0
\$\begingroup\$

This is my problem. I want to transmit from two transmitters and capture data with a single receiver. I bought two pairs of rf433 and was able to transmit data between each of these rx-tx pairs correctly with ardunio.

But sending from two tx and receiving by one rx was unable to accomplish. Then I tried to find out the reason and here is what I found. These rx and tx modules wont work vice versa. See this diagram:

enter image description here

Since they both transmit 433Mz this also should work fine. If they work in vice versa only, I am able to transmit from two tx.

But I am unable to find out the reason behind this. I would be very thankful if anyone can help with this problem.

Thanks in advance.

\$\endgroup\$
4
  • \$\begingroup\$ Please share the part number or the link of the RF devices. \$\endgroup\$
    – User323693
    Jun 28, 2015 at 9:24
  • \$\begingroup\$ @Umar these are the rf modules rayshobby.net/cart/433-rf \$\endgroup\$
    – Priyankara
    Jun 28, 2015 at 9:26
  • \$\begingroup\$ Are you attempting to transmit simultaneously the exact same data from two transmitters? \$\endgroup\$
    – Andy aka
    Jun 28, 2015 at 10:31
  • \$\begingroup\$ No not simultaneously only at a given time. can you help me with this problem? why can't they communicate? \$\endgroup\$
    – Priyankara
    Jun 28, 2015 at 10:33

1 Answer 1

0
\$\begingroup\$

The transmitters don't transmit at exactly the same frequency - there may be tens of kHz difference - the receiver however is matched to the transmitter and, from what I know and have read about these particular devices, there is a manual adjuster on the receiver to bring it into near-perfect alignment with the transmitter it is paired with.

enter image description here

Notice the screw terminal on the receiver - this is, I believe, an adjuster that can align the receiver's operating frequency with the transmitter. Basically this means that two randomly chosen transmitters are unlikely to be at the same frequency and, as a result, one setting of the screw on the receiver will not suit both transmitters.

They are $5 a pair so you get what you pay for.

\$\endgroup\$
3
  • \$\begingroup\$ Are you sure? I found that on stack overflow. Any idea? \$\endgroup\$
    – Priyankara
    Jun 28, 2015 at 11:49
  • \$\begingroup\$ yes you are right. i tested it now. Thank you very much for the information... \$\endgroup\$
    – Priyankara
    Jun 28, 2015 at 12:00
  • \$\begingroup\$ @Priyankara generally a more expensive receiver will lock onto a slightly different frequency across maybe a 1MHz bandwidth especially those that use FM. The units you have are kind of an exception and with no data sheet to tell otherwise it's just bad luck that they won't work as you expected. \$\endgroup\$
    – Andy aka
    Jun 28, 2015 at 12:22

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.