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Direct-sequence spread spectrum

In telecommunications, direct-sequence spread spectrum is a spread-spectrum modulation technique used to reduce overall signal interference. The direct-sequence modulation makes the transmitted signal wider in bandwidth than the information bandwidth. After the despreading or removal of the direct-sequence modulation in the receiver, the information bandwidth is restored, while the unintentional and intentional interference is reduced. With DSSS, the message bits are modulated by a pseudorandom bit sequence known as a spreading sequence; each spreading-sequence bit, known as a chip, has a much shorter duration than the original message bits. The modulation of the message bits scrambles and spreads the pieces of data, thereby results in a bandwidth size nearly identical to that of the spreading sequence; the smaller the chip duration, the larger the bandwidth of the resulting DSSS signal. Some practical and effective uses of DSSS include the Code Division Multiple Access method, the IEEE 802.11b specification used in Wi-Fi networks, the Global Positioning System.

DSSS phase-shifts a sine wave pseudorandomly with a continuous string of chips, each of which has a much shorter duration than an information bit. That is, each information bit is modulated by a sequence of much faster chips. Therefore, the chip rate is much higher than the information bit rate. DSSS uses a signal structure in which the spreading sequence produced by the transmitter is known by the receiver; the receiver can use the same spreading sequence to counteract its effect on the received signal in order to reconstruct the information signal. Direct-sequence spread-spectrum transmissions multiply the data being transmitted by a pseudorandom spreading sequence that has a much higher bit rate than the original data rate; the resulting transmitted signal resembles bandlimited white noise, like an audio recording of "static". However, this noise-like signal is used to reconstruct the original data at the receiving end, by multiplying it by the same spreading sequence; this process, known as despreading, is mathematically a correlation of the transmitted spreading sequence with the spreading sequence that the receiver knows the transmitter is using.

After the dispreading, the signal-to-noise ratio is increased by the spreading factor, the ratio of the spreading-sequence rate to the data rate. While a transmitted DSSS signal occupies a much wider bandwidth than a simple modulation of the original signal would require, its frequency spectrum can be somewhat restricted for spectrum economy by a conventional analog bandpass filter to give a bell-shaped envelope centered on the carrier frequency. In contrast, frequency-hopping spread spectrum pseudorandomly retunes the carrier and requires a uniform frequency response since any bandwidth shaping would cause amplitude modulation of the signal by the hopping code. If an undesired transmitter transmits on the same channel but with a different spreading sequence, the despreading process reduces the power of that signal; this effect is the basis for the code division multiple access property of DSSS, which allows multiple transmitters to share the same channel within the limits of the cross-correlation properties of their spreading sequences.

Resistance to unintended or intended jamming Sharing of a single channel among multiple users Reduced signal/background-noise level hampers interception Determination of relative timing between transmitter and receiver The United States GPS, European Galileo and Russian GLONASS satellite navigation systems. DS-CDMA is a multiple access scheme based on DSSS, by spreading the signals from/to different users with different codes, it is the most used type of CDMA. Cordless phones operating in the 900 MHz, 2.4 GHz and 5.8 GHz bands IEEE 802.11b 2.4 GHz Wi-Fi, its predecessor 802.11-1999. Automatic meter reading IEEE 802.15.4 Radio-controlled model Automotive vehicles Complementary code keying Frequency-hopping spread spectrum Linear feedback shift register Orthogonal frequency-division multiplexing The Origins of Spread-Spectrum Communications This article incorporates public domain material from the General Services Administration document: "Federal Standard 1037C". NTIA Manual of Regulations and Procedures for Federal Radio Frequency Management Civil Spread Spectrum History

Jean-Charles Tacchella

Jean-Charles Tacchella is a French screenwriter and film director. He was nominated for an Academy Award for Best Original Screenplay for his film Cousin Cousine, nominated for the Academy Award for Best Foreign Language Film and, remade in a US version starring Ted Danson and titled Cousins. Jean-Charles Tacchella studied in Marseilles and, just after the Liberation, left for Paris with the aim of becoming a film director, he joined L'écran Français when he was nineteen where he worked with Becker and Grémillon. While with the magazine, he wrote about filmmakers, actors and met André Bazin, Nino Frank, Roger Leenhardt, Roger Thérond and Alexandre Astruc, he became friends with Erich Von Stroheim, Anna Magnani, Vittorio de Sica and created the monthly “Ciné Digest” with Henri Colpi. In 1948, along with Bazin, Jacques Doniol-Valcroze, Claude Mauriac, René Clément and Pierre Kast, established Objectif 49, an avant-garde film club whose president was Jean Cocteau. Objectif 49 became the birthplace of the New Wave.

Jean-Charles Tacchella has since directed eleven features, many of which have had successful international careers and been awarded prestigious prizes. They include Voyage to Grand Tartarie, Cousin cousine, Le Pays bleu, It's a Long Time I've Loved You, Croque la vie, Staircase C, Travelling avant, Gallant Ladies, The Man of My Life, Seven Sundays, he is described as being "a smooth technician, Tacchella's camera work is fluid and precise". And his movie Traveling avant equivalent to the American film term "Tracking Shot", is described as "a semi-autobiographical paean to his youth as a cinema fanatic and cine-club enthusiast in post-war Paris", he was President of the Cinémathèque Française from 2000–2003. Typhon sur Nagasaki Jean Charles-Tacchella on IMDb

List of United States Supreme Court cases, volume 315

This is a list of all the United States Supreme Court cases from volume 315 of the United States Reports: Duncan v. Thompson, 315 U. S. 1 Ex parte Texas, 315 U. S. 8 Alton R. Co. v. United States, 315 U. S. 15 Taylor v. Georgia, 315 U. S. 25 White v. Winchester Country Club, 315 U. S. 32 Merion Cricket Club v. United States, 315 U. S. 42 United States v. Joliet & Chicago R. Co. 315 U. S. 44 United States v. N. E. Rosenblum Truck Lines, Inc. 315 U. S. 50 Lubetich v. United States, 315 U. S. 57 Glasser v. United States, 315 U. S. 60 Halliday v. United States, 315 U. S. 94 Southport Petroleum Co. v. NLRB, 315 U. S. 100 United States v. Wrightwood Dairy Co. 315 U. S. 110 Exhibit Supply Co. v. Ace Patents Corp. 315 U. S. 126 Wright v. Logan, 315 U. S. 139 Columbia River Packers Assn. Inc. v. Hinton, 315 U. S. 143 Cloverleaf Butter Co. v. Patterson, 315 U. S. 148 Helvering v. Alabama Asphaltic Limestone Co. 315 U. S. 179 Palm Springs Holding Corp. v. Commissioner, 315 U. S. 185 Bondholders Committee v. Commissioner, 315 U.

S. 189 Helvering v. Southwest Consolidated Corp. 315 U. S. 194 United States v. Pink, 315 U. S. 203 Young v. United States, 315 U. S. 257 Great Northern R. Co. v. United States, 315 U. S. 262 MacGregor v. State Mut. Life Assurance Co. 315 U. S. 280 NLRB v. Automotive Maintenance Machinery Co. 315 U. S. 282 Stewart v. Southern R. Co. 315 U. S. 283 United States v. Bethlehem Steel Corp. 315 U. S. 289 Riley v. New York Trust Co. 315 U. S. 343 Cudahy Packing Co. v. Holland, 315 U. S. 357 ICC v. Railway Labor Executives Assn. 315 U. S. 373 Purcell v. United States, 315 U. S. 381 Williams v. Jacksonville Terminal Co. 315 U. S. 386 Hysler v. Florida, 315 U. S. 411 Hotel & Restaurant Employees v. Wisconsin Employment Relations Bd. 315 U. S. 437 Thomson v. Gaskill, 315 U. S. 442 D'Oench, Duhme & Co. v. FDIC, 315 U. S. 447 United States v. Carolina Freight Carriers Corp. 315 U. S. 475 Howard Hall Co. v. United States, 315 U. S. 495 Butler Brothers v. McColgan, 315 U. S. 501 United States v. New York, 315 U. S. 510 United States v. Teamsters, 315 U.

S. 521 Pearce v. Commissioner, 315 U. S. 543 Stonite Products Co. v. Melvin Lloyd Co. 315 U. S. 561 Chaplinsky v. New Hampshire, 315 U. S. 568 FPC v. Natural Gas Pipeline Co. 315 U. S. 575 Puerto Rico v. Russell & Co. 315 U. S. 610 Spreckels v. Commissioner, 315 U. S. 626 Crancer v. Lowden, 315 U. S. 631 Puerto Rico v. Rubert Hermanos, Inc. 315 U. S. 637 Memphis Natural Gas Co. v. Beeler, 315 U. S. 649 Graves v. Schmidlapp, 315 U. S. 657 Pecheur Lozenge Co. v. National Candy Co. 315 U. S. 666 U. S. Industrial Chemicals, Inc. v. Carbide & Carbon Chemicals Corp. 315 U. S. 668 Tulee v. Washington, 315 U. S. 681 NLRB v. Electric Vacuum Cleaner Co. 315 U. S. 685 Miles v. Illinois Central R. Co. 315 U. S. 698 Carpenters v. Ritter's Cafe, 315 U. S. 722 Electrical Workers v. Wisconsin Employment Relations Bd. 315 U. S. 740 Jacob v. New York City, 315 U. S. 752 Muncie Gear Works, Inc. v. Outboard Marine & Mfg. Co. 315 U. S. 759 Bakery Drivers v. Wohl, 315 U. S. 769 Supreme Court of the United States United States Supreme Court cases in volume 315 United States Supreme Court cases in volume 315 United States Supreme Court cases in volume 315