VHF, UHF and Microwave Record Table - the latest table of records is available from the VHF SA Record page. Click here to get a copy. Compiled and updated by Paul, ZS6NK - latest version 10 June 2019. Updates to zssixnk@gmail.com
Focus on VHF and Above 18 August 2019
Audio File
As we heard last week tropoducting has advantages and disadvantages depending on what you are doing.
This week I want to take a look at the upper air data and try to understand a little bit about the relationship between temperature, pressure and humidity and the actual conditions experienced.
As mentioned previously upper air data is collected by weather balloons that are sent up twice daily. There are other methods used, such as sounding rockets and radiosondes that are dropped from aircraft, but balloons are by far the most common method used.
Locally these balloons are launched by the South African Weather Service from various weather stations around the country. There is a map in the text version of this program on the SARL webpage showing the world wide distribution of stations that record upper air data. Interesting to note that the number of stations in Africa peaked on the ‘90s, but by 2015 has decreased considerably.
igra_stationmap.jpg
So what is the relationship between temperature, pressure and humidity?
Of the three atmospheric variables that influence refraction, water vapor has the greatest effect. The more moisture there is the more refraction there will be.
Temperature on the other hand needs to be low. In other words the higher the temperature the less refraction.
Moisture and temperature are the two factors that affect refraction the greatest.
Pressure variations have a small influence on refraction.
Normal refraction occurs under normal (standard) atmospheric conditions in which moisture, temperature, and pressure all decrease with altitude.
Normal refractive conditions are found in areas with very weak (or no) inversions, deep moisture, moderate to strong winds, and very unstable, well-mixed conditions. There are often showers in the area, and distinct cloud elements (Cumulus or Cumulonimbus, open convective cells, wave clouds, streaks, or convective cloud lines). Synoptic influences include a cyclonic influence, post-frontal or unstable prevailing conditions.
Sub-refraction occurs when the temperature and moisture distribution creates increased refractivity with height, the wave path bends upward and the energy travels away from the surface.
In hot, dry areas (temperature > 30 degrees C, RH < 40%), solar heating produces a homogenous surface layer, sometimes hundreds of feet thick. Sub-refractive areas are also formed by warm, moist air moving over a cooler, drier surface, and near warm fronts because of warmer temperatures and an influx of moisture.
Ducting is an extension of super-refraction because the meteorological conditions for both are the same. The conditions that form a trapping layer are more intense than those that form a super-refractive layer.
With knowledge of the overall synoptic weather pattern, it is possible to make a rough determination of the refractive conditions associated with the high and low pressure areas and associated frontal regions as shown in the synoptic chart and sea surface temperature table.
Synoptic Chart.jpg
Sea Surface Temperature and Zd Table.jpg
Sounds very complicated to me. What is interesting is that sea temperatures are mentioned. May this be the reason we only get forecasts for ducting over the oceans? How is the refractive index for moist or humid air calculated? What about inland? Again more questions, than answers.
Well I have been following another thought process. We know that we need to look for temperature inversion, relative humidity and pressure. On the morning of 7 August the Long Distance VHF Group reported good conditions between Bloemfontein, Bethlehem and Gauteng.
So I went and looked for the Skew-T charts for stations that reported upper air data for the morning of 7 August. I could only find data for Irene and Upington.
Irene Skew-T Chart.gif
You will see that the chart for Irene shows a very sharp and narrow temperature inversion at the height of 4331m and pressure level of 609 hPa and then another temperature inversion around pressure level 450 hPa.
The relative humidity is not shown in the Skew-T chart, but if one examines the data that was recorded you will see that the relative humidy at 609 hPa was only 2% while between 450 and 500 hPa the relative humidity was higher at 12%.
Irene Data.png
Now Upington is way out to the West, but we know that our weather patterns move from West to East and the atmosphere is dynamic and continually changing, so let us see what Upington's data shows us.
Upington Skew-T Chart.png
Upington Data.png
Here we also see that where we have temperature inversion, the relative humidity tends to be higher.
Could this be an indicator of a tropoduct over divisions 4 and 6, albeit weak compared to that experienced over the oceans? Interesting isn't it.
I've no dought in my mind that this needs further study and data needs to be captured everytime we experience good long distance communications so that we can work out what is happening in the upper atmosphere and the relevance of it to our long distance weak signal communications on VHF and above.
Now for some VHF and above News.
The D4C contest station on the Cape Verde Islands now have a 432 MHz station up and running.
John EI7GL posted in his blogspot “So far in 2019, the D4C contest team on Cape Verde Islands off the west coast of Africa have made some pretty amazing contacts on 144 MHz. Using the call D41CV, they have worked across the Atlantic to the Caribbean, up to the UK, France and Ireland via marine tropo ducting and into Germany, Italy and Slovenia with a combined Sporadic-E / marine ducting mode.
Many of these contacts were well in excess of 4000 km in distance.
The D4C team have recently announced that they are now active on 432 MHz using a homemade 16 element "Pinocchio" Yagi with a wooden boom. A Transverter is connected to a FlexRadioSystem 6600M driving a solid state PA running 100W.
It is now only a matter of time for the team at D4C to start making long distance 70cm contacts as well.
Take a look at John EI7GL’s blogspot where he discusses the possibilities of making long distance contacts on 70cm.
144 & 432 MHz Yagi antennas on Cape Verde
D41CV-VHF-UHF-antenna.jpg
Last week we reported on UK radio amateurs who made a CW contact on 288 GHz over a distance of 175m.
This week we report on Australian radio amateurs reporting a first FT8 contact on 122 GHz. Roland Lang, VK4FB, and Stefan Durtschi, VK4CSD, completed what is being claimed as the world’s first FT8 contact on 122 GHz. The distance spanned during the August 11 contact was 92.08 kilometers. Signals were –17 dB on one end, and –20 dB on the other. Earlier this summer, VK4FB and VK4CSD claimed a new Australian record for an SSB contact on 122 GHz — 69.6 kilometres
We know of amateurs playing in the 10 GHz band primarily the downlink for QO-100. Are there any amateurs in South Africa working in the millimetre bands that is the bands higher than 10 GHz? Please let us know at vhfnews@sarl.org.za.
Looking at the Hepburn charts for this coming week it looks like tropo ducting will not be favourable for the West Coast, however conditions may be improving for the South East Coast from 18:00 UTC on 21 August 2019.
Well that is all for this week.
Please send your news snippets and information about activities on VHF and Above to vhfnews@sarl.org.za
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Focus on VHF and Above 11 August 2019
Audio version
Last week we started talking about tropoducting, what it is and we started talking about the forecasting of tropoducting and the data that is needed in order to predict or forecast when possible ducts could take place. I also mentioned three websites where tropo forecasting can be viewed and that forecasting of tropo-ducting is not a simple task and requires a good understanding of the upper atmosphere. This week I want to expand on that.
I closed last week saying that it is not only radio amateurs or DX listeners who have an interest in tropospheric ducting. Radar operators also have an interest in tropospheric ducting.
My search for information about tropoducting dug up some very interesting information. Two cases were mentioned:
In the first case it was reported that at night in the Gulf of Tonkin during the Viet Nam war, radar operators on two US warships reported echoes that were evaluated as attacking torpedo boats. General quarters was set for both ships and crewmen on both ships prepared to ward off the attackers. Combat Information Center personnel reported contacts at “1500 yards and closing,” then “1000 yards and closing.” Then the contacts would disappear. Several times within a few hours, numerous echoes were observed and evaluated as unfriendly attackers, only to disappear from the radar display when the range closed to 1000 yards.
In the second case it was reported that an Aircraft Carrier Strike Group was conducting flight operations in the Arabian Gulf. Enemy forces had deployed a reconnaissance aircraft to observe the activity. None of the radars on the Strike Group’s ships detected the enemy aircraft; the first to see the contact was a lookout on the aircraft carrier.
Both scary situations. So what happened here?
Well, when there is an abnormal distribution of temperature, moisture and pressure in the atmosphere, such as when we experience temperature inversion then the refractive index of the different layers of the atmosphere change.
Inversion.jpg
One type of refractive condition known as super-refraction can extend the normal detection range of radar and, if conditions intensify, produce false echoes or ghosting. Ghosting can cause returning echoes to fool the radar equipment into displaying faraway echoes as though they are much closer than they actually are. This was the case in our first example, and a great deal of time and energy were expended reacting to false echoes.
Super Refraction.jpg
Another type of refractive condition known as sub-refraction may produce a shadow zone (commonly referred to as a radar hole), sometimes allowing an aircraft or ship to approach within visual range but to remain undetected by radar, as in our second example. In this case, the radar equipment operated properly. But one can only imagine the consternation caused within the strike group!
Another refractive condition is known as a duct. A duct is a region of the atmosphere that traps EM waves (prevents them from spreading out), and thus allows them and their energy to propagate over long ranges.
Ducting.jpg
Another natural phenomenon that is related to refraction of electromagnetic waves in the atmosphere are mirages. The ship below seems to be floating above the horizon.
Mirage.jpg
The challenge in exploiting a duct is to know that it is there, and put a signal in it! A duct is a transitory feature, and will only trap certain frequencies. The wider the duct, the higher (and, typically, the more useful) the frequency that can be trapped and exploited.
These tropospheric conditions can last for quite a long time over the water and it would appear as if the oceans provide a more stable environment for them to exist. Similar to the stabilising effect that the oceans have on the day and night temperatures along the coast compared to inland where there is a large swing between the day and night temperatures.
Next week we will look at the some of the upper air data and try to understand a little bit about the relationship between temperature, pressure and humidity and the actual conditions experienced.
By the way if you look at the Hepburn charts for the Middle East, you will see how strong the tropoducting predictions are for the Arabian Gulf. You can also read more about the Gulf of Tonkin incident on the internet.
Now for some VHF and above News.
First UK 288 GHz CW contact. Video of the first UK two-way CW contact at 288 GHz which took place at Higham in Kent on August 2, 2019, between Roger Ray G8CUB/P and Chris Whitmarsh G0FDZ/P
The contact was over a distance of 175 metres in grid locator JO01FK60.
The clip begins with an earlier attempt on the same day over a longer distance of 1.2 km which resulted in a 589 signal being received one way from JO01FK60UC to JO01FK62JR.
Watch First UK 288GHz QSO
https://www.youtube.com/watch?v=Yw8hzjV5mC0
Closer to home the conditions along the East Coast was steadily picking up on Tuesday and Wednesday this week and Phil FR5DN on Reunion Island, Patrice 3B8FA on Mauritius and Deon ZS5DCF tried to make contact between 22:30 and 23:59 on Tuesday evening but did not succeed. On Wednesday they continued trying through the day but again did not succeed. Later in the early evening Lee ZS5LEE took up the challenge and finally succeeded to make a contact with Phil FR5DN at 18:07. Patrice 3B8FA continued trying to make contact with Lee ZS5LEE late into the evening, but was not successful. Well done on the contacts made.
Inland the conditions were great on Wednesday morning with the Bloemfontein beacon ZS4AFV being reported S8 by Carl ZS6CBQ and Rickus ZS4A S9+20 on FM. Rickus reported Kobus ZS6BOS as 59+40.
This coming week conditions along the West Coast look promising from 18:00 UTC on Wednesday 14 August.
West Coast 18:00 14 August 2019.jpg
Along the South and East Coasts Thursday 15 August may be good.
South East Coast 06:00 15 August 2019.jpg.
Well that is all for this week.
Please send your news snippets and information about activities on VHF and Above to vhfnews@sarl.org.za.
Focus on VHF and Above 4 August 2019
Audio Version
We all know that Tropospheric ducting is one of the propagation modes that provides for long distance communications on the higher VHF bands.
One of the topics discussed at the last VHF workshop was the so called West Coast phenomenon. The phenomenon is fundamentally Tropospheric ducting that occurs over the ocean and allows for the periodic long distance communications that takes place between the West Coast of South Africa and Namibia and St Helena Island. Hans ZS6AKV gave an excellent presentation regarding Tropospheric ducting, the various types of ducting, the heights at which the ducting takes place and what happens inside the duct. A discussion took place after the presentation, and as always more questions were asked than there were answers. Questions were also asked about inland forecasting of tropospheric ducting.
Forecasting of tropo-ducting is not a simple task and requires a good understanding of the upper atmosphere.
William Hepburn who produces the Hepburn Charts is a Meteorologist and Radio and TV DX enthusiast. He writes on his website “Using my many years of experience as a professional meteorologist and an avid radio/TV DX enthusiast...I began experimental text DX forecasts for the Toronto-Buffalo area in 1997 using E-mail. Once the Internet caught on, and the Worldwide TV-FM DX Association formed a newsgroup, the forecast coverage eventually grew to cover North America. With continual gains in experience and real-time feedback from DXers, I was able to refine my methods and to gradually improve the quality. Later I developed the Hepburn Tropo Index to attempt to quantify the strength of tropospheric ducting over different areas. Over time, the index has been adjusted and refined and now does a credible job of representing the zones of potential ducting.
In May 2000, I prepared my first forecast maps and the Tropospheric Ducting Forecast website was born. I created the maps by having a computer program emulate what I had been doing manually to prepare the text forecasts. As a result of this automation, I have been able to expand the forecasts' coverage to encompass much of the world. The forecasts are now popular with users around the world.”
As far as I can ascertain, William Hepburn is not even a radio amateur and all the wireless equipment that he lists on his blog are receivers.
There are other sources of tropospheric ducting forecasts as well.
Pascal F5LEN also has a website dedicated to tropospheric propagation forecasting.
Phil FR5DN on Reunion Island also does Tropo forecasting for the Southern Indian Ocean and focuses on predictions on the paths ZS2 and ZS5 to Reunion Island.
It is interesting to note that all these forecasts are over the oceans and there are no forecasts for ducting over the land masses. Why not?
I mentioned earlier that a good understanding of the upper atmosphere is required to forecast tropospheric ducting. What is this and how does one obtain data about the upper atmosphere?
Tropo-ducting does not happen at the surface, but at heights of around 500m to 3000m. Tropo-ducting also takes place when there is temperature inversion, which is when the air temperature at those heights gets warmer instead of cooling. The relative humidity of the air must be just right. This affects the refractive index of air. These conditions are also normally associated with the change of pressure between a high pressure system and a low pressure system. Sounds complex doesn’t it.
Where does this data come from and how is it obtained? The various weather services around the world collect this data by sending an instrument into the air called a radiosonde.
A radiosonde is a battery powered telemetry instrument usually carried into the atmosphere by a weather balloon and measures or calculates altitude, pressure, temperature, relative humidity, and both wind speed and wind direction. Radiosondes are an essential source of meteorological data, and hundreds are launched all over the world daily at 1200 and 2400 UTC. As far as I know there are still 7 stations dotted around South Africa that still send radiosondes into the air as well the research stations on Gough Island, Marion Island and SANAE in the Antarctic.
I have personally had experience with radiosondes and the collection of the data while doing a stint as the radio technician on Marion Island in the mid ‘80s. Amongst all the electronic equipment that I was responsible for was the receiving and tracking equipment used by the meteorologists who sent a balloon up twice a day at midday and midnight. This data was then relayed back to the South African Weather Service via radio telegraphy or RTTY in those days. We also shared data with the French Island of Crozet and relayed their data back to Pretoria.
Now you know where my curiosity with the the upper atmosphere and VHF propagation comes from. It is this curiosity that has started my research to try and find out more about how and why tropospheric propagation occurs and how one can possibly better predict it especially over the land masses where we also experience temperature inversions. When one looks at the forecasts one does wonder why the ducting always occurs in certain areas over the oceans. Again the question is why?
So many questions to be answered!
It is not only radio amateurs or DX listeners who have an interest in tropospheric ducting. Next week, I’ll reveal some more interesting information about tropospheric ducting.
Not much news this week with regards activity on the VHF and above bands, although I did report last week that the conditions along the coasts did not look good.
This week there should be a significant improvement on the prospects of contacts along both the West and South East Coasts.
On the West Coast good conditions are being reported in the Hepburn Charts for Monday 5 August in the late afternoon.
West Coast 18:00 5 August 2019.jpg
And on the South East Coast both the Hepburn Charts and Phil FR5DN are predicting good conditions for Monday 5 August and Tuesday 6 August.
SA FR518:00 5 August 2019.jpg
SA FR518:00 6 August 2019.jpg
Phil FR5DN has his beacon on, so listen out for it.
Well that is all for this week.
Please send your news snippets and information about activities on VHF and Above to vhfnews@sarl.org.za.
Focus on VHF and Above 28 July 2019
Audio version
This week I saw two articles on Sporadic E propagation. This first one was a presentation sent to me by Hans ZS6AKV who in turn received it from the HamSCI folk in the US. You can go and look at the presentation on the website of K9YC.
The second one is on the Electronic Notes website, where the basics of Sporadic E propagation is explained.
Here in South Africa the Sporadic E openings occur mostly in the middle of summer although not too long ago we reported about a Sporadic E opening that occurred between Gauteng and the Cape on 7 June 2019.
I spotted this antenna on the SARL forum posted by Johan ZS1I from Mossel Bay. It is a 2m/70cm DipYag/Dipole Antenna. It looks very interesting.
ZS1I 2m 70cm Antenna.jpg
For more information look at the site of AREDN Mossel Bay Mesh Network.
While you are there take a look at the other interesting antenna project on the site under projects.
Johan has also started the Reboot Amateur Radio Group and you can also find more information about the activities of the group, and the mesh network on the ARDEN Mossel Bay Mesh Network website
Chris ZS1FC posted a link on the Weskus Radio WhatsApp group to a wonderful repository of antenna handbooks all in PDF format.
You will have heard on the SARL news that there is some ISS SSTV activity on 29 and 30 July 2019. There is also activity being planned for 1-4 August 2019. Keep an eye on the ARISS-SSTV page at https://ariss-sstv.blogspot.com/.
Over at the RTL-SDR website is a very interesting demonstration of RSPDuo diversity being used to cancel local interference.
SDRPlay have recently published a video demonstrating how the new RSPduo diversity feature in SDRUno can be used to cancel local interference. The SDRplay RSPDuo is a 14-bit dual tuner, software defined radio, capable of tuning between 1 kHz - 2 GHz. It's defining feature is that it has two receivers in one radio, which should allow for interesting phase coherent applications such as diversity. The RSPDuo's diversity feature allows us to either combine two antenna signals together for an up to 3 dB increase, or for removal of an unwanted noise source via subtraction of signals.
In the video they show a broadcast AM signal that has it's SNR reduced by being on top of a local electrical noise source. They use a Bonito Mega-dipole on tuner 1, and a Bonito Mini-whip on tuner 2. The Mini-whip appears to receive the local interference stronger, so can be subtracted away from the Mega-dipole's signal with the diversity function. The result is improved SNR, and the noise is almost entirely cancelled.
I can see some very useful applications for this.
Most of the links to websites that contain more information mentioned this week are lengthy URLs, too long to give over the air. The links are available on the text version of this program that will be available after this broadcast on the SARL homepage.
Looking at the Hepburn charts for this coming week it seems that there will be no chance of Tropospheric ducting along the coasts of South Africa this week.
On Saturday morning the conditions inland were very good. Carl ZS6CBQ reported that he could hear the ZS4AFV beacon in Bloemfontein S9 in Krugersdorp. Rickus ZS4A was also reported as an S9. Here is a clip of the ZS4AFV beacon. Just listen to that crisp clear signal being received.
ZS4AFV Beacon 2019-07-27 at 07.37.56.mp4
Well that is all for this week.
Please send your news snippets and information about activities on VHF and Above to vhfnews@sarl.org.za.
Focus on VHF and Above 21 July 2019
Audio version
The highlight this week must certainly be the SARL / AMSAT SA VHF Workshop that was held yesterday at the National Amateur Radio Centre.
There was a lazy cold wind blowing when we arrived to find a contingent of fellow VHF enthusiasts from the Free State already waiting in the sun trying to keep warm.
This was however not a reflection of the rest of the day.
After Hans ZS6AKV and Nico ZS6QL welcomed everyone Dick ZS6BUN gave a very interesting presentation on Horizontal versus Vertical Polarisation. Dick had done a lot of research and presented the information that he found leaving us with no doubt in our minds as to which was better, Horizontal or Vertical polarisation for VHF and above. What is very important is that both transmitting and receiving station’s antennas must be polarised in the same plane, that is horizontal or vertical. Dick went on to explain the various factors that affect the attenuation of the signals and what happens to the signals one they leave the antenna.
There are many factors that affects the signal over the path between the transmitter and receiver, but at the end of the day, taking everything into consideration there is at least a 3 to 4 dB advantage that horizontal polarisation has over vertical polarisation. This is about half a S point and if the strength of the signal received at the receiver is very high, S9 and above, it may not even be noticed. However at low signal strengths and when working with weak signals, 3 to 4 dB does matter.
So at the end of the day working with weak VHF communication paths where a difference of 3 dB can result in logging a contact or not, there is no doubt that horizontal polarisation is the way to go.
Dick, thank you for that very informative presentation.
Brian ZS6YZ gave an overview on the VHF beacon project. This project is moving along well with the only item delaying the installation at the Bethlehem site is getting the radio to generate a clean CW signal. Brian ZS6YZ and Cor ZS6CR are working together on the radios and it is hoped that they will have the FM radios generating CW shortly.
Next up was a presentation of two Diamond antennas that Sam ZS6BRZ convinced the Diamond Antenna Corporation in Japan to donate to the SARL.
After refreshments Nico ZS6QL discussed what was needed to encourage more activity amongst the radio amateurs and especially mentoring or “Elmering” of the new radio amateurs. Nico has asked us to send him ideas for future workshops and programs that can help to promote more activity on the air.
Pine ZS6OB then discussed the components that make up the chain from your transceiver to the antenna and how every item added to the chain adds losses that you may not even be aware of and why it is important to use the best quality components that you can afford, especially at the VHF and above frequencies.
Hans ZS6AKV then went on to discuss what has become known as the West Coast Phenomena. What is it, how it seems to work and possible reasons why it is so strong.
Tom ZS1TA who had driven up from Cape Town also shared some of his insights to what was happening along the West Coast. This turned out to be good discussion and at the end of the day we all agreed that there is still a lot to be learned about Tropospheric propagation.
Hans then discussed the HF noise floor project and the possibility of expanding the project to include VHF as well as there certainly is a need to gather more data.
Brian ZS6YZ then finished off the day with a quick update on the Reverse Beacon Project, why it is an important component of the greater beacon project to be able to monitor the beacons and automatically log reception reports for later use for propagation studies in order to better understand radio propagation on the VHF and above bands.
There are some exciting suggestions already on the table to consider for future workshops. Please let us know what topics you would like to hear about.
Thank you to each and everyone who made the effort to attend the workshop it was really great to see the lecture room at the National Amateur Radio Centre so full.
Some other news is that Tom ZS1TA will not be returning directly to Cape Town and that he will be travelling around the country activating some rare grid squares mainly for EME contacts, but he does have 40m HF capabilities as well for the HF guys to are grid square chasers.
Peter ZS2ABF reports that the conditions along the South East Coast were good on Monday 15 July between himself and Dave ZS5DJ. On 16 and 17 July they tried again, but conditions did not allow them to make contact.
Along the West Coast contact was again made with St Helena Island on Friday 19 July. This time Derek V51DM in Namibia was talking via the Swakopmund repeater and later Robert V51RS spoke to Garry ZD7GWN from Ojtiwarongo via Echolink to the Windhoek repeater which in turn was connected to the Gamsberg repeater which is connected to the Swakopmund repeater. Johan V51JH also again made contact with St Helena. Well done guys. Conditions were excellent.
The next meeting of the VHF Work Group will be on 25 July at 20:00 on Skype. To participate in the work group, send your Skype name to vhfnews@sarl.org.za.
Please send your news snippets and information about activities on VHF and Above to vhfnews@sarl.org.za.
Focus on VHF and Above 7 July 2019
Audio version
This week, I want to talk a little about digital communications on VHF and above. Not the weak signal digital modes as used by the long distance VHF enthusiasts where the exchange is only callsigns and signal reports.
Let me explain.
Through my involvement in Hamnet we have certain challenges, on HF it is the current low sunspot activity causing not so great activity on the bands. Digital modes will however work great and I’ve already been testing JS8Call on HF. The other motivator to move to digital modes for disaster communications is that there are lots of times lists that need to be relayed, be it names of victims, search grids, logistic requirements and so forth. This can easily and more efficiently be sent via digital modes and programs like FLDigi and JS8Call has been written with this type of communication in mind.
But now what about the shorter range communications? Those distances which are just too short for HF and well within the range of VHF. The guys that play with the longer distance VHF comms will agree that one can get pretty good range on simplex using FM and even better if you use SSB.
One can always argue that NVIS on HF is the way to go.
So, let us get back to the scenario where we need to send a list of names.
Not all radio amateurs have HF equipment set up to do digital modes in the field. Some of the Hamnet members only have VHF/UHF equipment and it is only FM and not SSB either. What now?
Well it turns out that packet radio works very well on the VHF and UHF bands and at a higher baud rate of 1200 baud as opposed to 300 baud on HF. Some of the more senior hams will remember the days of the packet radio systems and the bulletin boards of a bygone era. Well that was at the time how we used to send messages to each other, and it worked well. Packet radio uses a protocol AX.25 which is still used today for APRS and Winlink2000. We all know APRS, the tracking system that we use extensively in Hamnet so that the JOC can see where all their resources are. APRS is used to send and receive "tactical situation data". Most people use APRS to send GPS position reports from their cars, but it can also be used to send short person-to-person text messages, weather data, and all sorts of other things. Winlink 2000 is a way to send and receive short emails over HF, VHF, or UHF: just the thing to help the larger community when disaster strikes. Both APRS and Winlink 2000 over VHF/UHF are based on AX.25 packet radio, which means that you would need some sort of Terminal Node Controller (TNC). Hardware TNCs are expensive, but now days there are software TNCs that can be used like MixW, AGWPE and Dire Wolf to name a few.
There are a number of resources available on the internet that can be reviewed.
Take a look at the website of Joe Cupano NE2Z where he demonstrates Amateur Radio Digital Modes with simple VHF/UHF Digital Stations https://cupano.com/
https://cupano.com/2018/04/23/digital-modes-with-vhfuhf_1/
https://cupano.com/2018/11/09/demonstrating-amateur-radio-digital-modes-with-simple-vhf-uhf-digital-stations-part-2/
https://cupano.com/2018/12/27/packet-radio-connected-modes-with-the-baofeng-uv-5r-part-1/
More information about sound card packet TNCs can be found on the website of David Stansbury KB3KAI https://kb3kai.com/sound-card-tnc
Just think about the possibilities. You can now scan a list of names, grid coordinates or stores requirements into your laptop in the field, send the list via packet radio over your FM hand held radio to the local JOC which can then send it on via HF.
So who is up to getting such a system operational to test the capabilities?
Let us finish of with some news.
The 144 MHz Trans-Atlantic path opened again on Saturday 29 June 2019.
On 16 June 2019, the Atlantic was spanned for the first time on 144 MHz when D41CV on Cape Verde Islands off the coast of Africa managed to work FG8OJ in Guadeloupe using the FT8 digital mode. Amazingly, that particular opening lasted for the best part of five days. On Saturday 29 June, FG8OJ in Guadaloupe managed to work D4Z in Cape Verde for the first time on SSB.
D4Z FG8OJ SSB QSO.mp3
According the the Hepburn Charts for this week, the conditions for the West Coast are looking good from around 00:00 UTC on 9 July. I’m sure the guys from Brazil will also be monitoring the 2m band for a possible contact.
Conditions along the South East Coast will also be improving this coming week with good conditions around 00:00 UTC on 10 July.
Do not forget about the VHF workshop that will take place on 20 July 2019 at the National Amateur Radio Centre in Honeydew.
For registration and the agenda go to the SARL website www.sarl.org.za.
The next meeting of the VHF Work Group will be on 25 July at 20:00 on Skype. To participate in the work group, send your Skype name to vhfnews@sarl.org.za.
Please send your news snippets and information about activities on VHF and Above to vhfnews@sarl.org.za.
Focus on VHF and Above 30 June 2019
Audio version
It was previously reported that France has proposed to CEPT that 144-146 MHz be allocated to the Aeronautical Mobile Service. Well it seems like there is now serious petitioning happening against this. There are at present two online petitions that you can add your name to. One or both of these campaigns are also on the local WhatsApp groups.
I find it interesting that there is suddenly a lot of excitement around this topic. There are lots of opinions expressed on social media groups, forums and the like. The problem is that the information that is available is not the whole picture, but only part of it and there is also a lot of misinformation being circulated and the social media applications make it so easy to share this misinformation without first doing some basic research to see what the real story is.
I also hear folk asking what is the SARL doing about such and such a problem as if the SARL is some higher organisation that is responsible to resolve issues. Well, I’ve news for you. We, you and I are the SARL. It is us and not them. I see and hear a lot of excuses why one cannot participate, but very few leave the comfort of their arm chairs and actually step forward and get involved.
This problem is not only here, but occurs everywhere. Listen to what Onno VK6FLAB has to say.
Foundations of Amateur Radio – The Regulator.mp3
I can assure you that the South African Radio League is not sitting idle and there are folk constantly working in the background attending various meetings, lobbying the authorities and participating in industry and regulatory working groups.
So what can we do and where do we start? Firstly, if you are not a member of the South African Radio League, become a member. Then make the effort to participate when input is requested from the members by the respective work groups that deal with the various issues at hand. If you can afford the time, then why not make yourself available to actively participate in a work group. You do not need to be in Pretoria or Johannesburg areas to participate and help make a difference.
The past week the conditions along the South East Coast has not been good as reported by Peter ZS2ABF.
Earlier yesterday there was a 6m opening between Gauteng and the Eastern Cape.
Looking forward to the week ahead on the Hepburn Charts, the conditions predicted in the North Atlantic next week is excellent for more contacts between Cape Verde and the Caribbean Islands.
North Atlantic 18:00 1 July 2019.jpg
In the South Atlantic and the West Coast the conditions are not good, but may be improving towards the later half of the week.
South Atlantic 12:00 4 July 2019.jpg
On the South East Coast conditions may be good this afternoon and evening for contacts up the coast. The rest of the week there seems to be no chance.
East Coast 12:00 30 June 2019.jpg
Do not forget about the VHF workshop that will take place on 20 July 2019 at the National Amateur Radio Centre in Honeydew.
For registration and the agenda go to either the AMSAT SA website at http://amsatsa.org.za/ or the SARL website www.sarl.org.za
The VHF Work Group met on Thursday 27 June on Skype. It was a short meeting as there is still work being done on the radio in order to generate a clean CW signal. Hopefully progress will be made this coming week and then an installation date can be determined for the beacon in Bethlehem.
The next meeting of the VHF Work Group will be on 25 July at 20:00 on Skype. To participate in the work group, send your Skype name to vhfnews@sarl.org.za.
Please send your news snippets and information about activities on VHF and Above to vhfnews@sarl.org.za.
Focus on VHF and Above 23 June 2019
Audio version
The highlight this week must be the historic contacts being made across the Atlantic between the Cape Verde Islands and the Caribbean Island of Guadeloupe.
The first contact was made on Sunday 16 June 2019 when the Atlantic was spanned for the first time when D41CV on Cape Verde Islands off the coast of Africa managed to work FG8OJ in Guadeloupe on 144.174 MHz using the FT8 digital mode. A distance of 3,867 kilometres
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Tropo prediction maps show a path right across the Atlantic and suggest that even more incredible contacts may be possible.
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The operator was Mark EA8FF using the beacon antenna as the "Pinocchio Yagi" had to be taken down to be improved after severe bad wind. The beacon antenna is an array of 6 horizontal polarised dipoles with an omnidirectional pattern.
Since this contact there have been numerous contacts across the Atlantic from D41CV. See the post Historic Trans-Atlantic Contact made on 144 MHz from Cape Verde to Guadeloupe on the blog of John EI7GL from Ireland for more information. The URL for John’s blog is https://ei7gl.blogspot.com/.
Now the challenge is to cross the Southern Atlantic between the West Coasts of South Africa or Namibia and Brazil.
Using AIS metadata to monitor propagation in the 2m band. Prognosis, monitoring and analysis of propagation conditions are a basis for kilometres and points in DX competition. As a new tool to monitor propagation in the 2m band, D4C has started receiving vessel AIS data.
AIS is a maritime NMEA standard, through which ships continuously transmit signals at approximately 12.5 Watts using a ground plane antenna. The evaluation of the AIS position data - which can, for example, be visualized by DXMaps under "AIS" - show when and how periods of enhanced propagation occur, in real time. Therefore, log data of successful radio connections are not used, but rather received signals on the 2 AIS channels at 162 MHz (+- 25KHz).
To receive AIS signals at D4C’s location (also D4Z and D41CV) on the Cape Verde Islands, the team concluded an antenna partnership with the company Vesseltracker.com in Germany, through which they received their AIS receiver equipment free of charge.
While at the preparatory meeting for WRC19 that I recently attended, I had the opportunity to chat to the folk from the Maritime Safety Authority about AIS. There are various AIS systems that are deployed on vessels. Some of these AIS systems make use of RF while others are satellite based, so when one uses websites like Vesseltracker.com then one needs to drill down to the vessel concerned to see which system the ship is using. Some of the long distances being reported could be from vessels using the satellite based systems.
Please remember that here in South Africa, you need a license to receive signals outside of the amateur bands so it is better to view the data on the websites than to receive the AIS signals yourselves.
While you are on the blog of John EI7GL, take a look at the post about Noctilucent Clouds.
In this week there have been reports about these clouds in Space Weather News as well.
The 2019 season for noctilucent clouds (NLCs) has been remarkable, maybe the best ever, with NLCs appearing as far south as Los Angeles CA and Albuquerque NM. What's going on? NASA satellites have just found an important clue. An unusual wave of moisture is surging through the mesosphere, boosting water concentrations to their highest level in at least 12 years. Visit Spaceweather.com for the full story and look at the fantastic photos of the Noctilucent clouds.
Hans ZS6AKV alerted me to this and I dug a little into it to find out more and whether there may be any chance of seeing these clouds locally and experiencing their effects on the VHF and above bands.
The Mesosphere is a layer between the Stratosphere and the Thermosphere. The Stratosphere being above the Troposphere. The Ionosphere also overlaps the Mesosphere. Looking at the numbers, the Troposphere is around 12 km thick. The Stratosphere extends to approximately 45 km, then the Mesosphere extends from 45 km to 85 km. Noctilucent clouds exist at a height of 76 km to 85 km. The D layer of the Ionosphere is from 60 km to 90 km and the E layer is 90 km to 150 km.
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The Mesosphere is the same layer where the meteors burn up in. We know that we get ionisation when the Meteors burn up that causes signal enhancement. We also know that the E layer of the Ionosphere is where Sporadic E propagation takes place.
Noctilucent clouds are known to exhibit high radar reflectivity in a frequency range of 50 MHz to 1.3 GHz. These radar echoes are called PMSE (polar mesosphere summer echoes). There are a lot of theories as to the cause of the radar echoes.
NASA has been studying these clouds through their AIM program since 2007.
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AIM’s data has led to more than 200 papers on Earth’s upper atmosphere. Here are a handful of key scientific discoveries:
· Overturning assumptions about the sun and noctilucent clouds: Observations from the 1980s and ’90s suggested that the appearance of noctilucent clouds is linked to the sun’s activity, which rises and falls in about 11-year patterns. But AIM’s data tell a different story: noctilucent clouds have been steadily increasing over the past decade, despite the sun’s regular changes in activity. The precise reason for this is still unknown.
· Noctilucent cloud and greenhouse gases: Scientists suspected that increased sightings of noctilucent clouds could be related to increasing greenhouse gases. Combining AIM’s data with 36 years of measurements from satellite instruments showed a correlation between more frequent noctilucent clouds and increases in water vapor, a greenhouse gas, and decreasing upper-atmosphere temperatures — a side effect of warming near the surface.
· Meteors help create noctilucent clouds: The ice crystals that form noctilucent clouds must form on a foundation of some kind. AIM’s data showed that this base is actually smoke from meteors — tiny microparticles produced when meteors burn up in Earth’s atmosphere.
· Tracking meteoric smoke: Before AIM’s launch, scientists primarily watched meteoric smoke — the tiny particles created when meteors burn up in the atmosphere — from just a few viewpoints with sounding rockets. AIM’s measurements have given scientists a new tool to watch this meteoric smoke, revealing for the first time the dynamics of how meteoric smoke moves through the atmosphere.
· Understanding the upper atmosphere: AIM helped scientists track how heat moves in the upper atmosphere, showing that heating in the mesosphere is more likely linked to circulation in the atmosphere rather than direct heating from the sun.
· Studying atmospheric waves caused by Earth’s rotation: AIM measures planetary waves, planet-scale waves caused by Earth’s rotation, that can influence weather across the globe. Over its 10-year mission, AIM has observed three of the four most extreme springtime planetary wave events seen since satellite observations began in 1978, raising questions about possible changes in the dynamics of the atmosphere.
· Teleconnection between the poles: AIM’s data showed that conditions in the stratosphere near the North Pole influence conditions in the mesosphere near the South Pole days or weeks later — even going so far as to influence the transition between seasonal conditions.
· How Earth’s weather affects the upper atmosphere: AIM’s measurements have also helped scientists track how air in the atmosphere moves vertically, as well as between the hemispheres. This helps scientists understand how events near Earth’s surface — like thunderstorms — might trigger changes in the upper atmosphere.
· Understanding the atmosphere from bottom to top: This new understanding of vertical linkages in the atmosphere was integrated into the first weather model that describes the entire atmosphere from the surface all the way to the upper mesosphere.
· The source of radar echoes: AIM solved the mystery of radar echoes in certain regions of the atmosphere during the summer. The same ice layer that produces noctilucent clouds is to blame for radar echoes, and the size of the ice crystals can even play a role.
Thanks for NASA for the information supplied.
Could we see these clouds in Southern Africa? Most likely not, but if they were to be seen it will probably be in the Southern Cape.
Could there be propagation enhancement from these clouds? Very possible, however there are very few amateurs at the latitudes where these clouds exist, so it could be more possible over the Northern Hemisphere than the Southern Hemisphere.
RF Noise just how bad is it? Recently large parts of South America were without electricity. When Argentina was plunged into darkness by a nationwide power cut Luciano Petruccelli LU3DX made a video showing just how much RF pollution is produced by electronic devices.
Watch his video showing how little interference there was during the power cut on June 16, 2019, followed by massive RF pollution when power was restored. At 42 seconds into the video clip you will see and hear a sudden increase in noise when the power was restored.
https://twitter.com/ure_es/status/1141397089047519234.
Do not forget about the VHF workshop that will take place on 20 July 2019 at the National Amateur Radio Centre in Honeydew.
For registration and the agenda go to either the AMSAT SA website at http://amsatsa.org.za/ or the SARL website www.sarl.org.za
Looking forward to seeing you there.
The next meeting of the VHF Work Group will be via Skype at 20:00 on 27 June 2019. If you want to join the VHF Work Group, send us your Skype name to vhfnews@sarl.org.za and we will add you to the call.
Please send your news snippets and information about activities on VHF and Above to vhfnews@sarl.org.za.
Focus on VHF and Above 16 June 2019
Audio Version
Last week we listened to what typical Meteor Scatter signals sound like. You could clearly hear the bursts of ionisation caused by the meteors burning up in the atmosphere.
This week we are going to listen to a couple of other VHF propagation modes.
Here in the inland areas of the country the long distance VHF communications are most likely Tropospheric Scatter. This type of propagation is also normally associated with changing weather such as a high pressure cell moving away and temperature inversions.
This first recording is a typically weak but stable CW tropospheric scatter signal of a beacon.
Tropospheric Scatter f5xal Beacon.mp3
And here is a SSB tropo scatter signal
Tropospheric Scatter 7x2ls SSB.mp3
Now along the coastal areas especially on the West Coast we get tropoducting taking place. Here is what tropoducting sounds like.
Tropoducting rw1zd.mp3
And another one recording locally the West Coast and St Helena Island.
Tropoducting ZS3JPY QSO ZD7GWM.mp3
Here in South Africa, Sporadic E season is usually late December and January. Sporadic E is strongest on the lower VHF bands. So what does Sporadic E propagation sound like over the radio?
This recording is a very strong SSB signal.
Sporadic E cn8st.mp3
Here is another recording, this time of a CW signal
Sporadic E yo6afp.mp3
While I have just said that usually Sporadic E openings occur in the summer months, this past week has seen Sporadic E openings between the northern provinces and Cape Town.
Mike ZS1TAF reports that he worked Willem, ZS6WAB and Servaas, ZS6SER on 50.200 MHz SSB between 16H10 and 17H20 UCT on 7 June.
QSB on band but great contacts both ways.
ZS6TWB Beacon was also heard on 50.044 MHz CW with a report of 57.
There were multiple ZS1 stations that worked both Willem and Servaas.
On 11 June Mike only worked Carl, ZS6CBQ. There were however other ZS1 stations who worked Carl and a few other ZS6 stations as well.
The following beacons were also heard:
ZS6TWB Beacon on 50.044 MHz CW reported as 56
ZS6WAB Beacon on 50.025 MHz CW reported as 59
ZS6JON Beacon on 50.050 MHz CW reported as 54
Mike says “This was a Sporadic E opening which is usually concentrated during the summer months.... Maybe this changes that Theory somewhat....”
That was a great opening and congratulations to all the guys that managed to exploit the favourable conditions.
We have previously reported that the frequency bands allocated to the Amateur Service are under attack. This threat has come to our attention.
France proposes 144-146 MHz for Aeronautical Mobile Service
The next meeting of the CEPT WRC-19 Conference Preparatory Group takes place June 17-21 in Prague
France has submitted a paper with the subject Agenda Item 10 revised proposal for an agenda item for new non-safety aeronautical mobile applications.
The paper says:
"The list of bands that are proposed for study of possible new allocations to the aeronautical mobile service on a primary basis is revised by adding the band 144-146 MHz, the bands 5000-5010 MHz and 15.4-15.7 GHz being maintained."
"The decisions of previous conferences have introduced some restrictions to the use and have imposed constraints on the development of aeronautical mobile applications within some existing mobile allocations traditionally used by the aeronautical mobile applications.
At the same time, the number of manned and unmanned aircraft equipped with sensors has grown significantly in the past 20 years together with the need of bidirectional low to high data rate communications.
Aeronautical applications like fire surveillance, border surveillance, air quality and environment monitoring, traffic monitoring, disaster monitoring, terrain modelling, imagery (visible, infrared, radar, meteo), video monitoring require non-safety communications between various types of aeronautical platforms.
Consequently the need of non-safety data communications between various types of aeronautical platforms increases and so the need for new frequency bands."
Remember, we are part of Region 1 and this is how it starts. It will now not be long and we will need to justify and defend our usage of the 2m band here as well.
Do not forget about the VHF workshop that will take place on 20 July 2019 at the National Amateur Radio Centre in Honeydew.
For registration and the agenda go to either the AMSAT SA website at http://amsatsa.org.za/ or the SARL website www.sarl.org.za
Looking forward to seeing you there.
The next meeting of the VHF Work Group will be via Skype at 20:00 on 27 June 2019. If you want to join the VHF Work Group, send us your Skype name to vhfnews@sarl.org.za and we will add you to the call.
Please send your news snippets and information about activities on VHF and Above to vhfnews@sarl.org.za.
Focus on VHF and Above 9 June 2019
Audio version
We have previously in tutorials spoken about the various propagation modes.
Bernie ZS4TX sent VHF news an email this week with some great information which I’m going to use as an introduction to how do you identify what VHF mode of propagation you may be experiencing and what it sounds like on the radio.
The ZS5KT beacon is being heard very well in Bloemfontein. Bernie says “I have been hearing the ZS5KT 144.420 CW beacon from grid KF50MF in grid KG30BX almost all the time during the few days I have been monitoring since I was alerted about the beacon being active.” The ZS5KT beacon has a 9 element Yagi with an output of 25W and Bernie has a 4 x 14 element Yagi array. The distance between KG30BX & KG50MF is 483.55 km.
Bernie also attached two screen shots with an audio recording at about the time the screenshots were taken. You need listen carefully and sometimes it may be difficult to hear the changes in the signal, but it will get easier over time.
Bernie says “On the first recording you will hear a short meteor burst at the beginning followed by the normal troposcatter signal.
Recording 1
On the second recording you will hear the signal enhancement for a few seconds as typically caused by aircraft scatter. The 2nd screenshot of the WSJT waterfall clearly shows the stronger signal and doppler shift caused by the aircraft scatter.
Recording 2
In the first recording Bernie sent you probably did not recognise the meteor burst. So what do meteor scatter bursts sound like?
Here is a recording of more pronounced meteor scatter pings recorded during the Leonids meteor shower in 2002. You will clearly hear the pings when the ionisation of the air takes place and then a burst of radio activity being reflected or scattered by the ionisation.
191102_0415_0430.mp3
Here is another recording of some meteor scatter bursts
svdl5mae.mp3
and lastly one of two short FSK441 meteor scatter reflections
k1uhf.mp3
If you now again carefully listen to the recording sent by Bernie, you will recognise the meteor burst.
Thank you Bernie for this information and thanks to EA6VQ for providing the other MS recordings.
The screenshots and recordings are available on the SARL web page.
Next week we will listen to another VHF and above propagation mode.
Now for some VHF and above news.
For those of you who like to play with Slow Scan TV or SSTV, the Raspberry Pi magazine, MagPi has a very nice article that describes how to set up a Raspberry Pi and a RTL-SDR dongle to receive SSTV pictures from the International Space Station. Follow the link https://www.raspberrypi.org/magpi/pictures-from-space-via-ham-radio/
The ISS regularly transmits SSTV images on the downlink frequency of 145.800 MHz. To find out when the ISS will be making SSTV transmissions keep an eye on the Amateur Radio on International Space Station (ARISS) SSTV blog page at http://ariss-sstv.blogspot.com/
Talking about satellites, Lightsail-2 is scheduled for launch June 22 and will have a Beacon on 437.025 MHz
LightSail is a citizen-funded project from The Planetary Society.
This cubesat will be propelled solely by sunlight, to Earth orbit. LightSail 2 is scheduled to launch aboard a SpaceX Falcon Heavy on June 22, 2019, and they will attempt the first, controlled solar sail flight in Earth orbit.
LightSail 2 will ride to space aboard the Department of Defense Space Test Program-2 (STP-2) mission which will send 24 spacecraft to 3 different orbits. LightSail 2 itself will be enclosed within Prox-1, a Georgia Tech-designed spacecraft originally built to demonstrate close-encounter operations with other spacecraft. Prox-1 will deploy LightSail 2 seven days after launch.
After a few days of health and status checks, LightSail 2's four dual-sided solar panels will swing open. Roughly a day later, four metallic booms will unfurl four triangular Mylar sails from storage.
The sails, which have a combined area of 32 square meters [344 square feet], will turn towards the sun for half of each orbit, giving the spacecraft a tiny push no stronger than the weight of a paperclip.
For about a month after sail deployment, this continual thrust should raise LightSail 2's orbit by a measurable amount.
LightSail 2 will fly in a 24-degree inclination, 720 km, circular orbit.
At latitudes of 42 degrees north it will reach a maximum elevation of 10 degrees above the horizon.
Lightsail-2 has been issued an experimental radio license WM9XPA and transmit on 437.025 MHz. A morse beacon will transmit the callsign every 45 seconds. A packet beacon will transmit AX.25, FSK 9K6 bps data.
Beacon information is available at:
http://tinyurl.com/ANS-153-Lightsail-Morse-Beacon
Documentation of the downlink telemetry data structure is posted at:
http://tinyurl.com/ANS-153-Lightsail-Telemetry
The VHF workshop will take place on 20 July 2019 at the National Amateur Radio Centre in Honeydew.
The main topic will be: Which is better, Vertical or Horizontal polarisation?
Come to the VHF workshop and listen to what Dick ZS6BUN has to say about Vertical vs Horizontal propagation.
We are also privileged have a presentation by Jan Pienaar ZS6OB or "Pine" as we all know him, and he will talk about Antennas, the most important link in VHF communication and discuss what is really important to look out for.
There will also be feedback on the progress of the two new beacons, a discussion on the West Coast propagation phenomenon and some quick fire sessions on the Reverse Beacon Project, a growing concern regarding the HF noise levels and why VHF and UHF has an important future in Amateur Radio.
The registration fee is R50 for SARL and AMSAT SA Members and R100 for non-members. For registration and the agenda go to either the AMSAT SA website at http://amsatsa.org.za/ or the SARL website www.sarl.org.za
Looking forward to seeing you there.
The next meeting of the VHF Work Group will be via Skype at 20:00 on 27 June 2019. If you want to join the VHF Work Group, send us your Skype name to vhfnews@sarl.org.za and we will add you to the call.
Please send your news snippets and information about activities on VHF and Above to vhfnews@sarl.org.za.
Examination
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home or while mobile in cars, boats or on foot.
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Worked
All ZS award
SA
Maritime Net