Ambient noise is one of the most important causes of LORA data reception. Installing filters can effectively improve the effect of ambient noise on LoRa data reception.


1.How can I determine the level of ambient noise?

    Ambient noise is objective, and changes in real-time, and only when it reaches a certain intensity will it affect LORA reception. Here is the method for calculating ambient noise.

  • About SNR

       SNR = RSSI - NOISE, so the noise level can be calculated by NOISE = RSSI - SNR.

NOTE: It is necessary to use the relevant parameters of  LORA packets with SNR < 0dB for evaluation. This formula is not valid if SNR ≥ 0dB.           


  • Through the Wireless analysis tool under COTX Hotspot  Web Management

    A method for calculating the average noise size of an assessment.

    NOISE = RSSI - SNR 

                =-98-(-18.8)≈ -79dB

                =-91-(-2.2)  ≈ -88dB

                     Average ≈ -83dB

NOTE: Ambient noise varies in real time and the average of several values over a period of time needs to be calculated in order to assess noise levels.


2.How much ambient noise requires the use of a filter?

NOISE filterRecommended from experience
Noise≥-95 Recommended installation
-95≤Noise≥-105 Optional installation
Noise ≤ -105Not recommended

 

NOTE: As a rule, filters have an insertion loss (signal loss) of around 2.5dB ± 1dB. 
           Therefore, it is not recommended to install filters with ambient noise ≤ -105dB,This may cause a reduction in earnings.



3.Filter effect assessment?

    RF reception is affected by a combination of environmental noise, rain and snow, density of surrounding equipment, antenna height etc. We can only Recommended Assessment methods from experience.

    It is recommended that a comprehensive assessment is made after 24 hours of filter installation.

  • Through the Wireless analysis tool under WEB MANAGENMENT


Basis of judgementExpectedDescription
Number of RF received packets/dayMoreThe most important indicator, which has a decisive impact on revenue.
Packets with RSSI < -110dBMoreIndicates more distant received signal capability
Percentage of BAD packetLessSignal quality improvement
NOISE valueLowerEffective filtering of ambient noise
  • If you do not have easy access to WEB MANAGEMENT, you can analyse it through Helium Explorer.


Basis of judgementExpectedDescription
Number of RF received packets/dayMoreThe most important indicator, which has a decisive impact on revenue.



4.About COTX filters

    COTX designs two EU868 filters specifically for LORA gateway devices.

Category
Supported frequencies
Scenarios
Remarks
SAW filter
EU868
Most scenarios
Normal ambient noise
Cavity filter 
EU868
4/5G base stations co-located, near large substations, etc. Scenarios with extremely bad electromagnetic signals
when noise is very high and SAW filters are not effective.


Note: The filter is designed as a band-pass filter and is not effective against co-channel interference.


Note: As a rule, filters have an insertion loss (signal loss) of around 2.5dB ± 1dB. 
         Therefore, it is not recommended to install filters with ambient noise ≤ -105dB,This may cause a reduction in earnings.