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Line-of-sight propagation

Line-of-sight propagation is a characteristic of electromagnetic radiation or acoustic wave propagation which means waves travel in a direct path from the source to the receiver. Electromagnetic transmission includes light emissions traveling in a straight line; the rays or waves may be diffracted, reflected, or absorbed by the atmosphere and obstructions with material and cannot travel over the horizon or behind obstacles. In contrast to line-of-sight propagation, at low frequency due to diffraction, radio waves can travel as ground waves, which follow the contour of the Earth; this enables AM radio stations to transmit beyond the horizon. Additionally, frequencies in the shortwave bands between 1 and 30 MHz, can be reflected back to Earth by the ionosphere, called skywave or "skip" propagation, thus giving radio transmissions in this range a global reach. However, at frequencies above 30 MHz and in lower levels of the atmosphere, neither of these effects are significant. Thus, any obstruction between the transmitting antenna and the receiving antenna will block the signal, just like the light that the eye may sense.

Therefore, since the ability to visually see a transmitting antenna corresponds to the ability to receive a radio signal from it, the propagation characteristic at these frequencies is called "line-of-sight". The farthest possible point of propagation is referred to as the "radio horizon". In practice, the propagation characteristics of these radio waves vary depending on the exact frequency and the strength of the transmitted signal. Broadcast FM radio, at comparatively low frequencies of around 100 MHz, are less affected by the presence of buildings and forests. Low-powered microwave transmitters can be foiled by tree branches, or heavy rain or snow; the presence of objects not in the direct line-of-sight can cause diffraction effects that disrupt radio transmissions. For the best propagation, a volume known as the first Fresnel zone should be free of obstructions. Reflected radiation from the surface of the surrounding ground or salt water can either cancel out or enhance the direct signal.

This effect can be reduced by raising either or both antennas further from the ground: The reduction in loss achieved is known as height gain. See Non-line-of-sight propagation for more on impairments in propagation, it is important to take into account the curvature of the Earth for calculation of line-of-sight paths from maps, when a direct visual fix cannot be made. Designs for microwave used ​4⁄3 earth radius to compute clearances along the path. Although the frequencies used by mobile phones are in the line-of-sight range, they still function in cities; this is made possible by a combination of the following effects: ​1⁄r 4 propagation over the rooftop landscape diffraction into the "street canyon" below multipath reflection along the street diffraction through windows, attenuated passage through walls, into the building reflection and attenuated passage through internal walls and ceilings within the buildingThe combination of all these effects makes the mobile phone propagation environment complex, with multipath effects and extensive Rayleigh fading.

For mobile phone services, these problems are tackled using: rooftop or hilltop positioning of base stations many base stations. A phone can see at least three, as many as six at any given time. "sectorized" antennas at the base stations. Instead of one antenna with omnidirectional coverage, the station may use as few as 3 or as many as 32 separate antennas, each covering a portion of the circular coverage; this allows the base station to use a directional antenna, pointing at the user, which improves the signal to noise ratio. If the user moves from one antenna sector to another, the base station automatically selects the proper antenna. Rapid handoff between base stations the radio link used by the phones is a digital link with extensive error correction and detection in the digital protocol sufficient operation of mobile phone in tunnels when supported by split cable antennas local repeaters inside complex vehicles or buildingsA Faraday cage is composed of a conductor that surrounds an area on all sides and bottom.

Electromagnetic radiation is blocked. For example, mobile telephone signals are blocked in windowless metal enclosures that approximate a Faraday cage, such as elevator cabins, parts of trains and ships; the same problem can affect signals in buildings with extensive steel reinforcement. The radio horizon is the locus of points at which direct rays from an antenna are tangential to the surface of the Earth. If the Earth were a perfect sphere without an atmosphere, the radio horizon would be a circle; the radio horizon of the transmitting and receiving antennas can be added together to increase the effective communication range. Radio wave propagation is affected by atmospheric conditions, ionospheric absorption, the presence of obstructions, for example mountains or trees. Simple formulas that include the effect of the atmosphere give the range as: h o r i z o n m i l e s ≈ 1.23 ⋅ h e i g h t

Arapahoe, Jefferson County, Colorado

Arapahoe was one of the first settlements in what is now the U. S. state of Colorado. Nothing remains of the now deserted ghost town in Jefferson County, except a historical marker on the south side of 44th Avenue, between the towns of Golden and Wheat Ridge. Gold prospectors founded Arapahoe City on November 29, 1858 during the advent of the Pikes Peak gold rush; the town was laid out by George B. Allen, according to founding treasurer Thomas L. Golden in a letter to the Missouri Republican it was named after the Arapaho tribe after chiefs warned residents to "quit their country". Arapahoe City was a base camp town laid out on a grid to serve miners washing placer gold from nearby Clear Creek; the placer, Arapahoe Bar, had been discovered by the Estes Party as far back as 1834 and mined in earnest since 1858. The town, the fourth founded in northern Colorado, was within western Kansas Territory; the 1860 census found 80 people living at "Arrapahoe City," including 17 females. An Arapahoe Post Office operated from January 17, 1860, until October 12, 1861.

Arapahoe had fifty houses, ranging from tents to log buildings. But the accessible parts of the placers were exhausted, the rapid growth of the town of Golden a few miles west caused many in Arapahoe to physically move their log buildings to Golden, so that by the end of 1860, Arapahoe City had shrunk to just a few cabins. By 1867, the town was gone. Arapahoe Bar was mined by hydraulic mining and dredge mining, featuring two of the pioneer electric mining dredges in the west, operated by Herman J. Reiling and the National Dredging Company; the company used the last remaining buildings of Arapahoe City for quarters, but before long all evidence of the town had vanished. The site of Arapahoe City is destroyed today. No Arapahoe City buildings are known to have survived, though it is possible some may have been moved to nearby Golden or Fairmount, the farming community descended from Arapahoe City; the two dredges, not advanced enough to save large amounts of the fine gold at Arapahoe Bar, were disassembled, one taken to French Gulch near Breckenridge and its twin taken to the American River around Sacramento, California.

The fate of the California dredge remains unknown, while the remains of the dredge at Breckenridge, now known as the Reiling Dredge, are being preserved. Thomas L. Golden, whom Golden, Colorado is named after John Hamilton Gregory, Colorado gold discoverer around present-day Central City, Colorado George Andrew Jackson, Colorado gold discoverer around present-day Idaho Springs, Colorado The historical marker locating Arapahoe is on the south side of 44th Avenue, 0.2 miles west of the intersection with McIntyre Boulevard, at 39°46′30″N 105°10′42″W, at an altitude of 1710 m. List of ghost towns in Colorado

1922 Wolverhampton West by-election

The Wolverhampton West by-election, 1922 was a by-election held for the British House of Commons constituency of Wolverhampton West in Wolverhampton on 7 March 1922. It was won by the Coalition Conservative candidate Sir Robert Bird; the seat had become vacant on when the sitting Conservative Member of Parliament, Sir Alfred Bird had died at the age of 72 on 7 February 1922. He had held the seat since the January 1910 general election; the Conservative candidate was son of Sir Alfred. The Labour Party candidate was 49-year-old Alexander Walkden, who had contested the seat in 1918; the Liberal Party, did not field a candidate at the last general election and decided not to do so again for the by-election. George Thorne, the Liberal MP for Wolverhampton East supported the Labour Party candidate. On an increased turnout, the result was a victory for the Coalition Conservative candidate, Sir Robert Bird, although his majority was somewhat reduced from that won by his father in 1918, he held the seat until 1929, regained it in 1931, stepped down at the 1945 general election.

Walkden stood again at the November 1922 general election, after contesting Heywood and Radcliffe in 1924, was elected as MP for Bristol South in 1929. Wolverhampton West Wolverhampton List of United Kingdom by-elections Craig, F. W. S.. British parliamentary election results 1918-1949. Chichester: Parliamentary Research Services. ISBN 0-900178-06-X. Historical list of MPs: W

Sheridan Township, Huron County, Michigan

Sheridan Township is a civil township of Huron County in the U. S. state of Michigan. The population was 736 at the 2000 census. Appin was a settlement founded by people from Scotland, it had a post office from 1894 until 1904. Ivanhoe is an unincorporated community in the Township on W. Atwater Road and M-53/S. Van Dyke Road 43°42′20″N 83°5′38″W with an elevation of 748 feet. President Nixon stopped in Ivanhoe during his trip up to Bad Axe in 1973. According to the United States Census Bureau, the township has a total area of 36.2 square miles, all land. As of the census of 2000, there were 736 people, 257 households, 200 families residing in the township; the population density was 20.3 per square mile. There were 279 housing units at an average density of 7.7 per square mile. The racial makeup of the township was 98.51% White, 0.41% Native American, 0.14% from other races, 0.95% from two or more races. Hispanic or Latino of any race were 0.27% of the population. There were 257 households out of which 37.0% had children under the age of 18 living with them, 65.4% were married couples living together, 6.2% had a female householder with no husband present, 21.8% were non-families.

19.1% of all households were made up of individuals and 7.0% had someone living alone, 65 years of age or older. The average household size was 2.82 and the average family size was 3.22. In the township the population was spread out with 28.7% under the age of 18, 7.1% from 18 to 24, 28.7% from 25 to 44, 23.4% from 45 to 64, 12.2% who were 65 years of age or older. The median age was 36 years. For every 100 females, there were 98.9 males. For every 100 females age 18 and over, there were 104.3 males. The median income for a household in the township was $39,850, the median income for a family was $45,583. Males had a median income of $31,875 versus $22,054 for females; the per capita income for the township was $19,065. About 3.9% of families and 6.5% of the population were below the poverty line, including 7.1% of those under age 18 and none of those age 65 or over. Romig, Walter. Michigan Place Names: The History of the Founding and the Naming of More Than Five Thousand Past and Present Michigan Communities.

Great Lakes Books Series. Detroit, Michigan: Wayne State University Press. ISBN 9780814318386

A Jolly Bad Fellow

A Jolly Bad Fellow is a 1964 British film directed by Don Chaffey. It stars Janet Munro. Leo McKern as Prof Bowls-Ottery Janet Munro as Delia Brooks Maxine Audley as Clarina Bowls-Ottery Duncan Macrae as Dr. Brass Dennis Price as Prof. Hughes Miles Malleson as Dr. Woolley Leonard Rossiter as Dr. Fisher Alan Wheatley as Epicene Patricia Jessel as Mrs. Pugh-Smith Dinsdale Landen as Fred George Benson as Inspector Butts The film was a box office disappointment. A Jolly Bad Fellow on IMDb

Bhale Donga

Bhale Donga is a 1989 Telugu action film produced by K. Devi Vara Prasad under the Devi Films banner, directed by A. Kodandarami Reddy, it stars Vijayashanti in the lead roles and music composed by Chakravarthy. The film was dubbed into Hindi under the title Qaidi no.1. The film was recorded as a Hit at the box office; the story begins with a swashbuckling thief, Surendra a master of disguise, who always targets Vidhatha, dictator of the city and he is being tracked down by SP Indrani, an efficient Police officer. Surendra contracts a multi-speciality hospital for work free of cost with all this money. Dr. Rekha, the younger sister of Indrani, is inspired by Surendra's good heart and starts loving him. After several other successful attempts, one day Surendra is caught by Rekha and when she questions him, he reveals his past, his father an honest person, had collected donations from the people of the town for the construction of hospital, with his partner Vidhatha. Vidhatha had double-crossed him and stolen entire account, placing the blame on his father, which led to his suicide.

That is. In another attempt, Surendra is trapped and arrested by Indrani, she tells him that he had been doing this for his welfare only, because she has a personal fight with Vidhatha, whose actual name is Vijay, her ex-lover, who had killed her parents and escaped from imprisonment. Now Surendra and Indrani join together. Whether they will be able take revenge against Vidhatha, whether Surendra will be able complete the hospital forms the rest of the story. Art: Srinivasa Raju Choreography: Siva Subramanyam, Taara Fights: Vijayan Story - Dialogues: G. Satya Murthy Lyrics: Veturi Sundararama Murthy Playback: SP Balu, S. Janaki Music: Chakravarthy Editing: Kotagiri Venkateswara Rao Cinematography: V. S. R. Swamy Producer: K. Devi Vara Prasad Screenplay - Director: A. Kodandarami Reddy Banner: Devi Films Release Date: 10 February 1989 Music composed by Chakravarthy. Lyrics were written by Veturi Sundararama Murthy. Music released on LEO Audio Company. VCDs and DVDs on - VOLGA Videos, Hyderabad Bhale Donga on IMDb