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Through the Wires: Analog & Digital Analog transmission uses signals that are exact replicas of a sound wave or picture being transmitted. The term "analog signal" came about because the variations in the carrier waves are similar, or analogous, to that of the voice itself. For example, in analog transmission, say a telephone system, an electric current or the reproduction of patterned sound waves are transmitted through a wire and into the telephone receiver. library.thinkquest.org /27887/print_it/analog_and_digital.htm   (831 words)

Analog transmission An analog signal is a continuous signal whose amplitude, phase, or some other property varies in a direct proportion to the instantaneous value of a physical variable. An example of an analog signal is the output power of an optical source whose intensity is a function of a continuous electrical input signal. The transmission of analog voice signals may also be attractive in small, short-haul systems. www.tpub.com /neets/tm/112-3.htm   (327 words)

Chapter 3 Digital transmission time is devided into periods of fixed length; the line is kept in one of only a few possible states (conditions) during each time period; at the end of each time period, it may change abrubtly to another of these states. The differrent between Digital and Binary transmission is that binary transmission is always digital, but not all digital transmission is binary, because each bit period can be only a zero or a one for binary transmission but 10 state from 0 through 9 was the original meaning of the term digital. For both modulation and demodulation, characterize whether the transmission line is analog or digital and whether the device attached to the transmission line is analog or digital. www.angelfire.com /bc/aumey/chapter3.html   (1209 words)

Analog Signal Transmission To understand the ways in which an analog signal is transmitted over a circuit, it is first important to understand the relationships that make analog signal transmission possible. V=IR While most single-channel analog signal transmissions use direct current (dc) variations in current or voltage to represent a data value, frequency variations of an alternating current (ac) also can be used to communicate information. For noise-resistant transmission over significant distances, the raw transducer signal is often converted to a 4-20 mA signal by a two-wire, loop-powered transmitter. www.omega.com /literature/transactions/volume2/analogsignal.html   (591 words)

ISDN training, ATM training and Broadband training - video course This Information Factory course "Introduction to ISDN, ATM and Broadband Transmission" is a continuation of our earlier course "Introduction to Digital Transmission." In the first course we described how the world's telephone networks were moving from their analog transmission methods onto a completely digital transmission network. The first task of the digital transmission systems in the United States and Europe was to replace the analog transmission systems used between the telephone company switching offices. Transmission - Transmission refers to the process of moving the voice signals across the telephone network. www.informationfactory.com /dig2sec1.htm   (3609 words)

Telecommunications Training - Digital Transmission Video Course Modern transmission technology came to the rescue by showing that it is easier and more cost effective to build a network that transmits digital signals. Using analog transmission techniques, such as those found on the existing telephone networks has presented a problem as newer services are brought into the network. Analog transmission and amplification had limits, since noise was usually amplified along with the voice signal. www.informationfactory.com /digsec1.htm   (2883 words)

Telecommunications - Encyclopedia.WorldSearch   (Site not responding. Last check: 2007-10-15) The transmission medium, by its physical nature, is likely to modify or degrade the signal on its path from the transmitter to the receiver. One of the roles of the telecommunications engineer is to analyse the physical properties of the line or transmission medium, and the statistical properties of the message in order to design the most effective encoding and decoding mechanisms. Early phone systems used analog transmission lines between central offices, but in the 1960s digital multiplexed circuits were used to send voice calls over a Time Division Multiplexed (TDM) circuit. encyclopedia.worldsearch.com /telecommunications.htm   (1016 words)

Physical Layer: Data Transmission Likewise, it is possible to translate analog voice data into digital form for transmission over digital computer circuits using a device called a codec. Analog Transmission occurs when the signal sent over the transmission media continuously varies from one state to another in a wave-like pattern. Analog voice data must be translated into a series of binary digits before they can be transmitted. www.angelfire.com /ut/cnst/chap04.html   (1665 words)

Analog Transmission Systems (Linktionary term) In an analog transmission system, signals propagate through the medium as continuously varying electromagnetic waves. The medium for an analog transmission may be twisted-pair cable, coaxial cable, optical-fiber cable, the atmosphere, water, or space. In fact, the only remaining analog portion of the phone system is the twisted-pair wire that runs between homes and the telephone companies' central offices, which are usually less than a mile distance from the subscriber. www.linktionary.com /a/analog.html   (341 words)

Analog vs. Digital Transmission One key difference between analog and digital transmission involves the bandwidth, or transmission capacity required for both schemes. Analog modulation, which is continuously variable by nature, can often require adjustment at the receiver end in order to reconstruct the transmitted signal. Digital transmission, however, because it uses only 1’s and 0’s to encode the signal, offers a simpler means of reconstructing the signal. www.fiber-optics.info /articles/analog-v-digital.htm   (377 words)

Telecommunication Knowledgebase   (Site not responding. Last check: 2007-10-15) Transmission is the process of sending text, image or audio data from one point to another. Digital transmission is widely considered better than analog transmission because it is more efficient, has fewer errors, is faster, more secure (allowing for encryption) and allows for integration of audio, video and data transmissions. Synchronous transmission is the other technique, where many characters are sent as a single block of data, which is referred to as a frame or packet. dmsweb.badm.sc.edu /grover/telecom/level1/physical.htm   (1486 words)

Product Category Results   (Site not responding. Last check: 2007-10-15) Analog Pressure Gauges (227 companies) Analog pressure gauges are mechanical devices that include bellows, Bourdon tubes, capsule elements and diaphragm element gauges. Analog Multimeters (96 companies) Analog multimeters are instruments that are used to measure electrical quantities such as voltage, current, resistance, frequency and signal power. Analog Voltmeters (69 companies) Analog voltmeters are instruments that measure voltage or voltage drop in a circuit. globalspec.com /ProductFinder/FindProducts?query=analog+transmission   (428 words)

Modem - Patent 6345070 The present invention relates to a modem that encodes a voice signal, converts the encoded voice signal to a passband signal, transmits the passband signal onto an analog transmission line, receives the passband signal from the analog transmission line, converts the passband signal to a code, and then decodes it into a voice signal. However, in the case of a voice/data multiplexing modem, at the transmitting end, the analog voice signal is first converted to a multi-bit code and then supplied to a transmitter together with a data signal. The analog signal is a signal converted from an encoded voice signal that is created by mapping a voice signal to a set of codes that excludes a particular code. www.freepatentsonline.com /6345070.html   (2476 words)

DTV Guide - a Whatis.com definition - see also: Fast Guide to DTV   (Site not responding. Last check: 2007-10-15) Analog transmission is in the form of a constantly variable wave; digital transmission consists of an electrical pulse which has two possibilities: on and off (or positive and negative), which are represented by a one and a zero (this is binary data, the same type of information that a computer understands). An analog signal degrades over distance and may be barely detectable at the farther reaches of the broadcast area - this is why the signal from a distant radio station fades in and out. Simulcast is also used for the transmission of simultaneous television and Internet services, the transmission of analog and digital radio broadcasts, and the transmission of television programs in different screen formats such as the traditional format and the wide screen format. whatis.techtarget.com /definition/0,,sid9_gci339456,00.html   (5276 words)

Analog Vs. Digital Transmission   (Site not responding. Last check: 2007-10-15) When the recording is transmitted it is modulated directly to a carrier wave, which is then transmitted through the air, cable, via satellite, etc. During this transmission, the carrier and the modulated signal will loose amplitude (power) and due to interference noise is introduced to the carrier and its modulated signal. Analog transmission systems are unable to maintain the quality the original has. The negative effects of the (still analog) transmission have been eliminated from the process. www.best-digital.info /Analog_vs._Digital_Transmissio_Gary_Davis.html   (1459 words)

Normalizing The IBOC And FM/AM-Analog Audio Signal Paths AM and FM transmissions use pre-emphasis to increase the high frequency energy in analog transmission and de-emphasis in the receiver to restore flat frequency response and mask noise in the channel. Analog FM is limited at both the high and low extremes of the frequency range. Analog AM is primarily a 3 - 5 kHz medium, due primarily to receiver limitations, however, IBOC imposes a 5 kHz limitation on the analog transmission. www.omniaaudio.com /tech/IBOC_level.htm   (1785 words)

Telecommunications Technology Fundamentals   (Site not responding. Last check: 2007-10-15) An analog wave form (or signal) is characterized by being continuously variable along amplitude and frequency. Those fluctuations in current are an analog of the actual voice pattern—hence the use of the term analog to describe these signals (see Figure 2.9). Analog facilities have limited bandwidth, which means they cannot support high-speed data. www.awprofessional.com /articles/article.asp?p=24687&seqNum=5   (1603 words)

IP Telephony Network Glossary   (Site not responding. Last check: 2007-10-15) Amplifiers are used in telecommunications on analog transmission lines to offset the signal loss that occurs as the signal is propagated along the line. One of the methods for IP fax transmission as defined by ITU-T. Fax relay defines the specification for the demodulation of standard analog fax transmission from originating machines equipped with modems, and their remodulation for presentation to a matching destination device, with the long-haul portion of the transmission being supported over an IP-based network. Transmission of analog information in digital form through sampling and encoding the samples with a fixed number of bits. www.cisco.com /univercd/cc/td/doc/product/voice/evbugl4.htm   (12670 words)

5.6 Comparing Analog and Digital Systems   (Site not responding. Last check: 2007-10-15) Most often though, the transmission system is already in place, and is either digital or analog (in some cases it may be a hybrid). It is primarily analog (at least where it interfaces to the user), and it is common to transfer data from computers over these lines. It is currently the trend to convert all analog information to digital - not so much to improve the transmission, but to allow the information to be manipulated by digital computers - filtering, storing, processing (for example, voice to text conversion), and so on. campus.murraystate.edu /tsm/tsm118/Ch5/Ch5_6/Ch5_6.htm   (315 words)

USRobotics Education Analog Glossary A modem self-test in which data from the keyboard or an internal test pattern is sent to the modem's transmitter, turned into analog form, looped back to the receiver, and converted back into digital form. A term used to measure the speed of an analog transmission from one point to another. Communications channels using analog modems are established at set bit rates, commonly 2400, 4800, 9600, 14,400, 28,800, 33,600, and higher. www.usr.com /education/analogglossary.asp   (2543 words)

Analog Electronic transmission that is sent by signals of varying frequency instead of sent as ON or OFF data transmission. Analog allows equipment to handle information that continuously changes such as voltage, current, wave, etc... Below is an example of an analog signal or how analog may be represented. www.computerhope.com /jargon/a/analog.htm   (58 words)

No Title Transmission is the act of propagation through the medium and receiving and processing of the signal. Analog data on an analog signal can tolerate more noise distortion and still be intelligible; however, this is not the case for digital data on an analog signal. Transmission medium is imperfect and these impairments affect the capacity of the channel -- the previous relationship between data rate and bandwidth does not tell the whole story since it ignores these distortions. www.rhsmith.umd.edu /is/aqiuol/726f97/mod2.html   (2816 words)

Telecommunications Technology Fundamentals > Analog and Digital Transmission   (Site not responding. Last check: 2007-10-15) There are a number of differences between analog and digital transmission, and it is important to understand how conversions between analog and digital occur. Those fluctuations in current are an analog of the actual voice pattern—hence the use of the term analog to describe these signals (see Figure 2.9). Analog facilities have limited bandwidth, which means they cannot support high-speed data. www.informit.com /articles/article.asp?p=24687&seqNum=5   (1631 words)

Analog Optical Transmission in a Cylindrical Fiber While theoretical analysis had indicated that such a transmission scheme was indeed possible, to the best of our knowledge, there have been no experimental demonstration of the feasibility of the technique. Transmission is then performed in either of two ways: pixels may be converted to digital format and transmitted in the time domain, by modulation of a carrier; alternatively, each pixel may be assigned to a single small waveguide. Direct analog transmission by a single multi-mode fiber is also plausible, and allows better utilization of the optical data-rate capability. www.calstatela.edu /faculty/fdanesh/fol1.html   (803 words)

Basic HD DVD question [Archive] - Home Theater Forum I've seen DVI transmission to digital displays be visibly inferior to analog YPbPr input, and this has to do with input/ouput implementation, and not at all to do with DAC issues. I'm simply saying an analog transmission of a digital signal offers a source of noise that is not there in a purely digital path. Analog circuitry in displays is a more complex matter, but that isn't a DAC issue, IMO. www.hometheaterforum.com /htf/archive/index.php/t-225043.html   (2048 words)

Why Digital... While FM transmission systems eliminate many of the problems found in AM systems, which result from difficulties in controlling the varying brightness level of light emanating from the diode, FM systems offer their own unique set of problems. For example, a multichannel analog system designed to carry four channels of video or audio might restrict the bandwidth allocated to each signal in order to accommodate all the desired signals to be transmitted. In addition, digital fiber optic transmission systems are available at prices similar to analog systems, and actually cost less overall to own and operate when considered within the context of an entire installation – including fiber, setup and maintenance costs. www.fiber-ed.com /res-fiber_advantages.htm   (2576 words)

Chapter 5: Physical Layer—Signal encoding   (Site not responding. Last check: 2007-10-15) When a signal (either analog or digital) such as a voice signal or data signal needs to be transmitted, the signal is often transformed (modified) into a form that is more suitable for the transmission medium. Digital transmission systems use “repeaters (or sometimes called as regenerators)” rather than the “amplifiers” that are used in analog systems. When using an analog modem, a PC is connected to a modem(usually into PC’s internal bus) and the modem is connected to an analog telephone line. www.ecst.csuchico.edu /~sim/278/notes/NOTE5.htm   (2888 words)

Multi-format Digital and Analog Video Audio Broadcast Transport Systems In addition to meeting HDTV transmission capabilities, the systems usually satisfy the requirements of additional audio SAP (Secondary Audio Programming) channels, also mandated by the FCC in accordance with the Americans with Disabilities Act of 1990. Additionally, incorporating erbium-doped fiber amplifiers, which operate in the 1550 nm window, could greatly extend the transmission range of the broadcast or cable operator, allowing them to reach a wider audience. While many solutions exist for both analog and digital video transmission, broadcasters and cable operators would most benefit from a transport platform that supports both, providing a migration path to implement FCC mandated DTV transmission while still allowing current analog equipment to be utilized. www.fiber-optics.info /articles/analog-digital-trans.htm   (550 words)

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