bandwidth (BW)
- Incommunications engineering, audio engineering and high- frequency engineering, the bandwidth is specified for a frequency range. The bandwidth is the frequency range in which electrical signals are transmitted with an amplitude drop of up to 3 dB. It is the frequency difference between the upper and lower frequencies that have an amplitude drop of 3 dB. The greater the bandwidth, the more information can theoretically be transmitted in a unit of time. In analog systems, the bandwidth is specified in Hertz( Hz), or kHz or MHz.
- In addition to bandwidth, which refers to the 3-dB point, there is also a bandwidth called percentage bandwidth. This rarely used percentage bandwidth refers to the difference between the lowest and highest frequencies, which equals 100% and is divided by the center frequency, which is the average between the highest and lowest frequencies. According to this definition, the bandwidth can assume values of more than 100 %.
- The term bandwidth is also often used synonymously in the transmission of digital signals, although the transmission rate or data rate is usually meant. There is, however, a connection between the bandwidth and the transmission rate, since in data transmission the achievable transmission speed depends on the bandwidth and the coding. If one bit is encoded per hertz, then the transmission rate in bits per second (bit/s) corresponds to the bandwidth value. At 100 MHz, this would be 100 Mbit/s; if two bits per hertz are encoded, this results in a value of 200 Mbit/s. This double value results if one bit is transmitted in each half-wave of the sinusoidal signal.
- In memory technology, the term bandwidth is used for the data transfer rate of memory chips. This data transfer rate is obtained by multiplying the clock frequency by the word length. According to this definition, a memory chip with a clock speed of 200 MHz and a word length of 8 bytes has a bandwidth of 1.6 GB/s.
- In display technology for monitors, the bandwidth, here also called pixel clock, describes which resolution a monitor can display at which refresh rate. For example, VGA with 640 x 480 pixels and a refresh rate of 60 Hz results in a bandwidth of 18.43 MHz.
