problem with sending data using RF module

[mister_e]

Seems to be the one you're using right?
http://szyishi.en.alibaba.com/produc..._Receiver.html

5. Output of receiver module come with noise, also can be no noise in case of special requirement, but the receiving sensitivity will be reduced

[rano_zen06]

Seems to be the one you're using right?
http://szyishi.en.alibaba.com/produc..._Receiver.html

yes, the model is what I'm using right now. It says the output come with noise and it seems like the main problem.Is there any chance for the receiver to get the sending data clearly without noise If I connect the data pin to LM 741 ?

[mister_e]

as i said you could use the internal analog comparator instead.

[rano_zen06]

as i said you could use the internal analog comparator instead.

ok..now there is 3 pin for comparator inside the 16F877A. How do I connect it with my
Receiver..?? I'm just a little bit confuse with C1out and C2 out which is port A.4 and Port A.5. What's the different between these 2 pins ?? which one should I use? and what is the instruction to turn on the internal comparator??

[mister_e]

OK, i'll start a new thread later about how using the internal comparators.

Do you have any oscilloscope?

In meantime you could do some test with an external comparator... LM339 and.. yeah lm741 or any other op-amp COULD work.

[rano_zen06]

OK, i'll start a new thread later about how using the internal comparators.

Do you have any oscilloscope?

yes, there's a digital oscilloscope at my lab. But at this time, my lab still not open for student. It's just 6.30 in the morning here..so, must wait for 2 hour before I can use it.
I will use the oscilloscope later to check the output of RF module.Then I will attach the picture of TX and Rx signal for your review.

[dhouston]

Almost all (in fact, all of the many that I've used) ASK RF receivers have a dataslicer just before the digital output. The dataslicer uses a comparator (as I explain at http://davehouston.org/RFTipsTricks.htm). Adding another comparator might be useful for educational purposes but is of little practical value (IMO). In this case, the only output from the receiver is digital so the noise pulses will have the same amplitude as the data and the duration of the noise pulses are likely to be nearly the same as the bit period. What kind of comparator circuit are you planning?

It is far simpler to use a relatively wide sync pulse followed by the data. The receiver can look for the sync pulse and only after receiving it, look for the data. The data can use almost any protocol desired, including RS232 with or without manchester coding. The single, wide sync pulse works much better than multiple $55 sync bytes. I also recommend sending 3 or more copies of each packet, including the wide sync pulse.

[dhouston]

yes, the model is what I'm using right now. It says the output come with noise and it seems like the main problem.Is there any chance for the receiver to get the sending data clearly without noise If I connect the data pin to LM 741 ?

If you read the page I referenced earlier, it gives you a method for dealing with the noise.