Inside Wireless: Noise Floor
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- čas přidán 2. 08. 2024
- 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.
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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 - Věda a technologie
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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.
Sergey, probably you do not understand the message of the video correctly. Let us rephrase it for you: Better SNR is what is the key, not the higher antenna gain itself. Better SNR beats higher gain all day long in practical life. There are tons of high gain antennas with poor radiation patterns out there. Blindly following the rule "Higher gain antenna IS ALWAYS the right solution" is the essential cause of the problems with RF pollution in WISP industry.
@@Rfelements мне нравится ваш канал, но тут вы не совсем правы, мне не хотелось бы думать, что маркетологи сказали что вам нужно говорить в видео, но вывод из него звучит "не покупайте антенны с большим усилением, покупайте наши рупоры". Вы могли сказать "решение проблемы в качественных антеннах с хорошей диаграммой направленности", но сказали что направленность одинакова для антенн с разным усилением - это неправильно.
@@winstonvrn Hello, we say 'use horns', not 'use our horns'. For WISP application, antennas with high gain should be used only when absolutely necessary.
@@Rfelements во-первых, большое спасибо за ответ! во-вторых, да, вы правы, вы сказали использовать рупор, но учитывая контекст, а именно то, на каком канале это видео, я думаю понятно, что вы хотели сказать, в-третьих, а что насчет "spatial filtering" вы считаете это тоже плохо в WISP, но ведь именно это и достигается в том числе за счет большего усиления.Я использовал ваши рупоры, они очень хорошие, но что касается усиления и WISP, я не могу с вами согласиться. п.с. и все же, если вернуться к видео вы показали диаграммы с разным усилением одинаковыми по направленности, но разными по размеру, это не соответствует действительности.
@WinstonVrn Spatial filtering could be helpful, if done right. The current state of the technology doesn't allow for beam forming capability affordable in WISP market. We are glad the horns work well for you!
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?
Any competitive APs are noise to your AP, so yes. A way to protect yourself from those is to use an antenna with minimum (ideally zero) side lobes.
Is higher negative floor noise is better or worse ?
The lower the noise floor, the better. For example -95 dBm is better noise floor than -85 dBm etc..
reduce transmitte power will reduce the noise 🙂
reducing transmitted power will only reduce the noise your antenna creates, the noise it receives remains the same, corresponding to the gain of the antenna and the side lobes it has. So reducing the Tx power is not the right solution potentially harming your link.
Generally, if anything should be reduced, it is the gain of the AP antenna - to the lowest possible, or use down tilt to decrease its coverage, which is very easy to do with our horn antennas.
@@Rfelements i tried many antennas in many positons then found the best solution in noisy area is reduce the tx power🙄
@@sammm9829If it helped you, that is great! However, generally, reducing the Tx power is not a universal solution to all issues with noise.
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.
This was very good explanation, mind going a bit more in detail if I message ya?
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 !
What exactly do you mean by the 'electronic noise'? Can you be specific please?
@@Rfelements Please contact us by email so we can send you details to review. We are basically searching a consultant who can solve the electronic noise problem we are facing with a particular product. Please contact me at sales@agstech.net and in the email title please put "Regarding Electronic Noise Troubleshooting".