Computer Simulation of a General Purpose Satellite Modem
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Abstract: The purpose of this research was to model and simulate the performance of a
digital phase shift keyed satellite modem. The probability of bit error (P sub b) at different
levels of energy per bit to noise power ratio (E sub b/N sub o) was the performance
what is Satellite modem
A modulator-demodulator (modem) is an electronic device that modulates transmitted signals and demodulates received signals. Modems are communications devices which employ digital modulation techniques to transmit binary data over analog communications channels. The modem generally provides an interface between digital devices and an analog communications system to thus make possible analog transmission of digital information between two terminals or stations. Such transmissions may be over a transmission link such as a telephone line, cellular communication link, satellite link, and cable TV, each of which being generally band-limited. Data modems are commonly used to send and receive data via telephone lines or other communications facilities. In a typical modem connection, clock synchronization time is insignificant when compared to the time it takes for the two modems to transfer data. Modulator/demodulators (modems) are essential components in most communication systems, including digital radios. A modem is used to provide wireless transmission between transmitting and receiving stations. Typically, two modems communicate over a single channel, with one modem at each end of the channel. Signal processing structures implemented at each modem provide encoding, modulation, filtering, interpolation, echo cancellation, signal detection, equalization, demodulation, and decoding functions. The advent of digital transmission systems intended primarily for broadcasting television signals, in particular but not exclusively satellite television systems, has opened up the possibility of using such systems for other purposes. One of these is to provide interactivity with the end user. In transmitting digital radio signals, most satellite communication systems utilize constant envelope modulating techniques. Constant envelope techniques are common because saturating high power amplifiers are typically used in these applications and it is desirable to minimize signal distortion.
Re: what is Satellite modem
A modem modulates outgoing digital signals from a computer or other digital device to analog signals for a conventional copper twisted pair telephone line and demodulates the incoming analog signal and converts it to a digital signal for the digital device. In recent years, the 2400 bits per second modem that could carry e-mail has become obsolete. 14.4 Kbps and 28.8 Kbps modems were temporary landing places on the way to the much higher bandwidth devices and carriers of tomorrow. From early 1998, most new personal computers came with 56 Kbps modems. By comparison, using a digital Integrated Services Digital Network adapter instead of a conventional modem, the same telephone wire can now carry up to 128 Kbps. With Digital Subscriber Line (DSL) systems, now being deployed in a number of communities, bandwidth on twisted-pair can be in the megabit range.
Short for modulator-demodulator. A modem is a device or program that enables a computer to transmit data over, for example, telephone or cable lines. Computer information is stored digitally, whereas information transmitted over telephone lines is transmitted in the form of analog waves. A modem converts between these two forms.