Hi
Dear friends.
Does someone knows how to convert RSSI to dbm
It is important to note that you should look at the power level and not the RSSI. The RSSI will be unique to each radio. For example, two radios mounted next to each other could show a difference of 400 RSSI but the power should be close to the same. So there is no conversion of RSSI to dBm.
We have received a few calls lately stating that the RSSI looks lower. This should not be an alarm. Concentrate on the dBm instead of RSSI.
Canopy_Support wrote: It is important to note that you should look at the power level and not the RSSI. The RSSI will be unique to each radio. For example, two radios mounted next to each other could show a difference of 400 RSSI but the power should be close to the same. So there is no conversion of RSSI to dBm.
We have received a few calls lately stating that the RSSI looks lower. This should not be an alarm. Concentrate on the dBm instead of RSSI.
So, at what dBm level should we start being concerned about connectivity losses?
If you look at the Module Specs section in the back of the manual for whatever equipment you are using, you’ll see the two fields you need.
For the AP, the Receiver Sensitivity is -83dB, and the CtoI is 3 dB. Which basically means “my ears are sensitive enough to hear -83dB, but I can only pick a signal out if its at least 3 dB stronger then the background noise.”
Thats a good baseline Andrew, as I have noticed that the RSSI level has been lower since a firmware upgrade (not sure which firmware), and have just gone by the dbm, and jitter, and link tests. A dbm of -80 seems to be the lowest power level for which a module can sustain an “acceptable” link. I have had modules with a good RSSI, but the power level was -81,-82, and the radio would not maintain a good link for any given time, moving the radio just slightly, I was able to get -79 and the difference was measureable.
That’s good information to know. I’ve really only been using those published numbers from Moto, as I have not run into a customer with that low of a signal yet.
Thanks
ghull wrote: Thats a good baseline Andrew, as I have noticed that the RSSI level has been lower since a firmware upgrade (not sure which firmware), and have just gone by the dbm, and jitter, and link tests. A dbm of -80 seems to be the lowest power level for which a module can sustain an "acceptable" link. I have had modules with a good RSSI, but the power level was -81,-82, and the radio would not maintain a good link for any given time, moving the radio just slightly, I was able to get -79 and the difference was measureable.
Yes, that's very good info...Thanks!
Motorola’s spec sheets show both the 900 MHz AP & SM having:
Carrier to Interference ratio (C/I) <3 dB
Nominal Receiver Sensitivity (dbm typical) -90
I’ve never been able to hold a link that is consistently above -82.
As a practical matter we do not deploy when power is above -80 and the jitter must average no higher than 3.
you really mean below -83 dbm don’t you
that has been our experience. If we can stay in the 70’s the throughput is good and there are no re registers
Any number >= -80 is acceptable. If I can’t get that on an install, I ether go higher or I don’t do the install 