Pulse-code modulation is a method used to digitally represent sampled analog signals. It is the standard form of digital audio in computers, compact discs, digital telephony and other digital audio applications. In a PCM stream, the amplitude of the analog signal is sampled at uniform intervals, each sample is quantized to the nearest value within a range of digital steps. Linear pulse-code modulation is a specific type of PCM where the quantization levels are linearly uniform; this is in contrast to PCM encodings. Though PCM is a more general term, it is used to describe data encoded as LPCM. A PCM stream has two basic properties that determine the stream's fidelity to the original analog signal: the sampling rate, the number of times per second that samples are taken. Early electrical communications started to sample signals in order to multiplex samples from multiple telegraphy sources and to convey them over a single telegraph cable; the American inventor Moses G. Farmer conveyed telegraph time-division multiplexing as early as 1853.
Electrical engineer W. M. Miner, in 1903, used an electro-mechanical commutator for time-division multiplexing multiple telegraph signals, he obtained intelligible speech from channels sampled at a rate above 3500–4300 Hz. In 1920, the Bartlane cable picture transmission system used telegraph signaling of characters punched in paper tape to send samples of images quantized to 5 levels. In 1926, Paul M. Rainey of Western Electric patented a facsimile machine which transmitted its signal using 5-bit PCM, encoded by an opto-mechanical analog-to-digital converter; the machine did not go into production. British engineer Alec Reeves, unaware of previous work, conceived the use of PCM for voice communication in 1937 while working for International Telephone and Telegraph in France, he described the theory and advantages. Reeves filed for a French patent in 1938, his US patent was granted in 1943. By this time Reeves had started working at the Telecommunications Research Establishment; the first transmission of speech by digital techniques, the SIGSALY encryption equipment, conveyed high-level Allied communications during World War II.
In 1943 the Bell Labs researchers who designed the SIGSALY system became aware of the use of PCM binary coding as proposed by Reeves. In 1949, for the Canadian Navy's DATAR system, Ferranti Canada built a working PCM radio system, able to transmit digitized radar data over long distances. PCM in the late 1940s and early 1950s used a cathode-ray coding tube with a plate electrode having encoding perforations; as in an oscilloscope, the beam was swept horizontally at the sample rate while the vertical deflection was controlled by the input analog signal, causing the beam to pass through higher or lower portions of the perforated plate. The plate collected or passed the beam, producing current variations in binary code, one bit at a time. Rather than natural binary, the grid of Goodall's tube was perforated to produce a glitch-free Gray code, produced all bits by using a fan beam instead of a scanning beam. In the United States, the National Inventors Hall of Fame has honored Bernard M. Oliver and Claude Shannon as the inventors of PCM, as described in "Communication System Employing Pulse Code Modulation", U.
S. Patent 2,801,281 filed in 1946 and 1952, granted in 1956. Another patent by the same title was filed by John R. Pierce in 1945, issued in 1948: U. S. Patent 2,437,707; the three of them published "The Philosophy of PCM" in 1948. The T-carrier system, introduced in 1961, uses two twisted-pair transmission lines to carry 24 PCM telephone calls sampled at 8 kHz and 8-bit resolution; this development improved capacity and call quality compared to the previous frequency-division multiplexing schemes. In 1967, the first PCM recorder was developed by NHK's research facilities in Japan; the 30 kHz 12-bit device used a compander to extend the dynamic range, stored the signals on a video tape recorder. In 1969, NHK expanded the system's capabilities to 32 kHz 13-bit resolution. In January 1971, using NHK's PCM recording system, engineers at Denon recorded the first commercial digital recordings. In 1972, Denon unveiled the first 8-channel digital recorder, the DN-023R, which used a 4-head open reel broadcast video tape recorder to record in 47.25 kHz, 13-bit PCM audio.
In 1977, Denon developed the portable PCM recording system, the DN-034R. Like the DN-023R, it recorded 8 channels at 47.25 kHz, but it used 14-bits "with emphasis, making it equivalent to 15.5 bits."In 1973, adaptive differential pulse-code modulation was developed, by P. Cummiskey, Nikil Jayant and James L. Flanagan. In 1979, the first digital pop album, Bop till You Drop, was recorded, it was recorded in 16-bit linear PCM using a 3M digital tape recorder. The compact disc brought PCM to consumer audio applications with its introduction in 1982; the CD uses a 44,100 Hz sampling frequency and 16-bit resolution and stores up to 80 minutes of stereo audio per disc. The rapid development and wide adoption of PCM digital telephony was enabled by metal–oxide–semiconductor switched capacitor circuit technology, developed in the early 1970s; this led to the development of PCM codec-filter chips in the late 1970s. The silicon-gate CMOS PCM codec-filter chip, developed by David A. Hodges and W. C. Black in 1980, has since been the industry stan
Franklin Archibald Dick was a St. Louis, Missouri attorney, he was assistant adjutant general to Nathaniel Lyon at Camp Jackson. Dick was born in Philadelphia on May 2, 1823, the only son of Archibald Thomas Dick and Hannah Rogers. Dick entered the University of Pennsylvania at the age of sixteen in 1839 as a law student, he graduated in 1842 and moved to the frontier town of St. Louis, where he practiced law from 1844 to 1861, he married Myra Madison Alexander, on November 25, 1851. Myra's sister, was married to Dick's close friend, Frank Blair, the son of Francis P. Blair Sr. a journalist and politician, an advisor to President Andrew Jackson, and, an organizer of the Republican Party. Franklin Dick supported Frank Blair's efforts to keep Missouri in the Union by serving on committees, at his urging became provost marshal general. President Lincoln used Frank Blair as an unofficial advisor on Missouri affairs during the war. Frank's brother, was President Abraham Lincoln's Postmaster General.
Dick kept private journals during the Civil War, recording events he observed in St. Louis, he describes a meeting on January 10, 1861 in his law office in which the St. Louis Committee of Safety monitored actions by the Southern sympathizers, many private meetings with Nathaniel Lyon. In St. Louis, after Camp Jackson was filled with secret rebels anxious for control of the St. Louis Arsenal, Dick told Frank Blair, borrowing their blind mother-in-law's dress and hat for Nathaniel Lyon to use for a disguise. Lyon was driven in Mira Alexander's carriage into Camp Jackson to observe General Frost and his troops, along with other visitors; that night Lyon and other Unionists met in Dick's law office and decided to capture Camp Jackson. At Lyon's urging, Franklin Dick served as his assistant adjutant general during the Camp Jackson affair on May 10, 1861, he writes of riding his horse in the midst of the fracas in front of the troops firing, ordering them to stop in the name of Captain Lyon, when Lyon was on the ground He describes Lyon's pity and emotion as "almost womanly" on seeing the dead and wounded after the incident, how they had to gallop around the city back to the arsenal to avoid an ambush.
Next, Dick was sent by Frank Blair to Washington to convey Blair's concerns about General William S. Harney's lenient ways of dealing with secessionists. Montgomery Blair took Franklin Dick to meet with President Lincoln and Secretary of War Simon Cameron. Dick had been directed to lobby for Nathaniel Lyon's ideas for the protection of St. Louis, ask for Lyon's confirmation as brigadier general, request Harney's removal. Dick returned to St. Louis with Lincoln's promotion for Lyon effective May 17, an order for Blair to remove Harney at his discretion; when Harney met with Southern sympathizer General Sterling Price to cooperate for peace together, events led to Frank Blair delivering the orders on May 30, 1862, opening the way for Lyon to take control of troops in Missouri. From on, Dick wrote long letters to Lincoln about his concern with the state of affairs in Missouri. After Camp Jackson was disbanded, Missouri was under martial law, remained so for the entire Civil War. Dick served on the Board of Assessments which fined Southern sympathizers.
Through his participation in the seizure of goods and banishment of Rebels and their families, he earned the hatred of many old St. Louisans, Conditional Unionists, Rebels. On November 5, 1862, Dick became a lieutenant colonel and Provost Marshal General under Major General Samuel Curtis, the new Commander of the Department of Missouri. In this position, Franklin Dick had to keep order in the state and oversee the local provost marshals, enforce Curtis's orders for the Confiscation Act and assess disloyal persons, supervise prisons and prisoners. In a letter dated January 26, 1863 to Montgomery Blair about his problems acting as Provost Marshal General, Franklin Dick says... The only semblance of the U. S. authority in a large part of the State, is the Provost Marshal system–it is an important matter to determine whether or not it shall be preserved. In a long letter forwarded by Gen. Curtis to Wash'n. some days ago, I gave some facts to show its operation... As I consider these matters of importance, I make them known to you and hope that you will present them to the President.
One more matter it is important to me to speak of –& that is, that St. Louis is the seat and centre of the rebel plots & Schemes, spies revel here; the women, & several of them of the better class act as mail carriers–at no time have the rebel sympathizers & secret workers been so active and bold as now–their course, of that of treason–These People ought to be sent South–Our Union People here know this, & urge it upon Genl. Curtis–I assure you that the authority of the Govt. here, before our face is despised & set at naught... In his journals, Dick talks of the time before the war in St. Louis when "... we felt as if we were forever safe," and contrasts that with his perspective in 1865, when "the People in the North have become accustomed to the war–here in Phil'a. the People go on just as in ordinary times–They gay continue their giddy amusements–the errands go on with business as usual, & the war is an interesting topic, which they keep more or less in mind." Dick did not feel safe in St. Louis.
He moved his family back and forth from St. Louis to Philadelphia for safety during the war, though he had to return to his law practice in
William "Bill" Chen is an American quantitative analyst, poker player, software designer. Chen holds a Ph. D. in mathematics from the University of California, Berkeley. He was an undergraduate at Washington University in St. Louis triple-majoring in Physics and Computer Science, was a research intern in Washington University's Computer Science SURA Program where he co-wrote a technical report inventing an Argument Game, he heads the Statistical arbitrage department at Susquehanna International Group. At the 2006 World Series of Poker Chen won two events, a $3,000 limit Texas hold'em event with a prize of $343,618, a $2,500 no limit hold'em short-handed event with a prize of $442,511. Prior to these events Chen's largest tournament win was for $41,600 at a no limit hold'em event at the Bicycle Casino's Legends of Poker in 2000. Chen has been a longtime participant in the rec.gambling.poker newsgroup and its B. A. R. G. E offshoot, he has been a member of Team PokerStars. With Jerrod Ankenman, Chen coauthored The Mathematics of Poker, an introduction to quantitative techniques and game theory as applied to poker.
In February 2009, he appeared on Poker After Dark's "Brilliant Minds" week, finishing in 5th place after his A♦ 3♦ lost to Jimmy Warren's A♠ A♥ after Chen pushed all-in on a flop of A♣ 3♣ Q♦. As of 2017, his total live tournament winnings exceed $1,900,000, his 38 cashes at the WSOP account for over $1,725,000 of those winnings. Bill Chen and Jerrod Ankenman; the Mathematics of Poker. Conjelco. ISBN 1-886070-25-3