RF communication (433MHz)

[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

[sirvo]

Bruce, I'll take that explanation then.. I also agree with that.

Thank you all!

[ ]'s

[Bruce]

Sylvio,

You might be able to filter out some noise, and help extend range, by adding a few small capacitors in your receiver circuit.

Start with 0.01uF to 0.1uF, and place them as close as possible to the Vcc and ground pins on the receiver.

Also make sure you have similar decoupling caps between the PIC Vcc and ground pins. Also as close as possible to these pins. If the oscillator isn't located too close to the receiver, this should help.