RFXtrx433 NoiseLevel questions

[DenisMartin]

Hi all,

In hardware viewer, noise level measured by RFXtrx is displayed in dB :

dB.jpg (11.78 KiB) Viewed 2662 times

On RFXCOM blog it's written that a level at 92 or below is ok with the standard antenna.

When I asked, the RFXCOM support answer me that the value of RF noise level that come from the RFXtrx is not a dBm value but a converted voltage level. I assume that it is kind of an amplitude detected by a power detector.

If so, imho, there is three options :
- If the 'converted voltage' is given in linear scale and we can convert it to dBm
Convert the voltage from RFXtrx to a negative dBm and display it like -80dBm
The lower the better (-92dBm is less noisy than -80dBm)

- If the 'converted voltage' is given in linear scale and we can't convert it to dBm.
Keep the voltage as it is, but remove the 'dB' mention on the hardware screen
The lower the better because it's related to 'noise amplitude' (60 is better than 90)

- If the 'converted voltage' is given in logarithmic scale, displaying it in dB is correct (and my post is useless )

What do you think ?

[niki_lauda]

My data
RFXCOM - RFXtrx433 USB 433.92MHz Transceiver
Version: Pro XL1/1028, Noise: 100 dB

So 100 dB is not a good score?
How can I improve it?
It is just an of the shelf Pro XL1/1028. Is it the position in the room/house? Do I need an better antenna?

[b_weijenberg]

Find a place with the lowest possible RF noise that is as far a possible away from RF sources like routers, Raspberry PI...
The receive range will be lower if a higher RF noise value. Even 100 is OK if you receive all your sensors and remotes.

With RFXmngr on a Windows laptop it is easy to find the best location. On each location press Reset in RFXmngr and the new RF noise value is displayed.
In Domoticz select Setup - Hardware, select the RFXtrx433 and click Update to see an updated RF noise value.

[azonneveld]

It also depends on the antenna used. My noiselevel with antenna is 94 db, without antenna ca 55 db.
I am using a Nagoya NA771 antenna, which provides significant better performance than the original antenna.

ps the original antenna is way too long, ca 25cm instead of 16.8 which is ideal for 433mhz.