But if the locked external gain is set to 25dB, that's the whole system
gain, not the addition of the "external" gain (over the bare patch) like
a reflector. For instance, you set external gain to +14 when using a
standard SM on a reflector and get the full legal +30dBm/20MHz or
+27dBm/10MHz for DFS channels. That's the way I've always understood the
external gain setting. So -5dBm auto Tx power probably means it thinks
it has 9dB + 25dB = 34dB total system gain which would be very incorrect.
On 12/1/2015 5:18 PM, Aaron Schneider wrote:
Darren -
We'll take a look but the external gain for 450D is locked because that is the
property of the HW with the attached dish and radome. This is not changeable
intentionally.
The internal HW of the 450d is actually an integrated 450SM in a new housing, so
there actually is some internal gain via the 9dBi patch antenna, so that would
account for the difference. So TxPower + internal patch gain + external dish gain
<= EIRP would mean -4 is our max TxPower for 5.4 FCC to stay <= 30 dB EIRP.
However, we will take a look - there was some feedback at Wispapalooza that some customers were having issues installing these in 5.4G band, but the tx power should be correct.
Regards,
-Aaron
-----Original Message-----
From: Darren Shea [mailto:[email protected]]
Sent: Tuesday, December 01, 2015 3:58 PM
To: [email protected]
Cc: Matt Mangriotis; Aaron Schneider
Subject: RE: [AFMUG] Canopy 14.1.1
Aaron,
I had a question about a change Cambium implemented on the 450D radios,
although it's not new to 14.1.1 (I think it started in 13.4): the Power Control
section on the Configuration -> Radio, External Gain setting is no longer
adjustable, and is locked in at 25dB. OK, but the radio seems to be thinking it's
got some sort of additional gain, because it won't transmit higher than -5dB
(reported in Link Status). Shouldn't the EIRP in the DFS band be 30dB, so it could
transmit as high as 5 dB? This seems to be causing a major connectivity issue in
the 5.4 band, but not in the 5.7 band, where transmit power is reported as
anywhere from 16 to 22dB on the same SM to the same test AP.
Why the disparity? Is there any hope for using 5.4 GHz frequencies on a 450D SM
to a tower you could not hit with a football?
