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Topic: communication between two JSN - SR04T (Read 2249 times) previous topic - next topic

lukasSirh

Hi, I stand before the question of whether the two sensors can communicate with one to another.
I try to set one sensor to sending and another sensor set to receiving. But i can't capture any signal on the receiver.

Please can anybody tell me if this is feasible. Thanks a lot.

pylon

You didn't provide a link to that product!

If it's the distance measuring sensor that Google finds I guess that the onboard electronic does ensure that your "communication trick" does not work. The sensor will listen for an echo only during a short time after it has sent a signal. That's only guessing as I don't know exactly how that sensor works.

DaveEvans

#2
Oct 17, 2017, 10:09 pm Last Edit: Oct 18, 2017, 01:37 am by DaveEvans
It depends on what you mean by "communicate." 

If you trigger them both at the same time, then when unit A receives the signal from unit B, it will tell you the half distance to unit B (and vice versa).

Unfortunately, if unit A happens to receive a reflection from its own signal before the signal from unit B arrives, it will tell you the distance to the reflecting object, not unit B.

If you only need "one way" communication and don't need the sensors to be waterproof, then you can fix the reflection problem by using HC-SR04 sensors and removing the transmitter transducer from the "receiving" unit.

lukasSirh

Hello,

link to the sensor: ultrasonic-sensor

And my use-case is: Use first sensor for send frequency to second sensor which is set up only for listening.
Second sensor be some-how (for now i dont know how) in water with battery (again i dont know which one) and will waint for signal after it receive signal will do some operation. First sensor will use for send some frequency signal to the first sensor. So first sensor will communicate to the second sensor. And the communication will be maybe realize with FSK.

So for now:
I have two this sensors, the first sensor produce some signal every 4 milisec and the second sensor only listen.
For inspiration i look at NewPing libraly to know how to set up sensors only for sending and only for listening.

But for now it doesnt work  :smiley-confuse:

DaveEvans

You are proposing to use that distance sensor in a completely non-standard way.  Good luck with that.

In post #2 I told you the easy way to set up a sensor to be a "receiver" (trigger transmitter and receiver  at the same time).  But if they are underwater and not connected by wires, good luck with that.

Another way to make a remote receiver would be to poll the output of one of the amplifying op amps downstream of the receiving transducer.  That can be done with the HC-SR04; I don't know if that could be done as easily, if at all, with your sensor, with its one transducer.  To do that, you would need to understand the schematic and operation of your sensor.  And you would need to have the skill to solder a connection to the proper location on the PCB.  Polling the output of an op amp wouldn't give you any distance information (unless you knew when the transmitter sent its pulse), but it would let you know that the receiver had received a signal from somewhere (or noise).   Good luck with that, too.

lukasSirh

You are proposing to use that distance sensor in a completely non-standard way.  Good luck with that.
Yes you are right :) , i want to use this sensors for sending and receiveing some frequency signal based on FSK.
I guess this sensors when received any signal (noise you said) send true to the input pin.
But i dont know if is there any synchronization during triger and echod signal :(.

Do you know any other possibility?

DaveEvans

#6
Oct 20, 2017, 07:23 pm Last Edit: Oct 21, 2017, 03:20 am by DaveEvans
But i dont know if is there any synchronization during triger and echod signal :(.

Do you know any other possibility?
Another possibility was described in my third paragraph in post #4.

jremington

#7
Oct 21, 2017, 02:45 am Last Edit: Oct 21, 2017, 02:46 am by jremington
Quote
i want to use this sensors for sending and receiveing some frequency signal based on FSK.
You could use the transmitter and receiver piezo elements, but for FSK signals, you will have to design and build all your own electronics.

DaveEvans

#8
Oct 21, 2017, 08:18 am Last Edit: Oct 21, 2017, 08:20 am by DaveEvans
Seems like a sort of OOK might work...

a. IF the device can be hacked to make a transmitter that can send the normal 8 pulses at any time (and not wait for an echo), and
b. IF it can be hacked to make a receiver (by the method mentioned in the 3rd para above in post #4).

After some initialization/synchronization transmission, to tell the receiver to get ready, then communication begins at regular intervals, where a train of pulses = 1 and silence = 0.

If slow OOK would ok, the hack mentioned in a. might not be necessary: would have to wait for the transmitter to time-out (from not receiving an echo...about 38 ms) before transmitting again.  That would control the interval timing.

lukasSirh

Seems like a sort of OOK might work...

a. IF the device can be hacked to make a transmitter that can send the normal 8 pulses at any time (and not wait for an echo), and
b. IF it can be hacked to make a receiver (by the method mentioned in the 3rd para above in post #4).

So do you mean that the device must be "physicaly" hacket? As i wrote i used NewPing  library for inspiration.

So i use some code from boolean NewPing::ping_trigger() for "transmitter".
And receivers input set up to listenig view digitalRead() arduino nativ method.


Another way to make a remote receiver would be to poll the output of one of the amplifying op amps downstream of the receiving transducer.  That can be done with the HC-SR04; ....
But i need waterproof device. On the other hand its may be good proof of concept.

DaveEvans

Second sensor be some-how (for now i dont know how) in water...
But i need waterproof device.
What do you mean by "in water"?  Do you mean: (1) below water, as in "underwater" or (2) in water, as "in a boat and might get splashed or occasionally wet"?

lukasSirh

What do you mean by "in water"?  Do you mean: (1) below water, as in "underwater" or (2) in water, as "in a boat and might get splashed or occasionally wet"?
I mean in water as "underwater".

DaveEvans

Does this sensor work (in the normal way, as a distance sensor) underwater?

jremington

For ultrasonic transmission to work in water, you must use a transducer designed for working in water.

They are quite expensive.

lukasSirh

Does this sensor work (in the normal way, as a distance sensor) underwater?
I dont know now :( i just try it at my desk, but according documentation this sensor might work underwater and like waterproof distance sensor.

I try it at my desk at first because i need proof if those two sensors can communicate between each other.

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