Inside Wireless: Noise Floor

In this Inside Wireless episode we talk about Noise Floor (NF). Noise is the signal a RF radio receives, but doesn’t understand. Noise floor tells us what is the strength of the noise in a given bandwidth and determines the Signal to Noise Ratio (SNR). SNR tells us how much stronger the useful signal is compared to the noise.

Want to keep the noise of your wireless network low? Check our award winning antennas that let you REJECT NOISE, SAVE SPECTRUM, and GROW SMART:

There are two categories the noise sources can be divided into:

1. Noise created by the radio itself due to the physics of the parts it is built from. There are many types of noise devices produce, such as thermal noise, flicker noise, shot noise, or burst noise. Sum of all these types of noise create the noise floor of a radio. In lab conditions, the noise floor is the jittery line at the bottom of the spectrum the radio works with. The useful signal is recognized by clearly higher level above the noise floor.

2. Man-made noise. The devices located near your radio produce signals seen as noise by your radio and are received through the antenna. The man-made interference is usually much stronger than the noise created by the radio itself and is the biggest problem of fixed wireless networks.

RF radio sees the signal quality primarily through the SNR given the strength of signal is between the noise floor and the maximum power. Interference decreases the SNR your radio is working with. Lower SNR means lower MCS rates seen as decreased overall throughput at the user end.

A frequent misunderstanding among WISPs is that the solution to interference is using an antenna with higher gain. Although higher gain antenna will increase the received signal strength, it can be harmful to the SNR at the same time. The sidelobes of an antenna decide how much added noise radio sees.

The traditional sector patch array antennas have huge sidelobes, so the added signal level due to higher gain is drowned in the added noise caused by the side lobes.

The best way to avoid increasing noise floor your radio is working with, is to avoid collecting the surrounding interference. Using an antenna without sidelobes such as horn, you push the noise floor down, improving your SNR. Despite the horn might have smaller gain, the lack of sidelobes improves the SNR so eventually the link performs better than with higher gain antenna.

If the interference in the area is heavy, the improvement when using horns can be marginal, so it’s good to keep in mind that every link should be treated as a separate case.

0:00 Intro
0:12 What is Noise Floor & SNR
0:25 Types of noise
1:20 Interference
1:29 Noise solution

#RFelements #InsideWireless #Antennas #AntennaTheory #WISP #NoiseFloor #RFNoise #SNR #SaveSpectrum #RejectNoise #growsmart #UbiquitiNetworks #CambiumNetworks #MimosaNetworks #Mikrotik

[Rfelements]

Didn't find the topic you're interested in among our videos? Comment below!

[cambiumnetworksru]

Hi there. This is again Sergey from Cambium. :) It's very controversial statement that higher gain antenna is the wrong solution. To prove that, you're demonstrating the animation where a terrible pattern becomes bigger. But the thing is - this animation demonstrates the same antenna pattern, which means the same gain.
G=e*D (efficiency * Directivity). Antenna with higher gain should have better directivity, which means narrower main lobes, and less side lobes. So higher gain antenna IS ALWAYS the right solution.

[nojiratzlaff]

I don't believe this is correct. The "jittery line" he's referring to is the Noise Level. The Noise Floor is the smallest level of noise your instruments can measure. Furthermore, the Noise Figure is the ratio of the Noise Floor to the Theoretical Noise Floor (-174 dBm/Hz). Let's see if I can clear up all the terminology.
Start with five signal levels, actual or theoretical (I'm making up all but one of the numbers):
Input signal = -47 dBm (the actual signal)
Noise Level = -67 dBm (the actual noise level, measured at the instrument)
Noise Floor = -140 dBm (the lowest noise level my analyzer can measure)
Theoretical Noise Floor = -174 dBm/Hz (the theoretically lowest possible noise level) at 20ºC
Noise Figure = (-140 dBm) - (-174 dBm/Hz) = 34 dBm/Hz (at 20ºC in this particular case, at the △f of interest)
And BTW, the Noise Factor is another term for Noise Figure.

[danimallegs]

still have a question. in an enterprise environment with many aps on channels 1, 6, and 11, if there are other rogue APs on the same channels, are those considered part of the noise floor because theyre unwanted?

[agstechnicalsupport]

We are looking for an experienced "electronic noise consultant" who would be assigned to a project involving our client's product. It is a contract based opportunity with good hourly pay. The issue is challenging as our client could not get rid of the electronic noise for some significant time. If you or someone you know of, with solid background in electronics and especially noise troubleshooting and elimination is available, please let us know by responding here to this message and let us provide you more details to see whether this would be a good project for you. Thank you in advance if you are willing to help us !

[M.MaX]

Is higher negative floor noise is better or worse ?

[sammm]

reduce transmitte power will reduce the noise 🙂