Next AREG Meeting: Stuart VK5STU – “An Overview of SAGRN Services, Technology and Operations”

The next AREG meeting will be held on Friday the 16th of June at the Fulham Community Centre – Phelps Court, Fulham.

A helicopter assisting with installation of antennas on a SAGRN tower.

This months presentation will be from Stuart VK5STU, talking about the SA Government Radio Network (SAGRN). Stuart will be covering the 5 services within the SAGRN and go through the technology employed across these services as well as coverage design and engineering considerations. He will also talk about how the network is operated and managed, and the challenges faced during major incidents.

Doors open at 7.15pm and the presentation kicks off at 7.45. Everyone is welcome to attend. If you’ve never come along to one of our meetings, we’d love to see you there, all guests are welcome. For our remote members, the meeting will be broadcast via Zoom.

After the talks we’ll all be given an opportunity to have an eyeball QSO among ourselves whilst enjoying a tea or coffee and a biscuit.

73, Mark VK5QI

No June Fox-Hunt

AREG regrets to advise that due to the proximity of the usual monthly fox hunt date to the Riverland Paddling Marathon (where many AREG members will be heading to), the June fox hunt will not be going ahead.

Stay tuned for details regarding our July hunt, to be posted here closer to the date.

73 from AREG!

AREG’s HF Spectrograph shows the effects of Solar Flares

An X-class Solar Flare imaged by the Solar Dynamics Observatory in 2012.

An X-class Solar Flare imaged by the Solar Dynamics Observatory in 2012.

Solar flares from the sun can result in many different effects on High Frequency (HF) propagation. The most immediate and noticeable is when the increased solar X-Ray flux resulting from a flare interacts with the ionosphere. These X-Rays charge the ionosphere’s D-layer (responsible of the absorption of the lower HF band during the daytime), and results in higher levels of absorption extending right up to the top of the band. This has the effect of reducing signal strengths right across the band, resulting in what is known as a ‘HF fadeout’.

X-Ray Flux data from the GOES satellites, provided by NOAA

Solar flares are categorised based on the peak X-ray flux they emit, with the different levels given letters A, B and C for relatively weak flares, and M and X for stronger flares, with X-class flares being the strongest. HF fadeouts are generally caused by M and X-class flares. A live plot of X-Ray flux data as observed by the Geostationary Operational Environment Satellites (GOES) is available here: https://www.swpc.noaa.gov/products/goes-x-ray-flux

Short Wave Frequency Coverage Prediction

HF Fadeout Coverage area for a M1.2 class flare, from the Space Weather Service website.

The Australian Space Weather Service provides a HF fadeout warning service via email, and you can also see reports of the most recent HF fadeout on their website.

AREG’s HF Spectrograph Service

AREG hosts many services at its remote HF receive site located near Tarlee, including multiple KiwiSDRs, skimmers for WSPR, FT8 and SSTV, and other higher performing receivers reserved for club members. We thank Swoop Internet for providing us with the internet service at this site, for free!

The HF receiver antenna (a broadband monopole) at AREG’s remote HF receive site.

Using software written by Mark VK5QI, AREG also generates a Spectrograph showing the state of the HF band over the last 3 days. A spectrograph is similar to the waterfall display you might have seen on other SDR receiver software, though in this case covering the entire HF band (0 – 30 MHz), and looking over a much longer timescale. Warmer colours (reds and yellows) represent stronger signals, and cooler colours (blues and greens) represent weaker ones. The spectrograph updates approximately every 30 minutes, and is available at the bottom of the Remote HF Receiver site page, or directly here.

A typical HF Spectrograph, with some features annotated.

The spectrograph gives us a ‘quick look’ at the state of the HF band. The strongest signals (red) are the bands of shortwave stations around 6, 7, 9 and 11 MHz, mostly propagating in from south-east Asia. The most obvious time-varying effect is the change in propagation conditions from day (propagation mainly at the higher end of the band), to night (propagation mainly at the lower end of the band), but we can also see other effects such as solar radio bursts, local noise issues, and of course HF fadeouts.

In the above figure, a number of HF fadeout events over the 18th through 20th May 2023 period have been marked, showing the X-Ray flux event they correspond to. The HF fadeouts can be seen as a sudden reduction in signal strength right across the HF band, followed by a slow return to normal. Note that we don’t see the effects of X-ray flux events occurring during our local night, due to the Earth sheltering us from those X-rays.

So, next time you think the HF band seems a bit dead, maybe go take a look at the AREG HF Spectrograph to see if there’s a HF fadeout in progress!

73 Mark VK5QI

Next AREG Meeting: Paul VK5PAS – Portable Operations on Troubridge Island

The next AREG meeting will be held on Friday the 19th of May at the Fulham Community Centre – Phelps Court, Fulham.

Unfortunately Paul is unavailable to give the talk at this meeting. Instead Grant VK5GR will be presenting on RTTY contesting. Thanks to Grant for agreeing to present on such short notice!

This months presentation will be from Paul Simmonds VK5PAS, on the recent Troubridge Island DXpedition. Paul will talk about how the expedition was planned, what antennas and equipment they used on the island, and discuss the results of the expedition and lessons learned.

Doors open at 7.15pm and the presentation kicks off at 7.45. Everyone is welcome to attend. If you’ve never come along to one of our meetings, we’d love to see you there, all guests are welcome. For our remote members, the meeting will be broadcast via Zoom, and we’ll try and get a recording of the talk for later upload to Youtube.

After the talks we’ll all be given an opportunity to have an eyeball QSO among ourselves whilst enjoying a tea or coffee and a biscuit.

73, Mark VK5QI

AREG’s VK5RSA Adelaide CBD repeater – supported by KernWi-Fi

One of the services that the Amateur Radio Experimenter’s Group provides is a network of repeater stations that cover the Adelaide metropolitan and surrounding areas. These systems operate on the 6m-23cm bands from 3 sites in and around Adelaide.

One of the first repeaters conceived by AREG was the Adelaide CBD repeater. Inspired in the 1990s by the original 438.025 VK3RCC repeater in Melbourne (which was located atop one of the hi-rise towers in Melbourne CBD), the intention was to reach the deep CBD buildings and the Adelaide foot hills shadowed by the existing repeaters atop the Mt Lofty ranges.

The AREG repeater in Adelaide was originally established on top of the original Angas Street police station building – then 11 stories high in Victoria Square. When that building was subsequently demolished, it was moved to another building off Flinders Street, where it ran for many years before finally developing a terminal fault.

Today, VK5RSA is back on what now is one of the best communications sites in the CBD. This is all thanks to the support AREG receives from KernWi-Fi, who are sponsoring access to Westpac House on King William Street in the heart of the Adelaide CBD.

VK5RSA operates on 438.025MHz TX -7.0MHz RX with 91.5Hz CTCSS

VK5 Linked Repeater Network

VK5 Linked Repeater Network Coverage Map

VK5RSA is also part of the new central SA linked repeater network. This network now includes 10 repeaters, stretching from the Adelaide area right across to the eastern border of SA, and south to Victor Harbor.

AREG offers it’s sincere thanks to Phil Kern at KernWi-Fi for his support for the project to re-establish VK5RSA – it is fantastic to have been able to restore this service for the amateur radio community in Adelaide – and from such a fantastic site too!


About our Sponsor

KernWi-Fi supply FibreNBN, Fixed Wireless Internet, VoIP, Event Wi-Fi and Radio Communications to residential and businesses all over Adelaide.  They also specialise in servicing the black spots of Adelaide.  To learn more, visit their website!

They are 100% Adelaide based and owned Licensed Carrier and work with many local communities to provide high speed internet services. They also sponsor various community groups across the state.

Next Fox Hunt – Friday 12th May

AREGs next car-based fox hunt will be held this coming Friday the 12th of May, starting from the car park of the North Adelaide Aquatic Centre Carpark at 6:30 PM. We’ll have three foxes deployed around the Adelaide area, on both the 2m and 70cm bands, so come along and have a go!

The frequencies will be:

  • 145.300 MHz (1W transmit power)
  • 144.390 MHz (100mW transmit power)
  • 439.400 MHz (50mW transmit power)

As usual, liaison will be on the VK5RSB Summertown 70cm repeater which operates on 439.900 (-5MHz) 91.5 CTCSS. Please come up on the repeater so we know how you are faring throughout the evening!

The event is open to anyone with radio direction finding equipment and will span most of the Adelaide metropolitan area. We would love to see you there!

73

Mark VK5QI

Save the date: AREG’s Adelaide Amateur Radio & Electronics Sale – Sunday November 26th

The event calendar this year is looking pretty good for South Australian Amateur Radio operators, with the South Coast Amateur Radio Club Buy & Sell coming up on the 23rd of April, and the Adelaide Hills Amateur Radio Society Buy & Sell on the 15th of July.

To round out the event calendar for 2023, AREG are happy to announce that Sunday November 26th will see the return of the AREG Amateur Radio & Electronics Sale! It will again be held at the DogsSA Training Facility in Kilburn as a car boot sale format. We will be inviting all of the SA Radio Clubs to participate as well as a number of commercial vendors!

More details will follow in coming months – but for now you simply need to:

Sunday

November 26th

2023

We hope to see you there!

Next AREG Meeting: Bob VK5FO – Coaxial Stub Filters – Friday 21st April

Update: This presentation was recorded, and is now available on Youtube.

The next AREG meeting will be held on Friday the 21st of April at the Fulham Community Centre – Phelps Court, Fulham.

This months presentation will be from Bob Phillips VK5FO, on the topic “Using Quarter Wave Coaxial Stubs as Notch Filters”. Bob will cover off the basic theory and characteristics of coax stub filters, demonstrate how to construct and tune them using a NanoVNA, and discuss their practical use-cases.

Doors open at 7.15pm and the presentation kicks off at 7.45. Everyone is welcome to attend. If you’ve never come along to one of our meetings, we’d love to see you there, all guests are welcome. For our remote members, the meeting will be broadcast via Zoom!

After the talks we’ll all be given an opportunity to have an eyeball QSO among ourselves whilst enjoying a tea or coffee and a biscuit.

73, Mark VK5QI