Analogue and digital technologies To understand the technologies of analogue and digital conversions we must first understand what analogue and digital transmissions are. Analog transmissions are a continuous variable in amplitude and frequency. The frequency band over which they operate defines analog circuits. People generally produce a bandwidth of 9,900 Hz with frequencies between 100 Hz and 10,000 Hz. Speech between 250 Hz and 3,400 Hz is considered intelligible speech and therefore network circuits use designed bandwidth limiting filters to filter out all frequencies above 4,000 Hz. For these reasons, analog circuits are low-rate data communications, with a maximum data rate of 33.6 Kps when analog circuits are on both ends of the circuit. Digital broadcasts are very different from analog broadcasts. A digital transmission is a series of pulses that are ones or zeros and these ones and zeros make up combinations to create characters in character sets. How the signal is transported depends on whether the network is electrical or optical. In an electrical grid, ones and zeros represent high or low voltage. With an optical network, either there is light or there is no light. Communications today are transmitted over a mix of digital and analog networks. Conversion is necessary so that data can be transmitted across various networks. Codecs are the devices that convert broadcasts from analog to digital. Modems are other devices that transmit digital signal to broadcasting conveniences. Modems control the variables of the electromagnetic wave to determine the ones and zeros. Conversions are weak points in the network, and errors and distortions can occur at these points. Advanta Technology...... half of article...... Cited Alturayef, M., Rodriguez, D. (2007). ADSL Technology, Retrieved May 6, 2014, from http://ecee.colorado.edu/~ecen4242/adsl/adsltechnology.htmAsh, J.D. (2007, December). Next Generation SDH: Will it Play a Role in Future Fixed Packet-Based Networks? Journal of Telecommunications Management, 1(2), 189.Bhatia, A (2007) 802.11 Retrieved May 7, 2014, from http://it.toolbox.com/wiki/index.php/802.11Diffen. (2014, May). AM versus FM. Retrieved from http://www.diffen.com/difference/AM_vs_FMDigital Transmission Hierachies. (2004). Retrieved from http://telecom.tbi.net/dighier1.html Poole, I. (2014, May). What is QAM quadrature amplitude modulation. Retrieved from http://radio-electronics.com/info/rf-technology-design/pm-phase-modulation/what-is-qam-quadrature-amplitude-modulation-tutorial.phpT-carrier. (2014). Retrieved from http://en.wikipedia.org/wiki/T-carrier