Joe - I just answered your forum post... but might as well repeat and add to it here too.
You guys are right in that the combination of the two factors are what matters to the modulation that the radio will achieve. You have to be above a certain absolute power level (RSL), but ALSO have enough distance (SNR) above the noise to decipher the bits. That is, even if you're receiving the intended signal at -55, but have noise at -70, the 15 dB separation (i.e. SNR) isn't enough to allow for 256QAM modulation. Regarding sensitivity levels, the easiest place for me to find these is in the Link Capacity Planner Tool: https://support.cambiumnetworks.com/files/capacityplanner/ You can input the radios you're using and it'll spit those out. During final product testing, we've determined that the 450b is equivalent to the 450i SM in these specifications, so until that tool gets updated with official numbers (which may vary slightly), I would use that. Hope this helps, Matt -----Original Message----- From: Af [mailto:af-boun...@afmug.com] On Behalf Of Joe Falaschi Sent: Friday, July 28, 2017 11:49 AM To: af@afmug.com Subject: Re: [AFMUG] Cambium 450b specifications Sure it would. We have some links reporting a SNR above 32db, enough to get 8x but are weaker than -56 signals. So both matter. Joe > On Jul 28, 2017, at 11:44 AM, Chris Wright <ch...@velociter.net> wrote: > > Wouldn't SNR play a bigger role than general signal level? What good is > -67.8dBm if the noise floor is -75dBm? > > Chris Wright > Network Administrator > > > -----Original Message----- > From: Af [mailto:af-boun...@afmug.com] On Behalf Of Joe Falaschi > Sent: Friday, July 28, 2017 9:28 AM > To: af@afmug.com > Subject: [AFMUG] Cambium 450b specifications > > We’re looking at some questions of why certain links are at certain > modulations (uplink is better than downlink). It’s explained by the spec > sheet of the current equipment and RX sensitivity. Basically the 450M AP can > do more with less signal than the CPE can. Specs below. In any case we were > then wondering what the new 450b RX sensitivity would be. There is a spec > sheet on the Cambium website but this isn’t listed. Anyone have this > information? > > 450M AP RX sensitivity > 1x = - 93.5 dBm > 2x = -88.6 dBm > 4x = -81.5 dBm > 6x = -75.9.0 dBm > 8x = -67.8 dBm > > 450SM RX sensitivity > 1x = -84 dBm > 2x = -80.5 dBm > 4x = -74 dBm > 6x = -66.9 dBm > 8x = -56 dBm > > 450i SM RX sensitivity > 1x = -85.9 dBm > 2x = -81.5 dBm > 4x = -75.8 dBm > 6x = -69.3 dBm > 8x = -61.6 dBm > > Joe Falaschi > e-vergent >
