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How to use Web SDR sites
This page is intended to serve as a basic guide for using 'Web SDR' websites to listen to radio activity in your web browser. If you want to learn how to setup your own SDR, click here.
What is SDR?
An example of a spectrogram 'waterfall' showing a section of the 2m band. The left most column is a strong signal of someone speaking using FM, with other transmissions to the right of it. Different sorts of transmissions (or interference) appear differently and you can learn to differentiate them just by looking.
'SDR' or 'Software-Defined Radio' is a radio system where part of the radio's operation is handled by software instead of the more typical analogue components. One of the main benefits to using an SDR is that it enables you to use an interface on a computer to control a radio and its operation. You could, for example, use a computer headset/microphone to speak with your radio, or use a keyboard as the 'PTT' button. Another feature which is ubiquitous to SDR software is being able to view a 'spectrogram', where you can see a visual representation of part of the radio spectrum. You will likely hear spectrograms referred to as 'waterfalls' because the spectrum is often displayed in a way where it moves vertically, although there are other layouts available.