136 kHz

136 kHz

The 136 kHz band is the lowest frequency band in which amateur radio operators are allowed to transmit. It is only available for use in some countries but there is a proposal at the WRC-07 World Radiocommunication Conference to make it a world wide amateur allocation.

The 136 kHz band is in the low frequency (LF) frequency band, just below the longwave broadcasting band. Before its introduction in the UK in 1998, operation on the even lower frequency of 73 kHz had been allowed from 1996 until 2003.

International frequency allocation

A number of European countries have already allocated the zone 135.7-137.8 kHz to amateur radio use based on CEPT/ERC Recommendation 62-01 E ("Use of the band 135.7-137.8 kHz by the Amateur Service", Mainz 1997). The allocation is on a secondary basis with a maximum e.r.p. power of 1 W. Otherwise the band 130-148.5 is allocated on a primary base to the Maritime Mobile Service and the Fixed Service. The main users are naval one-way transmissions and radiolocation systems.

The International Telecommunication Union's 2007 World Radiocommunication Conference (WRC-07) in Geneva agreed a secondary allocation 135.7-137.8 kHz to the Amateur Service on Friday November 9 (Lowfer).

Technical issues

Such low frequency transmissions require specialist, and therefore usually home made, equipment. In countries where it is allowed, maximum transmission radiated power is usually limited to 1 watt (0 dBW), but even this can be extremely difficult to achieve from practical home made equipment and antennas. Reception also poses problems due to considerable natural and man-made noise and interference (QRN and QRM).

Many users and experimenters have settled on extremely slow, computer-generated and displayed morse code as the most common transmission mode. This mode is known as QRSS, where the doubling of the S emphasises the extreme slowness. The international Q code "QRS" already stood for slow morse, or "Please send more slowly" in radio jargon.

Band plan

The 2005 IARU Region 1 Conference defined the band as follows [http://www.rsgb-spectrumforum.org.uk/Papers/Spectrum%20Forum%20Website%20Version%20(0606).htm] :;135.7 - 136.0 kHz:Station Tests and transatlantic reception window;136.0 - 137.4 kHz:Telegraphy;137.4 - 137.6 kHz:Non-Telegraphy digital modes;137.6 - 137.8 kHz:Very slow telegraphy centred on 137.7 kHz

United States

There is no 136 kHz amateur allocation in the United States. In 2002, indications from the Federal Communications Commission had been that 136 kHz privileges would be authorized soon. On May 14, 2003, however, the FCC declined to grant these privileges citing concerns over potential interference with power line communications used by electrical utilities to control the power grid.

The FCC added that amateurs wishing to experiment with 136 kHz communications may apply for experimental licenses or operate within existing Part 15 regulations for this part of the electromagnetic spectrum. In the case of Part 15, the field strength measured 300 meters from the antenna may not exceed 2400 microvolts per meter divided by the frequency in kilohertz, or approximately 17 microvolts per meter.

Australia

The ACMA has advised, the process leading to amendments of the ARSP that may lead to the creation of a secondary amateur service allocation on 137 kHz. Once the final WRC documents have been received from the ITU, ACMA will commence drafting amendments to the ARSP with the view to a public consultation period later this year ('08). After consideration of comments received, the ACMA is hopeful of publishing the new plan and accompanying changes in subordinate legislation by early 2009.

References

*cite book | last=Dodd | first=Peter | title=Low frequency experimenter's handbook | publisher=Radio Society of Great Britain
date=2000 | location=Potters bar,UK | isbn=1-872309-65-8
*cite book | author=Dennison, M. and Moritz, J. | title=LF Today: a guide to success on 136 and 500kHz | publisher=Radio Society of Great Britain | date=2007 | location=Potters bar,UK | isbn=9781-9050-8636-8

ee also

* Amateur radio
* Amateur radio bands
* Low frequency
* LowFER
* List of amateur radio organizations
* List of amateur radio operating modes


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