![]() The practical upper limit, which determines the bandwidth of the signal, depends on how “ideal” the square wave is - in other words, the sharpness of the edges. In fact, an ideal square wave contains components at all odd multiples of the fundamental frequency, in this case at 3 kHz, 5 kHz, 7 kHz, etc. This signal repeats at a frequency of 1 kHz, so we might assume that it has a bandwidth of 1 kHz. While the definition of bandwidth seems very straightforward, sometimes the application to common signals can be confusing. It’s interesting to note that an AM-modulated RF signal takes up twice the bandwidth of the transmitted audio, since both frequency sidebands are present that 20.4 kHz RF bandwidth is being used to send audio with a maximum bandwidth of 10.2 kHz. ![]() So, a transmitter operating on the 1000 kHz channel should only output frequencies between 989.8 kHz and 1010.2 kHz. As a concrete example, consider the medium-wave (aka AM) broadcast band in the US: each signal occupies a bandwidth of 20.4 kHz. If a signal has frequency components between 100 Hz and 300 Hz, we would say that the signal has a bandwidth of 200 Hz. In this case, the bandwidth of the signal is defined as the maximum frequency contained in the signal minus the minimum frequency. The term bandwidth is also used to describe the frequency range occupied by a signal. We’ll come back to digital bandwidth in a little while, to see how it’s connected to the next concept, that of signal bandwidth. Measuring the digital bandwidth of a network channel is as easy as sending a fixed number of bits and timing how long it takes this is what those broadband speed test sites do. In this case you would say that the download bandwidth is 50 Mbps. Your ISP might provision you 50/10 Mbps internet service for example, meaning you have 50 million bits per second of download capacity and 10 million bits per second of upload. In this case, it’s measured in bits per second. Perhaps the most common usage of the term bandwidth is for the data bandwidth of digital channels, in other words, the rate of information transfer. Let’s have a look at what we mean by the term bandwidth in various contexts. But, while the latter example might seem fundamentally different from the others, there’s actually a very deep and interesting connection that we’ll uncover before we’re done. We might speak about the bandwidth of a signal like the human voice, or of a system like a filter or an oscilloscope - or, we might consider the bandwidth of our internet connection. Besides this colloquial usage, there are several very specific meanings in an engineering context. Bandwidth is one of those technical terms that has been overloaded in popular speech: as an example, an editor might ask if you have the bandwidth to write a Hackaday piece about bandwidth.
0 Comments
Leave a Reply. |