Intermittent problems with my Jumbo Digital Radio Hotspot

Image: ZS1I Jumbo Hotspot using a Raspberry Pi 3 b

 

Before I provide more information about the problems I experienced with my Digital Radio Jumbo Hotspot, we need to look at the following: 

Intro:

In the world of DMR, there are two ways to gain access to the now worldwide network. One is a repeater, the other is using a hotspot. Which method is best is determined by several factors. One of the main factors is how far you are from the local repeater. If you are not within range of a repeater, a hotspot may be your only choice.

Both a hotspot and a repeater can be used to connect to a DMR network. So let's take a look at the networks.

The Brandmeister Network is the commonly associated with hotspot operation, while the DMR-MARC network is associated more with repeater operation.

What is a digital radio hotspot?

“Hotspots” are digital-only, small, low-power radio transceivers that connect to reflectors on the network. They are simple “gateways” that take the digital data from a radio and process it so that it may be streamed on the Internet.  They are purely digital and have no ability to process analog audio – that’s all done by the radio!

Do you need a hotspot for DMR?

A prerequisite for participation besides an assigned DMR-ID is the availability of a DMR-capable repeater within range. If there is no repeater in your range, you have the possibility to get the relay "in your own four walls" with the help of a "hotspot".

I am not going to go into full detail here regarding a hotspot.  Die videos underneath provide more than enough information on what a hotspot is and also the different hotspots.

Videos:

What is a Ham Radio Hotspot | Digital Voice Ham Radio - Ham Radio 2.0

 

Build your own DMR/DStar/Fusion hotspot for CHEAP – Dennis AD6DM

 

MMDVM Hotspots - What you need to know - VK4NGA

 

 

Now that we know what a hotspot is and what it is used for, I will provide you with more information on my hotspot before I go into the problems I recently experienced and how I fixed them.

About five years ago I bought my first DMR HT radio.  It is a TYT MD380 UHF Radio and  at the same time I also bought a Hytera MD785G UHF Mobile Radio which I bought secondhand from a radio amateur.  Both these radio were like new but I had one problem.  I did not have a hotspot nor a DMR repeater in my area.  I had to buy a hotspot to be able to utilize both radios for DMR.

I decided to import the hotspot from China as this is where I could source it cheaply.  The MMDVM Hotspot is called a Jumbospot which included a Metal Case, OLED screen and Antenna.

 

Features:

1. High performance 32-bit ARM processor

2. Black metal case

3. Supports DMR, P-25, D-Star and System Fusion

4. Onboard LEDs to show status (Tx, Rx, PTT, Mode)

5. Up to 10mW RF power.

6. Size and Weight：7 x 3 x 2.5 cm and 50g
   

Installation and Setup: 

The only other items I needed was a Pi Zero, SD Card and the Pi-Star Firmware.  These I sourced locally.  To cut it short I installed and plugged everything together and I was up and running in no time.  The hotspot worked like a dream although is was a bit sluggish at boot up.  This I attribute to the Raspberry Pi Zero V1.3.  I later switched to a Raspberry Pi 3b and a 3-D Printed case for the hotspot. The 3b is far quicker than the Zero. It booted in no time. 

Hot plugging because of Loadshedding killed my hotspot:

Everything went well until one day a spat of loadshedding/ caused the Pi to "freeze".  I could not shut down the hotspot (yes it was still running) other than to hot-uplug the power.  This is where all the trouble started and here is a warning:  Never ever hot-plug or unplug your Hotspot Raspberry Pi Power Plug or Ethernet plug.  This can and in my case caused a few nasty issues which I eventually solved after hours of fiddling around and re-installing new firmware.  I also found out the hard way that, do not run your hotspot during loadshedding if you do not have a battery back-up (UPS) and a reliable Internet connection.

Problems and solution:

Lets get to the real problems and the solution.   Last week I decided to install a Raspberry Pi Zero 2 W board as I needed the Pi 3b for another project.  In any way to use a Pi 3b with a Jumbospot is really a waste of resources.  I also decided to install everything in the original metal case.  When I installed the first Pi Zero (V1.3) I saw that the bottom of the Pi PCB was nano micros away from the metal surface of the case.  Way back then I used insulation tape to prevent the PCB from making contact with the metal.  This surely did the trick.  I installed the Pi Zero 2 and the JumboSpot PCB into the metal cabinet.  Screwed everything in place and closed the lid.  Added the antenna and plugged everything in.  Switched on and used the radio to access DMR via the hotspot.  Everything worked great.

After about half an hour I wanted to use the radio on TG91.  I tried to activate TG91 but nothing happens.  The Radio TX and the hotspot TX and RX lights comes on but nothing else.  No TX/RX, audio or OLED Screen activity forthcoming from the hotspot or the radio.  I could however excess the Pi-Star Firmware via SSH and the Dashboard.  BrandMeister also indicated that all is well under My Devices and the Logs did not give any errors.  Rebooting did not result in any change.  I had to shutdown the hotspot and then restart it after about 5 minutes.  After startup the hotspot would work flawlessly for about 5 minutes and then the same problem occurred as discussed supra.  It point blank refuses to work after 5 minutes.  Needless to say I looked for all sorts of things in the firmware that could cause this problem.  I updated and upgraded but the problem remained. I even re-installed an older version and the latest version of the Pi-Star Firmware.  No joy. I tried everything that I found online but to know avail.  The hotspot was like a donkey that did not want to be move.

Well the only choice was to go back to the Pi3 b.  This resulted in further issues.  Now BrandMeister indicate that the password was not recognized or wrong.  The funny part is that in My Devices on the BrandMeister website the connection under the hotspot ID was green and on the main Pi-Star dashboard everything was green that should be green.  I changed the password to a new one.  This also did not resolve the issue.  I decided to ask on the Amateur Radio 101 Telegram Group if anybody experienced the same issue at some stage or the other.  Nope this seems to be a first.  I received a few pointers from Christie ZS4CGR and Curtis ZS6CMO.  It was getting late and I decided to follow the advise of Christie which suggested that it could be the Internet aka loadshedding that caused the problem as he and other experienced intermittent Internet connections on that specific day.

Shutting everything down I decided to call it a day and decided that I would give the hotspot another try early the next morning when the Internet seems to be more reliant.  Before I moved out of the Shack I decided to revert back to the Raspberry Pi Zero 2 and the metal cabinet.  Everything installed I closed the Shack door and went to bed.

Do or die:

Early the next morning around 04h00 I was up and ready in the Shack.  Either it works or it goes to the dust bin or junk box.  Needless to say nothing has changed the problem still remained.  Sitting back in my chair I looked at the metal cabinet and a thought came to mind.  I will remove the lid and fire the hotspot up.  Well nothing happened,  still the same result as the day before, but with a new issue. The OLED Screen would not light-up. It stopped working.  This is now really getting bad.  I shutdown and disconnected all the cables.  Looking at the JumboSpot PCB another thought came to mind. Why would the OLED not light-up as it did the day before. Nothing has changed overnight hardware or firmware wise. I hauled out a magnifying class and started to examine the PCB. 

Joy and Jubilation.....It works!!

All the solder joints and OLED Screen looked fine but when I looked in underneath the OLED Screen PCB from the side a light bulb moment appeared.  Difficult to see I decided to use a small leverage screwdriver to carefully lift the OLED Screen PCB up from the JumboSpot PCB about 2mm in height.  Plugged everything back in and together and started the hotspot.  Well it booted OK and worked fine but what will happen after a 5 minutes time lapse?  Will the donkey attitude still be there.  Time will tell.  Five minutes passed and I anxiously pressed the PTT.  Low and behold the hotspot jumped into action.  After 10 minutes and later 20 minutes the hotspot was still working as it should.  No errors and the donkey was up and running.  Joy at last!!  I checked all the logs for errors but there were none and the hotspot is still up and running now nearly 3 days without any issues.  Problems solved!!

What caused this erratic behavior and errors?

In my opinion the plugging from one raspberry pi to another must have over time caused the OLED Screen PCB to move down a fraction touching the JumboSpot PCB slightly at first and then "killing" it eventually when I moved back to the Pi Zero 2, the evening before the OLED completely "died".  To prevent the OLED Screen PCB from pressing against the JumboSpot PCB I installed two homemade plastic spacers between the two boards.  (See the photo with red circles in this regard)  Thankfully nothing was damaged and all the Pi's, OLED and JumboSpot is working as they should.

Hope this helps somebody that experience the same issues

I hope that this topic might be of assistance to others who might in future experience the same issues as I did.  I would however suggest that you add the plastic spacers when you first install/build the Jumbo Spot Hotspot.  This will save you many hours of fault finding and frustration.  Despite all the issues I must admit that I learned a great deal trying to solve the issues.  Sometimes it is worthwhile when something like this happens as you learn and gain very useful experience on how hotspots work.

Images:  (Click on images for larger view.)

Update 8: The GRHub Network, Mossel Bay now provides Inter-Linking Radio Services

 

I do not have a digital radio or hotspot but would like to play with DMR.  How can I accomplish this?

No problem at all.  You do not need a DMR-, Digital Radio or HotSpot to use the various VHF/UHF digital radio modes.  I am not going to go into detail here as there are already several posts on this Blog that answer this question.  I will however provide the links to these posts if you perhaps missed them:

Another way to use Digital Radio Modes if you do not have an RF Radio = DroidStar 

ZS1I DMR Bridge now permanently linked to the GRHub Network, Mossel Bay

DMR Bridge now active in the Garden Route Area and "test driven" by Majorke ZS5V from KZN.

 

I would however like to provide feedback regarding activity on the ZS1I DMR Talk Group,  ZS1I GRHub Network, the ZS1I DMR Bridge and using DroidStar for VHF/UHF Digital Radio Modes.

NEW!!  ZS1I DMR Talk Group (TG 65511)

I have setup a new DMR Talk Group - TG 65511.  This talk group serves the following purposes:

1.  Permanent Link to the ZS-Link Network and GRHub Network 

2.  Experimental Talk Group for any radio amateur that would like to experiment with DMR

3.  Bulletin Relay Talk Group

4.  General Chat Group

Note:  Please note that if you do use this talk group your broadcast / tests will also be heard on the ZS-Link-, GRHub- and AREDN Mesh Network.

This talk group (65511) is open for any radio amateur to use.  It is NOT there for private use! 

ZS1I GRHub Network

I am grateful to report that the GRHub Network functions very well despite Loadshedding and Internet Outages.  I added several automated services lately to enhance the network. I would also like to thank all those who use and connect to the ZS Link and GRHub Network.  A special word of thanks must go to all the repeater owners/custodians/clubs, RF link stations, node owners and individual network owners who forms the backbone of the ZS Link Network in South Africa. Let's not forget those who work behind the scenes to maintain and extend the ZS Link Network, Repeaters and Nodes. Without your dedication and participation this network would have collapsed long time ago. Activity on the ZS Link Network in South Africa is rife.  I thank you all!!

ZS1I DMR Bridge

This bridge has been a useful addition the the GRHub Network and hopefully to the ZS Link Network.  It is now permanently linked to the network.  The ZS1I DMR Bridge is now the gateway to some who cannot afford to buy a digital radio, hotspot etc or might "want to get their feet wet first."  There are ways and means to use DMR and other digital radio modes without  a radio or hotspot.  I indicated before that you can use your analog VHF/UHF radio to work digital radio modes via the ZS1I DMR Bridge.  I am so grateful to those who made this possible by writing software and creating applications for this purpose.

DroidStar to the rescue!

There are some radio amateurs that does not have radios and equipment to use the digital radio modes.  On the other hand some might first want to play with DMR to see what it is all about and whether it is worth buying such equipment. Well you do not need to buy a digital radio to use the VHF/UHF digital radio modes.  DroidStar came to the rescue! I am grateful to report that DMR activity is daily on the increase in the Southern Cape and other parts of South Africa.

My article available HERE hopefully resulted in creating interest in this regard.  Further information was also made available on the Amateur Radio 101 Telegram Group.  I would like to thank each and every person that provided help and information on this group to assist new users of VHF/UHF digital radio modes.  The Amateur Radio 101 Telegram Group really rocks!  Thank you to all those who post interesting information on this Group.

I would like to welcome the following radio amateurs to the VHF/UHF digital radio modes:

1.  Thys ZS1TBP

2.  Christie ZS4CGR

3.  Zayn ZS3VO

 

I had the privilege to make contact  on DMR with the above radio amateurs.  

I also heard along the grapevine that there are others that are interesting in using the VHF/UHF digital radio modes.  We eagerly await to either hear you on the air or to assist you in getting started in VHF/UHF digital radio modes.  Give us a shout if you need any help.

Enough for now.

Finally:  I would once again like to invite clubs and radio amateurs to use and keep on using the ZS-LINK and GRHub Network if they so wish. These networks are not a private, club only or special allocated network venture.  It is open for general use by any radio amateur.

Thank you to those who support and use the ZS-Link Network regularly.  Highly appreciated!!

NEVER FEAR THAT YOU ARE "TYING UP THE NETWORK SYSTEM" - IT IS THERE TO BE USED AND ENJOYED!!

Any other uses for ADSL Filters lying around and gathering dust?

I recently experienced Bluetooth noise on a cheap Chinese AC-DC Integrated Amplifier/Radio/Etc. in my shack.  As we know by now all the necessary / "unnecessary" components were remove by the manufacturer to save costs.  I needed a filter to filter the bluetooth noise coming from the built in bluetooth module.  I have a few old ADSL Filters lying around and I decided to test one of these filters to filter the Bluetooth noise.  No this is not the ideal filter but I decided to install this filter.  Lets first read what is the function of a ADSL filter:

"A low-pass filter, also known as an ADSL filter, filters out all high frequency signals. This ensures that your high frequency ADSL signals do not interfere with voice calls on the same line which use lower frequencies.

Asymmetric digital subscriber line (ADSL) is a type of high speed Internet connection that uses existing telephone infrastructure to deliver Internet service. Telephone equipment like phones and fax machines aren’t designed for ADSL signals. As a result, phones can interfere with Internet connections and vice versa. ADSL micro filters were created to keep normal phone signals and ADSL separated, even though they are running on the same wires. ADSL micro filters are installed between telephones and your phone jack.
ADSL filters prevent your Internet signal from interfering with the voice part of your phone line. When ADSL interference occurs, it typically sounds like a series of fast clicks. ADSL filters also ensure that your lines are terminated correctly by preventing signal reflections that can cause errors on your ADSL Internet connection.
If your ADSL Internet connection works correctly when your telephone equipment is disconnected from your phone line, but stops working when telephone equipment is connected to the line or is in use, then there might be a problem with your ADSL filter installation.
All telephone equipment and other non-ADSL devices that might use telephone lines (like home alarm systems) must be connected to a line that has been filtered at some point. How many filters you need and where they should be installed depends on how your phone wiring is laid out; just make sure that your ADSL modem is not on a filtered line while all other devices that use your telephone line are filtered.
A DSL filter or POTS filter is an analogue low-pass filter installed between analogue devices (such as telephones or analogue modems) and a plain old telephone service (POTS) line, in order to prevent interference between such devices and a digital subscriber line (DSL) service operating on the same line.
Without DSL filters, signals or echoes from analogue devices at the top of their frequency range (low end frequency) can result in reduced performance and connection problems with DSL service, while those from the DSL service at the bottom of its range (high end frequency) can result in line noise and other issues for analogue devices.
DSL filters are passive devices, requiring no power source to operate. A few high-quality filters may contain active transistors to refine the signal."

ADSL Filters Explained   (PDF)

Now that you know more about ADSL Filters and their function you will realize that it is not an ideal filter for what I wanted to use it for.  None the less I installed it and the bluetooth noise disappeared.  However in the process I lost a bit of volume (audio) on the amplifier but for my purpose it is doing what I want it to do and the little volume lost does not effect my use of the amplifier.

Having a look at the filter their might be some components that can be used as ("filters") 1:1 transformers in a soundcard interface for RF radios.  I have not tested this in practice but will do so when I experiment again with a soundcard interface.

Now onto the title of this topic:  "Any other uses for ADSL Filters lying in the junkbox?  If you have any suggestions please share them with us.

Images:  Click on images for larger view.

 

Amateur Radio Day for the Youth at Stanley Island in Plettenberg-Bay (11November 2023)

 

On Saturday 11 November, the Eden ARC arranged an amateur radio day for young people at Stanley Island in Plettenberg-Bay. Andries, ZS1SMP, and his son Aiden, ZS1ATS arranged the event and members of the Club participated. Andries wrote the RAE in May and Aiden in October. There were between 17 and 20 young people who first had to learn the phonetic alphabet and speech procedures. After some guidance, some of the young people spoke to Christie, ZS4CGR in Luckhoff. Certificates were handed over to all who completed the event and two young people said they wanted to take the ZU exam in 2024. Boerewors rolls and cold drinks were provided and the youth went swimming. Thanks to Andries, ZS1SMP and his son Aiden, ZS1ATS; Gerrit, ZS1KLO; Corne, ZS1COR; Willie, ZS2CC and Eben, ZS1HEB.

Herewith a photo portal as well as images:  Click on images for larger view. 

Video Picture Collage:

28 October 2023 - HOTA activation: "Palinggat Homestead 1809", Still Bay

The above site was recently activated by Corne ZS1COR.  Johan ZS1AAC was also present in support of the days activities.  The images underneath reflect the history and activation of the site which was registered on H.O.T.A.

 

History of "Palinggat Homestead"  built in 1809 :

The Palinggat homestead in Langenhoven Street, now the ‘home’ of the Archaelogical Museum and the Stilbaai Tourism Bureau, was built in 1809 and was declared a national monument in 1985. Take a walk through the museum that includes the Blombos Museum of Archaeology, feed the eels and visit the shop filled with lots of local goods, crafts and gifts and have some tea on the ‘stoep’ or under the milk wood trees.

The little Platbosch School Museum section will take many a visitor back to their own school days and the history of schools in the area can be viewed here.

Walk around the building to view the ‘funeral wagon’ that was used between 1880 and 1920 in the Riversdale / Albertinia district.

Images:  (Click on images for larger view.)

 

What is HOTA?

H.O.T.A (Heritage on the air) is an amateur radio group that strives to motivate radio amateurs to learn more about history, and to keep history alive by activating a multitude of historical sites by using SSB, AM, FM, CW and even with Heliographs. Radio amateurs have great fun going out in the field and visiting places and areas where once history was made. Even if you do not like history there is places that were visited that might be of interest to you. You can even combine your other hobbies with H.O.T.A. Now that you have a faint idea of H.O.T.A it is time to learn more about H.O.T.A and the fun radio amateurs have and can have in activating historical sites. If you want to learn more about H.O.T.A you can visit the Heritage on the Air website by clicking HERE.