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Alex M0TOT has been challenging himself with more projects from the Instructables community. Here we have his implementation of Tom Heylen's experiment with a pair of Arduino Unos each fitted with HC-12 UHF wireless modules.
Alex notes that:
"In theory, the current, on the Rx, that can be sourced or sunk between Pin 13 and ground is 40 mA, but apparently that is for short periods only. It is recommended that it is kept at 20 mA - enough for an LED or a relay with a rated coil-power which is low. Anything else might require an optocoupler or transistor circuit."
And Tom writes in his article:
"In this instructable you will learn how to communicate between Arduinos over a long distance up to 1.8km in open air.
The HC-12 is a wireless serial port communication module that is very useful, extremely powerful and easy to use.
First you will learn how to make a wireless instant messenger with the least effort possible. Then we will move on to light up an LED with a push button and then you will learn a few useful string functions and operations for serial communication.
The last part of the instructable is not necessary but you will learn how to use the HC-12 module like a pro."
His project is fully documented here: https://www.instructables.com/Long-Range-18km-Arduino-to-Arduino-Wireless-Commun
and you can download the documentation (including the various Arduino sketches) here:
The HC-12 Wireless Module User Guide (v2.3B, as used in this project) with all the relevant AT commands is here:
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- Written by: Alex M0TOT
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Last winter we had three or four power outages in our village, so I decided to have a look at the possibility of constructing a small back-up system in the event of power cuts.
I decided to have the system operating only during the winter months, this meant that it would not be on standby all the time. I regulated the hours by using a standard mains operated programmer that incorporated a battery back-up. I limited the hours to between 1600 and 2300 hours. If there was a power failure in that period, then the 12 Volt LED light would come on, depending on the sensitivity of the light sensor. It works, but is not too complicated or over-sophisticated.
Regards
Alex Henderson M0TOT
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- Written by: Richard G0LFF
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Digi modes, like Marmite, are either loved or hated, not much inbetween.
As many of you know, I have been involved in the development of digi modes for over twenty years now with Dr Joe Taylor K1JT. The early development was for Earth-Moon-Earth and Meteor Scatter communication. In the past we had used high speed CW with tape recorders for sending and receiving MS bursts. All good fun and before the advent of cell phones and email, skeds were arranged either/or by mail or the 20m band if one was licenced.
Over the years many modes were tested and discarded as more efficient modes with error correction built-in evolved.
Back in 2013/14 I was working Japan during the summer Es season on 6M using JT65 without any competition at all. Eventually a G3 enquired how I was getting all these far east contacts logged on 6M when nobody else was hearing any sign of long-haul comms. When I explained my methods, there was much poohooing and in modern speak thumbs down to me and my methods.
When the 2015 Es season started I was astounded by the high number of EU stations calling Japan and the far east with digi modes. It was now hard for me to get a look-in with my very modest setup comprising an Icom IC-736 into a homebrew short boom 5 element LFA yagi mounted on the back wall of my terraced house. As the terrace ran basically north/south I had to beam over my concrete tiled roof for moon-set. This threw my angle of radiation right up, and I was getting the moon reflections at about 20 degrees. However I managed to work Lance, W7GJ running barefoot.
Eventually a mode called FT8 by Dr Joe Taylor K1JT and Steve Franke K9AN evolved specifically for long-haul 6M Es DX. It was released on 29th June 2017. My log for that date shows I worked PA5JS followed by Kev G0CHE - both of whom had been experimenting the digi modes with me. The HF fraternity soon picked up on FT8 as solar cycle 24 was fading and worldwide comms were extremely poor using legacy analogue modes. The rest, as they say, is history. A stripped down version named FT4 came into being. It is half the cycle of FT8 resulting in it being 3db down in efficiency.
FT8 for all its controversy has helped many to learn basic computer skills marrying their rig to PC and visa versa as well as keeping the HF bands alive during the solar minima.
The late Bill Somerville, G4WJS, was responsible for tidying up the WSJT suite of apps and giving them a professional look.
Does it replace CW and/or SSB? No, it is just another string to the bow so to speak. The doomsters and gloomsters would have you believe it is the death knell of Amateur Radio as we know it, but then if we look back to 1939 when Single Side Band was introduced, they forecast that it would never last!
FT8 is limited to a maximum of 13 characters including spaces giving minimal contact detail as do DX contacts using legacy modes.
100W of FT8 is the equivalent of 1kW of SSB.
I decided to have a day on FT4 & 8 using a maximum of 10W into a single wire loop in my loft on 17, 12 & 10M bands.
The result speaks for itself.
| Africa (Reunion Island) | 1 |
| Asia | 6 |
| Europe | 2 |
| North America (US Virgin Isles) | 1 |
| Oceana (Indonesia) | 2 |
| South Atlantic/MM | 1 |
DXpeditions are turning more and more to FT8 due to its efficiency. A lot are using MSHV, an app capable of running six streams simultaneously. Although this is not Fox & Hounds mode it is advisable to operate in F/H mode when calling them as this will clear you, the hound of QRM when they pick you up to complete the QSO.
I did not use F/H mode on the 2nd & 3rd most wanted DXCC’s and consequently lost both contacts after being picked up. Lesson learnt.
The three most popular apps for FT8 are WSJTX, JTDX & MSHV. I prefer JTDX for HF.
FT8 is a low signal mode, not a low power mode.
Attached photos are:
A 6M digital opening to the far east (top)
My log for the 10W ops on 21/08/2023 (left)
My 6M EME QSL card (below)
I strongly recommend to anybody contemplating adding FT8 to their operating modes to watch this lecture by Dr Joe Taylor, Nobel Laureate in Physics for his discovery with Russell Alan Hulse of a 'new type of pulsar, a discovery that has opened up new possibilities for the study of gravitation'.
https://www.youtube.com/watch?v=233HQs_8JGQ
Be aware that FT8 is a key down mode as is AM & FM so use the rig output power allocated to AM as a power guide.
Dick Hide G0LFF
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Alex and I are seemingly both interested in the same experimental zone at the moment, and here he has built an interesting 'Long Range Wireless' setup for UHF which he found on the Instructables website at https://www.instructables.com. This is a 'maker' community that was purchased by Autodesk around eleven years ago, and fortunately they haven't tried to turn it into a money-maker or promotional tool. It contains an extremely wide variety of very do-able projects and is worth looking up.
There are several radio-related practicals hosted there including this one. It's an Arduino-based data communication link which utilises an HC-12 wireless UART serial port module at each end, which in theory - given the right conditions - can achieve a range of up to 1km.
Alex had kindly provided a photo of his setup, and a copy of the HC-12 User Guide.
There is no need to repeat the content of that guide here, and although the translation into English isn't perfect, it is pretty clear what's going on if you wish to try it yourself.
I'm currently building something very similar to support the SDR Training Academy course, so I'll also be cloning this project to see how the two compare.
This is an ISM band experiment capable of operating in a frequency range of 433.4MHz to 473.0MHz at max 20dBm, BUT it is obviously your responsibility to ensure you stay within the UK ISM band limits. At the time of writing, these limits for the 433MHz allocation are 433.05 to 434.79MHz. Assuming you stay within that slot, there is no operating licence required due to the low power radiated. I've included the relevant Ofcom document FYI as of March 2023.
Thanks again to Alex M0TOT
| HC-12 Wireless Communication Module v2.4 | Ofcom UK ISM bands Frequency Allocation Table |
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This has been documented plenty of times across the web, but I recently had cause to make a small modification to mine, which necessitated the lid coming off. A perfect opportunity then to take a photo and post it on the website. I built this one back in 2019 and it made a noticeable difference to my noise levels, as well as giving peace of mind that I was doing the right thing.
What modification did I make? I just replaced the 4-gang strip hanging off the output with a Belkin surge-protected item - the BSV400.
You can get all the details, component list and theory at Ian's website here: https://gm3sek.com/2019/10/11/clean-up-your-shack-2019.
Berni M0XYF
Update
I've had some feedback from Adrian M0TCD, which was enlightening and useful:
"I don't like the way the input and output leads run so close together in your mains filter as it could allow interference to cross between them. You could put the filter on the left and the fair-rite on the right to overcome this."
Which, after checking against the original design, is a mistake on my part, so I'll be fixing that sometime in the near future!
