RF Interferance

[Toley00]

First of all I wanna wish you all a very good year 2007.

Recently, a friend tried to convert me to ATMEL AVR/MEGA.
I've try and yes they are faster, yes they are powerfull and yes there's a basic that offer more functions than PicBasic Pro.
But what they don't have is a community like here.
If there's AVR Freaks, we can easily call you PIC Junkies ;).
Thanks to all of you, especially Darrel Taylor, MisterE and Melanie.
You have put PicBasic programming to a higher level!

Secondly, I think it would be great to add a RF topic in the communication section.
It's not easy to find information on RF in the forum since it's only 2 letters long.
But I know how to search on the forum this is not my question :).

Finally enough talking here is my question.
I've build a pair of RF receiver transmitter (rfPIC).
They seems to work good but i'm unable to make them communicate properly cause the receiver looks like it always catch information from another source (I don't know where it come from at this time).
I use the 433.92 MHz band and I think this band is already widely used and maybe saturate...

Is there a way I can safely use this band or I have to change to another "free band" that will also be saturate soon.

Thank you.

[skimask]

Finally enough talking here is my question.
I've build a pair of RF receiver transmitter (rfPIC).
They seems to work good but i'm unable to make them communicate properly cause the receiver looks like it always catch information from another source (I don't know where it come from at this time).
I use the 433.92 MHz band and I think this band is already widely used and maybe saturate...
Thank you.

Are you using them with serial comm's (i.e. serial into the TX and serial out of the RX)?

[Toley00]

Yes this is how I do it for now at 2400 bauds, I will upgrade to a Manchester routine as soon as I'm sure the communication is possible.

But even without my transmitter powered, I always receive random data. That's why I think there's another source around. I don't have any field strength meter, but the receiver chip as a pin who serve to indicate the level of the incomming signal. I put this pin in a ADCIN pin of my PIC and mesure it periodically. With my transmitter ON the reading is about 90-100 and without transmitter I still read around 25-30 and receive random data.

I also made some test with SERIN2 and a wait ($AA,$AA) modifier. Then the random data did not enter but mine is not read all the time I said about 1 time on 25. This is another fact that make me think I'm not the only one using this 433.92MHz Band...

Today I'm gonna take a walk and find a place where I don't receive any interferance and make some test there. I just wish I don't have to go 250 km far at the cost of gaz ;).

[Dave]

Toley00, What do you mean "catch information from another source "? Does the receiver have a squelch control? If not then the data slicer is probably picking up noise when there is no transmission. What protocol are you using? are you looking for a "sync byte or period"? are you trying to connect the receiver directly to an RS232 port?

Dave Purola,
N8NTA

[Toley00]

Hi Dave, I think I was in the wrong track. Effectively what I received seems to be only noise and not "another source" (I probably watch to much X-Files when I was young ;)).

My receiver's output is connected to a PIC who show the results on a LCD.

Now I'm working on a protocol and it's not as simple as I first think. For a first test, I try to send only 3 bytes of data but I expect to be able to send more. I convert them to Manchester but now I have to send 3 words. I send before 2 times $AA I read here that it's necessary for the receiver to adjust is AGC.

My problem is that I use the SEROUT2 command to send data but it has to be 8 bits wide and I'm unable to seperate word array into lowbyte and highbyte. I receive an error message.

SEROUT2 DATPIN,16780,[$AA,$AA,MAN[0].LOWBYTE]

ERROR Line 47: This style array syntax not supported, (rf675tx02.bas)

Do I have to use independant word variable for each manchester encoded byte or is there another way ? Is the SEROUT2 method is not appropriate for this kind of comminucation ?

I've put a lot of time in this project and really want this to work so any help will be very appreciate thank you.

[skimask]

Hi Dave, I think I was in the wrong track. Effectively what I received seems to be only noise and not "another source" (I probably watch to much X-Files when I was young ;)).

My receiver's output is connected to a PIC who show the results on a LCD.

Now I'm working on a protocol and it's not as simple as I first think. For a first test, I try to send only 3 bytes of data but I expect to be able to send more. I convert them to Manchester but now I have to send 3 words. I send before 2 times $AA I read here that it's necessary for the receiver to adjust is AGC.

My problem is that I use the SEROUT2 command to send data but it has to be 8 bits wide and I'm unable to seperate word array into lowbyte and highbyte. I receive an error message.

SEROUT2 DATPIN,16780,[$AA,$AA,MAN[0].LOWBYTE]

ERROR Line 47: This style array syntax not supported, (rf675tx02.bas)

Do I have to use independant word variable for each manchester encoded byte or is there another way ? Is the SEROUT2 method is not appropriate for this kind of comminucation ?

I've put a lot of time in this project and really want this to work so any help will be very appreciate thank you.


See Section 7.6 of the PBP manual. All questions will be answered there pertaining to your errors.

[Toley00]

I may be wrong but I believe that PIC12F675 has a 14 bits core even if it's a 12F series.

[skimask]

I may be wrong but I believe that PIC12F675 has a 14 bits core even if it's a 12F series.

rf12F675 = 12 bit
12F675 = 14 bit
don't ask me why...you'd figure they'd give them different designations or something...