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 filter | Recommended from experience |
| Noise≥-95 | Recommended installation |
| -95≤Noise≥-105 | Optional installation |
| Noise ≤ -105 | Not 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 judgement | Expected | Description |
| Number of RF received packets/day | More | The most important indicator, which has a decisive impact on revenue. |
| Packets with RSSI < -110dB | More | Indicates more distant received signal capability |
| Percentage of BAD packet | Less | Signal quality improvement |
| NOISE value | Lower | Effective filtering of ambient noise |
- If you do not have easy access to WEB MANAGEMENT, you can analyse it through Helium Explorer.
| Basis of judgement | Expected | Description |
| Number of RF received packets/day | More | The 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.
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