Modem Wikipedia. This article is about network hardware. For the political party, see Mo. Serial Web Utility 3Com Phone' title='Serial Web Utility 3Com Phone' />Dem. A modem modulator demodulator is a network hardware device that modulates one or more carrier wave signals to encode digital information for transmission and demodulates signals to decode the transmitted information. The goal is to produce a signal that can be transmitted easily and decoded to reproduce the original digital data. Modems can be used with any means of transmitting analog signals, from light emitting diodes to radio. A common type of modem is one that turns the digital data of a computer into modulated electrical signal for transmission over telephone lines and demodulated by another modem at the receiver side to recover the digital data. Modems are generally classified by the maximum amount of data they can send in a given unit of time, usually expressed in bits per second symbol bits, sometimes abbreviated bps, or bytes per second symbol Bs. Modems can also be classified by their symbol rate, measured in baud. View and Download Orban OPTIMODFM 5500 operating manual online. Digital Audio Processor. OPTIMODFM 5500 Processor pdf manual download. Vendor Model Version Access Type Username PASSWORD Privileges Notes 3COM CoreBuilder 7000600035002500 Telnet debug synnet 3COM CoreBuilder 7000. Latest trending topics being covered on ZDNet including Reviews, Tech Industry, Security, Hardware, Apple, and Windows. TCP 0 Reserved TCP 1 Port Service Multiplexer TCP 2 Management Utility TCP 3 Compression Process TCP 4 Unassigned TCP 5 Remote Job Entry TCP 6 Unassigned. I came across this a while back, unfortunately I did not make note of the source. Its come in handy a few times. Manufactor Product Revision Protocol User. NETCRACK original source of software cracks serials keygens and patches since 1999. InformationWeek. com News, analysis and research for business technology professionals, plus peertopeer knowledge sharing. Engage with our community. The baud unit denotes symbols per second, or the number of times per second the modem sends a new signal. For example, the ITU V. By contrast, the original ITU V. Dialup modemeditHistoryeditNews wire services in the 1. However, the modem function was incidental to the multiplexing function, so they are not commonly included in the history of modems. Modems grew out of the need to connect teleprinters over ordinary phone lines instead of the more expensive leased lines which had previously been used for current loopbased teleprinters and automated telegraphs. In 1. 94. 1, the Allies developed a voice encryption system called SIGSALY which used a vocoder to digitize speech, then encrypted the speech with one time pad and encoded the digital data as tones using frequency shift keying. Mass produced modems in the United States began as part of the SAGE air defense system in 1. SAGE director centers scattered around the U. S. and Canada. SAGE modems were described by AT Ts Bell Labs as conforming to their newly published Bell 1. While they ran on dedicated telephone lines, the devices at each end were no different from commercial acoustically coupled Bell 1. The 2. 01. A and 2. B Data Phones were synchronous modems using two bit per baud phase shift keying PSK. The 2. 01. A operated half duplex at 2,0. B provided full duplex 2,4. The famous Bell 1. A dataset standard was also introduced by AT T in 1. It provided full duplex service at 3. Frequency shift keying was used, with the call originator transmitting at 1,0. Hz and the answering modem transmitting at 2,0. Hz. The readily available 1. A2 gave an important boost to the use of remote low speed terminals such as the Teletype Model 3. ASR and KSR, and the IBM 2. AT T reduced modem costs by introducing the originate only 1. D and the answer only 1. BC modems. Acoustic couplersedit. Ignite Keygen Photoshop there. The Novation CAT acoustically coupled modem. For many years, the Bell System AT T maintained a monopoly on the use of its phone lines and what devices could be connected to them. However, the FCCs seminal Carterfone Decision of 1. FCC concluded that electronic devices could be connected to the telephone system as long as they used an acoustic coupler. Since most handsets were supplied by Western Electric and thus of a standard design, acoustic couplers were relatively easy to build. Acoustically coupled Bell 1. A compatible 3. 00 bits modems were common during the 1. Well known models included the Novation CAT and the Anderson Jacobson, the latter spun off from an in house project at Stanford Research Institute now SRI International. An even lower cost option was the Pennywhistle modem, designed to be built using parts from electronics scrap and surplus stores. In December 1. 97. Vadic introduced the VA3. Like the 1. 03. A, it used different frequency bands for transmit and receive. In November 1. 97. AT T introduced the 2. A modem to compete with Vadic. It was similar in design, but used the lower frequency set for transmission. One could also use the 2. A with a 1. 03. A modem at 3. According to Vadic, the change in frequency assignments made the 2. In 1. 97. 7, Vadic responded with the VA3. Vadics 1,2. 00 bits mode, AT Ts 2. A mode, and 1. 03. A operation. Carterfone and direct connectioneditThe Hush a Phone decision applied only to mechanical connections, but the Carterfone decision of 1. FCC introducing a rule setting stringent AT T designed tests for electronically coupling a device to the phone lines. This opened the door to direct connect modems that plugged directly into the phone line rather than via a handset. However, the cost of passing the tests was considerable, and acoustically coupled modems remained common into the early 1. The rapidly falling prices of electronics in the late 1. In spite of being directly connected, these modems were generally operated like their earlier acoustic versions dialling and other phone control operations were completed by hand, using an attached handset. A small number of modems added the ability to automatically answer incoming calls, or automatically place an outgoing call to a single number, but even these limited features were relatively rare or limited to special models in a lineup. When more flexible solutions were needed, 3rd party dialers were used to automate calling, normally using a separate serial port to communicate with the dialler, which would then control the modem through a private electrical connection. The introduction of microcomputer systems with internal expansion slots made the first software controllable modems common. Slot connections gave the computer complete access to the modems memory or IO channels, which allowed software to send commands to the modem, not just data. This led to a series of popular modems for the S 1. Apple II computers that could directly dial the phone, answer incoming calls, and hang up the phone, the basic requirements of a bulletin board system BBS. The seminal CBBS was created on an S 1. Hayes internal modem, and a number of similar systems followed. The Smartmodem and the rise of BBSsedit. The original model 3. Hayes Smartmodem. In later years, US Robotics Courier modems were common at many BBSs because they had better compatibility with more brands of modems. The next major advance in modems was the Hayes Smartmodem, introduced in 1. The Smartmodem was an otherwise standard 1. A 3. 00 bits direct connect modem, but it was attached to a small microcontroller that watched the data stream for certain character strings representing commands. This allowed both data and commands to be sent through a single serial port. The now standard Hayes command set included instructions for picking up and hanging up the phone, dialing numbers, and answering calls, among others. This was similar to the commands offered by the internal modems, but unlike them, the Smartmodem could be connected to any computer with an RS 2. The introduction of the Smartmodem made communications much simpler and more easily accessed. This provided a growing market for other vendors, who licensed the Hayes patents and competed on price or by adding features. Through the 1. 98. This led to rapid growth of online services with their large file libraries, which in turn gave more reason to own a modem. The rapid update of modems led to a similar rapid increase in BBS use, which was helped by the fact that BBSs could control the modem simply by sending strings, rather than talking to a device driver that was different for every direct connect modem. The 3. 00 bits modems used audio frequency shift keying to send data. In this system the stream of 1s and 0s in computer data is translated into sounds which can be easily sent on the phone lines. In the Bell 1. 03 system, the originating modem sends 0s by playing a 1,0. Hz tone, and 1s at 1,2. Hz, with the answering modem transmitting its 0s on 2,0. Hz and 1s on 2,2.