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Showing posts with label Amateur Radio. Show all posts
Showing posts with label Amateur Radio. Show all posts

Friday, July 17, 2026

Is Social Media killing amateur radio on-the-air activity?

 

In a recent discussion with a fellow radio amateur we discussed the use of WhatsApp, Telegram and even Facebook as a means of forwarding messages, images and discussing general amateur radio content.  And then we ask why is there so little activity locally on the amateur radio bands.  In the past before social media we "forward" messages, images and related discussions by means of voice/digital communications on HF, VHF and UHF radio.  The new trend to use social media instead of amateur radio has a big impact on HF, VHF and UHF activity.  Do we rather use social media then the amateur radio bands?  

I know that certain matters cannot be discussed on the air and for that purpose social media can be quite useful.  However we need to be careful that we do not use social media more that amateur radio for amateur radio related matters.

Questions that we would have asked in the past on air or even discuss are now being asked on social media.  Who can still remember how we used Packet Radio to ask questions and learn from answers.  Are we shooting ourselves in the foot?

When it comes to using the amateur radio bands I certainly think that we use social media much more than the amateur radio bands. If this trend continues we will have no leg to stand on, once our frequency spectrum comes under threat.  I would also like to warn again of amateur radio getting too secluded and group bound. 

Unity creates strength but I get the idea that we are becoming to fragmented and group bound. We really need to guard that we do not become our own worst enemy when it comes to the above matters. I might be completely out of line here but feel that it is necessary that we take note of the above. 

Finally I would like to encourage radio amateurs to use the amateur radio bands even if it is just for a good old rag-chew.  At least that way we keep the bands occupied and active.  

Social media does have a place in amateur radio and can be useful in some instances.  I am not against using social media for certain amateur radio matters but our main focus should be to use the amateur radio bands more than social media unless we do not care that we can loose some of our bands in future due to inactivity.

Amateur Radio should be our first choice when communicating with our fellow radio amateurs.  Be smart..... rather use Amateur Radio instead of Social Media.

PS/  Don't shoot the messenger.  Rather give the above a thought and decide if it is true or false or maybe! 

Wednesday, July 15, 2026

South Africa's own Oscar- DMR 1 Satellite. Will this DMR Satellite ever go to Space?


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

I wrote several articles in the past where I refer to innovation in Amateur Radio.  This morning a thought came to mind on why is there currently not a satellite with a DMR Transponder (repeater) up in space?  I was trying to think "out of the box" and look at ways and means to turn my thoughts into reality, if there is such a possibility.

Thinking "out of the box" is absolutely a great way to approach innovation in amateur radio.  Amateur Radio has a rich history of development driven entirely by amateurs experimenting with limited resources and unique constraints. 

However, true innovation in this hobby relies on a balance between unconventional thinking and foundational science. 

Why Out-of-the-Box Thinking Works

  • Resourcefulness: Limited power regulations and frequency bands force you to find clever ways to maximize efficiency.

  • Historical Precedent: Amateurs invented weak-signal digital modes (like FT8) and bounce signals off the moon (EME) because someone asked "what if?"

  • Cross-Pollination: Bringing concepts from computing, machine learning, or material science into radio often yields breakthrough results.

The Innovation Blueprint in Amateur Radio

To make your creative ideas successful, pair your out-of-the-box thinking with these structured approaches:

  • Master the Fundamentals: You must understand Maxwell's equations, wave propagation, and circuit design to break the rules effectively.

  • Identify Real Constraints: True innovation solves a specific problem, such as reducing noise, shrinking antenna size, or bridging communication gaps during disasters.

  • Iterate and Test: Build prototypes, collect data, and use antenna analyzers or software simulation tools to prove your theories.

  • Share with the Community: Amateur radio thrives on open-source collaboration. Presenting your ideas on forums, Git repositories, or at club meetings helps refine them.

Prominent Areas Needing Innovation

If you are looking for modern challenges to apply your creativity, focus on these emerging sectors:

  • AI and Machine Learning: Using neural networks for predictive propagation filtering or automated signal decoding in dense noise.

  • Alternative Materials: Experimenting with meta materials, fractal geometry, or everyday conductive liquids for stealth antenna designs.

  • Digital Signal Processing (DSP): Developing open-source algorithms to extract ultra-weak signals from high-noise urban environments.

  • Green Energy Integration: Creating ultra-efficient, off-grid solar or kinetic power management systems for remote field operations.

Now reading the above my thoughts ran away with me regarding a DMR transponder (repeater / beacon / node / hotspot) payload on a South African satellite.  Can it be done and is it possible to communicate using  DMR via a satellite?  Is there a satellite specifically named "Oscar-DMR 1" in existence or being built in South Africa's space programme or amateur radio history. Currently this type of communications is not possible.

If you are waiting for a homegrown South African satellite or an OSCAR (Orbiting Satellite Carrying Amateur Radio) series spacecraft to launch, here is the factual reality of what has actually happened and what is currently in progress.

The Real South African Satellites

South Africa has already successfully launched multiple satellites. If you are looking for local aerospace achievements "seeing the daylight," they have already made it to space: 

  • SUNSAT (SO-35): Launched in 1999, SUNSAT was South Africa's very first satellite, built by Stellenbosch University. Critically, it carried an amateur radio payload and was officially designated as OSCAR 35 (SO-35) by AMSAT. It saw plenty of daylight before its mission ended. 

  • ZACUBE-1 & ZACUBE-2: Developed by the Cape Peninsula University of Technology (CPUT). ZACUBE-1 (TshepisoSAT) launched in 2013, and ZACUBE-2 launched in 2018. 

  • MDASat-1 Constellation: In January 2022, South Africa successfully launched a three-nanosatellite constellation via a SpaceX Falcon 9 rocket. These operational maritime domain awareness satellites track shipping traffic off the South African coast. 

ZS1I created the fictional "DMR 1" Satellite Name 

The term DMR stands for Digital Mobile Radio, which is a widely popular land-based digital protocol used by radio enthusiasts and businesses across South Africa. 

  • Terrestrial, Not Space: Amateur radio operators in SA heavily utilize the South Africa DMR Repeater Network. This network relies on ground-based repeater towers, not dedicated South African "DMR satellites." 

  • Conflation with Commercial Satellites: You may be thinking of commercial mobile satellite services or push-to-talk satellite radios that interface with DMR-style dispatch systems on the ground. 

Future South African Space Missions

If you are wondering about the next major government-backed leap into orbit, the Department of Science and Innovation has active plans: 

  • National Communication Satellite: The government has been exploring multi-billion-rand plans to acquire or launch a dedicated communications satellite to bridge the digital divide and reduce reliance on international space entities.  However this look like a very "far in the future" project with many logistical and financial issues to first solve.

  • Deep Space Ground Tracking: While not a satellite itself, South Africa broke ground on a massive, state-of-the-art Deep-Space Ground Station in Matjiesfontein (Karoo), built in partnership with NASA to track future lunar missions. 

Sadly you cannot work DMR (Digital Mobile Radio) directly through orbiting amateur radio satellites.  Hopefully by means of innovation in technology my thought on building such is satellite is not far fetched and will not forever just be a thought.  In South Africa building such a satellite will be problematic but that is a topic for another time.

Let's see why this can or cannot currently be implemented.  

You can absolutely build a physical DMR repeater and launch it into orbit on a satellite. However, doing so introduces a severe physics and timing challenge that standard DMR protocols are not designed to handle. 

The core issue is the speed of light and the Doppler effect.

The Timing Problem (TDMA Breakdown)

DMR relies on TDMA (Time Division Multiple Access). It divides a single frequency channel into two distinct time slots (Slot 1 and Slot 2). 

  • The Rule: Each radio must transmit in an incredibly precise window—exactly 30 milliseconds long.

  • The Margin: The standard protocol only accounts for standard terrestrial distances, leaving a guard timing buffer of about 1.25 milliseconds to handle propagation delay. 

When a satellite is orbiting overhead (even a Low Earth Orbit, or LEO satellite at ~500 km), the distance from the ground station to the spacecraft changes continuously and rapidly. Because the radio waves must travel hundreds of kilometers to space and back, the propagation delay exceeds that 1.25 ms guard window.

Consequently, your radio's packet arrives late, shifts out of its slot, and bleeds into the adjacent time slot. This completely breaks the synchronization, causing the repeater's onboard computer to reject the handshake. 

The Frequency Problem (Doppler Shift)

DMR uses 4FSK digital modulation. It relies on precisely mapping four distinct, narrow frequency shifts to represent binary data. 

Because a LEO satellite travels at roughly 27,000 km/h, the frequency shifts dramatically as it approaches and moves away from you. This Doppler shift warps the digital signal. While a human ear can decode an uncorrected analog FM signal through a bit of static, a digital DMR modem will see the warped 4FSK signal as corrupted gibberish and refuse to decode it. 

How to Make a Space-DMR Repeater Work

If an amateur radio group or space agency wanted to make a true DMR satellite work, they would have to implement one of two workarounds:

  1. Modify the Radio Firmware (Software Solution)
    The ground station's DMR radio would need custom firmware capable of predicting the satellite's exact orbit. The radio would then have to continuously alter its timing (transmit early or late to hit the slot perfectly) and automatically adjust its frequency to cancel out the Doppler shift in real-time.
     

  2. Put the Spacecraft in a Geostationary Orbit (Hardware Solution)
    If you put the DMR repeater on a geostationary satellite (35,786 km above Earth), the satellite remains stationary relative to the ground. This eliminates the Doppler shift entirely. While the time delay would be much larger, it would be
    constant, allowing engineers to build custom terrestrial radios with a massive, fixed timing buffer specifically for space.
     

Consolation Prize 

There is currently a "consolation prize" on how you can use your DMR Radio to connect to satellites indirectly.

You can use your DMR radio to connect to satellites indirectly by talking through an MMDVM hotspot (or a local digital repeater) connected to the internet. From there, your signal is routed to space through a commercial geostationary satellite (such as QO-100) using an up/down converter, a dish, and an SDR (Software Defined Radio). 

Unlikely that a dedicated amateur satellite named "Oscar - DMR 1" will be built in South Africa

It is highly unlikely that a dedicated amateur satellite named "Oscar - DMR 1" will be built specifically for standard DMR voice communications in South Africa. While amateur radio organizations like AMSAT constantly develop new spacecraft, standard commercial DMR protocol is fundamentally incompatible with the physics of Low Earth Orbit (LEO) satellites.

The Geostationary Exception, there is hope!! 

The only way a true DMR transponder could work in space is on a Geostationary (GEO) satellite like QO-100. Because GEO satellites remain completely stationary relative to the Earth's surface, there is zero Doppler shift or changing propagation delay. While there is no official "Oscar - DMR 1" payload planned, experimental digital voice links are routinely tested via GEO transponders using specialized ground stations.  More on this in a future article once I put on my "out of the box" and "innovation" hat.

Was this article a waste of time?  NO definitely not.  I now have more questions than answers that I will be looking into.

ED. This article was compiled by ZS1I with the assistance of AI. 

How to automatically Connect and Disconnect an AllStar3 Node to another AllStar Node


Here is a short and easy method on how to connect and disconnect an AllstarLink 3 (ASL 3) node on a schedule.  You need to leverage the ASL3 asterisk CLI tool (asterisk -rx) inside two basic bash scripts. Then, you map those scripts to system execution times using Linux's built-in crontab utility.  

Note:  I know there are more than one way to effect these connections but here I concentrate on the newcomer to Linux and ASL3.

You will create two lightweight bash scripts that sends a command to your local Asterisk instance telling it to connect or disconnect to your target node at specific times.  To instruct  Linux to run the scripts automatically at specific times we will be using the cron tasks scheduler utility.

Let's get started.

Prerequisites: Finding Your Node Numbers

Before starting, write down your two node numbers. You will need them in the steps below:

  1. Your Local Node Number: The number assigned to your physical AllStarLink 3 hotspot or server.

  2. The Target Node Number: The number of the remote node, reflector, or hub you want to connect to.


Step 1: Open Your Node Terminal

  1. Open your terminal program (like PuTTY on Windows, or Terminal on a Mac).

  2. Log into your AllStarLink 3 node using your username and password.

  3. You should see a command prompt waiting for your input (usually ending with a $ sign).


Step 2: Create the Morning Connection Script

We will use a basic text editor inside Linux called nano to create the morning connection command.

  1. Type the following command to create a new file named connect.sh and press Enter:

    bash

    sudo nano connect.sh

  2. A blank screen will open. Copy the text below, but replace <YOUR_NODE> and <TARGET_NODE> with your actual node numbers. Do not include the < > brackets.

    bash

    #!/bin/bash
    /usr/sbin/asterisk -rx "rpt fun <YOUR_NODE> *3<TARGET_NODE>"

    Example of what it should look like if your node is 1234 and the target is 5678: /usr/sbin/asterisk -rx "rpt fun 1234 *35678"

  3. Save and Close the file:

    • Press Ctrl + O on your keyboard (this means "Write Out" / Save).

    • Press Enter to confirm the file name.

    • Press Ctrl + X to exit the text editor and return to the main screen.

  4. Give Permission to Run: Linux blocks files from running automatically until you give them permission. Type this command and press Enter:

    bash

    sudo chmod +x connect.sh


Step 3: Create the Evening Disconnection Script

Now, we will do the exact same thing to create the command that disconnects your node.

  1. Type the following command to create a new file named disconnect.sh and press Enter:

    bash

    sudo nano disconnect.sh

  2. Copy and paste the text below, making the exact same node number replacements as before:

    bash

    #!/bin/bash
    /usr/sbin/asterisk -rx "rpt fun <YOUR_NODE> *1<TARGET_NODE>"

    (Note: The *3 changed to *1, which tells AllStarLink to disconnect instead of connect).

  3. Save and Close the file:

    • Press Ctrl + O

    • Press Enter

    • Press Ctrl + X

  4. Give Permission to Run: Type this command and press Enter:

    bash

    chmod +x disconnect.sh


Step 4: Find Your Secret "Home Path"

Linux needs to know the exact folder path where your scripts live so it can find them later.

  1. Type this command and press Enter:

    bash

    pwd

  2. It will print out a path on your screen. It will look something like /home/admin or /root.

  3. Write this down exactly as it appears. We will use this in the final step.


Step 5: Schedule the Automation (04:00 to 20:00)

We will now use the Linux calendar tool called crontab to schedule your scripts at 04h00 and 20h00.

  1. Type this command to open the scheduler and press Enter:

    bash

    crontab -e

    (If Linux asks you to choose an editor, press 1 and hit Enter to choose nano).

  2. Use the arrow keys on your keyboard to scroll all the way down to the very bottom of the file.

  3. Paste the following two lines at the bottom. Replace /home/yourusername with the exact path you wrote down in Step 4:

    text

    0 4 * * * /home/yourusername/connect.sh >/dev/null 2>&1
    0 20 * * * /home/yourusername/disconnect.sh >/dev/null 2>&1

    • How it works: The 0 4 means Minute 0 of Hour 4 (04h00). The 0 20 means Minute 0 of Hour 20 (20h00 in 24-hour military time).

  4. Save and Close the file:

    • Press Ctrl + O

    • Press Enter

    • Press Ctrl + X

The terminal will say  crontab: installing new crontab

Your node will now automatically connect every morning at 04h00 and cleanly disconnect every evening at 20h00! 

Inside crontab -e , you can also use three-letter text abbreviations instead of numbers for the days of the week if it is easier to remember (e.g., SUN, MON, TUE, WED, THU, FRI, SAT).

For example, a weekend-only entry can look like this:  0 4 * * SAT,SUN

Lets add a bit of "meat" to the above method of connecting and disconnecting an ASL3 Node to another AllStar Node.

An automated system to connect and disconnect specific nodes at different times and days

This step-by-step guide will walk you through setting up an automated system to connect and disconnect specific nodes at different times and days using cron and Bash scripts.

Overview of How It Works

Instead of creating separate files for every single node, we use one connection script and one disconnection script.

We pass the specific node ID (like 49355 or 647030) as an "argument" from the scheduler (cron). The script reads that number, plugs it into your connection command, and executes it.

[cron scheduler] ──(sends node ID)──> [connect.sh] ──> Executed for that node only

Step 1: Create the Automation Scripts

We will place these scripts in a folder called scripts inside your user's home directory.

1. Create the Directory

Open your terminal and run:

Bash

mkdir -p ~/scripts

2. Create the Connection Script

Create and open a new file called connect.sh:

Bash

nano ~/scripts/connect.sh

Paste the following code inside it:

Bash

#!/bin/bash

# 1. Check if the user (or cron) forgot to provide a node number
if [ -z "$1" ]; then
    echo "ERROR: No node specified. Usage: $0 <node_id>"
    exit 1
fi

# 2. Assign the argument to a readable variable
NODE_ID=$1

echo "=========================================="
echo "STARTING CONNECTION: Node $NODE_ID"
echo "Timestamp: $(date)"
echo "=========================================="

# 3. YOUR CONNECTION COMMAND GOES HERE
# Replace the line below with your actual command. 
# Use $NODE_ID wherever the node number needs to go.
echo "Connecting to node $NODE_ID now..."

# Example placeholder (Uncomment and modify if using something like OpenVPN):
# openvpn --config "/home/$USER/vpn/${NODE_ID}.ovpn"

3. Create the Disconnection Script

Create and open a new file called disconnect.sh:

Bash

nano ~/scripts/disconnect.sh

Paste the following code inside it:

Bash

#!/bin/bash

# 1. Check if the user (or cron) forgot to provide a node number
if [ -z "$1" ]; then
    echo "ERROR: No node specified. Usage: $0 <node_id>"
    exit 1
fi

# 2. Assign the argument to a readable variable
NODE_ID=$1

echo "=========================================="
echo "STOPPING CONNECTION: Node $NODE_ID"
echo "Timestamp: $(date)"
echo "=========================================="

# 3. YOUR DISCONNECT COMMAND GOES HERE
# Replace the line below with your actual command.
echo "Disconnecting node $NODE_ID now..."

# Example placeholder:
# killall openvpn

4. Make the Scripts Executable

Linux security requires you to explicitly grant permission for scripts to run. Execute this command in your terminal:

Bash

chmod +x ~/scripts/connect.sh ~/scripts/disconnect.sh

Step 2: Test Your Scripts Manually

Before letting the automation take over, test that the scripts successfully receive your node variables. Run these commands in your terminal:

Bash

~/scripts/connect.sh 49355
~/scripts/disconnect.sh 49355

You should see an output in your terminal confirming it attempted to connect to node 49355.

Step 3: Configure the cron Schedule

cron is the built-in Linux background service that runs tasks at specified times.

1. Open the Cron Editor

Run the following command to edit your personal schedule:

Bash

crontab -e

If it asks you to choose an editor, press 1 for nano (the easiest one).

2. Add Your Node Schedules

Scroll to the very bottom of the file and paste the following lines exactly as shown.

Important: We use ~/scripts/... to point to your home directory, and save logs to your home folder (~/cron_node_...log) to prevent any permission issues.

Code snippet

# ===================================================================
# NODE 49355 SCHEDULE (Fridays)
# ===================================================================
# Connect at 5:00 AM on Friday (Day 5)
0 5 * * 5 /bin/bash /home/USER/scripts/connect.sh 49355 >> /home/USER/cron_49355.log 2>&1

# Disconnect at 8:00 PM (20:00) on Friday (Day 5)
0 20 * * 5 /bin/bash /home/USER/scripts/disconnect.sh 49355 >> /home/USER/cron_49355.log 2>&1


# ===================================================================
# NODE 647030 SCHEDULE (Saturdays)
# ===================================================================
# Connect at 6:00 AM on Saturday (Day 6)
0 6 * * 6 /bin/bash /home/USER/scripts/connect.sh 647030 >> /home/USER/cron_647030.log 2>&1

# Disconnect at 7:00 PM (19:00) on Saturday (Day 6)
0 19 * * 6 /bin/bash /home/USER/scripts/disconnect.sh 647030 >> /home/USER/cron_647030.log 2>&1

3. Critical Adjustment: Fix the Username Path

cron requires absolute system paths to be completely reliable.

  1. In the text you just pasted, look for /home/USER/.

  2. Replace USER with your actual Linux account username. (If your username is johndoe, the path becomes /home/johndoe/scripts/...).

4. Save and Exit

  • If using Nano: Press Ctrl + O then Enter to save.

  • Press Ctrl + X to exit back to the normal terminal.

You should see a message saying: crontab: installing new crontab.

Step 4: Troubleshooting & Monitoring Logs

Because cron tasks run invisibly in the background, the entries above are designed to output everything they do into dedicated text files so you can check on them.

To see if your scripts are running smoothly or to view errors, read your log files using the cat command:

Bash

cat ~/cron_49355.log
cat ~/cron_647030.log

If you ever want to add a third or fourth node in the future, you do not need to modify your scripts at all. Simply open crontab -e again and add two new lines with the new node number and your preferred times.

Comment:  Zayn ZR3VO from Orania is currently using this automated connect and disconnect method and he indicated that it is working well.

Images:  (Click on images for larger view.) 

 

Saturday, July 11, 2026

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!!

Is Social Media killing amateur radio on-the-air activity?

  In a recent discussion with a fellow radio amateur we discussed the use of WhatsApp, Telegram and even Facebook as a means of forwarding ...