Join the conversation  on VHF, UHF weak signal communication


Weak Signal communication


AMSATSA  VHF/UHF workshop in conjunction with SARL


P O Box 90438
Garsfontein 0042
South Africa
Tel:  012 991 4662
Fax: 012 991 5651






 VHF/UHF Workshop

Presented by the SARL and AMSATSA

20 October 2018
SARL National Amateur Radio Centre

09:00 Registration

09:30 Welcoming
Nico van Rensburg ZS6QL SARL President

09:30 WRC19 Agenda items that impact on VHF and UHF Amateur Radio spectrum
Hans van de Groenendaal ZS6AKV

There are a number of agenda item at WRC19 which take place towards the end of 2019 that could have an impact on Amateur Radio if they are agreed to as they current stand.

09:45 Focus on VHF and above – why it needs your support
Brain Jacobs ZS6YZ

10:00 RSGB Video “Regular 3000+km 0n144 MHZ by meteor Scatter and Tropo

10:55 Beacon coordination to gain maximum benefit
Brian Jacobs ZS6YZ

Beacons are a method to be able to monitor propagation on the VHF and above bands. Properly coordinated omni-directional beacons that follow the IARU recommendations will make it easier to monitor the beacons electronically, allowing us to continuously collect data that can be used to analyse how the propagation changes over time for example as weather patterns move across the country. At the same time having this information readily available will enable you to quickly get on air to exploit the propagation openings as they occur.  Brian will also discuss the next steps: Appoint VHF/UHF Manager, compile definitive list of current VHF/UHF beacons, convert to IARU recommendations, Build a beacon monitoring system. 

11:30 Refreshment break

12:00 Build a simple 3cm band transmitter (and receive it with an SDR receiver)
Cor Rademeyer ZS6CR

With suitable inexpensive modules and components available locally, it is now easy to experiment on the 3 cm band (10.0 GHz - 10.5 GHz) without having specialised microwave knowledge.  The most important building blocks needed to get going, are a PLL based (low drift) Low Noise Block (LNB) as used with satellite television dishes, and a HB100 microwave motion detector module. Details of the HB100 microwave module are discussed, as well as how to configure a transmitter and an SDR based receiver. The transmitter and receiver will be demonstrated by transmission and reception of CW and SSTV signals.

12:30 SARL Noise Monitoring Programme and HamSCI SA
Hans van de Groenendaal ZS6AKV and Brian Jacobs ZS6YZ

Review of the current HF noise monitoring programme and a discussion on the emerging need of action.  Should VHF and UHF frequencies be included in the initiative. How severely is weak signal communication affected by noise? How will WPT affect the noise level?

12:50The “4 6 Long Distance VHF/UHF Group
Carl Minne ZS6CBQ

13:00 Operating on 23 cm and Aircraft Scatter
Rickus de Lange   ZS4A

The presentation is about the experiences with 23cm between Bethlehem and Krugersdorp. It also focusses on Aircraft Scatter and experience gained over the past few years including recordings and pictures.

13:30 Linear Amplifiers for VHF/UHF – Black Widows for the unwary
Dick Coates ZS6BUN

14:00 Open discussion

14:15 ends

Booking required.

Download the booking form here and mail back with proof of payment to




Who has registered to attend
VHF/UHF Workshop 20 October 2018  
Name   Callsign
Casper Hecter ZL6679
Anton Janovsky ZR6AIC
Gerry Williams ZR6GRY
Tom Ambrose ZS1TA
Rikus de Lange ZS4A
Rikus de Lange ZS4A
Jaco Putter ZS4JP
Pierre Lindeque ZS4PF
Danie Terblanche ZS6AGB
Vernon Fryer ZS6AIG
Hans v d Groenendaal ZS6AKV
Hennie Rheeder ZS6ALN
Andrew van Heerden ZS6AVH
Marinus Brand ZS6BM
Dick Coates ZS6BUN
Carle Minne ZS6CBQ
Cor Rademeyer ZS6CR
Gert Botha ZS6GC
Graham Busse ZS6GL
Jasper Malan ZS6JMA
John Sygo ZS6JON
Koos Greyvenstein ZS6KSG
Bert von Rahden ZS6LP
Paul Smit ZS6NK
Nico van Rensburg ZS6QL
Willem van der Merwe ZS6WIM
Brian Jacobs ZS6YZ
Alexis Callea   


Why Radio Amateurs should be concerned about the rising RF noise levels?
Worldwide the RF spectrum use is continuing to grow as technology progressively makes more use of wireless connectivity. The spectrum has become steadily more polluted as the number of non-compliant and faulty pieces of electronic devices including substandard equipment has also risen over the years.

The reluctance and short- sightedness of regulators in various countries to act against manufacturers of non-compliant electronic devices and equipment, leaves the radio amateur fraternity with no other alternative but to get involved in collecting the necessary RF noise floor data and to support initiatives for proper interference regulation and action against radio frequency pollution on a world-wide level. 

On 15 June 2016, the FCC office of engineering and technology technical advisory council opened a noise floor technical inquiry in the form of ET docket no. 16-191 to seek answers to the following basic questions: 

·     Is there a noise problem?

·     * Where does the problem exist? Spectrally? Spatially? Temporally?

·     * Is there quantitative evidence of the overall increase in the total integrated noise floor across various segments of the radio frequency spectrum?

·     * How should a noise study be performed? 

Unfortunately, most feedback was anecdotal and not accompanied with measured quantitative data.  This is largely because the responders did not have the instrumentation resources nor the budget to provide the quantitative evidence being sought. Despite the scarcity of quantitative data submissions, one clear outcome of this TAC technical inquiry is an unmistakable consensus among the responders: A noise floor study is not only needed but long overdue. 

In the USA and spreading to Europe radio amateurs and scientists have joined forces in Ham Radio Science Citizen Investigation (HamSCI*), a collaboration between radio amateurs and scientists to advance scientific research and understanding through amateur radio activities. While the group is currently more focused on radio propagation, ionospheric studies and space weather, the concept would work well to make meaning full contributions to study the increases in the RF noise floor. 

It may sound complex but with the right software, a raspberry pi and a HF dongle it is very easy to create monitoring stations in many parts of the world, create a universal server where the data is upload and develop algorithms to review the data after a period of time.  

The SARL has a number of pilot stations operating and has configured a server to where the monitoring stations automatically upload their data. 

It is fully understood that there are issues, such as antenna and receiver calibration, that still need to be solved. Under the current pilot system each participating radio amateur can review his own data and monitor the changes in the RF noise level in his immediate area.  

The SARL is continuing to fine tune the software for the monitoring station. The diagram below illustrates the basic station setup