[x]
Create

Here is what users have to say about High Frequency

useravatar
Entry added by CWAnswers Join us and contribute your knowledge as well.
Comment
Share this
Share with a friend: high frequency
Your name
Your email
Recipient Email

High frequency (HF) radio frequencies are between 3 and 30 MHz. Also known as the decameter band or decameter wave as the wavelengths range from one to ten decameters (ten to one hundred metres). Frequencies immediately below HF are denoted Medium-frequency (MF), and the next higher frequencies are known as Very high frequency (VHF). Shortwave (2.310 - 25.820 MHz) overlaps and is slightly lower than HF.

Welcome to CWAnswers

CWAnswers is your guide to the sprawling world wide web. The directory aims to provide a useful guide made by users. You can share your knowledge as well - simply sign up and edit your first entry. For questions just contact the team at support - at - cwanswers.com.

Weblinks for High Frequency

Top 10 for High Frequency

Things about High Frequency you find nowhere else.

Select content modules

Comments about High Frequency

Please leave your comment using the comment button above the article
Share with a friend: high frequency
Your name
Your email
Recipient Email

Images found for High Frequency

High Frequency 1High Frequency 2High Frequency 3
High Frequency 4High Frequency 5High Frequency 6
High Frequency 7High Frequency 8High Frequency 9

Wikipedia About High Frequency

High frequency (HF) radio frequencies are between 3 and 30 MHz. Also known as the decameter band or decameter wave as the wavelengths range from one to ten decameters (ten to one hundred metres). Frequencies immediately below HF are denoted Medium-frequency (MF), and the next higher frequencies are known as Very high frequency (VHF). Shortwave (2.310 - 25.820 MHz) overlaps and is slightly lower than HF.

Propagation characteristics

Since the ionosphere often refracts HF radio waves quite well (a phenomenon known as skywave propagation), this range is extensively used for medium and long range radio communication. However, suitability of this portion of the spectrum for such communication varies greatly with a complex combination of factors:

  • Sunlight/darkness at site of transmission and reception
  • Transmitter/receiver proximity to terminator
  • Season
  • Sunspot cycle
  • Solar activity
  • Polar aurora

These and other factors contribute, at each point in time for a given communication path, to a

  • Maximum usable frequency (MUF)
  • Lowest usable high frequency (LUF) and a
  • Frequency of optimum transmission (FOT)

Exploitation of, and limits imposed by, these characteristics

When all factors are at their optimum, worldwide communication is possible on HF. At many other times it is possible to make contact across and between continents or oceans. At worst, when a band is 'dead', no communication beyond the limited groundwave paths is possible no matter what powers, antennae or other technologies are brought to bear. When a transcontinental or worldwide path is open on a particular frequency, digital, SSB and CW communication is possible using surprisingly low transmission powers, often of the order of tens of watts, provided suitable antennae are in use at both ends and that there is little or no man-made or natural interference. On such an open band, interference originating over a wide area affects many potential users. These issues are significant to military, safety and amateur radio users of the HF bands.

Uses

080913-N-0000F-111.jpg

CB radios operate in the higher portion of the range (around 27 MHz), as do some studio-to-transmitter (STL) radio links. Some modes of communication, such as continuous wave morse code transmissions (especially by amateur radio operators) and single sideband voice transmissions are more common in the HF range than on other frequencies, because of their bandwidth-conserving nature, but broadband modes, such as TV transmissions, are generally prohibited by HF's relatively small chunk of electromagnetic spectrum space.

Noise, especially man-made interference from electronic devices, tends to have a great effect on the HF bands. In recent years, concerns have risen among certain users of the HF spectrum over "broadband over power lines" (BPL) Internet access, which is believed to have an almost destructive effect on HF communications. This is due to the frequencies on which BPL operates (typically corresponding with the HF band) and the tendency for the BPL "signal" to leak from power lines. Some BPL providers have installed "notch filters" to block out certain portions of the spectrum (namely the amateur radio bands), but a great amount of controversy over the deployment of this access method remains.

Search results for High Frequency

High Frequency Machines - NexTag.com

Find Our Best Deals for High Frequency Machines at NexTag.com. Save Big on Computers, Electronics, Software and More! Read High Frequency Machines Reviews.www.nextag.com/high-frequency-machines/search-html

High-Frequency Automotive Power Supplies - Maxim

High switching frequency and high voltage operation do not go together. ... High-frequency operation is becoming important as more and more electronic ...www.maxim-ic.com/appnotes.cfm?an_pk=3893

Tieling Yufei High Frequency Equipment Ltd. - High disposition sun ...

... is a technology-based enterprise to develop high frequency heating equipment. ... The rug high frequency heat bonding special-purpose machine ...yfgp.en.alibaba.com/

Vestal High Frequency Line Watches | Zappos.com

Zappos.com - vestal high frequency line watches. The premiere destination for online shoes, plus Vestal clothing, accessories and more. Free Shipping on vestal high...www.zappos.com/n/es/d/722673350/page/1.html

How to Use High Frequency for Facials | eHow.com

How to article - how to use high frequency for facials. High frequency sound has been used since the 1980s for cosmetic purposes. It produces heat in the deeper...www.ehow.com/how_2154502_use-high-frequency-facials.html

Images found for High Frequency

High Frequency 1High Frequency 2High Frequency 3
High Frequency 4High Frequency 5High Frequency 6
High Frequency 7High Frequency 8High Frequency 9

News about High Frequency

Gas Analyzers measure trace impurities in argon.

ThomasNetUtilizing high frequency argon discharge ionization detector, Models AR710 and AR720 analyze trace impurities, such as H2, N2, O2, CH2, CO, and CO2 in argon down to ppb range. Features include laminar low volume flow system, hands-free operation, VCR® fittings to ensure leak-free connections, and mass-spec leak tested valves. Analyzers are available with options such as 4-20 mA output, auto ...http://news.thomasnet.com/fullstory/826546

Hemisphere R220 Receiver

AG WeeklyHemisphere GPS introduces the R220 GPS Receiver. It is the first finished product to be powered by Eclipse, Hemisphere GPS’ patented dual frequency technology. The R220 GPS Receiver provides extremely accurate, versatile, and robust positioning, in virtually any environment, anywhere in the world.http://www.agweekly.com/articles/2009/05/09/news/new_product...

StratoComm Supports U.S. Stratospheric Regulatory Efforts

PR Newswire via Yahoo! FinanceStratoComm Corporation has long supported ongoing regulatory efforts directed to assuring availability of telecommunications frequency spectrum required for use in the operation of High Altitude Platform Stations .http://biz.yahoo.com/prnews/090508/ny13965.html?.v=1

Cable Barriers In Interstate 540 approved

The Morning NewsFAYETTEVILLE — Crashes involving cars crossing freeway medians happen with "high frequency" along Interstate 540 between Arkansas 265 and Arkansas 112 in Washington County, and Arkansas 62 and Arkansas 102 in Benton County, the state Highway Commission announced Thursday.http://www.nwaonline.net/articles/2009/05/08/news/050809azhi...

Endwave Awarded Development Contract from Nokia Siemens Networks

Business Wire via Yahoo! FinanceSAN JOSE, Calif.----Endwave Corporation , a leading provider of high-frequency RF solutions for mobile communications networks, announced an agreement with Nokia Siemens Networks for the development of transmit-receive modules for Nokia Siemens Networks' FlexiPacket Microwave™ backhaul radios.http://biz.yahoo.com/bw/090508/20090508005181.html?.v=1

News about High Frequency

GSRTC buses no match for jeeps

Times of India ... brought sharply into focus on Thursday when over 200 commuters protested on Ashram Road for 45 minutes against poor frequency ... Officials claim high number of trips, but they also include buses from various areas headed for Sachivalaya. Darshana ... http://timesofindia.indiatimes.com/Ahmedabad/GSRTC-buses-no-...

'New-Old' Rules Drive Real Estate Market

CNBCIan Shepherdson, chief U.S. economist at High Frequency Economics, noted this spring that falling housing prices are likely to slow heading into the summer months and possibly show improvement, cautioning that "foreclosures are weighing heavily on ... http://www.cnbc.com/id/30562839

Construction and home sales offer hope that the recession is easing

Kansas City StarIan Shepherdson, chief U.S. economist at High Frequency Economics, wrote in a research note.However, economists cautioned that the construction rebound could be temporary, given all the problems facing the industry as a severe financial crisis ... http://www.kansascity.com/business/story/1178377.html

U.S. ISM index to show non-manufacturing contracted

Guardian UnlimitedThe nonmanufacturing ISM index likely rebounded in April, consistent with the fading of weakness already evident in ... IAN SHEPHERDSON, CHIEF U.S. ECONOMIST, HIGH FREQUENCY ECONOMICS, VALHALLA, NEW YORK:http://www.guardian.co.uk/business/feedarticle/8488880

Sunfire's High Resolution Speaker System is Honored with 2009 Mark of ...

PR.comBoth HRS speaker models utilize a high performance 1" ring-radiating, silk-dome tweeter with extended high frequency response and smooth off-axis dispersion. This tweeter is similar to those found in expensive audiophile speakers costing many times ... http://www.pr.com/press-release/149465

Search results for High Frequency

High Frequency Media: Milwaukee HD Video Production Service

High Frequency Media: Milwaukee video production service providing versaltile and effective media solutions for an expansive range of clients.http://www.highfrequencymedia.com/

High-frequency - definition of High-frequency by the Free Online ...

high frequency. n. Abbr. HF. A radio frequency in the range between 3 and 30 megahertz. high frequency. Noun. a radio frequency between 30 and 3 megahertzhttp://www.thefreedictionary.com/High-frequency

Radio Frequency Heating High Frequency Heating RF welding HF welding ...

We supply and service radio frequency and induction heating equipment and plastic, ultrasonic and teflon welders to New Zealand, Australia and the Pacific. We work with the ... http://www.highfrequency.co.nz/

High Frequency Gravity Waves in UFOs in History Channel

High Frequency Gravity Waves: http://topsecretairspace.blogspot.com/2009/05/knowing-future-cia-911-ufos-and.html ' When Smith, who maintains a personal friendship with Ron ... http://boards.history.com/topic/Ufo-Hunters/High-Frequency-G...

high frequency - definition of high frequency by the Free Online ...

high frequency. n. Abbr. HF. A radio frequency in the range between 3 and 30 megahertz. high frequency. Noun. a radio frequency between 30 and 3 megahertzhttp://www.thefreedictionary.com/high+frequency

Wikipedia results for High Frequency

High frequency - Wikipedia, the free encyclopedia

High frequency (HF) radio frequencies are between 3 and 30 MHz. Also known as the decameter band or decameter wave as the wavelengths range from one to ten decameters (ten to one ... http://en.wikipedia.org/wiki/High_frequency

High frequency ventilation - Wikipedia, the free encyclopedia

High frequency ventilation is a type of mechanical ventilation that employs very high respiratory rates (>60 breaths per minute) and very small tidal volumes (usually below ... http://en.wikipedia.org/wiki/High-frequency_ventilation

High Frequency Active Auroral Research Program - Wikipedia, the free ...

The High Frequency Active Auroral Research Program (HAARP) is an investigation project to "provide a research facility to conduct pioneering experiments in ionospheric phenomena ... http://en.wikipedia.org/wiki/Project_HAARP

Extremely high frequency - Wikipedia, the free encyclopedia

Extremely high frequency is the highest radio frequency band. EHF runs the range of frequencies from 30 to 300 gigahertz, above which electromagnetic radiation is considered to be ... http://en.wikipedia.org/wiki/Extremely_high_frequency

Ultra high frequency - Wikipedia, the free encyclopedia

Ultra high frequency (UHF) designates a range with a short antenna of electromagnetic waves with frequencies between 300 MHz and 3 GHz (3,000 MHz).http://en.wikipedia.org/wiki/Ultra-high_frequency
  • Recent
  • Mine
  • Watched
  • Commented
You must be logged in to perform this operation
You must be logged in to perform this operation

Search this site

Videos found for Frequency

Frequency (Official HH Video)

Frequency (Official HH Video)Filmed & edited by: imSuck Original release date: Jan 23, 2006 Description: The battle between humans and Covenant wages on. The Spartans have developed shields that completely...Flash - Video

POLITICS: Local elections could be ...

POLITICS: Local elections could be decided on frequency of rubbish collectionsIn an unusual development, it seems that next week's local elections in England could actually be decided on a local issue. And that's rubbish collections. On the doorsteps, as...MPEG 4 - Video

Change AutoRecover Save Frequency

Change AutoRecover Save FrequencyChange how often Excel saves AutoRecover data for your workbooksFlash - Video

Home Recording EQ Frequency Splitti...

Home Recording EQ Frequency Splitting - HypnoticAudioSecretsHow to split up sound into different ranges for EQ during mixing. Frequency chart shows how musical instruments relate to each others ranges.Flash - Video

Low Frequency Club - Girlfriend Is ...

Low Frequency Club - Girlfriend Is BetterVideo directed by Marco Miraglia and Stefano Sipani. I Low Frequency Club sono in tre e vengono da Brescia. Il loro suono ³¡ decisamente elettronico anche se sotto lo strato di...Windows Media - Video

Answers for High Frequency

Hammond, of Texashigh frequency?Hammond, of TexasOver 50 here and can hear it fineAlvin YorkHow do I block high frequency broadband signals from my modem?Alvin YorkThere is not much you can do to your modem. But you can have your girlfriend go to the hearing doctor, and ask for earplugs that filter high freq. noise. A co worker has the same problem. This is what...James SWhats the difference between High frequency and Low frequency hearing loss?James SSound occurs over a wide spectrum of frequencies. The human ear is sensitive to a frequency band withing that spectrum. Since sounds occur at different frequencies, you will not be able to hear the ...Just MeHave you used a high frequency mouse trap?Just MeDon't waste your money. They are a scam. A recent article, People And Rodent Pests in PCT Online, a rodent control trade magazine, likewise concludes "Ultrasonic and electromagnetic rodent repel...nongdan_xitinWhat kinds of bug react to high frequency sound?nongdan_xitinFemale mosquitoes make a high-pitched buzz with their wings. This vibrates any nearby males' antannae and they fly toward the sound. So male mosquitoes might. I'm not sure, though. Just sounded like a...
Contact Us[X]
Your name
Email
Subject
Your comment
[X]