Pulse-code modulation

Pulse-code modulation (PCM) 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 regularly at uniform intervals, and each sample is quantized to the nearest value within a range of digital steps.

Linear pulse-code modulation (LPCM) is a specific type of PCM where the quantization levels are linearly uniform. This is in contrast to PCM encodings where quantization levels vary as a function of amplitude (as with the A-law algorithm or the μ-law algorithm). Though PCM is a more general term, it is often 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, which is the number of times per second that samples are taken; and the bit depth, which determines the number of possible digital values that can be used to represent each sample.

PCM (disambiguation)

PCM or pulse-code modulation is a digital representation of an analog signal.

PCM may also refer to:

Computing

Technology

PCM30

The pulse code modulation (PCM) technology was patented and developed in France in 1938, but could not be used because suitable technology was not available until World War II. This came about with the arrival of digital systems in the 1960s, when improving the performance of communications networks became a real possibility. However, this technology was not completely adopted until the mid-1970s, due to the large amount of analog systems already in place and the high cost of digital systems, as semiconductors were very expensive. PCM’s initial goal was that of converting an analog voice telephone channel into a digital one based on the sampling theorem.

PCM30 describes an application of pulse-code modulation (PCM) in which 30 telephony analog signals are binary coded into a digital signal stream. The term is used today mostly as a synonym for the encoding of 30 channels each with a signalling rate of 64-kbit/s. This rate is also used in the first stage of European PDH technique, so PCM30 is also known as E1.

PCM1

Pericentriolar material 1, also known as PCM1, is a protein which in humans is encoded by the PCM1 gene.

Function

The PCM1 protein was originally identified by virtue of its distinct cell cycle-dependent association with the centrosome complex and microtubules. The protein appears to associate with the centrosome complex during the cell cycle. Dissociation occurs during mitosis when PCM1 is dispersed throughout the cell. Immunolabeling studies performed found that PCM1 was present in centriolar satellites and in electron dense granules between 70 and 100 nm in diameter. These were originally thought to be scattered only around the centrosomes, but further studies proved that PCM1 was also found throughout the cytoplasm.

PCM1 was shown to be essential for cell division because PCM1 antibodies cause cell-cycle arrest when microinjected into fertilized murine eggs. Targeting of centrin, pericentrin and ninein was also dramatically reduced after PCM1 depletion using siRNA, overexpression of PCM1 deletion mutants and PCM1 antibody microinjection. As a result of this depletion, the radial organization of the microtubules was found to be disrupted, but did not appear to effect microtubule nucleation.

Lexicon (company)

Lexicon is an American company that engineers, manufactures and markets audio equipment as a brand of Harman International Industries (HII), with offices in Salt Lake City. Originally founded in 1971 and headquartered in Waltham, Mass., the company was acquired by HII in 1993.

Lexicon traces its history to the 1969 founding of American Data Sciences by MIT professor Dr. Francis F. Lee and engineer Chuck Bagnaschi, developers of digital audio devices for medical heart monitoring.

The company is widely known as the OEM developer of the multi-speaker audio system for the Rolls-Royce Phantom— as well as the Hyundai Genesis, Hyundai Equus and Kia K900.

Professional audio equipment

Digital delay systems

Lexicon is sometimes credited as the inventor of commercial digital delay products. The first product to market was the popular Delta T-101 delay in 1971, followed by the Delta T-102 in 1972.

Reverb and effects

Lexicon is considered "the godfather of digital reverb", as one of the early players on the reverb/reverberation market. The company was among the first to produce commercially available digital reverb equipment, beginning in 1978 with the Model 224. In 1986, Lexicon released the 480L (costing more than some cars), a successor of the 224XL.

PT-91 Twardy

The PT-91 Twardy ("hard","tough" or "resilient") is a Polish main battle tank. It is a development of the T-72M1 and first entered service in 1995. The PT-91 was designed at the OBRUM (OBRUM for Ośrodek Badawczo-Rozwojowy Urządzeń Mechanicznych – Polish for Research and Development Centre for Mechanical Appliances) and is produced by the Bumar Łabędy company – part of Polish military consortium – Bumar Group. Changes from the T-72 include a new dual-axis stabilized fire-control system, reactive armour, a more powerful engine, transmission and new automatic loader. Unlike many other T-72 upgrades the Polish Army PT-91s are upgraded using elements created almost exclusively by domestic companies (this includes new engine, fire control system and all communication system elements). Many of those elements were used to upgrade existing fleets of T-72 tanks in countries like in Czech Republic – T-72M4 CZ, Georgia – T-72SIM-1 or India – T-72 Ajeya Mk2.

History

In the late 1980s the Polish Army modernized all of its obsolete T-55 tanks to the T-55AM Mérida standard. The successful conversion convinced the General Staff that similar modernization could also be applied to other Soviet-designed tanks made in Poland and used by the Polish Armed Forces. In late 1988 it was decided to prepare a project of modernization for the T-72M1 design – using the experience from production of licensed T-72M (obiekt 172M-E3 – Polish army designation T-72), T-72M1 (obiekt 172M-E5), T-72M1K (Polish army designation T-72M1D).