US Radio Spectrum

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US Radio Spectrum

July 23, 2017

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https://www.ntia.doc.gov/files/ntia/publications/2003-allochrt.pdf

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Boden Fortress - A long time secret place in Sweden

During the first world war the secret Boden Fortress was completed with its five very huge forts blasted into mountains surrounding Boden city in northern Sweden. They all were abunded as late as in 1998. The Rödberget fort is now a major tourist attraction in Boden. Björn, SM0YUZ knows a lot of these places and he took me on a guided tour to some of them. Many photos can be seen here (sorry text in Swedish) and here you can read the fascinating story of Boden Fortress. Björn, SM0YUZ standing in front of the huge Stora Åberget fort. The ugly Radiobunkern in Boden Fortress is a historical site as it was from here in 1921 the first public broadcast programmes in Sweden were transmitted. Link to an article in a Swedish newspaper.

Airshow memory

On Saturday June 6, 1953, 57 years ago, there was a very big airshow over central Stockholm in Sweden. The city was celebrating its 700 years birthday. Leif, my twin brother, and I was on a hill top, Observatorielunden in the city center, staring with big eyes up in the sky. A huge Royal Swedish Airforce fleet of more than 600 (!) airplanes was flying in all kind of formations. Being nine years old at that time this sight was burned into our memories. (Photos by Yngve Norrvi) I do specially remember this little airplane tumbling above our heads. It was Lilldraken SAAB 210 making its public debut. A scaled-down jet fighter testbed for the double- delta concept in the development of the SAAB 35 Draken . The wingspan was 4.9 m and length 9.1 m. Top speed was 650 km/h. How to build a 1/72 scale resin model of Lilldraken see video here . (Photos copyright SAAB AB) After this show we became very interested in airplanes, building models etc.

ROS - A new digital mode

ROS, developed by José Albert Nieto Ros, is a new digital mode under test. Using spread spectrum and 1 or 16 Baud signalling rates it is designed to cope with disturbancies, low level signals, meteor scatter and moon bounce says José. He claims that receiving signals down to -35 dB (!) with 1 Bd signalling rate and -30 dB (!) with 16 Bd are possible. Today I tested 16 Bd reception on 14.1011 MHz. My set-up is shown above with the PC microphone close to a Yaesu FT-857D. This PC screen dump shows that I did receive PA0JMK in The Netherlands calling YU1RP in Yugoslavia. Unfortunately the vertical screen resolution of my mini-PC is not large enough to show the waterfall part of the ROS GUI. ROS home page from where you can download the software, instructions etc. is here and a video is here . The ROS mode has caused som stir as it occupies a large bandwidth of 2.2 kHz in the HF bands. The mode has become forbidden to use in the U.S. because of the spread spectrum part of it.

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