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IN HAMNET's Amateur Radio Report........a week of much activity - read more...........

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Something has gone terribly wrong. Normal ways of doing things are not working. The fastest way to turn an emergency into a full disaster is to lose communications.

Radio Amateurs understand emergencies. For over 70 years they have provided emergency communications for organisations. When normal ways of communication fail or get overloaded Radio Amateurs will be there.  

HAMNET, the National Emergency Communications division of the South African Radio League (SARL), provides communications for emergencies and can mobilise experienced communicators who with their own radio equipment will back up official channels or take over when all else fails.


The SARL represents all Radio Amateurs in South Africa at all levels of Government and through the IARU at the International Telecommunications Union. Radio Amateurs or "Hams" use two-way radio communication to make contact with other radio amateurs all over the world. They are even able to use satellites and on occasion speak with astronauts. Radio Hams can do this from home or while mobile in cars, boats or on foot.

Radio Hams have a full range of communication modes at their disposal. These include plain voice, Morse code, numerous digital computer modes and even graphical modes like television. A licensed radio amateur is able to join in experiments using all these modes.





Headquarters Report 

SUNDAYS - during the AMATEUR RADIO TODAY transmission, starting at 10h00 South African Standard Time (SAST), on HF and on many VHF and UHF repeaters around the country. (Current bulletin posted below)

Western Cape ZS1DZ or ZS1DCC

On the 1st Wednesday evening of the month, HAMNET's Western Cape monthly meeting is held at 19h30 SAST at Tygerberg Hospital's Provincial Emergency Management Centre.  

The radio bulletin is transmitted at 19h30 SAST on a Wednesday evening, on the local 145.700MHz repeater, with relays on to 1845 or 3760, and 7110kHz LSB, 144.300MHz USB, and Echolink, via ZS1DCC-R, on the 2nd and consecutive Wednesdays of each month.

Eastern Cape ZS2PE or ZS2BRC

There is a weekly net on 52.950MHz at 20h00 SAST on a Wednesday evening, and local HAMNET news is included in the PEARS bulletin on Sunday morning at 08h45 SAST on the 145.700Mhz repeater, with a relay on to 7098kHz LSB.

Northern Cape ZS3NC

Free State ZS4DCC

KwaZulu Natal ZS5DCC or ZS84SIG

Quarterly meetings are held on the 2nd Saturday afternoon of the month, at 12h30 for 13h00 SAST, either at Ethekwini Disaster Managment Centre or the 84th Signals Unit in Durban. The next 2 dates are 10/9 and 10/12. 

On Sunday mornings at 07h00 SAST, on 145.625MHz, there is a bulletin, also relayed on to 3760 and 7110kHz. 

There is a formal radio bulletin at 19h30 SAST once a month on a Wednesday evening,on the 145.625MHz Highway repeater, and informal nets at the same time, and on the same frequency, every other Wednesday evening.

Gauteng South ZS6

Monthly meetings are held on the first Thursday of the month at 19h00 SAST at the East Rand Branch clubhouse. On all other Thursday evenings, a social gathering is held at the same venue to chat or maintain equipment. 

Gauteng North ZS6PTA

Limpopo ZS6

Mpumalanga ZS6

Northern Western Province ZS6 







From IARU region 1 sources comes news that Radio Amateurs in Cyprus have been active in emergency duties tackling the biggest forest fire the island has ever dealt with in the Solea region. VHF is being used, and local hams are asked to keep the emergency frequencies clear there. High winds and very high temperatures are fanning flames, and thick smoke hinders the 16 aircraft involved. Some 25 square kilometres of forest have burned so far, and 4 villages are in danger of destruction. Sad news refers to the deaths of two fire-fighters, and serious injuries to two others.


At the other extreme, our climate is affected by icy temperatures, with the Snow Report Alert showing pictures of snow on high ground near Ceres, the Swartberge and on Sneeuberg. The Alert also forecasts that a strong cold front due to hit the Western Cape tonight will bring a small amount of snow tomorrow morning on the Hottentots-Holland mountains, the Matroosberg and Ceres ranges. The good news is that from this week, our days will start getting longer as our orbit around the Sun, inclined as it is at 23 degrees to the vertical, starts to bring the Southern Hemisphere more into the direct line of radiation from the Sun. Personally, I can't wait!

John ZS1JNT sent me a link to a video presentation describing the way in which GPS signals received on the ground vary, like stars twinkling, as our position on Earth disappears into and out of the night. The changes in ionisation of the F1 and F2 layers of the ionosphere as night-time ensues changes the refraction angle of the GPS signals causing minor variations in accuracy at your site. These are most prominent at dusk and dawn, but were also unexpectedly shown to occur in the middle of the night too, when the F layer should be stable and unvarying. However, research by Air Force satellites seem to suggest that the F layers actually shear past each other in opposite directions, possibly resulting in the twinkling effect of GPS signals, and causing your GPS position to wander a bit. This variability is impossible to cancel out, unlike the time differential between the relative time on board the GPS satellite's atomic clocks and earth-time, which is continually corrected for by the GPS system.


ARRL news this week is full of descriptions and plans for the Field Day event taking place as we speak. The ARRL's Programmes and Services Committee has also expressed appreciation for the work done by the National Traffic System, or NTS, which was gratefully thanked and congratulated on their outstanding public service communications efforts.

To quote: "NTS plays a vital role in providing a messaging component for Amateur Radio's public service mission, including preparation and training for emergency communications," their resolution asserted. It also noted that the Programmes and Services Committee has been working to create the League's Second Century public service communications delivery plan, and, while reviewing the League's current operations over the past several years, "the PSC has seen and has greatly appreciated the valuable contributions of NTS members", said the ARRL.


In a grand development to improve and make safe internet access around the globe, NASA has taken a step toward creating a Solar System Internet by establishing operational Delay/Disruption Tolerant Networking (DTN) service on the International Space Station.

The DTN service will help automate and improve data availability for space station experimenters and will result in more efficient bandwidth utilization and more data return.


DTN works by providing a reliable and automatic "store and forward" data network that stores partial bundles of data in nodes along a communication path until the parts can be forwarded or retransmitted, then re-bundled at the final destination - either to ground stations on Earth, robotic spacecraft in deep space, or, one day, humans living on other planets. This differs from traditional Internet Protocols that require all nodes in the transmission path to be available during the same time frame for successful data transmission.

The first use of the service as an operational capability on a space mission marks the beginning of the space station as a "node" in the evolving Solar System Internet. In addition to use in space, DTN can benefit environments where communications are unreliable, such as disaster response areas.


NASA worked closely with one of the "fathers of the internet," Dr. Vinton G. Cerf, vice president and chief internet evangelist for Google and a distinguished visiting scientist at NASA's Jet Propulsion Laboratory in Pasadena, California, to develop DTN. Dr. Cerf sees extended benefits of this networking service that can be used here on Earth.

"Our experience with DTN on the space station leads to additional terrestrial applications especially for mobile communications in which connections may be erratic and discontinuous," said Dr. Cerf. "In some cases, battery power will be an issue and devices may have to postpone communication until battery charge is adequate. These notions are relevant to the emerging 'Internet of Things'. "


To ensure wide adoption of DTN, NASA has worked with the Internet Research Task Force (IRTF), the Consultative Committee for Space Data Systems(CCSDS), and the Internet Engineering Task Force (IETF) for international standardization. In addition, many DTN implementations are publicly available as open-source code, making them available to the growing number of collaborators in space, including university researchers, commercial networking developers, CubeSat developers, and space station payload developers.

This is Dave Reece ZS1DFR reporting for HAMNET in South Africa.









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This page last modified: 3/12/2013