Transmission works with wires but not always with wireless

[Jerson]

I am using the Laipac 315 MHz RF modules and I serout only once and it works with wires 100% of the time. When I try wireless it works once in a while. On the other hand, when I serout 5 times the wireless works most of the time but does not work once in a while. I have added 4 $55s for a preamble and manchester encoded everything.

JYI1:

Firstly, I feel a name is more suited to talking in a forum. Anyway, after seeing your code, I do feel you can look for the 55,aa alone as the marker to your data. You may not see the 4x55s followed by the aa considering that the Laipac receiver module is ASK(correct me if I am wrong).

I have used similar modules with PIC and implemented a wireless joystick which works like you say almost 100% of the time. There is an occasional hiccup due to which I would not get 100%. To achieve this, I know that RF shielding of the receiver is priority #1. I did not Manchester code my data, that could be the reason for the almost 100% accuracy. Also, the modules I have used (Summitek) specify the data rate in the region of almost 1200 baud and not 2400 baud as you use. Perhaps you need to look into this as well.

Jerson

[jyi1]

Yes Laipac uses ASK and has 2400 bps. I do not understand why the $55,$55,$55,$55,$aa is not always picked up by the receiver when I send it once. It seems like I need to send it the same thing 5 times for it to pick up reasonably well.

[Jerson]

The module needs time to get above the noise floor before it can decode the $55 stream correctly. That is why I suggested to just look for the $55,$AA in your code; you still have to transmit the $55s before you send the $AA. Those should be considered as padding and ignored in the receiver. You may increase it beyond the 4 that you have now to improve performance if you will.

Transmit $55,$55,$55,$55,$55,$AA,"data"
Receive .................."ah there it is","data" You ignore the first 4x$55


Jerson

[jyi1]

So I should basically send a couple of $55 and then just wait for $55, $aa only?
I'm thinking of coding it like: serin2 PORTB.0, 16780, [WAIT($55, $aa) ,encoded1], would this be good enough?

[Jerson]

I think you got the point. Still, tell us your name. JYI1 sounds like a name from the new StarTrek series

Jerson

[jyi1]

I think you got the point. Still, tell us your name. JYI1 sounds like a name from the new StarTrek series

Jerson

I discover that even if I send $55 4, 6, 8, 10, 20 times but it still picks it up occasionally. On the other receiver end I am looking for $55, $aa.

[dhouston]

I have used these extensively (although I get mine direct from WenShing in Taiwan). These are superregenerative ASK receivers. They need a pronounced preamble in order to set the AGC and receive threshold. They work quite well at low data rates using a protocol like the NEC protocol (used by X10 for their wireless remotes) which I've detailed here...

• http://davehouston.net/rf.htm

You might also benefit from reading this page...

• http://davehouston.net/rf-noise.htm

You need a fairly good balance between pulses and spaces (which Manchester encoding guarantees) but the fact that you need to send several copies in order to receive reliably indicates you need the initial copies to set the threshold and AGC.

Which output pin are you using? Using the linear (analog) output can complicate things. It's usually best to use the digital output. A good receiving antenna is important. An eggbeater is easy to build and matches the 50-ohm input impedance of the receiver.

• http://davehouston.net/eggbeater.htm

You can capture the output(s) from the receiver using a soundcard as I show here...

• http://davehouston.net/learn.htm

which can give you an idea of the quality of the signal as received.

Bruce Reynolds sells the 433.92MHz version of this receiver. I believe he has some example projects with PBP code on his website.

BTW, the fact that your code works with a hardwired connection is another indication that your problems are related to RF signal quality.

Good luck.

[mpardinho]

i had many bug with RF 433mhz
try pause 5 to pause 50

im my circuit pause 5 word perfect
without pause not work for me

my simple test

   ...
transmiter:
   for i =  1 to 30
      serout data_out, N2400, ["<", "A", "B", ">", i]
      PAUSE 5
   next i

   ...
receive:
   serin data_in, N2400, "<ABDC>", TIME_OUT, I
   if i=1 then .........

TIME_OUT:
goto receive