Wireless FM remote control.

[fuzzy]

Hi

I'm programming a remote relay controller using PIC.

Pic sends serial (rs232) data trough wireless 433MHZ or 868MHZ.

Transmitter sends some code bytes and receiver gets on serial receiver and decode those bytes.

I use a lot of different codes so that receiver can only be swithced on by its own transmitter. receiver stops working in the moment it doesn't receive data from its own transmitter. Transmitter doesn't send a stop code(i think it's more secure).

The problem is that in that way i can't use 2 or more devices couple at the same time in the same place.

Can you suggest me a way to use them at the same time?

Thanks a lot

[Guest]

Send an address preamble with the data - All receivers look for and respond only to their own address.

HTH - Steve H.

[fuzzy]

It's not address problem. Any transimtter has it's own address. and receiver works only with its own address. but i need 2 or more couples working at same time.

sharing the same frequency.

[Guest]

Ethernet (and other network schemes) have methods to handle data collisions by sending CRC codes and if errors are received (meaning they get corrupted by another transmitter) then the transmitter trys again. When you share the same 'wire' or frequency this is the only way I know of to handle data collisions. This method, however requires transceivers on both ends.

If you only have transmit on one side and receiver on the other than you will have to figure out (statistically) how many times you need to transmit the data so that the receiver is assured to get at least one good reception packet.

Then every transmitter will need to send multiple packets every time.

If the transmitters are all transmitting continuously then you are at a dead end with your proposed scheme as you cannot prevent one transmitter from drowning out a neighbor. Without some sort of spread spectrum the receivers can't be prevented from being 'blocked' by the wrong transmitter.

HTH - Steve H.