Join the conversation  on VHF, UHF weak signal communication


Weak Signal communication


AMSATSA  VHF/UHF workshop in conjunction with SARL

 VHF/UHF Workshop

Presented by the SARL and AMSATSA

20 October 2018

The following papers are available for download

Beacon Coordination: Brian Jacobs ZS6YZ download here

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

Operating on 23 cm and Aircraft Scatter: Rickus de Lange   ZS4A  download here








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