Section 3
Transmitters and Receivers

SDR transmitters and receivers

3M1 Recall that the SDR receiver takes in all electromagnetic signals from the antenna and digitises this input for processing in software.

As with a standard receiver the SDR (Software Defined Radio) receiver receives all the electromagnetic RF from the antenna and selects those which are in a digital format and further digitises the signal for processing in Software.

In a nut shell the a SDR Receiver is a rather special computer which makes sense of a digital signal which you and I would not be able to comprehend.

Recall that a mathematical operation enables all the signals to be sifted into separate frequency components.

Being digital means that it is all about numbers and as such a mathematical operating in the receiver to enable (convert) the signals into separate frequency components such that it can be understood as normal audio.

Recall that the required signal is selected using a filter defined in software.

The required signal is selected by using a filter which is part of the software.

Recall that demodulation is carried out in software.

The demodulation of the digital signal is carried out in software.

Recall that Software Defined Radio (SDR) receivers convert incoming signals to digital format and then perform filtering and demodulation on the signal using software and that SDR transmitters generate modulated radio signals using software.

So just to go through it again - The SDR receiver converts the incoming signals to digital format so that filtering and demodulation can be carried out on the signal using software. A signal which has been generated in an SDR transmitter is generated by a modulated radio signal using software.

So all in all both the transmitters and receiver rely upon computers and software to perform the tasks so that you can hear / receive the audio in a form that can be understood.

The origin of some of the text on this page is from the RSGB with additions by the web master