Although what Joe says is true, the system is balanced more so than the math would indicate. This is due to most users ears requiring more than .15uV sensitivity to pick out a weak signal. realize that the SINADs of BOTH the repeater and the mobile rig would be additive when the mobile is in a fringe area. If a user is into the system and is, say 50% noise and the repeater's transmitter is being received at an S1, say 30% noise, that adds to 80% noise. That's pretty noisy!!
For a typical user's DSP (the one between their ears) to be able to process a weak signal into the repeater's receiver, they need to be able to hear the repeater's transmitter almost full quieting. This is the reason that all links between receivers strive to be absolutely full-quieting and have good audio characteristics. If not, all of the system noise and distortions are additive. Scott Scott Zimmerman Amateur Radio Call N3XCC 474 Barnett Rd Boswell, PA 15531 ----- Original Message ----- From: "MCH" <[EMAIL PROTECTED]> To: <Repeater-Builder@yahoogroups.com> Sent: Thursday, September 04, 2008 4:38 PM Subject: Re: [Repeater-Builder] Re: GE uhf high power > The math isn't that hard. 200W (53.01 dBm) is about 7.6 dB over 35W > (45.44 dBm), so the RX would have to be about 7.6 dB better than 0.15 uV > (-123.5 dBm), or about -131 dBm which is 0.06 uV. > > The antenna gains and losses cancel each other out since they apply to > both TX and RX. > > Joe M. > > Nate Duehr wrote: >> Kevin Custer wrote: >> >>> BTW: I have one of the stations that Fred mentioned at one of my >>> sites. It belongs to Jeff DePolo. >>> It will run 200+ watts all day and night, and with a good MASTR II >>> receiver (hand selected) with a Chip Angle preamp, it takes all of the >>> 200 watts to keep up with it. It is matched pretty well with a modern >>> 35 watt mobile. >> >> Now THAT I'd like to see the math on. Just how high does receiver >> sensitivity have to get to "balance" with a typical say, oh... .15uV >> "modern" UHF mobile and it sending out 35W... what would the "perfect" >> numbers be. >> >> Someone who enjoys the math more than I do maybe will feel bored enough >> to calculate it. I guess you'd need the antenna gain numbers also. >> What are you running on that system, Kevin? >> >> Nate WY0X > > ------------------------------------ > > > > Yahoo! Groups Links > > > -------------------------------------------------------------------------------- No virus found in this incoming message. Checked by AVG - http://www.avg.com Version: 8.0.169 / Virus Database: 270.6.16/1651 - Release Date: 9/4/2008 6:57 AM
