amateur radio audio from a personal computer to any AllStar, Echolink, Analog RF Repeaters, Analog RF Links,  HF Radio, AREDN Mesh Network,  DMR Bridge or DMR Repeater etc.   Some time ago I published and article on how to setup a Mumble Bridge and why one would setup such a bridge.  Well one of the reasons was to relay amateur radio audio digitally without patch boxes and cables.  I have tested the current setup successfully in broadcasting any audio to all linked devices using the Mumble Bridge and Server linked to the 467650 AllStar Mumble Node.  It works great and make things so much easier when broadcasting or relaying audio.  This setup also increased the activity on the ZS1I HUB Network as Brandmeister Hoseline audio was tested successfully.

 

 

8.  Test broadcasts of Amateur Radio Newsline and ARRL News: When and where - On the ZS1I HUB Node Wednesdays-  at 19h30 and Fridays evenings at 19h30.  In a previous posting I mentioned the idea in creating a on demand news node setup which will allow users to privately listen to a variety of bulletins whenever they have the time.  Currently I am busy with test broadcasts as listed supra.  You can now listen to the above amateur radio news on the ZS1I HUB Network until further notification. Both setups work great in providing further activity to the ZS1I HUB Network.

 

Well there you have it. The decline in Amateur Radio during the winter is neutralized by creating activity if there is very little or none!  Activity keep amateur radio alive and well!!

Update: What progress is being made with the ZS1I - 6 Meter CW Beacon in the Southern Cape Area?

Well I have been asking this question to myself several times since this project was launched.  The project has not been shelved although due to other "gremlins" in the shack the priority and importance was down-scaled a few times until other breakages were fixed.  I am sure that you will agree with me that the 6m Band in the middle of Winter is fairly dead and the priority is on the low side.  Just to re-cap here is the links to the project for those that might have missed it.

1.  Building Low Budget Antennas - DIY Delta Loop Antenna for the 6 Meter Band ( 50 - 54 Mhz)

2.  Building Low Budget Antennas - DIY Moxon Antenna for the 6 Meter Band (50 Mhz)

3.  The ZS1I - 6 Meter Magic Band Project in the Southern Cape Area of South Africa. (Part 1)

4.  Heads Up - Here comes the Next Generation Amateur Radio Beacon (s) for the Southern Cape!! (Part 2)

5.  Update: Next Generation Amateur Radio Beacon (s) for the Southern Cape!! (Part 3) 

Now when I found the time I worked on the 6 Meter CW Beacon.  I also ordered a few parts that I am waiting for to continue the project.  The image below depict the work done so far on the beacon.  There is not many things left to do, that's if the "gremlins" stay away from the work-bench.

I will keep those interested updated about the project and when the beacon is switched on and on the air.  Updates to follow!

 Image:  ZS1I 6m Meter CW Beacon - work in progress

The ZS1I 40M WSPR Beacon is back on the air in Mossel Bay, South Africa

My previous post relating to the 40m WSPR Beacon available HERE refers.

The ZS1I 40 Meter Beacon located in Mossel Bay, South Africa is back on the air using the solar power supply.  So far the supply is running smoothly without any hick-ups.

Particulars of the ZS1I Ultimate 3S Beacon:

• Call: ZS1I
• Freq.: 7.038 600 Mhz
• Band:  40 Meters (7 Mhz)
• Grid:  KF15BT
• Power:  250 mW
• Mode: W-2  (WSPR2)
• Antenna:  EFHW (49:1 Balun)
• TX Period:  Every 10 Minutes
•  Beacon on the air from:  7 October 2025 @ 10h00 SAST
  
•  First Spotter: 10h20 ZS5SAM (Div 1)   Barrydale. (Distance 134 km)

Time to get the 6m CW Beacon on the air.  I will be working on this beacon in the coming days if "Murphy" stay out of my Shack. 

Image: ZS1I DX Report - Pedro LU7ABF  (Click on image for larger view.)  

The 40m WSPR Beacon needed a new Power Supply - AKA Solar Power Supply

Image: Solar Power Supply  (Click on image for larger view.) 

The ZS1I 40M WSPR Beacon has been off the air for the last two weeks due to the failure of a cheap 220v AC - 12v DC switch mode power supply.  I opted not to replace the power supply with another switch mode power supply.  I decided to go the solar power supply route and constructed the above supply for the beacon.

You might ask but why such a tall format solar power supply.  As usual I use what I have available in the junk box.  This power supply can also be used as a all in one supply.  The solar panel for the beacon is installed outside apart from the supply itself but if I want I can add the panel to the two aluminium stays at the back of the supply.  The solar supply can then be moved in the direction of the sun but not only that the operator will have access to the solar controller display information at any time while operating his radio from the supply. 

There is really no need to explain how the solar power supply was constructed.  The photos below provide you with more than enough information to build your own.  Remember to add fuses on the input and output of the supply should anything go wrong.

Herewith further information about the power supply: 

Model:  TX1210

Battery Voltage:  12 v

Charge Current:  10 A

Discharge Current:  10 A

Max Solar Input: <50 v

Equalization:  14.4 v

Float Charge:  13.7 v (Adjustable)

Discharge Stop:  10.7 v (Adjustable)

Discharge Connect: 12.6 v (Adjustable)

USB Output:  5 v / 3 A

The WSPR Beacon is now back on the air and running of the solar power supply. I am monitoring the beacon as well as the solar power supply to ensure that the beacon is now functioning optimal again.

More information about the beacon available HERE and HERE

Images:  (Click on images for larger view.)

New AllStarLink3 - Mumble Bridge (Additions / Extensions) to the ZS1I HUB Network in Mossel Bay (Part 3)

(Click on image for larger view.)

Time to get to the "real juicy bit" on how to install all the "ingredients" to setup the Mumble Bridge / Server / Client.  

Now how do you install and setup an ASL3 / Mumble Bridge / Server / Client?  Million dollar question?   Now there are very few tutorials out there on the Internet that will assist you in installing a ASL3 / Mumble Bridge.  I will however explain in this article how I went about installing and setting up the ZS1I Mumble Bridge on a Raspberry Pi 3 b with the assistance of AI.

For the purpose of this tutorial I am not going to explain how to install AllStarLink Ver 3 on an SD Card for use on a Raspberry Pi. The  ASL3 Landing Page includes the ASL Manual.  Click on the above link and you will be redirected to a comprehensive online manual for AllStarLink Ver 3.  Here you will find all the necessary information to install AllStarLink Ver 3 successfully.

With regards to installing and setting up the Bridge we need to install and setup a public and private node, edit files, test connections to nodes, install and setup Mumble Server, open ports on you Internet Router and a few "odds and ends".  More information on the sequence list available HERE.  Do not run away!  It is fairly simple to get the ASL3 Mumble Bridge up and running.  Having knowledge of Linux and the Raspberry Pi will make it easier to navigate through all the installations and setups. Even if you do not have experience in this regard you will be able to install ASL3 and the Mumble Bridge if you follow all the instructions carefully.

Let's get going!!

Image 1 (Click on image for larger view.) 

I assume you already booted the PI and that you are on the Landing Page as displayed above.  (Image 1) To get to the landing page just enter the Raspberry Pi's IP address in you Internet Browser.  I use Firefox.   Click on Web Admin Portal window.  The AllStarLink System Manager page will open.  Login with your username and password.  (Image 2) 

Image 2 (Click on image for larger view.) 

Image 3  (Click on image for larger view.)

A new window will open , called the cockpit,  displaying many options. (Image 3)  At the top a banner will be displayed  - Web console is running in limited access mode.
Click on "Turn on Administrative Access".   You will now have Administrative Access.  On the left side of the page go to Terminal and click on it.  Terminal will open.  After the $ sign type:

sudo asl-menu [enter]

The asl-menu will open and here we are going to setup a New Private Node.

The AllStarLink Main Menu will open.  Select 1 Node Settings  [enter to select]

In the Node Setup Main Menu select 1 - Allstar Node Setup Menu [enter to select]

A new menu Allstar Node Select Menu will open .  Select A - Add Node  [enter to select]

Enter new node number:  I used 1977 ( Anything between 1800 - 2000.  Do not use private node number already used in other AllStarLink Nodes)

Question will appear asking:  What configuration settings should we use for Node 1977?

Select 0  None of the above (show all settings) [enter to select]

Node 1977 info will appear:

1  Node Number:  1977

2  Node Password:                (Leave blank.)

3  Node Call sign:  ZS1I   (Enter you call sign here)

4  Radio Interface:  Select No Radio interface or Hub Node

5  Duplex Type:  Select 0  Half / Full duplex with no telemetry link -  Use  space bar to select.  Select half duplex.  Next select Back and Back again.  Select 2  Restart Asterisk  <- Needed   [enter to select]

Asterisk will restart

Node Setup Main Menu will appear again.  Select 3  Update Asterisk AMI Password

Enter to select.  If you have not changed it do in now.  I already changed mine earlier.

Select 4 Update Asterisk IAX Port.  Enter Change Port.  I used 4566 -  Ensure that this port forwarding is also opened in you Internet Router.

Exit Main Menu

Select <Back>

The AllStarLink Main Menu will open.

Asterisk must be restarted to make your changes alive.  Are you sure you want to exit now.  (Note:  Asterisk restart can be done selecting 7 Logout/Reboot/Shutdown.  Select 3)

Select Yes and [enter]

Type the following at the prompt in the Terminal

sudo systemctl restart asterisk.service  [enter]

After  restart type the following at the prompt in the Terminal   

cd /etc/allmon3  [enter]

then sudo nano allmon3.ini [enter]

Go to the bottom of the page and enter the  following:

[1977]

host=127.0.0.1

user=admin

pass= xxxxxx  ;your asterisk AMI password we created earlier

 

Let's save the info

Hit Ctrl + X

Yes

[enter]

 

Reboot the node.  At the prompt type:

sudo reboot now [enter]

Go to Web Admin Portal (Click on Window)

Log in again 

AllStarLink System Manager will show up (Cockpit)

Turn on Administrative Access

Let's go to the Allmon3 page

Open and Internet Browser Tab  and type

https://IP Address /allmon3/  [enter]

Browser Page will Refresh.  If not just click refresh button (reload current page)

Node 1977 has been added once the page has reloaded. We now have two nodes displayed.  AllStarLink3 Node (467650) and 1977.  

Image:  Allmon3 Monitoring Dashboard (Click on image for larger view.) 

Login to Allmon3  (left side of page under nodes)

Username:  ZS1I

Password:  XXXXXX

We now need to check if node 1977 can connect to the AllStarLink3 Node you choose.

Choose the block with the two links on the right side of the Allmon3 Monitoring  Dashboard page

Select  command and select connect

Node # = 1977

Permanent = No

Click  Execute

 

The two nodes will be connected.  See Connect State.  It says  ESTABLISHED at both the nodes.

Now Disconnect by clicking on  X left to Node 1977 - Hover over it. The X will turn to a maroon colour.  Screen will come up to disconnect node.  Just click Execute.

The two nodes will now be disconnected.

 

But hey we do not want to connect the two nodes plus the main 49355 node manually.  We want it done automatically.

 

For this to happen we will be using the script provided by KF5FMU on his GitHub page available HERE.  I am not going to go into detail on how to install the script as this has been nicely set out by Freddie KF5FMU on his GitHub pages.  I will however provide an example of my check-connection.conf script file below.

 

check-connection.conf (Script File)

$cd /etc/asterisk/local/ [enter]

sudo nano check-connection.conf [enter]

# AllStarLink 3 Check Connection Configuration

# Created by install-asl3-check-connection.sh

# Your local AllStarLink node number

LOCAL_NODE="467650"

# Space-separated list of target nodes that should stay connected.

TARGET_NODES="1977 49355"

# Connection prefix:

# *3 = transceive connect

# *2 = monitor connect

CONNECT_PREFIX="*3"

# Wait this many seconds after issuing each reconnect command.

RECONNECT_DELAY_SECONDS="2"

# Set to "yes" for extra terminal output when run manually.

# Set to "no" if you want quieter cron logs.

VERBOSE="yes"

# Full path to the Asterisk binary.

ASTERISK_BIN="/usr/sbin/asterisk"

 

If you setup everything correctly and rebooted your Raspberry Pi your selected nodes should now automatically connect to each other. (See image below)

 

(Click on image for larger view.) 

 

Onto the installation of DVSwitch on the Raspberry PI.

 

Go to the Cockpit

Select Terminal (Click on it)

At the prompt enter:

sudo su -  [Enter]

root@asl3:~#

You now have root access. 

 

Let's install DVSwitch:

 

At the prompt type:

wget dvswitch.org/bookworm [enter]

chmod +x bookworm [enter]

. /bookworm [enter]

apt update [enter]

apt install dvswitch-server [enter]

When DVSwitch server is finished installed reboot the Pi

sudo reboot now [enter]

 

We are going to leave DVSwitch as is - no setup - as we will only use the Analog_Bridge folder where we will install a few other firmware files.  Amongst the files will be the mumble_bridge.py (Python) script file.

 

Time now to install Pymumble  

 

To install pymumble on a Raspberry Pi, you need to install its system dependencies first, followed by the Python package itself.

1. Update Your System

Ensure your Raspberry Pi packages are up to date. 

    • Open your terminal.
    • Run: sudo apt update
    • Run: sudo apt upgrade -y

2. Install System Dependencies

pymumble relies on Opus audio codecs and specialized development libraries.

    • Run: sudo apt install python3-dev libopus-dev gcc -y

3. Install pymumble

 
Use pip to install the package. Depending on your OS version, you may need to use a virtual environment.

Option A: Using a Virtual Environment (Recommended for Raspberry Pi OS Bookworm and newer) 

    • Create a environment: python3 -m venv myenv
    • Activate it: source myenv/bin/activate
    • Install the library: pip install pymumble

Option B: System-wide Installation 

 

    • Run: pip3 install pymumble 

4. Verify the Installation

Check that the library imports correctly.

    • Run: python3 -c "import pymumble; print(pymumble.__version__)"
    • If no error appears, the installation was successful. 

Time now to install Pymumble 

Image:  See the ZS1I_467650_Bot  (Click on image for larger view.)

Pymumble is an open-source library that allows you to build custom clients and automated bots for Mumble, a popular privacy-focused, self-hosted voice chat server. Written in Python, it acts as a programmatic interface to connect, speak, listen, and manage server channels.   You will notice on the image above that I opted to use an automated bot for Mumble.  I called it the ZS1I_467650_Bot.  The ZS1I_467650_Bot will automatically connect to the Mumble Server.

Key Features of Pymumble

• Audio Streaming: It allows developers to stream audio directly into Mumble channels (e.g., custom music or soundboard bots) and record incoming audio streams. 

• Event Callbacks: The library triggers events based on server activity, such as when a user connects, disconnects, speaks, or creates a channel. 

• Server Management: It functions as an automated administrative tool to move users, mute/deafen, or send text messages programmatically. 

Common Use Cases

•  Music Bots: Frequently used to create dedicated audio bots (often playing stereo or high-fidelity streams) that provide music in Mumble voice channels. 

• Recording Bots: Used for writing custom scripts to record conversations and save speech data. 

• Amateur Radio Bots: In amateur radio, Pymumble is primarily used to bridge the gap between traditional radio frequencies (RF) and internet-based Voice over IP (VoIP) networks. Radio Amateurs leverage Mumble because its open-source, ultra-low latency Opus audio codec preserves signal clarity—making it a popular tool for building custom gateways, internet links, and remote station controllers.

Getting Started

The library is available and actively maintained across multiple active forks, such as the Azlux Pymumble GitHub Repository and the reworked Sourcehut Pymumble Library.

Note:  I used Option B to install pymumble and it worked first time around.

 

Image:  Mumble_Bridge.py in Thonny Python IDE

Installation of the Mumble_Bridge.py script file 

It is now time to install the Mumble_Bridge.py script file that was created in collaboration with AI.  The script file will be installed in the Analog_Bridge directory located at $ /opt/Analog_Bridge.  Name of the file = mumble_bridge.py (6.6kb Python file dated 8 June 2026 18:38:09) Copy this script file to the Analog Bridge folder using FileZilla or the Terminal. ( $ /opt/Analog_Bridge/Mumble_Bridge.py)

Please take note of the following relating to the Mumble_Bridge.py script:

Open Source Sharing (License File)

 

Copyright (c) 2026 Johan ZS1I and Artificial Intelligence (AI)

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including the rights to use, copy, 
modify, merge, and publish copies of the Software, subject to the following 
conditions:

1. The Software is NOT to be sub-licensed or sold in copies for commercial 
   purposes under any circumstances.
2. Any distributed or modified versions of this Software must retain the 
   above copyright notice, this list of conditions, and this disclaimer.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON INFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN  CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

Mumble_Bridge.py script file can be downloaded by clicking HERE.

Time to install the tcpdump network packet analysis utility program

 

You might not need this firmware but if you run into audio packet issues then this software will assist you in solving the issues.  This firmware  needs to be installed on the Raspberry Pi 4.

 

Always a good thing to reboot your Raspberry Pi after the installation of firmware.  Reboot now.

 

 

Image: Mumble Client

Install the following firmware on the PC that will host your Mumble Client and Server.  

 

I use a Dell Optiplex PC running Linux Mint 22.3 for this purpose. 

 

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

 

In the Terminal window run the following commands:

 

sudo apt update && sudo apt install mumble -y 

 

Image:  Mumble 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. 

 

In the Terminal window run the following commands:

 

sudo apt update && sudo apt install mumble-server -y 

 

After installation reboot the PC:  sudo reboot now 

We are nearly finish installing all the firmware needed.  The final firmware installation will be done on your mobile phone.  I use an Oppo phone which runs Android.  Here is how I installed the Mumble Client.

Image:  Plumble Phone Client 

Plumble Free Ver 3.2.0 nowadays called Mumla - Mumble VoIP can be downloaded from the Google 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 4.  I found that the performance is just better and faster and there is no clashing/fighting between the firmware.

Enough for now.  In Part 4 we will be looking at the setup and configuration of all the firmware to ensure clean, crisp, good audio between all the network connections.