I have an issue with two sectors running an epmp2000 + smart antenna. The level of Downlink RSSI is pretty different between the estimated from AP and the signal measured from SM.
I tried lots of settings about TX power, antenna gain but still I can't solve it.
In this example, the estimated downlink rssi from AP is -49 dBm, but the SM measure -57 dBm.
Boths are wrong, the calculated level of signal in this case (power 27dbm, gain of AP 18dbi, gain of SM 16dbi, distance 0,7 km) should be -43 dbm, anyway the closer value is the RSSI estimated on AP side.
For accurate DL RSSI reporting, always look at the SM reported RSSI, as that is an actual measurement of the signal level. The DL RSSI reporting at the AP in an estimate.
Thank you for your answer, I still can't understand why the rssi level is so low, it should be 10 - 15 db higher and I tried all angles of the sectors. Maybe there is a problem with radio or antenna?
Thank you for your answer, I still can't understand why the rssi level is so low, it should be 10 - 15 db higher and I tried all angles of the sectors. Maybe there is a problem with radio or antenna?
Best regards
Hi,
Have you tried to use Tools -> eAlign at the SM to get the best possible alignment? Also, if you are using the Cambium sector antenna, it has a 2 degree electrical downtilt on it. Have you accounted for that?
We are seeing similar results here, making it hard on the installers to determine if the link should be installed. Interestingly the tower reported signal strengths are at the levels we would "expect" for the location. We also have Ubiquiti equipment on the same tower and when we check signal using that equipment get the signals shown on the AP side of the Cambium link. Always seems to us as well the SM is down about 10 db. We are running 3.3 on both SM and AP, have tried 3.4 and no difference.
I'm checking SM's RSSI numbers from eAlign and comparing the numbers found on its AP gettered from Monitor->Wireless Web UI. Here are some field data collected between one AP/SM pair. I also put SNR values just for reference.
AP version: 3.3 AP hw: GPS SM version: 3.4.1 SM hw: Integrated
AP Downlink RSSI: ~-45dBm AP Uplink RSSI: ~-61dBm SM Downlink RSSI: ~-61dBm
AP Downlink SNR: ~35dBm SM Downlink SNR: ~35dBm
SM shows the same "downlink" numbers both on eAlign and Monitor->Wireless Web UI.
The numbers reported by the AP makes sense as the SM is close (<1km), giving it a good downlink signal strength, and ATPC should be governing uplink signal to ~-60dBm.
Aren't SM reporting uplink numbers as "Downlink" both at eAlign and Monitor->Wireless?
I did small misalignments while monitoring with eAlign to check for signal drop, however it fluctuates arround ~-60dBm while SM Tx power increases. I need to really misalign it to see considerable signal drops.
Also worth noting that cnMaestro (on premises) is reporting -60ish dBm numbers on both Downlink and Uplink for that SM. The -45ish dBm only shows on AP Web UI or SNMP.
