"निम्न आवृत्ति (LF)": अवतरणों में अंतर

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Rescuing 4 sources and tagging 0 as dead.) #IABot (v2.0.1
पंक्ति 11:
== सामरिक प्रयोग ==
== प्रयोग एवं अमेच्योर ==
A 2.1&nbsp;kHz allocation, the [[136 kHz]] band (135.7&nbsp;kHz to 137.8&nbsp;kHz), is available to [[amateur radio]] operators in some countries in Europe, New Zealand and French overseas dependencies. The world record distance for a two-way contact is over 10,000&nbsp;km from near [[व्लादिवोस्तोक|Vladivostok]] to [[न्यूज़ीलैण्ड|New Zealand]].<ref name="ZLUA0">{{cite web |publisher=The World of LF |url=http://www.wireless.org.uk/newspic92.htm |title=QSO ZL/UA0 on 136 kHz |access-date=29 जनवरी 2008 |archive-url=https://web.archive.org/web/20070929025210/http://www.wireless.org.uk/newspic92.htm |archive-date=29 सितंबर 2007 |url-status=live }}</ref> As well as conventional [[Morse code]] many operators use very slow computer controlled Morse code or specialized digital communications modes. A proposal at the WRC-07 [[World Radiocommunication Conference]] aims to make this a worldwide amateur radio allocation.
 
The UK allocated a 2.8&nbsp;kHz sliver of spectrum from 71.6&nbsp;kHz to 74.4&nbsp;kHz beginning in April 1996 to UK amateurs who applied for a Notice of Variation to use the band on a noninterference basis with a maximum output power of 1 W ERP ([[effective radiated power]]). This was withdrawn on 30 जून 2003 after a number of extensions in favor of the European-harmonized 136&nbsp;kHz band.<ref name="ofcom">{{cite web |publisher=[[Ofcom]] |url=http://www.ofcom.org.uk/static/archive/ra/topics/spectrum-strat/future/strat02/strategy02app_a.doc |title=UK Spectrum Strategy 2002 |access-date=29 जनवरी 2008 |archive-url=https://web.archive.org/web/20070930031406/http://www.ofcom.org.uk/static/archive/ra/topics/spectrum-strat/future/strat02/strategy02app_a.doc |archive-date=30 सितंबर 2007 |url-status=live }}</ref> A 1-watt transmission of very slow Morse Code between G3AQC (in the UK) and W1TAG (in the USA) spanned the [[Atlantic Ocean]] for 3275 miles on November 21-22, 2001.
 
In the United States there is a special license free allocation in the longwave range called [[LowFER]]. This experimental allocation between 160&nbsp;kHz and 190&nbsp;kHz is sometimes called the "Lost Band". Unlicensed operation by the public is permitted south of 60 degrees north latitude, except where interference would occur to ten licensed location service stations located along the coasts. Regulations for use include a power output of no more than 1 watt, and an antenna/ground-lead length of no more than 15 meters, and a field strength of no more than 4.9 microvolts/meter. Also, emissions outside of the 160&nbsp;kHz&ndash;190&nbsp;kHz band must be attenuated by at least 20&nbsp;dB below the level of the unmodulated carrier. Many experimenters in this band are amateur radio operators.
पंक्ति 21:
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A regular service transmitting [[radioteletype|RTTY]] marine meteorological information on LF is the German Meteorological Service (Deutscher Wetterdienst or [https://web.archive.org/web/20150714040848/http://www.dwd.de/ DWD]). The DWD operates station DDH47 on 147.3&nbsp;kHz using standard ITA-2 alphabet with a transmission speed of 50 baud and FSK modulation with 85&nbsp;Hz shift<ref>{{cite web |url=http://www.dwd.de/de/wir/Geschaeftsfelder/Seeschifffahrt/Sendeplaene/Sendeplaene.htm | title=DWD Sendeplan | accessdate=2008-01-08 |archive-url=https://archive.is/20120730093823/http://www.dwd.de/de/wir/Geschaeftsfelder/Seeschifffahrt/Sendeplaene/Sendeplaene.htm |archive-date=30 जुलाई 2012 |url-status=dead }}</ref>.
 
== रेडियो नौवहन संकेत ==