The next meeting of the Amateur Radio Experimenter’s Group will be held on Friday September 20th. The presentation tonight will be given by Theo VK5IR who will take us through what he has learned as he has set to home brewing his 20-6m HexBeam antenna. The HexBeam antenna design is well known to many in AREG but Theo is the first in the club to home brew one. This could kick off a whole new round of antenna construction experimentation at the club!
AREG meets at the Fulham Community Centre, Phelps Court, Fulham. Doors open at 7.15pm with the meeting starting at 7.45pm sharp. Visitors are most welcome!
The Amateur Radio Experimenters Group Inc will hold it’s Annual General Meeting on Friday August 16th, at the Fulham Community Centre, Phelps Court, Fulham, starting at 7.45pm.
The AGM will recap the year that was for AREG with the presentation of the reports by the committee. All positions will then be declared vacant, and the election of the office bearers and committee will be held.
After the AGM, refreshments will be served and there will be ample opportunity to socialise and talk about the exciting year ahead!
Visitors are always welcome! We hope to see you there!
The next meeting of the Amateur Radio Experimenters Group will be held on Friday July 19th. Doors open at 7.15pm with the presentations starting from 7.45pm.
AREG is very pleased to announce that our guest speaker for the evening is Neil Abraham VK5KA.
Neil has a lifetime’s experience designing RF transformers (among many other things) for a prominent commercial HF radio manufacturer here in South Australia. In this presentation, Neil will open a window into the world of RF transformers and impedance matching, showing how they can be used in your every day amateur radio station experiments.
Neil says the following about his presentation:
I am not going to cover every thing there is to know about RF transformers.
I hope to give you enough info so you can design and make your own transformers.
I am going to limit this to transformers that are used to help match HF antennas and feed lines.
If ever you have experimented or had a desire to experiment with designing your own antennas, invariably at some point you will face the issue of how to match that antenna to your transmitter. This presentation will be a great introduction to this most useful aspect of the radio art-form.
Visitors are most welcome! Following Neil’s talk, there will be a short business meeting, followed by tea, coffee and cake and a chance to talk about your own antenna matching challenges with Neil. We hope to see you at the club!
Where do we meet?
AREG meetings at the Fulham Community Centre (formerly known as the Reedbeds Community Centre), on Phelps Court in Fulham.
AREG has long been seeking a location to establish a remote SDR receive site as a way of allowing members to escape the ever increasing levels of RF interference one sees in suburbia. Finally, the beginnings of this project are taking shape, with a trial system now in place at a location ~100km north of Adelaide.
This meeting will introduce the KiwiSDR system, and show people what was installed , as well as how to use it. We will also show the next steps with the antenna system and talk about ways of using the SDR system in your every day activities. We will also talk about the wider worldwide SDR network and how you can find your way around it.
(It should be noted that the system itself is being restricted to members only at this time due to the temporary nature of the trial site and internet feed).
The meeting will be held on Friday June 21st at the Fulham Community Centre, 1 Phelps Court, Fulham. The doors will open at 7.15pm with the meeting to start promptly at 7.45pm The presentation will commence immediately after a short business meeting.
Members and non members alike are both welcome at club meetings. If you would like to know more, why not come along and introduce yourself!
Thanks to Mark VK5QI, AREG is pleased to announce a new service has been added to the VK5RWN Repeater site. Mark has been developing a RadioSonde automated receive system which allows all of the Bureau of Meteorology weather balloon data to be collected and be made available on the internet. The data is available via the SondeHub instance of the HabHub High Altitude Balloon Habitat platform. You can access it here:
What can you see? Where all the active weather balloons are right now!
If you’re located in South Australia and are considering going out to recover a sonde, or have recovered one, please use the Facebook Group or the mailing list to announce your intentions! This helps avoid disappointment if others are intending to recover the same sonde.
Want to learn more? Read on…..
For quite a while now I’ve been interested in tracking and recovering radiosondes. These are meteorological instruments regularly launched by weather balloon from many locations around the world. Here in South Australia the Bureau of Meteorology launches them from Adelaide Airport twice daily (2315 and 1115Z), along with a few other locations around the state.
A Vaisala RS41 radiosonde found with the help of the radiosonde_auto_rx tracking network!
Radiosondes transmit in the 400-403 MHz band (usually on either 400.5/401.5/402.5 MHz), and there is a range of software, both closed and open source available to decode their telemetry. Not being entirely happy with the existing offerings, I started work on my own software, which became radiosonde_auto_rx (or ‘auto_rx’ for short).
auto_rx runs on a Raspberry Pi (or any other Linux machine) and automatically scans for and decodes radiosonde signals. Telemetry is uploaded to APRS-IS and the Habhub tracker for mapping purposes, and can also be viewed locally via a web interface. Most of the common radiosonde models are supported, including the Vaisala RS41 which is launched here in Adelaide. There are currently 147auto_rx stations in operation worldwide (16 here in VK5), and so far (as of 2019-05-25 10Z) 19415 individual radiosondes have been logged.
So why do I bother doing this? Many radiosondes are (in part..) highly recyclable! The Vaisala RS41 contains a good quality GPS receiver, a micro-controller, and a radio transmitter – perfect for re-programming for use as a high-altitude balloon payload, as we have been doing on many recent Project Horus flights. In fact, the RS41 is the ‘reference platform’ for the new high-performance balloon telemetry system developed by David Rowe and I.
Chasing and recovering radiosondes is also great practice for Project Horus launches, with a few of the new Horus regulars starting out tracking radiosondes, and many others around VK5 regularly out chasing the BOM’s radiosonde launches. We use the same mapping software for both radiosonde and Horus chases.
To help improve tracking coverage, I proposed to install an auto_rx receiver station at one of AREG’s premier repeater sites, overlooking the Adelaide plains. Thanks to the generosity of AREG members in approving this proposal, the receiver was installed over the easter break. A big thanks to Ben VK5BB for assistance in fabricating an antenna bracket, and helping with the installation!
Hardware Details
The auto_rx receiver station installed in a rack at the site.
The auto_rx receiver hardware consists of a Raspberry Pi 3, with two RTLSDR v3 dongles attached, allowing simultaneous reception of 2 sondes. The incoming RF from the antenna is filtered through an interdigital filter (passband 400-403 MHz, stop-band attenuation > 90 dB) before being going through a preamplifier and splitter to the two dongles. The estimated system noise figure is about 5dB, mostly from the insertion loss of the filter. Given this is a very RF-noisy site (co-located DSTAR repeaters, and many commercial services on a tower a few hundred metres away), the higher noise figure is an acceptable tradeoff – without the filter the receivers would immediately overload!
All the equipment is mounted within a 2RU rack-mount chassis, with all power and network inputs heavily filtered to avoid coupling in unwanted RF. The total power draw of the unit is ~10W.
View from the antenna!
The antenna is an AEA co-linear (kindly donated to the project by Ivan VK5HS) mounted to the side of the repeater hut. Being ~450m above sea level, the antenna has direct line-of-sight to the Adelaide airport, and essentially anywhere to the west of Adelaide.
Receiver Performance
Receiving a radiosonde on the ground at Adelaide Airport
With such excellent line-of-sight, the station regularly receives signals from the Adelaide Airport radiosondes before they launch, and often even during the ground-test and calibration activities performed on the radiosonde within the Bureau of Meteorology building at the airport.
Also often visible are radiosonde launches from the Ceduna and Woomera receiving stations, which typically rise above the horizon when they reach ~10km altitude. Coverage to the east is not quite as good, being blocked by the Adelaide Hills, however radiosondes are regularly tracked down to ~1 degree elevation.
Would you like to know more?
More information on the radiosonde reception software is available on github at https://github.com/projecthorus/radiosonde_auto_rx .
A conference presentation delivered by myself and Michael Wheeler (VK3FUR) where we discuss the re-use of the Vaisala RS41 radiosondes is also available (see below)
You can track radiosondes launched from Adelaide Airport (and many other launch sites around the globe!) by visiting the Habitat Tracker at this link.
Thanks again to all those who helped make this possible!
The next meeting of the Amateur Radio Experimenter’s Group will be held (yet again) one week early on Friday May 10th. This time it is a result of the Federal Election which has cancelled our hall booking for our normal night of May 17th. The doors will open at 7.15pm with the business meeting commencing at 7.45pm. The presentations for the evening will begin by 8.00pm. The event will be followed by coffee and cake!
AREG Lightning Talks
Photo by Mark VK5QI of Lightning over Adelaide 24th October 2014
This months meeting is a return to one of our favourite formats, the member lightning talk. While the talks are not about “lightning”, members are invited to give a lightning fast 5 minute introductory presentation on their latest experiment or project. Our time keeper Mark will keep things moving ensuring a lively and diverse range of topics can be covered over the 30-40 minutes of the presentations.
Members who would like to make a presentation should announce it on the club mailing list beforehand so we can plan the program order accordingly, although “drop ins” on the night will also be welcome. Projector slides if you want to show something should be sent to Grant, VK5GR on email prior to the event.
Afterwards, members of the audience will have the opportunity to get up close and personal with the presenters and talk to them in more detail about their projects and experiments. In this way we hope to promote sharing of what experiments the members are undertaking at this very moment.
Visitors are always welcome!
AREG is very happy to welcome visitors to our club meetings, so come along and find out what the membership of AREG is experimenting with!
The club meets at the Fulham Community Centre, Phelps Court, Fulham.
Thanks to Easter this year, the AREG meeting is being held 1 week early on Friday April 12th, starting at 7.45pm. Doors open at 7.15pm.
This months presentation is by David VK5DGR, who will introduce FreeDV, talking about it’s capabilities and development as well as how you can try it yourself.
David will also discuss the latest developments in FreeDV and will hopefully give us a sneak peak of what is coming just around the corner.
We will also discuss the up-coming FreeDV QSO Party, the rules and what you need to do to be able to take part! The FreeDV QSO party is being held over the weekend of April 27th and 28th.
At the club business meeting we will also be discussing a working bee to recover the original attempted remote SDR site over the Easter/Anzac day break as well as the pending River Paddling Marathon 200 community event which is supported by AREG each year over the June long weekend.
So why dont you come along and find out what we are up to today in the Amateur Radio Experimenters Group Inc. The clubrooms are located at the Fulham Community Centre, Phelps Court, Fulham.
The moon at moon set (4am) with our 6m EME antenna – Photo by Scott VK5TST
Several weeks ago, members of AREG headed out into the country side to try an experiment that many had wanted to do for many years – bounce a signal off the moon. With the help of Peter VK5PJ who has the necessary high power permits, we were able to achieve just that!
The team involved will take people through the events of that weekend and share what we learned about EME procedures, RadHaz management, JT65A and what it takes to send a radio signal over a half a million km journey to the moon and back.
Meeting Date and Time
NOTE This month’s AREG meeting is occurring one week early on the 2nd Friday of the month, so as to avoid clashing with the John Moyle Memorial Field Day Contest the following weekend. The hall will open at 7.15pm and the meeting will commence at 7.45pm sharp with a short AREG business meeting. The guest presenters will start by ~8pm. The presentation will be followed by coffee and cake and an opportunity to discuss EME with those who were there.
AREG meets at the Fulham Community Centre, Phelps Court, Fulham (formerly known as the Reedbeds Community Centre).
