Answer to Question #10762 Submitted to "Ask the Experts"

Category: Micro/Radio Waves, Radar & Powerlines — Satellite Dishes

The following question was answered by an expert in the appropriate field:


Since the SWM ODU acts as a transponder, then if you do not operate your television (TV), does the satellite dish and the transponder stop actively bouncing back signals to one another? In other words, does this wireless form of communication disengage once you are not watching satellite TV actively? Or is there always a continuous stream of wireless RF signal? I am perfectly okay with the former versus the latter theory.


The SWM ODU (known in long form as a Single Wire MultiSwitch (SMU) Outdoor Unit (ODU)) is used with some satellite television (TV) systems. It takes the radiofrequency signal from the satellite dish antenna and distributes it, with further processing, throughout the home. This is normally done using coaxial lines (not wireless transmission).

See Tech-FAQ, DirecTV SWM

SWMs are mounted in various locations in different systems, sometimes right behind the satellite dish and sometimes inside the house. However, different systems vary. If you have questions about how your particular system is configured, you should contact a TV cable service technician. That said, I am pretty sure that there is no wireless data transmission in your system, only coaxial lines to carry the signals.

Health agencies have not concluded that low-level radiofrequency energy associated with wireless communications is hazardous at all. See for example the World Health Organization's statement on electromagnetic fields and public health.  

Kenneth R. Foster

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Answer posted on 7 August 2013. The information posted on this web page is intended as general reference information only. Specific facts and circumstances may affect the applicability of concepts, materials, and information described herein. The information provided is not a substitute for professional advice and should not be relied upon in the absence of such professional advice. To the best of our knowledge, answers are correct at the time they are posted. Be advised that over time, requirements could change, new data could be made available, and Internet links could change, affecting the correctness of the answers. Answers are the professional opinions of the expert responding to each question; they do not necessarily represent the position of the Health Physics Society.