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!!

TYT MD-380 (UHF) DMR Tranceiver - Yes I have one and I do use it!!

I have been asked on several occasions whether I ever use a radio on DMR as it would appear that all the articles I post has to do with DMR applications that runs on a cellphone or PC.  In a past article I explained that with all do respect amateur radio is not only about real radios.  I use what I have available and that will serve the purpose that I have intended for it.  In other words I use the communications medium for a specific reason and purpose.  It is definitely not a hard and fast rule.  I use old valve tech to the newest surface technology, VoIP, Digital Voice modes etc. whenever I feel like using at the time. 

I do have several radios and use them as and when the need arise.   In this article I am going to look at the TYT MD380 DMR Handheld radio which I acquired several years ago when DMR was still in its infancy in South Africa.  Now why would I write and article about this specific radio.  It is really quite simple.  The TYT MD-380 is a popular, budget-friendly DMR (Digital Mobile Radio) handheld transceiver widely used by amateur radio operators and professionals. It offers a great entry point into digital communications, providing both analog FM and digital DMR Tier II capabilities.

Key Specifications & Features

• Frequencies: Available in distinct single-band models: TYT MD-390 VHF (136 - 174 MHz) or TYT MD-380 UHF (400 - 480 MHz). (Dual-band models like the MD-UV380 are also available).
• Power Output: Selectable high (5 W) and low (1 W) power settings.
• Channels & Zones: 1,000 channels, organized into user-defined zones (16 channels per zone accessible via the rotary knob).
• Display: Full-color LCD display showing channel, zone, battery life, and signal strength.
• Battery: Typically comes with a 2000 mAh Li-ion battery, providing roughly 9 to 12 hours of active use.
• Audio: Equipped with an AMBE+2 digital vocoder for clear digital audio. 

Programming

While the MD-380 allows basic front-panel configuration for frequencies and tones, advanced digital features (like assigning DMR talkgroups and contact lists) require PC programming. 

• Software: Requires the free TYT CPS (Customer Programming Software) for Windows.
• Cable: Requires a specific TYT USB programming cable (often uses a standard Kenwood 2-pin connector on the radio end). Note that this software is not natively supported on Mac computers. 

For a complete breakdown of the radio's features, menu options, and everyday functionality:

 

1.  TYT MD-380 - Miklor   Click HERE

2.  TYT MD-380 - Miklor Review   Click HERE

3.  TYT MD-380 - Radiosification Video   Click HERE

 

So far you wrote nothing about the out of ordinary about this radio!   That how it is.  I have never seen the need to purchase a radio with all the bells and whistles that never gets used and I do not buy a radio with the intend that I might use the bells and whistles some day.  O! and I do not have anything against bells and whistles.  My motto is to purchase a practical KISS  radio that is upgrade-able if it ever becomes necessary.  Enough of this.  Let's get to the upgrading of the TYT MD-380 radio.  

 

Thanks to the ingenuity of a few fellow radio amateurs for coming up with firmware that will "revolutionize" the MD-380. There are several different firmware upgrades available.

 

WARNING:  Please use the correct firmware for your specific radio.  I used the following tutorial to upgrade my MD-380,  available HERE.  I would suggest further reading for complete documentation with graphics of the added features available HERE. [PDF]  

I installed the following firmware for my TYT MD-380:   MD-380Toolz Ver  1 April 2018 CP Ver - V 01.37. 

The software builds upon the original custom open-source firmware project for the Tytera MD-380, which was reverse-engineered and developed by Travis Goodspeed (KK4VCZ) and his counterparts in the amateur radio community. 

MD380Tools is  custom, open-source firmware and a software toolkit designed for the TYT MD-380 (and similar DMR radios). It bypasses the limitations of the factory firmware, providing you with highly requested features like Promiscuous Mode (listening to all talk groups on a timeslot), full digital contact list storage, a microphone volume meter, and customized background images. 

Key Features

• Full Database Support: Allows you to load the complete global DMR user database so the radio displays the caller's name, callsign, and location. 
• Promiscuous Mode: Bypasses Talk Group restrictions so you can monitor all traffic on your current frequency, color code, and timeslot without needing to program specific groups. 
• Custom Tweaks: Adds features like a visual microphone volume meter, screen customization, custom boot screens, and backlight timeouts. 

Requirements & Preparation

Before flashing your radio, you will need:

1. Programming Cable: The standard USB programming cable that comes with the MD-380.
2. Firmware File: The open-source patching tools, which are officially maintained via the Travis Goodspeed MD380Tools GitHub Repository.
3. Backup: Use your standard MD-380 CPS (Customer Programming Software) to read your radio and save your current codeplug (radio settings and channels) to your computer before attempting any updates.

Installation & Flashing

Note: Installing custom firmware carries a small risk. Always ensure your radio is fully charged and the USB cable is not disturbed during the flash.

Further information on upgrading the TYT MD-380 is available HERE and HERE. 

Having paid less that 1K for this radio and upgrading it with the firmware MD-380Tools resulted in a very useful DMR Radio that I use daily to excess / monitor the ZS1I DMR Repeater in Mossel Bay.  I love this radio and I am sure that many others feel the same.

 

There you have it changing a budget and fairly aged DMR into a very useful DMR Radio.  Finally I do have amateur radio radios and I use them more frequent than some might think.  No pun intended!  As said before I like to use what I have available at the time for a specific purpose.

 

Images:  Click on images for larger view.

 

 

Chronological organized list of every terminal command used to diagnose, configure and secure ASL3 to Mumble Bridge (Part 4)

Here is the complete, chronologically organized list of every terminal command I used throughout this build to diagnose, configure, and secure the ZS1I AllStarLink 3 to Mumble Bridge.

1. Service Control & Restart Sequence

These commands were used to cleanly clear hung socket ports, reload system profiles, and restart the core components of the radio-to-Mumble link.

bash

# Restart the core AllStarLink 3 Asterisk telephony engine
sudo systemctl restart asterisk

# Stop the Asterisk engine to clear stuck configurations
sudo systemctl stop asterisk

# Force kill any hidden or orphaned background Python script processes
sudo killall -9 python3

# Reload systemd when changes are made to background service files
sudo systemctl daemon-reload

# Enable the bridge service to automatically launch on system boot
sudo systemctl enable mumble_bridge.service

# Start the background bridge service link
sudo systemctl start mumble_bridge.service

# Stop the background bridge service link
sudo systemctl stop mumble_bridge.service

# Force-restart the background bridge service link to load code updates
sudo systemctl restart mumble_bridge.service

Use code with caution.

2. Manual Testing & Execution

Used to run the Python script interactively in the terminal window to see real-time error logs and connection confirmations.

bash

# Run the Mumble bridge script manually in foreground console mode
python3 /opt/Analog_Bridge/mumble_bridge.py

Use code with caution.

3. Log Inspection & Troubleshooting

Used to view the live system journals to trace errors like the audio tracking state exceptions.

bash

# View the last 50 lines of the bridge log and follow new messages live
sudo journalctl -u mumble_bridge -n 50 -f

# Follow the live output stream logs of the bridge script
sudo journalctl -u mumble_bridge -f

# View the last 20 lines of the bridge script history logs
sudo journalctl -u mumble_bridge -n 20

Use code with caution.

4. Asterisk CLI Console Management

Used to log directly into the running Asterisk core to watch node registrations and verify channel properties.

bash

# Access the live Asterisk running console interface
sudo asterisk -r

# Enter the Asterisk console with maximum verbosity enabled for packet tracking
sudo asterisk -vvvvr

Use code with caution.

5. Network Diagnostics & Packet Sniffing

Used to discover the true 352-byte packet length structure and track down why your phone's audio was originally dropped [2026-06-07 15:52:20.811].

bash

# Update the system repository list to fetch diagnostic tools
sudo apt update

# Install the tcpdump network packet analysis utility
sudo apt install -y tcpdump

# Snoop loopback traffic on port 33001 to view audio frames coming FROM Asterisk
sudo tcpdump -i lo udp port 33001 -XX

# Snoop loopback traffic on port 35001 to view audio frames going TO Asterisk (limited to 5 packets)
sudo tcpdump -i lo udp port 35001 -XX -c 5

# Snoop loopback traffic on port 35001 continuously to verify phone mic streaming activity
sudo tcpdump -i lo udp port 35001 -XX

Use code with caution.

6. Firewall & Security Configuration

Used to check and explicitly open up network pathways on your host computer for Mumble traffic.

bash

# Explicitly authorize UDP packets through the Linux firewall on port 64738
sudo ufw allow 64738/udp

# Explicitly authorize TCP packets through the Linux firewall on port 64738
sudo ufw allow 64738/tcp

# Reload the firewall configuration table to lock in the open port rules
sudo ufw reload

Use code with caution.

7. File System, Permissions, & Script Automation

Used to create the automatic night backup files and schedule them inside the system clock tracker.

bash

# Open and edit the system service runner definition file
sudo nano /etc/systemd/system/mumble_bridge.service

# Open and edit the main operational Python script file
sudo nano /opt/Analog_Bridge/mumble_bridge.py

# Create the automated evening script backup utility file
sudo nano /opt/Analog_Bridge/backup_bridge.sh

# Make the backup shell script executable so the system can run it
sudo chmod +x /opt/Analog_Bridge/backup_bridge.sh

# Execute the backup script manually right now to create an immediate backup copy
sudo /opt/Analog_Bridge/backup_bridge.sh

# Open the root system task automation scheduler to add the 17:00 execution rule
sudo crontab -e

Use code with caution.

8. Linux Mint Desktop User-Space Audio Control

Used to reset your computer's sound graph context and unlock hidden system volumes when configuring the client app.

bash

# Reset and restart PipeWire, PulseAudio emulation, and WirePlumber audio managers
systemctl --user restart pipewire pipewire-pulse wireplumber

# Launch the PulseAudio Volume Control graphical matrix panel
pavucontrol

# Launch the low-level kernel hardware command-line audio mixer
alsamixer

Use code with caution.

---

You now have a complete index of every command used in this project that will enable you to successfully install and setup your own ASL3 to Mumble Bridge.