My current thoughts on the Meshtastic and Meshcore "hype" and why I prefer AREDN!

Why all the hype about Meshtastic and Meshcore nowadays in Amateur Radio?  Is there really a hype in this regard?   To answer the hype question I must honestly answer yes, if you look around you will literally find hundreds of videos and articles in this regard. I have been watching and reading quite a bit regarding these two entirely different open-source software projects since Meshtastic started a few years ago and Meshcore joined in later.  A few local radio amateurs in the George area setup a few nodes and some information were exchanged amongst radio amateurs in the area.  I looked into the feasibility of setting up such a mesh network at the time but came to the conclusion that it will be of no benefit to me or the general public as I was already running a AREDN ( Amateur Radio Emergency Data Network) Network on 2.4 Ghz and 5.8 Ghz in the Mossel Bay area.  The benefits of an AREDN Mesh Network clearly over shadowed Meshtastic and Meshcore.   But you are talking a lot of rubbish now!  What about emergency communications?  Surely Meshtastic and Meshcore can be used during a disaster to assist in emergency communications?

Let me explain a few reasons why I decided not to go the Meshtastic or Meshcore route and let me make it very clear that I an not against any of these open source projects.  I might in future consider to join both these open source projects depending on further development of the software, hardware and a substantial price drop etc.

Here is a few reasons why I rather use AREDN: (I will only provide a cryptic explanation.)

• An AREDN (Amateur Radio Emergency Data Network) system is a high-speed, self-discovering wireless mesh network built specifically by and for amateur radio operators using commercial off-the-shelf radio hardware. It is fully open source.  Its source code, custom Linux-based firmware, and build tools are publicly available on GitHub under the GPL-3.0 license. This allows amateur radio operators to inspect, modify, and contribute to the network's software development.
• I already have all the equipment setup for the AREDN Mesh Network including a fully functional web-site and server. It can connect to the ZS1I AllStar Hub Network and DMR Repeater and Bridge Network even when the Internet goes down.  I can connect  AREDN to any repeater, radio link, digital radio link etc for emergency communication use.
• The AREDN Mesh Network has already been successfully used during the Knysna Fire Storm in 2017 and proved that it is up to the task of providing voice, video, image, text, email and data communications. (forwarding and storage)
• The AREDN Mesh Network can be split into several mesh networks.  For example the 2.4 Ghz network can be opened for public use and a person only needs his cellphone (without a cellular network connection) to communicate to the AREDN 2.4 Ghz Network or a node in his/her vicinity.  This will allow the public important direct access communications during a disaster.  Same as Meshtastic and Meshcore but with more power and directional gain antennas for AREDN.
• Video / Images / Email and Data Communications are vital during a disaster.  AREDN can provide these with ease having great bandwidth etc. One can even "tap" into existing CCTV Cameras that might be offline or install portable cameras on tripods if there is a need for it.
• Now let's look at the cost.  For what I am getting from a Meshtastic or Meshcore node / repeater I might just as well use commercial off-the-shelf radio hardware for AREDN which is found in abundance secondhand or sometimes as give-a ways.   On several occasions I received freebee's which I used as AREDN Mesh Nodes.  Older and redundant antennas for 2.4 Ghz and 5.8 Ghz can be obtained free from many Internet Service Providers and the general public.  All the antennas I currently use was free of charge. 
• I hear you say but the Meshtastic and Meshcore nodes are small and compact and can be used with solar battery power.  Yes the form factor is small and compact but have a look at the AREDN web-site to see how small and compact some of the AREDN nodes are and they can also use solar battery power.
• RF Power Output -  As radio amateurs we are permitted to use higher power than any of the Meshtastic or Meshcore nodes can provide.  Higher power is not always the answer but it is available if needed.  Always just use enough power that is needed to make a reliable connection / contact.  I am not a QRO operator by any means but it is good to know that one can use higher power if needed.
• Interconnection of AREDN to other amateur radio equipment and networks.  This is were AREDN is shining and I have touched on this earlier.  Bridging / interconnection / linking call it what you want has become very important in this day and age.  On many occasions in the past I have talked about the  disparity in radio communications among emergency responders—often called a lack of interoperability—occurs due to incompatible hardware frequencies, differing agency protocols, and decentralized funding. Police, fire, and medical teams often use completely separate networks that cannot talk to each other directly during a crisis.  
• In my opinion AREDN is a far better and trustworthy mesh network system.  Agree there are also some areas that need to be upgraded but the AREDN Team is working tirelessly to release software and hardware updates to keep AREDN in the loop and relevant today.

Finally:  I am not against Meshtastic or Meshcore.  Each one has it's own rightful, place and uses and I think that it is wonderful technology that needs to be developed even further.  So before I jump on the "hype wagon" several changes and new features need to be released to make it an attractive option for me to use as an emergency communications tool. By all means feel free to follow the Meshtastic, Meshcore or AREDN "route".  Let's see what the future will bring in this regard.

Setting up an auto Connect and Disconnect cron job in ASL3 to automatically connect one node to another node.

Some time ago I wrote and article on how to easily and automatically connect and disconnect an AllstarLink 3 (ASL 3) node on a schedule.  In that article you needed 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. 

The article is available HERE.

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

In this article I will provide an even simpler method to automatically connect and disconnect one node to another node.  We going to setup a cron job in ASL3 to automatically connect to other nodes.  Just a word of caution - you still need to monitor your dashboard as "murphy" can cause havoc at any time.  Please do monitor your dashboard or your radio for any connection issues. 

To set up an automatic connect and disconnect schedule on AllStarLink 3 (ASL3), you can execute Asterisk CLI commands directly inside the system's crontab. This method bypasses the older built-in Asterisk scheduler, making it highly reliable and easy to modify.

Follow this step-by-step guide to configure your scheduled connections.

Step 1: Open the System Crontab

Log into your ASL3 node via SSH. Open the root user's cron scheduler using your preferred text editor (like nano) by running:

bash

sudo export EDITOR=nano
sudo crontab -e

Step 2: Add Your Connect and Disconnect Cron Jobs

Scroll to the bottom of the crontab file and add your scheduling strings. Use the following format template:

text

# Structure: Minute Hour DayOfMonth Month DayOfWeek 

/usr/sbin/asterisk -rx "rpt fun <YourNode> <Command><TargetNode>"

Example Schedule:

If your local ASL3 node number is 61234 and you want to automatically join a weekly net on Node 55555 every Monday night:

• Disconnect all active connections at 18:55 (6:55 PM) on Monday:

  text

  55 18 * * 1 /usr/sbin/asterisk -rx "rpt fun 61234 *76"

  (Note: *76 is the standard command to disconnect all links, serving as a clean slate before your net starts).

• Connect to Target Node 55555 at 19:00 (7:00 PM) on Monday:

  text

  00 19 * * 1 /usr/sbin/asterisk -rx "rpt fun 61234 *355555"

  (Note: *3 is the standard link command followed by the target node ID).

• Disconnect from the Target Node at 20:30 (8:30 PM) on Monday:

  text

  30 20 * * 1 /usr/sbin/asterisk -rx "rpt fun 61234 *155555"

  (Note: *1 is the specific link disconnect command). 

Step 3: Save and Verify

1. Save the file in nano by pressing Ctrl + O, then Enter.

2. Exit the editor by pressing Ctrl + X.

3. Verify your entries are correctly loaded into the scheduler by running:

   bash

   sudo crontab -l

Quick Syntax Reference

• Time Format: Crontab requires 24-hour military time.

• Days of the Week: 0 or 7 = Sunday, 1 = Monday, 2 = Tuesday, 3 = Wednesday, 4 = Thursday, 5 = Friday, 6 = Saturday.

• Asterisk Path: Ensure you specify the full path /usr/sbin/asterisk so the cron daemon can find the execution file without environment paths.

Do I need a script file for this to work or will the above suffice?

The crontab lines provided above will work perfectly fine on their own without any external script files. For your goal of a simple but effective method, putting the commands directly into the crontab is the absolute best approach. It keeps your system clean because you do not have to manage, execute-protect, or worry about the file paths of separate script files.

Why this direct method is highly effective:

• Fewer moving parts: The system reads the time, triggers the Asterisk command directly, and connects.

• Easy to modify: If a net time changes, you just run sudo crontab -e and change the numbers in one single file.

• No permission bugs: Running scripts sometimes fails if you forget to make the file executable (chmod +x). Direct cron commands avoid this completely.

The only rule to keep it working:

Just ensure that your node number and DTMF steering prefixes match your rpt.conf file. (For example, if your system uses something other than *3 for connect and *1 or *76 for disconnect, change those prefixes in the crontab strings to match your setup).

Here is an extract, optimized text block for your information.

This is added to the bottom of your crontab using  

sudo crontab -e:

text

# ====================================================================
# AUTO CONNECT & DISCONNECT SCHEDULE FOR NODE 49355
# ==================================================================== 

# SARL BULLETIN (Sunday Morning)
# Connect at 08:00 SAST, Disconnect at 08:30 SAST
00 08 * * 0 /usr/sbin/asterisk -rx "rpt fun 49355 *33373742"
30 08 * * 0 /usr/sbin/asterisk -rx "rpt fun 49355 *13373742"

# AMATEUR RADIO TODAY (Sunday Morning)
# Connect at 09:55 SAST, Disconnect at 11:05 SAST
55 09 * * 0 /usr/sbin/asterisk -rx "rpt fun 49355 *33373742"
05 11 * * 0 /usr/sbin/asterisk -rx "rpt fun 49355 *13373742"

Pro-Tips for Your Setup: 

• Time Zone Check: Ensure your underlying Linux operating system is set to South African Standard Time (SAST) by typing date in the command line. Cron follows the system clock. 

 • The Asterisk *3 and *1 commands: These lines assume your system uses standard Transmit/Receive (permanent or normal) linking prefixes. If you prefer to use Monitor Only (receive only) mode for the Sunday news bulletins so local transmissions don't interrupt the broadcast, change the connection prefix from *3 to *2 (e.g., *23373742). 

Verification Reminder:

After saving the changes, remember to type date into your SSH terminal to make sure your Linux system clock is actually synchronized to local South African time, as cron relies strictly on the system time to execute.

Finally: 

That's it you now have an automated connect and disconnect schedule that will assist you in connecting to other nodes.  Just a reminder to monitor you dashboard to ensure that the setup runs smoothly.

Compliments to the DMR-ZA Net Controller and Participating Stations - "ET phoned home last night during the Net!!"

Image:  ET phoning home, thanks to the DMR-ZA Net! 

Some time ago I "complained" in general about the operating procedures of some of our fellow radio amateurs in South Africa.  Articles  HERE, HERE and HERE. I indicated that ET cannot phone home from certain Nets in South Africa where bad operating practices exist.  This of cause all tongue in the cheek but these blatant transgressions and bad incidents is of great concern, not only to me but many others as well.  However one Net and that is the DMR-ZA Net is showing how it should be done.

Last night I listened to the Net and to Brian ZS5BR, the Net Controller. I would like to complement all those who participated in the Net and in particular Brian ZS5BR who "controlled" the Net.  This is how a net should function and on the forefront was the excellent operating procedures of everybody involved in the Net.  I listen to a few nets and also participate in some nets in South Africa but the DMR-ZA Net's outstanding procedures make it a real pleasure to listen and participate in.  Great practice by all those involved.

No I am not going to go into detail but join this Net on a Tuesday evenings at 19h30 SAST and experience the net for yourself.  The DMR-ZA Net has set the standard of how it should be done.  It took me back to the olden day's where it was of the utmost importance and pride to run a net professionally and using good operating procedures and practices.  

A big thank you to all involved in the DMR-ZA Net - "ET was able to phone home last night thanks to the DMR-ZA Net!! 

How to Install the No-IP DUC on a Raspberry Pi for ASL3 Node 49355

Lets install the No-IP DUC from No-IP but before we do that lets look at No-IP DUC, what it is and where can I obtain more information:

No-IP/DDNS (Dynamic Domain Name System) is a service that associates a domain name with a changing IP address. ISPs often assign dynamic IP addresses, which can be problematic for hosting services such as CurrentWare for a remote setup.

No-IP/DDNS solves this by mapping the domain name to the changing IP address using client software or network device configurations. It ensures consistent access to services by automatically updating the DNS record with the latest IP address information.     

Click HERE to obtain more information about No-IP.

Let's get started! 

Make an account with No-IP and Create Host Name.

You will be able to install No-IP’s Dynamic Update Client on Raspberry Pi in just a few minutes using Terminal. 

Installing the service is simple to do, and requires little knowledge of Linux.

You will need to create a directory for the client software to be installed.

Open Terminal and type the following. After each entry press “Enter“.  

sudo mkdir /home/ZS1I/noip [enter]

ls [enter] (noip will be listed)

cd /home/ZS1I/noip [enter]

After creating the folders for the DUC it is time to download the software.

Within the Terminal window  type the following. After each entry you will press “Enter”.

wget http://www.no-ip.com/client/linux/noip-duc-linux.tar.gz

tar vzxf noip-duc-linux.tar.gz

Next navigate to the directory you created to locate the downloaded files. (/home/ZS1I/noip)

cd noip-2.1.9-1

Now install the program.

sudo make

sudo make install

After typing “sudo make install” you will be prompted to login with your No-IP account username and password. After logging into the DUC answer the questions to proceed. When asked how often you want the update to happen you must choose 30 or more. The interval is listed in minutes, if you choose 30 the update interval will be 30 minutes. If you choose 15 the interval will be 15 minutes.

Please enter the login/email string for no-ip.com  ***********
Please enter the password for user  **********
 

3 hosts are registered to this account.

Do you wish to have them all updated?[N] (y/N)  N

Do you wish to have host [one.ddns.net] updated?[N]

Do you wish to have host [two.ddns.net] updated?[N]

Do you wish to have host [three.ddns.net] updated?[Y]

Please enter an update interval:[30]  30

Do you wish to run something at successful update?[N]

sudo /usr/local/bin/noip2

To confirm that the service is working properly you can run the following command.

sudo noip2 ­-S (Capital “S”)

Notes:

To start Noip2: sudo /etc/init.d/noip2 start [enter]

Test Service: sudo noip2 -S [enter]

Check if No-IP DUC is installed:

1. Modern noip-duc version = sudo noip-duc –version [enter] (49355 not using modern version)

2. Legacy noip2 version = sudo noip2 -S [enter]

Output:

ZS1I@49355:~ $ sudo noip2 -S

No noip2 processes active.

Configuration data from /usr/local/etc/no-ip2.conf.

Account configured for:

host dmrrepeater.ddns.net

host zs1iallstar1.ddns.net

host zs1imumble.ddns.net

Updating every 30 minutes via /dev/eth0 with NAT enabled.

ZS1I@49355:~ $

Quick System-Wide Search:

ZS1I@49355:~ $ sudo whereis noip2

noip2: /usr/local/bin/noip2

ZS1I@49355:~ $

#5 - Amateur Radio News and Announcements (21 July 2026)

Reminder:  Do tune into the DMR-ZA Net this evening at 19h30 SAST

Herewith a list of different equipment / apps and images that cross transmit / receive the DMR-ZA Net on a Tuesday evening. (Click on images for larger view.)

1.  ZS1I 49355 AllStar Hub Network which incorporates Echolink. (ZS1I-R)

2.  DMR / DVSwitch /AllStar Bridge (TG 65522)

3.  ZS1I MMDVM Digital Repeater (TG 65522)

4.  145.550 Mhz Analogue Simplex RF Link Mossel Bay area.

5.  DroidStar / VoxDMR Applications for DMR  TG655

6.  ASL3 to Mumble Bridge PC (Mumble Client) as well as Mobile Phone (Plumble Client) 

7.  BrandMeister - Hoseline Application (PC or Mobile Phone - Receive only.)

8.  DVSwitch Mobile Application (PC or Mobile Phone)

9.   Many Analog-Repeaters and Links are connected to the ZS1I Hub Network on a daily basis.  Some of these analogue repeaters will be connected to the ZS1I Hub Network on a Tuesday evening and they might also be linked to other repeaters country- and world wide.  So why not link up with your local analogue repeater.  You might just be able to connect to the DMR-ZA Net on a Tuesday evening at 19h30 SAST. 

Finally:  There are an abundance of means illustrated above to connect to the DMR-ZA Net on a Tuesday evening at 19h30 SAST.  The DMR-ZA Net is an open net and all radio amateurs are welcome to join / connect to the net.  Brian ZS5BR is the net controller and I would like to thank him for professionally conducting the net each Tuesday evening.  Highly appreciated!! 

Upgrading the ZS1I AllStar Hub Node to the "latest and greatest" firmware currently available.

Image above:  ASL3 Landing Page (Dashboard)  Click on image for larger view.)

"Latest and greatest"  firmware  ......  Huh?  Big deal?   No, but after  9 years of using HamVoip Firmware on the ZS1I AllStar Hub it is time to upgrade to ASL3 Firmware and also to update the Supermon Dashboard. 

Let me just make it very clear.  There is nothing wrong with HamVoip and it served me well, however there comes a time when new firmware does not "play ball" anymore with HamVoip and as I run the Hub I wanted to add new features to the the Hub Node.  Thanks HamVoip, Jim Dixon WB6NIL (SK), David K4FXC, Doug WA3DSP and the rest of the HamVoip Team for creating this wonderful application for Amateur Radio.

Well I upgraded to ASL3 firmware a week ago and has been working on and off on setting up the "new" ZS1I AllStar3 Hub.  I must apologize to many of the stations who during the past few days were disconnected after rebooting the 49355 Node several times.  Sometimes it was necessary to work on the node while stations were connected and this resulted in a few disconnects.

The final switch over took place on the 20 July 2026 and so far the Hub has been running without any issues.  I will make a few changes to the setup of the node and ASL3 firmware and will also be adding 2 x Dashboards to monitor and control several other nodes connected to the ZS1I AllStar Hub Network.  Echolink has been included and is available at ZS1I-R Node 929614.  Other nodes, links, bridges etc. is running great and has been linked to the ZS1I Allstar Hub.  I will in a future posting explain what new features ASL3 brings to the ZS1I Hub Network.

Finally:  If there are any issues please get in touch with me and I will look into them.  I trust that ASL3 will provide a great new service to the many radio amateurs that connect to the ZS1I Hub.

Images:  (Click on images for larger view)

Image above:  Out with the old.  Supermon 6.2+ served me well since 2017.

Image above:  In with the New.   Supermon 8+  Thus far it is running flawlessly.  So many new features and updates. 

Image above:  ASL3 Node Overview. 

 Image above:  AllScan Dashboard for the ZS1I Hub

 Image above:  Allmon3 Dashboard for the ZS1I Hub

ZS1I 40m WSPR Beacon is reeling in stations never spotted before in the Southern Cape

The ZS1I 40m WSPR Beacon is alive with stations never spotted before in the Southern Cape at the QTH of ZS1I.  This is great news and I wonder if this is a change in the winter HF conditions to the start of the Spring / Summer HF conditions?  Well let's see what happens in the next few weeks.  Great to see so much activity and new spotters on 40m WSPR.

 (Click on image for larger view.)

 (Click on image for larger view.)

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! 

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.