My calculator says, -75 at 15 miles from the AP with a 20db transmit, 8 db antenna, and 24 db on the RX side, leaves you with a fade margin of -0.686 in perfect world conditions, not taking into account earth curvature, fresnel zone incursions, weather, or tower height which will all add loss, the fade margin is only going to be worse.
Let me know where I've gone wrong in my calculations, that tells me that connection isn't going to be stable or viable. http://www.wisp-router.com/wirelesscalculators.php#budget Regards Michael Baird > Do you have a calculator for signal levels? They are powerful tools. > > Lets say that we have an AP putting out 20dB into an 8dB omni. That's 28dB > or roughly .6 watts. At the client end we'll use a 24dB grid with a 24dB > radio output (max allowed under the 3 for 1 rule) for 48dB or 60 watts. > > That calculates out to an rssi of -75. Still in the "sweet zone". With an > AP output of only 17dB we'd still have an rssi at the remote end of -78, > well within the capabilities of today's radios. > > Work it the other way and you'd have -71 coming back to the AP (the eirp on > the cpe is higher than the AP can be). > > Wanna know what's really fun? Plug 20 miles into the calculator and we're > still at -81 for the rssi at the customer end. That's with an 8dB omni and > 17dB transmitter. NO amp! Still well within the capabilities of today's > radios. > > Naturally, you'll need pretty clean air and radios that can be adjusted for > range to make this work. But there it is.... > > That help? > marlon > > ----- Original Message ----- > From: "Robert West" <robert.w...@just-micro.com> > To: "'WISPA General List'" <wireless@wispa.org> > Sent: Tuesday, June 30, 2009 11:26 AM > Subject: Re: [WISPA] Antenna Recommendations > > > >> What type of signal you getting on your systems at 15? The land here is >> pretty flat, not much variation, some trees, no pine at all. Your basic >> flat as a pancake farmland. What's your setup? >> >> >> -----Original Message----- >> From: wireless-boun...@wispa.org [mailto:wireless-boun...@wispa.org] On >> Behalf Of Marlon K. Schafer >> Sent: Tuesday, June 30, 2009 12:32 PM >> To: WISPA General List >> Subject: Re: [WISPA] Antenna Recommendations >> >> roflol >> >> We routinely go 15 or more to an omni. And we don't use amps and rarely >> even go all the way up to 36 watts eirp. >> >> Overall system design is important. Not just big omnis and amps.... >> >> Maybe I need to get out there and do some consulting work again? sheesh >> Who's been teaching people for the last 2 or 3 years? >> >> marlon >> >> ----- Original Message ----- >> From: "Robert West" <robert.w...@just-micro.com> >> To: "'WISPA General List'" <wireless@wispa.org> >> Sent: Monday, June 29, 2009 3:13 PM >> Subject: Re: [WISPA] Antenna Recommendations >> >> >> 10 is a dream........... I know. But been thinking of going sector. Not >> many users there at the moment but replacing the antennas may be a good >> reason to upgrade the whole mess. Really only need a good 3 to 5 miles >> but >> further is always better for redundancy. >> >> >> >> >> -----Original Message----- >> From: wireless-boun...@wispa.org [mailto:wireless-boun...@wispa.org] On >> Behalf Of RickG >> Sent: Monday, June 29, 2009 1:32 PM >> To: WISPA General List >> Subject: Re: [WISPA] Antenna Recommendations >> >> I wouldnt use an omni to go 10 miles. Why not sector? >> -RickG >> >> On Mon, Jun 29, 2009 at 12:31 PM, Robert West<robert.w...@just-micro.com> >> wrote: >> >>> Would like to get 10 miles out of it for overlap but can go less. >>> >>> -----Original Message----- >>> From: wireless-boun...@wispa.org [mailto:wireless-boun...@wispa.org] On >>> Behalf Of RickG >>> Sent: Sunday, June 28, 2009 11:42 PM >>> To: WISPA General List >>> Subject: Re: [WISPA] Antenna Recommendations >>> >>> How far do you need to go? >>> -RickG >>> >>> On Sun, Jun 28, 2009 at 2:24 PM, Robert West<robert.w...@just-micro.com> >>> wrote: >>> >>>> I'm in need to replace some older Omni antennas, 2.4 and 5.8, to connect >>>> >>> to >>> >>>> a Mikrotik 600a. Running the R52H cards for both bands with a dish for >>>> >>> the >>> >>>> 5.8 backhaul.. I'm not in the mood to experiment with the unknown, any >>>> recommendations on what is working for you? And what doesn't! Land is >>>> flat, rural farmland, small scattering of trees. We're up 70 feet in >>>> >> this >> >>>> location. >>>> >>>> >>>> >>>> Thanks! >>>> >>>> >>>> >>>> Robert West >>>> >>>> Just Micro Digital Services Inc. >>>> >>>> >>>> >>>> >>>> >> ---------------------------------------------------------------------------- >> >>> ---- >>> >>>> WISPA Wants You! Join today! >>>> http://signup.wispa.org/ >>>> >>>> >> ---------------------------------------------------------------------------- >> >>> ---- >>> >>>> WISPA Wireless List: wireless@wispa.org >>>> >>>> Subscribe/Unsubscribe: >>>> http://lists.wispa.org/mailman/listinfo/wireless >>>> >>>> Archives: http://lists.wispa.org/pipermail/wireless/ >>>> >>>> >>> >>> >> ---------------------------------------------------------------------------- >> >>> ---- >>> WISPA Wants You! 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Join today! >> http://signup.wispa.org/ >> ---------------------------------------------------------------------------- >> ---- >> >> WISPA Wireless List: wireless@wispa.org >> >> Subscribe/Unsubscribe: >> http://lists.wispa.org/mailman/listinfo/wireless >> >> Archives: http://lists.wispa.org/pipermail/wireless/ >> >> >> >> -------------------------------------------------------------------------------- >> WISPA Wants You! Join today! >> http://signup.wispa.org/ >> -------------------------------------------------------------------------------- >> >> WISPA Wireless List: wireless@wispa.org >> >> Subscribe/Unsubscribe: >> http://lists.wispa.org/mailman/listinfo/wireless >> >> Archives: http://lists.wispa.org/pipermail/wireless/ >> > > > > -------------------------------------------------------------------------------- > WISPA Wants You! 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