Hi All, I was wondering if someone could answer these questions for me please? Q1. If I stuck an antenna out, will it receive all the different signals e.g. Music Radio, TETRA, WiFi? Q2. What is the difference between these? I thought it was the frequency e.g. TETRA uses 300-400 MHz, WiFi uses 2.4 GHz and Music Radio uses whatever you set it. Q3. How does my computer know which one is WiFi? Is it by the frequency the signals are traveling at? Q4. If I place an antenna outside and there are different signals but I wanted to single out one of them (e.g. TETRA), will I have to listen for waves traveling at 300-400MHz and then do an FFT of that, a peak at any frequency between 300 to 400 MHz would mean there has been a transmission of data at that frequency? Will this apply to wifi too? I am not after learning about the encryption/decryption bit at the moment. I just want to know how you tune your equipment to identify different signals or what differentiates these technologies. I honestly don't really have much idea of what I am talking about but interested to learn so can you also please suggest a book to help me better understand what I am after? A book for beginners would be ideal. Thanks.