EIRP is the TRANSMIT total of BOTH the radio and the antenna gain. So with a 4 watt, 36dB limit at the ap, you can't legally run a 1 watt (30 dB) radio into a 13dB sector. You can only transmit 36-13 or 23 dB (about a quarter watt) with a config like this.
And it doesn't take that much power at the base station to do amazing things anyway. I have systems with a total of 28dB (about a half watt) that will deliver 2 to 3 megs to a client 15 to 16 miles away. Point to Multipoint. High powered base stations just muck up the airways anyway. The more power you put out at the AP the more likely you are to have a system that's always fighting your other ap's. Anyway, the question below was what receive level was there to get such good throughput at such a long distance. That's a function of TX power but ALSO antenna gain. I try to build my systems to use antenna gain at the CPE for power vs. high power radios. I wish I had a dollar for every high power system we have talked people into swapping out with low powered systems over the years. Reliability and performance always goes up. I can think of NO exceptions to that rule. marlon ----- Original Message ----- From: <os10ru...@gmail.com> To: "WISPA General List" <wireless@wispa.org> Sent: Sunday, November 01, 2009 8:29 AM Subject: Re: [WISPA] Backhaul Questions > Doesn't it stand for "effective isotropic radiated power"? Isn't your > EIRP the same no matter what receive antenna is on the other end? > > I get your point, to have a sufficiently strong signal at the distant > receiver you could lower the transmit power and make up for it with a > more effective receive antenna. > > Respectfully, > Greg > On Nov 1, 2009, at 11:24 AM, Marlon K. Schafer wrote: > >> Yeah. >> >> People all too often forget that eirp is a RECEIVE number not a >> TRANSMIT >> number. All it takes is big, big ears and you can hear the other >> end from a >> very long ways away. Makes for much less noise in the area too. >> >> I hate the trend toward high power radios with low power antennas. >> >> You guys do realize that 2.4, 900 and 5.8 gig bands limit you to a 6 >> (that's >> S-I-X) dB antenna if you use a 1 watt (30 dB) radio? Base station >> especially. For CPE you can use higher gain cpe antennas on 5 gig >> and still >> be OK within the rules. >> >> But all of these stupid, noisy, wasteful, cpe systems with 1 watt >> radios and >> 19dB panels make a mess of your networks. (and mine) >> >> marlon >> >> ----- Original Message ----- >> From: "Mike Hammett" <wispawirel...@ics-il.net> >> To: "WISPA General List" <wireless@wispa.org> >> Sent: Saturday, October 31, 2009 10:50 AM >> Subject: Re: [WISPA] Backhaul Questions >> >> >>> 30 dB EIRP with a 44 DBi antenna on each side over 73 miles >>> produces -75 >>> signal. I'll let him say what he did to make it work, but it's >>> certainly >>> possible. >>> >>> >>> ----- >>> Mike Hammett >>> Intelligent Computing Solutions >>> http://www.ics-il.com >>> >>> >>> >>> >>> From: Bret Clark >>> Sent: Saturday, October 31, 2009 11:02 AM >>> To: WISPA General List >>> Subject: Re: [WISPA] Backhaul Questions >>> >>> >>> Man...what is the EIRP on these links that people are posting high >>> bit >>> rates? As someone else stated, gotta wonder if the FCC won't start >>> getting >>> suspicious at some point. >>> >>> Travis Johnson wrote: >>> 73 miles... and I get 28Mbps total (14Mbps each direction) using a >>> 20mhz >>> channel. >>> >>> Travis >>> >>> >>> Josh Luthman wrote: >>> Travis is getting 28 megs on a really long backhaul - like 58 miles? >>> >>> You will not see >30. >>> >>> On 10/31/09, Eric Rogers <ecrog...@precisionds.com> wrote: >>> Ok guys...Looking for both Mikrotik experience and others. We >>> currently >>> have a Mikrotik backhaul between each of our towers using NStreme >>> and we >>> have been extremely happy with the performance. We recently >>> upgraded a >>> tower because we were hitting 15M or so during peak times and was >>> afraid >>> it couldn't handle much more. We upgraded that backhaul to a >>> Motorola >>> PTP for future capacity. >>> >>> >>> >>> The questions: >>> >>> >>> >>> MT Gurus: >>> >>> Each backhaul ranges in distance, each ranges from 3 miles (3 >>> backhauls) >>> and the rest are about 12 miles (5 backhauls). Since we have been >>> using >>> Mikrotik, I have reliably seen up to 10 Meg, and I am afraid 15 Meg >>> is >>> pushing the envelope on a 20 MHz channel. >>> >>> >>> >>> How much capacity can I reliably push on a 20 MHz channel using >>> NStreme? >>> >>> >>> >>> Other Gurus: >>> >>> I understand the following are loaded questions, but budget is around >>> $1000-3000 range and the capacity needs to be around the 60Meg mark >>> (30 >>> each way or without a defined 1:1 guarantee, capability to flex and >>> be >>> able to push 30M each way). >>> >>> >>> >>> If I start upgrading to larger backhauls on busy links, what type of >>> equipment should I look at? >>> >>> What can support VoIP? >>> >>> Anything that GPS times for frequency reuse? >>> >>> Anything work in the 5.4GHz range at a 12 mile distance? >>> >>> >>> >>> Eric Rogers >>> >>> Precision Data Solutions, LLC >>> >>> (317) 831-3000 x200 >>> >>> >>> >>> >>> >>> -------------------------------------------------------------------------------- >>> 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! 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! 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! 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/
