On 3/8/2010 2:33 PM, Kevin Custer wrote: > > > Steve wrote: > > It seems logical that if a rptr tx is running 200w, and the mobile > is running say 50w then it is going to be one way ie mobile hears rptr > but rptr don't hear mobile too well > > Common misconception. > > Lets say the mobile radio has a receive sensitivity of -116 dBm and 50 > watts of transmitter power. The repeater has a receive sensitivity of > -122 dBm - how much power will it take to balance out the receive > advantage of the repeater? If you said 6 dB, you are correct. 50 watts > with a 6 dB improvement is 200 watts. > > I have seen several VHF and UHF repeater systems with -125 dBm actual > sensitivity on air - connected to the antenna and duplexing. You do the > math... > > 400 watts is the answer. > > The original poster mentioned an LDG voter and remote links. If the > repeater has remote receivers that will increase the distance of > operation from the transmitter, he'll need all of his 200 watts. > > Kevin Custer > And a /properly /configured voter can easily add 4-6 dB to efffective sensitivity just though diversity effects, never mind getting the receiver closer to the user.
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