Measuring HF noise around a city
Some years ago NATO did a report about increasing noise in the HF spectrum because it was concerned that the reliability of its HF communications would be affected—the HF band being its ultimate fallback position for long distance communications.<p>If I recall correctly, the report said the noise floor had risen some 6 to 8dB in recent years (see the report for exact details).<p>About a decade later I was at a SMPTE broadcast equipment show and whilst discussing AM broadcast transmitters with the manufacture of said devices I mentioned the NATO figure for the HF spectrum. He retorted where had I been in recent years and said that the figure was over over 17dB.<p><i>Note: his company manufactured a range of transmitters and only some were in the normal AM broadcast band, other transmitters were for HF and FM broadcasting. There was no mistake that were were referring to the HF spectrum, i.e. 3 - 30MHz<p>____________<p>Edit:  Just found the report on my PC, I&#x27;ve not had time to go through it so check my above figure.  I&#x27;ll try and see if it the links is still available, if so I&#x27;ll add it as another edit:<p>HF Interference, Procedures and Tools<p>Final Report of NATO RTO Information Systems Technology (IST)<p>Panel Research Task Group IST-050&#x2F;RTG-022  (or Research Task Group IST-050).<p>Published June 2007<p>___________<p>2nd Edit:  Here&#x27;s what I found, I haven&#x27;t fully checked but I think they&#x27;re all the same:<p><a href="https:&#x2F;&#x2F;manualzz.com&#x2F;doc&#x2F;18577111&#x2F;hf-interference--procedures-and-tools--interférences-hf--" rel="nofollow">https:&#x2F;&#x2F;manualzz.com&#x2F;doc&#x2F;18577111&#x2F;hf-interference--procedure...</a>...<p>Panel Research Task Group IST-050&#x2F;RTG-022 (or Research Task Group IST-050).<p>Download:  <a href="http:&#x2F;&#x2F;www.darc-c12.de&#x2F;system&#x2F;files&#x2F;$$TR-IST-050-ALL.pdf" rel="nofollow">http:&#x2F;&#x2F;www.darc-c12.de&#x2F;system&#x2F;files&#x2F;$$TR-IST-050-ALL.pdf</a><p>Internet Archive: <a href="https:&#x2F;&#x2F;archive.org&#x2F;details&#x2F;DTIC_ADA473220" rel="nofollow">https:&#x2F;&#x2F;archive.org&#x2F;details&#x2F;DTIC_ADA473220</a></i>