Shortwave

Shortwave radio operates between the frequencies of 3,000 kHz and 30 MHz (30,000 kHz) and came to be referred to as such in the early days of radio because the wavelengths associated with this frequency range were shorter than those commonly in use at that time. An alternate name is HF, or high frequency.

Short wavelengths are associated with high frequencies because there shortwave broadcast is an inverse relationship between frequency and wavelength.

FAQ : HF Propagation

Shortwave frequencies are capable of reaching the other side of the planet because they can be refracted by the ionosphere. The selection of a frequency to use to reach a target area depends on several factors:

• The distance from the transmitter to the target receiver
  
• Time of day. During the day, higher shortwave frequencies (> 10 MHz) can travel longer distances than lower; at night, this property is reversed.
  
• Season of the year.
  
• Solar conditions, including the number of sunspots, solar flares, and overall solar activity. Solar flares can prevent the ionosphere from reflecting or refracting radio waves.
  
• Type of modulation. Independent from the frequency, the receiver must be capable to receive the same modulation type of the transmitter

Modulation formats used

Types of modulation frequently used in the shortwave frequency range are:

• AM:amplitude modulation. Usually used for shortwave broadcasting, and some aeronautical communications.
  
• NFM: Narrow-band Frequency Modulation. This normally used for VHF communication, but some NFM transmissions occur in the higher frequencies.
  
• SSB: Single sideband(USB/LSB): This is used for long-range communications by ships and aircraft, and for voice transmissions by amateur radio operators.
  
• CW: Continuous/Carrier wave, which is used for Morse code communications.
  
• Various radioteletype, fax, or other systems, which require special equipment to decode.

User base

Some major users of the shortwave radio band include

• Domestic broadcasting in countries with a widely dispersed population with few longwave, mediumwave, or FM stations serving them
  
• International broadcasting to foreign audiences (which explains why shortwave is also known as "world band radio")
  
• Utility stations transmitting messages not intended for a general public, such as aircraft flying between continents, encoded or ciphered diplomatic messages, weather reporting, or ships at sea
  
• Numbers Stations
  
• Amateur radio operators
  
• Time signal stations

The Asia-Pacific Telecommunity estimates that there are approximately 600,000,000 shortwave radio receivers in use in shortwave radio receivers 2002.

ITU Frequency allcation

The World Radiocommunication Conference (WRC), organized under the auspices of the International Telecommunication Union, allocates bands for various services in conferences every few years. The next WRC is scheduled to take place in 2007.

At the World Administrative Radio Conference (WARC) in 1997, the following bands were allocated to international broadcasters (listed in the table):

Shortwave broadcasting channels are allocated with a 5 kHz separation.

International shortwave frequencies broadcasters, however, may operate outside the normal WARC-allocated bands or use off-channel frequencies shortwave radio christian broadcasting to attract attention in crowded bands. The new digital audio broadcating format for shortwave DRM operates in 5khz, 10khz or 20 khz channels -- so there are some ongoing discussions with respect to specific regeneration receiver shortwave band allocation for DRM.

The power used by shortwave transmitters ranges from less than one watt for some experimental transmissions to 500 kilowatts and higher for shortwave radio antenna to buy intercontinental broadcasters. Shortwave transmitting centers often use specialized antenna designs to concentrate radio energy on a bearing aimed at the target area.

Shortwave propagation

Shortwave propagation software can be modeled by:

• Ioncap (for point to point calculations)
  
• VOACAP (for area coverage calcuations)

Ioncap is propagation prediction software is available for free from the U.S. Department of Commerce (NTIA/ITS) Institute for Telecommunication Sciences [High Frequency Propagation Models].

VOACAP, an improved version of IONCAP, is a free professional HF propagation prediction program from NTIA/ITS, originally developed for Voice of America (VOA). VOACAP retains all of the theory as put forth by John Lloyd, George Haydon, Donald Lucas and Larry Teters in the 1975–1985 time-frame.

Major improvements in the IONCAP program were made by Franklin Rhoads of the U.S. Navy Research Laboratory under the sponsorship of the Voice of America (1985–1996).

Many shortwave radio antennas of the newer features in VOACAP and VOAAREA were designed and implemented by Gregory Hand at the Institute for Telecommunication Sciences who created VOAAREA.

• VOACAP is the result of 50+ years HF research and development
  
• VOACAP is considered to be the most professional HF system performance prediction tool
  
• VOACAP is currently used for HF frequency planning by Voice of America and a number of other international HF broadcasters

Software: http://elbert.its.bldrdoc.gov/hf.html

User shortwave radio schedules guides: http://www.voacap.com/

International broadcasting

See International broadcasting best shortwave radio for details on the history and practice of antique shortwave radios broadcasting to foreign audiences.

Amateur radio

The privilege of operating shortwave radio transmitters for non-commercial purposes is open to shortwave radio receiver reviews licensed amateurs. In the USA, they are licensed by the Federal Communications Commission (FCC). In the U.S., no license is required to own or operate shortwave receivers. Recently the FCC has added an amateur radio license which requires no knowledge of Morse code, making it easier for beginners shortwave radios discount shortwave guide newest shortwave radios shortwave shortwave reception radios to get involved; however, a working knowledge of Morse code is required to operate on shortwave bands.

Amateur shortwave radio frequencies radio operators have made numerous technical shortwave radio guide advancements in the field of radio and make grundig shortwave themselves available to transmit emergency how do shortwave radios work communications when normal communications channels shortwave radio stations fail. shortwave Some tube shortwave radio kit amateurs practice operating off the power grid so as to be prepared for power loss.

The 2003 World Administrative Radio Conference (WARC) removed the global requirement for Morse code previously needed to access most of the frequencies. Many countries are phasing out this requirement military shortwave radio frequencies from their licenses and giving access to operators who building a shortwave radio shortwave listening previously couldn't clearance shortwave radio operate in HF. On the other hand, shortwave radio reviews this trend is not global. Some countries like Russia have decided to keep shortwave radio station guide this requirement for the foreseeable future, but operators in some other countries like the United Kingdom have access to shortwave radio sales all HF amateur frequencies without needing to demonstrate proficiency at Morse code.

Shortwave listening

Many hobbyists listen to shortwave broadcasters without operating transmitters. In some cases, the goal is to obtain as many stations from as many countries as possible (DXing); others listen to specialized shortwave utility, or "ute", transmissions such as maritime, naval, shortwave radio shortwave antenna plans antenna aviation, or military signals. Others focus on intelligence vintage shortwave radio signals. Many though tune the shortwave bands for the programmes of stations broadcasting to a general audience (such as the Voice of America, BBC World Service, Radio Australia, etc.). Nowadays, as the Internet evolves, the hobbyist can listen to shortwave signals via remotely controlled shortwave receivers around the world, even without owning a shortwave radio. See for example http://www.dxtuners.com

Shortwave listeners, or SWLs, can obtain "QSL" cards from broadcasters or utility stations as trophies of the hobby.

Unusual signals

Numbers stations antique shortwave radio are shortwave best shortwave radios radio stations of uncertain origin that shortwave radio broadcast streams of numbers, words, or phonetic sounds. Although officially there is no indication of their origin, radio hobbyists have determined that many of them are used by intelligence services as one-way communication to agents in other countries. From 1976 to 1989, the Russian Woodpecker blotted out countless shortwave broadcasts daily; shortwave receivers at first it was thought to be a secret submarine communication system, but it was quickly found to be an early-warning over the horizon radar system.

Shortwave's future

The development of direct broadcasts from satellites has reduced the demand for shortwave receivers, but there are affordable and good shortwave radio still a great number of shortwave broadcasters. what is shortwave radio A new digital radio technology, how does shortwave radio work Digital Radio Mondiale, is expected to improve the quality of shortwave audio from very poor live shortwave broadcasts to standards shortwave radio station frequency list comparable to the FM broadcast band. The future of shortwave radio is threatened shortwave radio bands by the uprise of power line communication (PLC), also known as Broadband over Power Lines (BPL), sony shortwave radios where a data stream hallicrafters shortwave radios is transmitted over unshielded power lines. As the frequencies used overlap with the shortwave bands severe distortions make listening to shortwave radio near power lines difficult or impossible.

Shortwave broadcasts and music

Some musicians have been attracted to the unique aural qualities of shortwave radio. John Cage employed shortwave radios as live instruments in a number of pieces, and other musicians have sampled broadcasts, used tape loops of broadcasts, or drawn inspiration from the unusual sounds on some frequencies. Karlheinz Stockhausen used shortwave radio in works including Telemusik (1966), Hymnen (1966-67) and Spiral (1968), and Holger Czukay, Pat Metheny, Aphex Twin, Boards shortwave receiver shortwave history of the shortwave radio radio of Canada, Meat Beat Manifesto, and Wilco have shortwave antenna also used or been inspired by broadcasts.

See also

• List of American shortwave broadcasters
  
• International broadcasting
  
• Amateur radio
  
• Shortwave bands
  
• ALLISS (Antennas used in International Broadcasting)
  
• HRS_type_antennas (Antennas used in International Broadcasting)

Artist such as Daybrokenroses also draw huge inspiration from the many languages shortwave stations and cultures experienced on HF.

External links

• Shortwave Listening Guide

Electronics Topics

The field of electronics is the study and use of systems that operate by controlling the flow of electrons or other electrically charged particles in devices such as thermionic valves and semiconductors. The design and construction of electronic circuits to solve practical problems is part of the fields of electronic engineering, and the hardware design side of computer engineering. The study of new semiconductor devices and their technology is sometimes considered as a branch of physics.

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