Not able to work with 2 RF modules..

[laxman3018]

i am working On a project where i am sending signal from pc to a ROBOT car by RF modules(433mhz) ..transmitter is connected to my pc by microcontroller and reciever is on car..
and there is one more pair of RF module(433mhz) whose trasmitter is on ROBOT car and Receiver is connected to my pc through microcontroller..
BUT problem is that when i am switching on both RF module then non of them are working....If i am switching off one RF module then other is working vice versa..
what is the problem...????

 

[MikeMl]

It is called "duplex" transmission. You cannot simultaneously transmit and recieve at one location using the exact same or even nearby frequencies, because the transmitter blocks the receiver. To make this work, one link could transmit on 433Mhz and the other on 2.4Ghz, for example.

Or as you have already found out, you can use "simplex" transmission, where the two transmitters are never keyed simultaneously, but alternatively.

 

[laxman3018]

can i use 433MHz transmitter and 315 mhz transmitter

 

[laxman3018]

It is called "duplex" transmission. You cannot simultaneously transmit and recieve at one location using the exact same or even nearby frequencies, because the transmitter blocks the receiver. To make this work, one link could transmit on 433Mhz and the other on 2.4Ghz, for example.

Or as you have already found out, you can use "simplex" transmission, where the two transmitters are never keyed simultaneously, but alternatively.

how to do this simplex transmission.....

 

[MikeMl]

can i use 433MHz transmitter and 315 mhz transmitter

Maybe. You will have to separate the receiver antenna from the transmit antenna as much as possible. Tough to do on a robot

 

[MikeMl]

how to do this simplex transmission.....

The normal state is that neither transmitter is keyed. If the controller needs to send a packet to the robot, it first checks to see if the robot receiver is busy. It sends out a short packet only if there is no signal being received. Reverse the roles of transmitter and receiver at the Robot. Key is to make the packets short, and always leave some dead time between them, so that if the other end has a pending packet to send, it gets the chance.