OK, I think you’re saying he should be able to dial up 26 dBm xmt power legally, and with 1 dB cable loss, 27 dBm should be legal. That seems correct.
I thought you were saying 1 dB of cable loss should allow 3 dB more xmt power per the 1-for-3 rule, which is not correct. From: Mathew Howard Sent: Friday, July 29, 2016 4:58 PM To: af Subject: Re: [AFMUG] UBNT AF-2X Problems... Where Do You Go For Help? Yes... if I read the original post right, the radio is currently only putting out 24dbm, and he wants to increase it to 27dbm - if you can have 26dbm conducted power at the antenna (which is what I've always assumed, and I believe what the UBNT gui normally allows) you would only need 1db of cable loss. On Fri, Jul 29, 2016 at 4:15 PM, Ken Hohhof <[email protected]> wrote: I don’t follow your math. The most likely interpretation is that conducted power is at the antenna end of the cable, so if you have 1 dB of cable loss, you can increase radio xmt power 1 dB to compensate. The other interpretation would be that cable loss subtracts from antenna gain. So if you have 1 dB of cable loss, then in effect you have 1 dB less antenna gain, and can increase xmt power by 1/3 of a dB. Oh, one more thing, make sure you aren’t getting caught in the difference between aggregate vs per stream power levels. UBNT products are pretty clear about this in the GUI though. From: Mathew Howard Sent: Friday, July 29, 2016 3:56 PM To: af Subject: Re: [AFMUG] UBNT AF-2X Problems... Where Do You Go For Help? I'm pretty sure that you could increase transmit power to compensate for cable loss, which would mean you'd only need 1db of cable loss to be able to up the transmit power by 3db... and anything that's being called "long cables" is almost certainly going to be more than 1db. On Fri, Jul 29, 2016 at 2:27 PM, Ken Hohhof <[email protected]> wrote: Is this in FCC area? FCC rules for 2.4 GHz PTP are 30 dBm max transmitter power with 6 dBi antenna, for a total +36 dBm EIRP. Then for antenna gain above 6 dBi, you have to reduce xmt power 1 dB for every additional 3 dB of antenna gain. Also this is independent of channel width, it’s not dBm/MHz. So you have an 18 dBi dish, that’s 12 dBi of additional antenna gain, so you would have to reduce xmt power by 1/3 of 12 dBi or 4 dB, to +26 dBm, and max EIRP would be +42 dBm. How many dB do you figure you’re losing in the long cables? I’m unclear on whether cable loss counts against xmt power or antenna gain. If you’re losing several dB in the cable, I can see where you’d want the full +30 dBm xmt power from the radio. From: Christopher Gray Sent: Friday, July 29, 2016 1:20 PM To: [email protected] Subject: [AFMUG] UBNT AF-2X Problems... Where Do You Go For Help? I've had an open ticket about the AF-2X for over a month. I have not been able to actually work with anyone on the issue. It has been "escalated" but without any positive results. Is there a better way to talk to someone about the airFiber? The spec sheet says a US AF-2X has a maximum Tx power of 30 dBm... but it only goes up to 24 dBm. [I'm running an 18 dBi dish on one end with long cables, and I need the additional 3 dB Tx power). When changing channel width, the Rx power does not change (Rx power is usually measured in dBm/20Hz on most UBNT hardware, so power usually goes up 3 dB when halving the bandwidth, but I can't get a straight answer as to whether they use the same units on the AF line). Long story short, I'm going to have to get rid of this AF-2X hardware and switch back to ePMP. The AF-2X would be the better choice if I could get the power levels I need to make this link work. I would much rather solve the AF problems.. -Chris
