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Most Traveled Cities in the United States

• Sep 20, 2010 from pixelstoreus(PIXELSTORE.US) in *
  Most Traveled Cities in the United States
  Masters rowers are a dynamic group who lead busy lives, and careers that take them all over the country. With the opportunity to travel comes the opportunity to see what rowing is like in a different city, and take in some sites, time willing. Boathouse Finder (www.BHFinder.com) provides a very useful geographic search of rowing clubs and boathouse around the country and throughout the world.
  
  If you have any rowing travel-related stories, wed love to hear about them. You can email us at info@bhfinder.com.
  AUSTIN
  Austins Town Lake is arguably the perfect spot to row. The 6 miles of water is dammed at both ends, so there is no strong current. The weather is mild throughout the year, so rowing never stops; in fact the winter is the preferred time to row among local rowers, and spring breakers. There are no motorboats or jet skis allowed (except for coaches launches), so no need to worry about getting waked.
  Rowing Dock is a privately owned, privately managed rowing club and boat rental facility located on the west end of Town Lake. Here the water is calm and the lush banks create a serene atmosphere. It is easy to get to from MoPac or downtown, and it offers a large parking lot. Rowing Dock is open a dock attendant is on duty all year during busy hours to help patrons with boats. With proof of skill and current membership in any recognized club, out of town rowers can rent the recreational single sculling boat. Other patrons may rent from a selection of single, double or triple kayaks or quad water cycles. Check the website or call for hours.
  Austin Rowing Club is a non-profit run by an elected board. It hosts the two major regattas in Austin each year. They offer sweep rowing and sculling. ARC is located in downtown Austin near the Four Season Hotel; if you get the timing of your row right, you could enjoy the nightly bat flight from Congress Bridge, which can be seen from ARC.
  CLUBS ALLOWING GUEST ROWING
  Austin Rowing Club
  Rowing Dock
  Texas-Rowing-Center
  SITES OF INTEREST
  Worlds largest urban bat population under Congress Bridge; nightly flights spring, summer, early fall
  4 miles of Waterfront hike and bike trails around Town Lake
  Bob Bullock Texas State History Museum & IMAX Theatre
  Shopping SOCO and the Drag
  SOCO first Thursday
  (evening shopping, festival-feel)
  LBJ Library
  State Capitol and grounds
  MAJOR REGATTAS
  Fall: Pumpkin Head Regatta; October
  Spring: Heart of Texas Regatta; March
  
  BOSTON
  Boston and Cambridge are rife with rowing history. Nine boathouses line the Charles River. Four belong to clubs: Union, Riverside, Cambridge, and Community Rowing. Five belong to colleges: MIT, Boston University, Harvard, Radcliffe, and Northeastern. Guest rowing can be difficult depending upon which club you contact as some clubs require sponsorship from a member. Cygnet Rowing Club, with two boathouse locations, offers hourly rentals of single sculls.
  Dividing Boston and Cambridge, the Charles River is an elegantly serpentine aquatic ribbon that varies in width from about 200 meters to more than a kilometer. During warm weather, and even not so warm weather, it is alive with all manner of rowing craft, sailboats, kayaks, duck boats, excursion boats, and powered pleasure craft. The round-trip distance from the Science Museum to Watertown and back is about seventeen miles. On the average morning the entire length of the river is rowable, although the chop tends to kick up below the Boston University (BU) bridge after nine a.m. Almost all the college programs have agreed to use wakeless launches, which has maintained the generally flat conditions, and only on impossibly windy days (or winter, when the river freezes) is the entire river unrowable. The scenery along the way ranges from intensely urban to quietly suburban. The river is bordered by Memorial Drive on the north bank, and Storrow Drive on the south, and a bike path runs the entire length of the river on both banks.
  CLUBS ALLOWING GUEST ROWING
  Cambridge Boat Club
  Community Rowing Inc. of Boston
  Cygnet Rowing Club
  Riverside Boat Club
  SITES OF INTEREST
  Boathouses dot both shores from the Lower Basin out to Watertown. Faneuil Hall Marketplace and Quincy Market are hugely popular settings for dining and shopping. Whale watch excursions leave from the inner harbor throughout the day, as to harbor island excursions. Jacques Cousteau once proclaimed that Boston Harbor is the most beautiful harbor in the world as one enters from the sea.
  The Freedom Trail brings history alive for millions every year, while the duck boat tours unite the experience of river and city. The Museum of Fine Arts, Fenway Park (home of the Red Sox), the Boston Public Library, and the Hatch Shell (riverside outdoor performances of all kinds) are just a sampling of rewarding outings awaiting the curious traveler.
  MAJOR REGATTAS
  Fall: Head of the Charles
  Summer: Cromwell Cup
  Spring: Riverside Sprints
  
  CHICAGO
  Visitors to Chicago are often surprised...

About GPS

• Oct 01, 2010 from weatherforecas
  About GPS
  Global Positioning System
  
  The Global Positioning System (GPS) is the only fully functional Global Navigation Satellite System (GNSS). Utilizing a constellation of at least 24 medium Earth orbit satellites that transmit precise microwave signals, the system enables a GPS receiver to determine its location, speed/direction, and time.
  
  Developed by the United States Department of Defense, it is officially named NAVSTAR GPS (Contrary to popular belief, NAVSTAR is not an acronym, but simply a name given by Mr. John Walsh, a key decision maker when it came to the budget for the GPS program[1]). The satellite constellation is managed by the United States Air Force 50th Space Wing. The cost of maintaining the system is approximately US0 million per year,[2] including the replacement of aging satellites, and research and development. Despite these costs, GPS is free for civilian use as a public good.
  
  GPS has become a widely used aid to navigation worldwide, and a useful tool for map-making, land surveying, commerce, and scientific uses. GPS also provides a precise time reference used in many applications including scientific study of earthquakes, and synchronization of telecommunications networks.
  
  Simplified method of operation
  
  A GPS receiver calculates its position by measuring the distance between itself and three or more GPS satellites. Measuring the time delay between transmission and reception of each GPS microwave signal gives the distance to each satellite, since the signal travels at a known speed the speed of light. These signals also carry information about the satellites location and general system health (known as almanac and ephemeris data). By determining the position of, and distance to, at least three satellites, the receiver can compute its position using trilateration.[3] Receivers typically do not have perfectly accurate clocks and therefore track one or more additional satellites, using their atomic clocks to correct the receivers own clock error.
  
  [edit] Technical description
  
  Unlaunched GPS satellite on display at the San Diego Aerospace museum
  
  Unlaunched GPS satellite on display at the San Diego Aerospace museum
  
  [edit] System segmentation
  
  The current GPS consists of three major segments. These are the space segment (SS), a control segment (CS), and a user segment (US).[4]
  
  [edit] Space segment
  
  The space segment (SS) is composed of the orbiting GPS satellites, or Space Vehicles (SV) in GPS parlance. The GPS design calls for 24 SVs to be distributed equally among six circular orbital planes.[5] The orbital planes are centered on the Earth, not rotating with respect to the distant stars.[6] The six planes have approximately 55 inclination (tilt relative to Earths equator) and are separated by 60 right ascension of the ascending node (angle along the equator from a reference point to the orbits intersection).[2]
  
  Orbiting at an altitude of approximately 20,200 kilometers (12,600 miles or 10,900 nautical miles; orbital radius of 26,600 km (16,500 mi or 14,400 NM)), each SV makes two complete orbits each sidereal day, so it passes over the same location on Earth once each day. The orbits are arranged so that at least six satellites are always within line of sight from almost everywhere on Earths surface.[7]
  
  As of September 2007, there are 31 actively broadcasting satellites in the GPS constellation. The additional satellites improve the precision of GPS receiver calculations by providing redundant measurements. With the increased number of satellites, the constellation was changed to a nonuniform arrangement. Such an arrangement was shown to improve reliability and availability of the system, relative to a uniform system, when multiple satellites fail.[8]
  
  [edit] Control segment
  
  The flight paths of the satellites are tracked by US Air Force monitoring stations in Hawaii, Kwajalein, Ascension Island, Diego Garcia, and Colorado Springs, Colorado, along with monitor stations operated by the National Geospatial-Intelligence Agency (NGA).[9] The tracking information is sent to the Air Force Space Commands master control station at Schriever Air Force Base in Colorado Springs, which is operated by the 2d Space Operations Squadron (2 SOPS) of the United States Air Force (USAF). 2 SOPS contacts each GPS satellite regularly with a navigational update (using the ground antennas at Ascension Island, Diego Garcia, Kwajalein, and Colorado Springs). These updates synchronize the atomic clocks on board the satellites to within one microsecond and adjust the ephemeris of each satellites internal orbital model. The updates are created by a Kalman filter which uses inputs from the ground monitoring stations, space weather information, and various other inputs.[10]
  
  GPS receivers come in a variety of formats, from devices integrated into cars, phones, and watches, to dedicated devices such as those shown here from manufacturers Trimble, Garmin and Leica (left to right).
  
  GPS receivers come in a...

Newfoundland Travels-Labrador

• Oct 11, 2010 from weatherforecas
  Newfoundland Travels-Labrador
  On Wednesday, August 27, 2003 we have a beautiful day for traveling in Labrador. We are traveling on the Trans Labrador Highway. Our first stop was LAnse Amour, the site of a grave 7,500 years old. This was found by a group of students who thought that the rock pattern was quite unusual. Under the rock they found an enshrouded child of about twelve, face-down, painted in red with a flat rock on the lower back. Artifacts associated with the burial include a walrus tusk, a number of stone and bone projectile points, a bird bone whistle, paint grinding tools, an antler pendant, a toggling harpoon and a decorated ivory eagle.
  Down the road is the Amour Lighthouse, the tallest one in Newfoundland Province. Even its presence has not stopped ships from the treacherous shores. In 1922, the HMS Raleigh, a 12,000 Ton cruiser, avoiding an iceberg, ran aground. Its wreckage is strewn on the shore. During WWII two ships collided in the dense fog in the straits, because there was a warning of a U-boat in the area. Ironically two other ships were lost in the straits that day too, but in a different area. The Strait of Belle Isle is not only an iceberg alley, but also a shipwreck alley.
  Up the road at Red Bay archeologists are still uncovering the first industrial whaling factory in the world. Founded in the 1540s by the Basque fishermen, from the area between France and Spain, the whale oil was used to light up Europe. During its peak, over 2,500 whalers in Labrador, produced approximately 20,000 barrels of oil annually. Using chalupas, a boat not a sandwich, they harpooned the right whales and brought them ashore for processing. In the harbor on Saddle Island archeological digs are still in process. Many artifacts are on display in the local museum, including pieces of the wreckage of The San Juan, a whaling ship, found near the modern wreckage of the Bernier, caught in the same type of storms associated with the Labrador Coast. Many sites exist on the mainland, but have not been explored, because they are on private property. The Basque industry died around 1600, due to their involvement with the Spanish Armada.
  At Red Bay, the paved road ends. A new gravel road leads to Cartwright, opening the coastal towns for tourism and commercial development. After traveling 40 or so km on the road, we parked for the night at one of the numerous gravel pits used for the construction of the roadbed.
  Today we spent six hours driving the gravel road from Red Bay to Cartwright, a distance of 312 kilometers or 187 miles. The road is approximately ten yards wide and is very will groomed. The speed limit is 70 kph or 42 mph. All along the road are sweeping vistas of pine forest and mountains, something akin to driving the Northern Passage through the Adirondacks. Approximately 80 kilometers from Cartwright is the junction for the planned road to Goose Bay of an additional 250 kilometers.
  Most of the towns along the route are bypassed by the new road. There are few services on the highway itself. In Lodge Bay, gas and sundry items are available at Monas One Stop; no diesel. Diesel is available at Marys Harbour at C & Js Automotive. St. Marys is the embarkation point for Battle Harbour Island and National Historic District. Known as the unofficial capital of Labrador, Battle Harbour was a major base for salt cod fishing in Labrador during the 19th Century. The area looks pretty much like it did in 1909. The fishery continued until the 1990s and then was donated to the people. Until the advent of the highway this year the island was pretty inaccessible, except by boat. Today interpreters in traditional dress guide the tourist through a typical fishing village of the 19th and 20th centuries. Accommodations are available for overnight stays.
  50 k. from Marys Harbour is Port Hope Simpson on the beautiful Alexis River. Restaurants, sleeping accommodations, fuel and a hospital are available there. This is the last vestige of civilization for the next 187 k. There are very few places to turn off the highway to rest. Most people just park at the side of the road. Most of the traffic encountered were construction vehicles along a 50 k. stretch.
  The roads in Cartwight are in complete contrast to the highway: rutted and corrugated. We parked with other trailers at the ticket office parking lot, located near the dock.
  Spent a quiet day in Cartwright. We boarded the Sir Robert (not James) Bond Ferry at 4:30 for a 7:00 sailing. The ship was full to capacity, everyone returning home from vacation or making the best of a three day weekend before returning to school or work. The ship is far from luxurious. During the night many people, who did not have a broom closet size room, slept on the deck. The strangest thing about the ship is the food service. The cafeteria was open only until 6:30, hour before sailing. Only snacks and the bar were open during the sailing itself. Wanted to see the Wunderstrand, a mile long white sand...

Radio propagation

• Sep 28, 2010 from weatherforecas
  Radio propagation
  Free space propagation
  In free space, all electromagnetic waves (radio, light, X-rays, etc) obey the inverse-square law which states that the power density of an electromagnetic wave is proportional to the inverse of the square of the distance from the source or:
  Doubling the distance from a transmitter means that the power density of the radiated wave at that new location is reduced to one-quarter of its previous value.
  The power density per surface unit is proportional to the product of the electric and magnetic field strengths. Thus, doubling the propagation path distance from the transmitter reduces each of their received field strengths over a free-space path by one-half.
  Modes
  Radio frequencies and their primary mode of propagation
  Band
  Frequency
  Wavelength
  Propagation via
  VLF
  Very Low Frequency
  330 kHz
  10010km
  Guided between the earth and the ionosphere.
  LF
  Low Frequency
  30300 kHz
  101km
  Guided between the earth and the D layer of the ionosphere.
  Surface waves.
  MF
  Medium Frequency
  3003000 kHz
  1000100m
  Surface waves.
  E, F layer ionospheric refraction at night, when D layer absorption weakens.
  HF
  High Frequency (Short Wave)
  330 MHz
  10010 m
  E layer ionospheric refraction.
  F1, F2 layer ionospheric refraction.
  VHF
  Very High Frequency
  30300 MHz
  101 m
  Infrequent E ionospheric refraction. Extremely rare F1,F2 layer ionospheric refraction during high sunspot activity up to 80MHz. Generally direct wave. Sometimes tropospheric ducting.
  UHF
  Ultra High Frequency
  3003000 MHz
  10010cm
  Direct wave. Sometimes tropospheric ducting.
  SHF
  Super High Frequency
  330 GHz
  101cm
  Direct wave.
  EHF
  Extremely High Frequency
  30300 GHz
  101mm
  Direct wave limited by absorption.
  Surface modes
  Main article: Surface wave
  Lower frequencies (between 30 and 3,000kHz) have the property of following the curvature of the earth via groundwave propagation in the majority of occurrences.
  In this mode the radio wave propagates by interacting with the semi-conductive surface of the earth. The wave clings to the surface and thus follows the curvature of the earth. Vertical polarization is used to alleviate short circuiting the electric field through the conductivity of the ground. Since the ground is not a perfect electrical conductor, ground waves are attenuated rapidly as they follow the earth surface. Attenuation is proportional to the frequency making this mode mainly useful for LF and VLF frequencies.
  Today LF and VLF are mostly used for time signals, and for military communications, especially with ships and submarines. Early commercial and professional radio services relied exclusively on long wave, low frequencies and ground-wave propagation. To prevent interference with these services, amateur and experimental transmitters were restricted to the higher (HF) frequencies, felt to be useless since their ground-wave range was limited. Upon discovery of the other propagation modes possible at medium wave and short wave frequencies, the advantages of HF for commercial and military purposes became apparent. Amateur experimentation was then confined only to authorized frequency segments in the range.
  Direct modes (line-of-sight)
  Line-of-sight is the direct propagation of radio waves between antennas that are visible to each other. This is probably the most common of the radio propagation modes at VHF and higher frequencies. Because radio signals can travel through many non-metallic objects, radio can be picked up through walls. This is still line-of-sight propagation. Examples would include propagation between a satellite and a ground antenna or reception of television signals from a local TV transmitter.
  Ground plane reflection effects are an important factor in VHF line of sight propagation. The interference between the direct beam line-of-sight and the ground reflected beam often leads to an effective inverse-fourth-power law for ground-plane limited radiation. [Need reference to inverse-fourth-power law + ground plane. Drawings may clarify]
  Ionospheric modes (skywave)
  Main article: Skywave
  Skywave propagation, also referred to as skip, is any of the modes that rely on refraction of radio waves in the ionosphere, which is made up of one or more ionized layers in the upper atmosphere. F2-layer is the most important ionospheric layer for HF propagation, though F1, E, and D-layers also play some role. These layers are directly affected by the sun on a daily cycle, the seasons and the 11-year sunspot cycle determines the utility of these modes. During solar maxima, the whole HF range up to 30MHz can be used and F2 propagation up to 50MHz are observed frequently depending upon daily solar flux values. During solar minima, propagation of higher frequencies is generally worse.
  Forecasting of skywave modes is of considerable interest to amateur radio operators and commercial marine and aircraft communications, and also to shortwave broadcasters.
  Meteor scattering
  Meteor scattering relies on reflecting radio waves off...