Scott, No, I was not kidding.
I am NOT suggesting using gear that does not adequately support DFS2. But lets consider a TLink45 for example that is DFS2 certified..... The DFS2 spec ONLY requires that you to listen and detect Radar, and not transmit IF Radar is "HEARD". If radar is NOT heard, you have the right to broadcast on the channel. Nothing in DFS2 defines the size or type of antenna that has to be used to hear. It is feasible that if you can't hear them, that they can't hear you. And yes believe it or not, the difference between a 23 db panel and a pacwireless 29db more directional dish has been enough difference between hearing radar or not in some cases, to keep the radio from constantly jumping channels. If you really want to get clever you can spend $1500 and install a drum antenna, that has excellent side isolation. (as much as 60db F/B ratio spec). The purpose in my comment was not to sugget ability to "over power" the radar, as that would not be possible or ethical. Instead the goal is to prevent hearing each other. I have had situations where re-point 60 degrees off from my original path, has been enough to make 5.4Ghz usable versus not usable for a new prospect. It is also only necessary for the AP to scan if the CPE follows, so what side you mount your AP (or MU) can make a difference between whether the Radar is heard. The question with 5.4Ghz is "How can I take advantage of it to use it?" 5.4Ghz in a standard PtMP business class offering for primary service is completely useless in much of America. (Atleast the DC Metro tri-state areas). And for PTP one really can't affor to have service disrupted. You have to be creative to use it. One way is for non-mission critical best effort mesh type deployments. For example, it would be great if Highway safety used it for their street light networks to downloading traffic violation tickets :-) Wouldn't it be great if we just got half the tickets half the time when the system worked :-) We also use 5.4 for backup links, or paths that have backup route paths. What I hate about DFS is the randomness. Its a 2 week to 1 month process to learn whether a 5.4Ghz link will be "reliable" without premature hopping. So the best thing to do is design it from day one to be as interference resistence as possible. We use the most directional antenna appropriate for our link from day 1, to avoid the risk and costs associated with the risk. DFS activating and Hopping channels should be the last reult effort to preventing interference with Radar, and links should be optomized to prevent that. We'll also try numerous channels in advance, and record which channels don't hop, to maximize the chance that if it does in the future, we know what channels are most likely to not hop in the future, without redoing tests. This allows us to minimize downtime, if Radar jumps on our link 2 weeks down the road. I'm also starting to think that GPS syncing might be a better idea for high risk 5.4Ghz PTMP cell site links, just because if there is a heavilly loaded cell site, the damage would be minimized if the radio jumped to the channel of another radio. (We don't currently use any GPS synced equip). But with the trend of Full Duplex comming back, it might not be to bad to use syncing. Tom DeReggi RapidDSL & Wireless, Inc IntAirNet- Fixed Wireless Broadband ----- Original Message ----- From: "Scott Carullo" <sc...@brevardwireless.com> To: "WISPA General List" <wireless@wispa.org> Sent: Tuesday, April 21, 2009 10:22 AM Subject: Re: [WISPA] DFS Radar Question > With your calculator, take your front to back attenuation for your dish > (or > side) and apply 410000 watts to it from direction chosen and let me know > what you end up with lol... > > You can't possibly combat it at all cause if your on the same freq your > going to get a visit from some people that have been in better moods > asking > why they have a stripe on their radar screen... It don't take a lot of > power when their receive it about 60db gain with 1 deg sweeping dish that > listens in every direction that is made to hear a reflection off a rain > drop or bird at 200 miles... > > You were kidding right > > Scott Carullo > Brevard Wireless > 321-205-1100 x102 > > -------- Original Message -------- >> From: "Tom DeReggi" <wirelessn...@rapiddsl.net> >> Sent: Tuesday, April 21, 2009 10:13 AM >> To: "WISPA General List" <wireless@wispa.org> >> Subject: Re: [WISPA] DFS Radar Question >> >> The only good answer to combat DFS is to use directional PTP antennas > with >> good F/B ratios. >> >> I'd give 5.4G back to the FCC in a heartbeat, if they gave us 5.3Ghz back > >> without DFS and low power requirements. >> >> If you ask me.... Either 5.3 radars or 5.4 radars should be forced to >> upgrade to the other band, and free up the other :-) >> >> Tom DeReggi >> RapidDSL & Wireless, Inc >> IntAirNet- Fixed Wireless Broadband >> >> >> ----- Original Message ----- >> From: "Adam Goodman" <a...@wispring.com> >> To: <sc...@brevardwireless.com>; "WISPA General List" > <wireless@wispa.org> >> Sent: Monday, April 20, 2009 4:51 PM >> Subject: Re: [WISPA] DFS Radar Question >> >> >> I had some trouble with radar (think it was radar) last year. >> Interferences could be from many sources. It sa problem because you >> can't just go sit there for a couple of weeks with a spectrum analyzer >> listening for noise. It would be nice if there was a reasonably priced >> logger. Or with Internet connectivity. All this is probably a pipe >> dream as I have never seen anything with such functionality. >> >> >> >> >> On Mon, Apr 20, 2009 at 4:37 PM, Scott Carullo >> <sc...@brevardwireless.com> wrote: >> > >> > Anyone know of a radio that can just listen passively and scan through >> > channels and report back on radar signals heard on what frequencies? > That >> > would be a great tool to have to scope out certain areas of interest > to >> > know ahead of time what radar DFS issues might be present... >> > >> > Scott Carullo >> > Brevard Wireless >> > 321-205-1100 x102 >> > >> > -------- Original Message -------- >> >> From: "Blair Davis" <the...@wmwisp.net> >> >> Sent: Monday, April 20, 2009 4:30 PM >> >> To: "WISPA General List" <wireless@wispa.org> >> >> Subject: Re: [WISPA] Gell Cell? >> >> >> >> >> > > ---------------------------------------------------------------------------- > >> > ---- >> >> WISPA Wants You! 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