ELoran and Amateur Radio - A Study in Co-existence Dr Paul Williams - - PowerPoint PPT Presentation

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eloran and amateur radio a study in co existence
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ELoran and Amateur Radio - A Study in Co-existence Dr Paul Williams - - PowerPoint PPT Presentation

Jan 24, 2024 20 likes •191 views

ELoran and Amateur Radio - A Study in Co-existence Dr Paul Williams (The GLAs of the UK and Ireland) Professor David Last (Consultant to the GLAs) Dr Nick Ward (The GLAs of the UK and Ireland) Carrier-wave interference with Loran Amateur Radio

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SLIDE 1

ELoran and Amateur Radio - A Study in Co-existence

Dr Paul Williams (The GLAs of the UK and Ireland) Professor David Last (Consultant to the GLAs) Dr Nick Ward (The GLAs of the UK and Ireland)

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SLIDE 2

Carrier-wave interference with Loran

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SLIDE 3

Spectrum from 50kHz -150kHz Amateur Radio 135.7-137.8kHz

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SLIDE 4

ITU Radio Regulations, Volume 1, Chapter 1, ‘Terminology and Technical Characteristics’, 2004

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SLIDE 5

Spectrum from 50kHz -150kHz near Anthorn

90kHz 110kHz

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SLIDE 6

Spectrum from 135kHz -139kHz near Anthorn

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SLIDE 7

100Hz-wide slice of spectrum at 100kHz near Anthorn

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SLIDE 8

100Hz-wide slice of spectrum at 137kHz near Anthorn

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SLIDE 9

Loop antenna rotated through 90 degrees

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SLIDE 10

Groundwave propagation curves (from ITU 368-7)

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SLIDE 11

Radiated power from Anthorn in Radio Amateur Band

Field strength Radiated power Single spectral line 6dBµV/m 50µWatt Whole amateur band (284 spectral lines) 14mWatt

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SLIDE 12

Amateur Radio techniques at 136kHz

  • Entire band only 2.1kHz wide
  • Data transmissions or V-E-R-Y S-L-O-W Morse code
  • Each dot 3-30 seconds, each dash 9-90 seconds
  • Bandwidth less than 1Hz
  • Visual reception
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SLIDE 13

Waterfall diagram (from http://jpmere.online.fr/Grabber/Grabber.htm)

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SLIDE 14

US Loran spectral lines (from http://www.imagenisp.ca/jsm/136.html)

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SLIDE 15

Reception less than 1Hz from a Rugby Loran spectral line

(from ttp://homepage.ntlworld.com/mike.dennison/index/lf/gallery/s52ab.htm)

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SLIDE 16

Techniques for combating Loran!

(from http://www.timewave.com/support/ANC-4/anc4.html & http://www.carc.org.uk/assets/Downloads/vlffilter.pdf)

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SLIDE 17
  • Anthorn’s Loran signal is correct
  • No spurious transmissions in the amateur band
  • Just 50µWatt per spectral line
  • Lessay, Ejde and Sylt pre-date Anthorn
  • Effective techniques to combat Loran
  • But still …