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Changing receive sensitivity via software

Posted: Sun Mar 01, 2009 3:38 am
by jpjust
Hello, folks.

Is there any way to change the receive sensitivity via software? Let's suppose I have an AP running ROS and all of its clients are connected at -70 dBm or higher. So, I'd like to set the receiver sensitivity to, let's say, -75 dBm, so, lower signals from other radios couldn't interfere my system.

If ROS hasn't this feature yet, you guys could at least think about it :)

TIA

Re: Changing receive sensitivity via software

Posted: Sun Mar 01, 2009 11:02 pm
by RK
That's not possible.
You can't block radio waves weaker than X because by the time you can measure their strength, they are already in the system and it is too late.

Re: Changing receive sensitivity via software

Posted: Mon Mar 02, 2009 2:43 am
by illiniwireless
I think that it would be possible but not a likely addition to the minipci cards. You would be better off putting a smaller antenna up. Much cheaper than designing a new card.

They do make adjustable amplifiers and you can control the recieve sensitivity on them as well so maybe they will add it to the cards in the future.

Re: Changing receive sensitivity via software

Posted: Mon Mar 02, 2009 8:56 am
by RK
You would be better off putting a smaller antenna up. Much cheaper than designing a new card.
This way he'll get a weaker signal from his clients AND pick up more noise.

Re: Changing receive sensitivity via software

Posted: Mon Mar 02, 2009 2:25 pm
by jpjust
I've read somewhere that Adaptive Noise Immunity changes card's sensitivity dynamically to avoid interference (I don't know if it is true, but that's what I've read). From this reading, I've had the idea to change the sensitivity manually.

I've thought about using low gain antennas already, but as RK said, this will also reduce the signal received from my clients.

Re: Changing receive sensitivity via software

Posted: Mon Mar 02, 2009 3:01 pm
by tgrand
It is best practice to main tain a 20db (or better) signal to noise threshold.
If the signal is too strong at the client end and you need to use a more directional antenna (higher power) in order to avoid noise sources, then an attenuator must be used.

Re: Changing receive sensitivity via software

Posted: Fri Mar 13, 2009 2:05 am
by nest
Adaptive Gain allows the RF Pre-Amplifier to reduce their gain in the presence of strong adjacent channel or in-band signals causing intermodulation or blocking interference. Not for weak signals causing interference.

See my posting on this subject previously: http://forum.mikrotik.com/viewtopic.php ... 27&start=0

If you are getting interference from unwanted sources, reduce the aperture (beamwidth) of the antenna as this reduces what it can see so that (hopefully!) it also stops seeing the signal that is causing you the interference. It also increases the receive gain of the system, thus improving the S/N ratio. This usually translates into antennae with a higher gain.

Also, a well designed antennae (rather than one copied to look the same as another but actually using different materials and very slightly different dimensions) should have less sidelobes, therefore less opportunity to pick up signals outside of it's main beam. Poorly designed (cheap?) antennae tend to have sidelobes that look in all the wrong places, thus increasing interference potential. I have seen Chinese copies that look really good on the outside, but when tested show very poor radiation patterns.

Ron.

Re: Changing receive sensitivity via software

Posted: Sat Oct 05, 2019 10:24 pm
by saenito
I saw in a MUM's video from canada called "How using MikroTik Backhaul Solution Innovative designs" the expositor talking about Rx-Sensitivity as a feature but i could locate it in MikroTik, maybe is a new feature for new firmware versions, cause i use long term ones