I suppose to do remote keyless entry (RKE) for door opening as a commercial product, there is DC motor which drive the door to open or close (receiver side), on transmitter side (remote) three button for 'OPEN' ,'CLOSE' and 'STOP'.

I'm new to RF, but I completed this project using a cheap 433 MHz transmitter and receiver model, and made compact size remote with that tx module, both tx and rx module is interfaced with ATmega88PA SMD package. For data processing I used the USART protocol for data transmission.

I'm using 3 V coin cell battery so it has a low range of transmission, but I overcome this with the antenna set, and now I'm getting the expected range (not bad).

The problem comes here: It is interfering with other 433 MHz. There is a water level controller in my company, and it will transmit data continuously for 30 min from the water tank to motor control room. During that time my receiver is not taking my signal since my remote is powered with 3 V, and that water level controller is powered with 9 V using HOLTECH encoder also.

So it's not good idea for selecting modules for commercial products. I want an RF IC for overcoming these problem. It should have its own protocol, since I wasted a month with these modules. It should be easy to configure.

  • 1
    \$\begingroup\$ You might want to rephrase especially the title to make it sound less like a product recommendation question, which are offtopic here, and more like a question to find a solution for your interference \$\endgroup\$
    – PlasmaHH
    Sep 1, 2015 at 7:28
  • \$\begingroup\$ done! @PlasmaHH \$\endgroup\$
    – masternone
    Sep 1, 2015 at 9:45
  • \$\begingroup\$ That frequency band REQUIRES each device not to transmit for more than a specific % of the total time. If the water level controller keeps the channel continuously busy, that device is illegal. \$\endgroup\$
    – FarO
    Sep 1, 2015 at 11:10
  • \$\begingroup\$ You might look at the 2.4 GHz chips/modules - they do more of the signal integrity work on-board and are frequency agile so with a good hopping scheme you can share the band (as you are required to) with other uses. \$\endgroup\$ Mar 12, 2016 at 20:23

1 Answer 1


Changing the protocol will not help ! The water tank system is disturbing the 433 MHz band no matter what protocol you use. The protocol only determines HOW the data is transferred on the channel you're using. You still use the same channel so both systems will still disturb each other.

A solution could be to have your device on a different channel in the 433 MHz band. Here is a list of 433 MHz channels. Try to find out what channel each device uses, maybe they use the same channel maybe not. If they use the same channel maybe you can use a different channel for your device. You probably would have to buy a different transmitter then. Not sure how to determine what channel that transmitter will use. Maybe all cheap transmitters use the same channel.

Another solution will be to use a different frequency band. If the use of the 315 MHz band is allowed in your country (you must check !) you could get a receiver and transmitter at 315 MHz. This will be insensitive to 433 MHz so it will not be disturbed by the other 433 MHz signal.

  • \$\begingroup\$ Lots of devices can share the same band and channel if the protocol allows selection (e.g. the protocol identifies the target receiver by device class or unique ID). Obviously this works best for short, infrequent messages which is what the ISM band is designed for. \$\endgroup\$
    – David
    Sep 1, 2015 at 7:56
  • \$\begingroup\$ thxs moustache and david, i cant select channel the module has only 4 pin (data,vcc,gnd,ant), \$\endgroup\$
    – masternone
    Sep 1, 2015 at 8:44
  • \$\begingroup\$ @david i can identify the receiver only when my signal picked by receiver module and give it to microcontroller,since the water lvl controller sending data continuously my receiver module picking that signal only not my signal \$\endgroup\$
    – masternone
    Sep 1, 2015 at 8:49
  • 3
    \$\begingroup\$ The channel is determined by the frequency of a resonator on the transmitter and receiver, in these cheap devices you cannot change that frequency. I agree with David that the 433 MHz band is for short infrequent messages, not 30 minutes of continuous use like that water tank system ! In other words: the water tank system is not playing nice by using the channel for that long. There's nothing wrong with what you build, the water tank system should be changed actually ! \$\endgroup\$ Sep 1, 2015 at 8:50
  • \$\begingroup\$ Mission accomplished then :-) My pleasure ! \$\endgroup\$ Sep 1, 2015 at 9:34

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