Bandpass filter?

[eigenphase]

I am suffering from reception issues with my setup although I am using the right hardware I think (NooElec NESDR Nano 3, external 433MHz antenna).

I only need to receive 433MHz signals; now I have heard I could add a bandpass filter. This makes sense because then all the blockers and other signals would be filtered out and the SNR should increase. However, there will also be a few dB of insertion loss and probably additional matching losses.

I wonder why I could not find anything related to rtl433. Is this a good idea and if so, any recommendation for a 433MHz bandpass filter?

[zuckschwerdt]

Record your band and check it for interference. https://triq.org/rtl_433/ANALYZE.html
If there is a source of interference then shift the frequency away from it.

A bandpass on already only 250k is not really recommended.

[eigenphase]

Record your band and check it for interference. https://triq.org/rtl_433/ANALYZE.html

Ok, let me try this, even though intermittent interference I would not see with is.

If there is a source of interference then shift the frequency away from it.

That I couldn't because the frequency of my devices is fixed, right?

A bandpass on already only 250k is not really recommended.

Oh got it, so anti-aliasing filter of 250Hz bandwidth exists already? Then, I agree, noise would not be decreased. But it comes after the AFE, so a blocker could still saturate the AFE.

Btw, do you have suggestions to tune and optimize -g, -f and -p in a systematic way (without just trial & error)?
I tried shifting upwards a few kHz yesterday (-f 433940000) but nothing really changed (neither worse nor better).

PS: I only control the receiver, my transmitters are a mix of 11, 23, 73, 280 and custom decoder for Reolink.

[serialrf433]

There are many different types of antennas. In such cases like you described playing around with different antenna types is in most cases the best solution.