Any idea for two transmitters one receiver wireless communication module?

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Madakafa

Joined Dec 16, 2016
1
Hello everyone, I am undergraduate electrical engineering student. I have a project for Analog Electronics course. I should design a system which tries to equate the heat of two stations with a controlled cooler with wirelessly received heat information. The system basicly will look like as the picture in attachments. The confising point is that I am supposed to implement two transmitters one receiver wireless communication module. And the minimum distance should be at least 1 meter. What do you think to best way for wireless communication for this project. There may be lots of choses lik using two speaker and a microphone or using two laser and an LDR. I tried to use two laser (with changable duty cycle respect to changing temperature). I can transmit that square wave to my receiver (LDR). But I could not find a solution transmitting two information to a single receiver. Any idea?
 

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WBahn

Joined Mar 31, 2012
26,398
But I could not find a solution transmitting two information to a single receiver. Any idea?
You have to channelize the two transmitted signals so that the one receiver can differentiate them. There are several ways to do this. One is to use some kind of a MAC (medium access control) protocol so that each transmitter knows when to be silent while the other transmitter transmits. But this requires that the transmitters also be equipped with receivers so that they can determine when to transmit. You could have each transmitter transmit its data multiple times with gaps in between that are staggered so that you can ensure that each message will get an opportunity to be transmitted while the other transmitter is silent. You can channel-encode the message using frequency-division multiplexing or direct sequence spread spectrum techniques. You could also use concurrent-code spread spectrum if you have adequate low-level control over the transmitter and receiver.
 

JohnInTX

Joined Jun 26, 2012
4,392
Consider setting the transmitter intervals such that they are not integer multiples of each other with a large least-common-multiple and make the intervals long with respect to the time it takes to send one packet. Send the data with a checksum or CRC to verify its integrity. If they happen to transmit at the same time, the CRC will be bad, discard the data. Next time, they won't be in sync and each packet will get though.
 

ScottWang

Joined Aug 23, 2012
7,007
The output current of non-inverter input is very tiny, so why not just using the same method as inverter input(voltage divider) of the last stage?
 
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