RF communication (433MHz)

[sirvo]

I think that might be the answer to your question. The faster one is using more power so less is available to the transmitter.

As I editted:

The batteries were brand new, 16500mAh, with top current of 400mA. The TX current of RXQ2 gets at most a peak of 16mA)

The delta current between crystals is about 0,1mA. It's too small to cause an effect using this powerfull battery, don't you agree?

Thanks!

[Ioannis]

Have you tried to exchange the modules (only modules, not the antennas or the PIC driving part) and see if there is any difference?

Ioannis

[sirvo]

No, I haven't yet..

I'll do the exchanging and let you know the answer.

Thanks again.

[rsocor01]

Sirvo,

Are you sure all the modules are transmitting at the same frequency? The higher the frequency the higher the transmitted power, but also the higher the frequency the higher the attenuacion. Longer wavelenth signals travel farther than shorter wavelength ones.

Robert

[sirvo]

Hello Robert,

The firmware uploaded to pic is the same for every device. Therefore, all the RF frequency are the same. In this case, 433.1MHz (RXQ2 allows the range 430.0 to 440.0MHz, 200kHz step).

About the RXQ2 exchanging test, I have done that today. And the answer is: Still the same weird thing. The board with 2MHz crystal gets further than the 4Mhz one....

So, the RXQ2 is not the problem.. then, what is it???

[ ]'s

[Bruce]

then, what is it???

It's the 4MHz oscillator in your receiver circuit, which introduces more noise, which reduces receiver sensitivity, which = shorter range...;o)

[Ioannis]

After your results I too agree with Bruce. What can you do? Just use metal screening of the 4MHz osc to reduce harmonics transmission reaching RF receiver input.

Also changing frequency may help but my guess is not very much.

Ioannis