Unformatted text preview: The voltage ratio is 8/3. The power ratio is 8*8/(3*3) or in dB, 10 log(64/9) = 20log(8/3) dB. Thus, if you go to the shop and buy an amplifier (sometimes called a booster) to amplify your TV signal so that you have better reception and that amplifier has 10dB gain, what is the power gain and the voltage gain? Note that TV and many video and RF signal systems (say, your radio) have 75 ohm impedance at both in and out. This is so that it is matched to the impedance of "air" or "freespace". Otherwise, there will be reflections and you won't receive well. EM wave is light! Mismatch in impedance is the same as light going from say, water to air. However, do note that hifi amplifier do not have the same input and output impedance!...
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This note was uploaded on 08/02/2009 for the course ECE EE2009 taught by Professor Prof.c.c.ko during the Fall '07 term at National University of Singapore.
- Fall '07