RF Transmitter Receiver Recommendation?

[mackrackit]

I would recommend anything from here.
http://www.rentron.com/PicBasic/RemoteControl.htm
The TWS-434A and RWS-434 is what I would try from your project description.

To receive data from different transmitters into one receiver, each transmitter could have a unique value in the checksum. Then the receiver MCU will know where the data came from. Lots of possibilities here.

[markedwards]

Thanks Dave for the recomendation. The Rentron parts look perfect. I'm not sure how to deal with multiple remote transmitters trying to send data at the same time. I'm thinking transceivers might be easier, I can request data from the selected remote.

Mark

[mackrackit]

I'm not sure how to deal with multiple remote transmitters trying to send data at the same time

If the remotes are constantly sending data then you should be good with sending an ID.
What you basically do is treat the ID like a checksum. If the checksum is correct the data is saved/used. Same with an ID. If ID=r1 then data is from remote #1.

[ardhuru]

If the remotes are constantly sending data then you should be good with sending an ID.
What you basically do is treat the ID like a checksum. If the checksum is correct the data is saved/used. Same with an ID. If ID=r1 then data is from remote #1.

Dave, in that case wouldnt there be constant collisions in the incoming packets, affecting the validity of the actual data seen by the receiver?

Anand

[mackrackit]

Dave, in that case wouldnt there be constant collisions in the incoming packets, affecting the validity of the actual data seen by the receiver?

Anand

Receivers are constantly being flooded with noise from everywhere. That is why the checksum or some other way of knowing if the signal being received is good or data we are after. If the ID is part of that then we know the data is good and where it came from.

[ardhuru]

No, thats not what I meant; if all transmitters are transmitting together, wont the receiver ALWAYS see a 'composite' signal thats actually a mix of more than one signal?

Anand

[dhouston]

It's not likely that all transmitters are transmitting all the time. Most jurisdictions have rules limiting such transmissions to intermittent transmissions spaced well apart.

In that scenario, building in both an ID byte and error checking is sufficient. The NEC protocol (used by X10 for ~40 years) works quite well. There's a PBP example at http://davehouston.org/PIC-RX-TX.TXT. If you need to send more than 2 payload bytes, you can extend this.

Transceivers that transmit only when queried also work quite well but at large increase in cost. The simple transmitter and receiver like those Bruce sells are inexpensive and available from many sources worldwide. http://davehouston.org/modules.htm