Using 2 Ultrasonicsensors for localisation

Hi everyone,
i am trying to handle a project, where i want to locate the transmitter (also a ultrasonic sensor) with a few ultrasonic sensors.
I want to use 3 sensors (all in the air) to receive the trigger-signal from transmitter 1 (on the ground). But it actually doesn't work that 2 sensors work together in that way, that sensor 1 is sending the signal out and sensor 2 is receiving the trigger-signal from sensor 1 (his echo). I tried to put some paper on the trigger of sensor 2 (i only need the echo!), but then the Arduino gave out 0 cm.
Both sensors are working individually perfect. But sensor 1 doesn't register the trigger-signal from sensor 2 and the same problem on the other way.
I hope, that someone can help me to fix this problem or if it is not possible,to tell me this.
Enclosed my code.

Best regards


int maximum_distance=700; // should not irritate-> in "one" direction is the distnce unnecessary
int minimum_distance=2;
double measured_distance;
double bygone_time;
void setup() {
pinMode(7,OUTPUT);//Trigger Arduino Sensor 1
pinMode(8,INPUT);//Echo Arduino Sensor 1

pinMode(12,OUTPUT);//Trigger Sensor 2 //paper on it
pinMode(13,INPUT);//Echo Sensor 2


void loop() {





Serial.println(bygone_time); //to overview

measured_distance=bygone_time*0.03432; //temperature irrelevant, if the Project doesn't work
if(measured_distance>=minimum_distance && measured_distance<=maximum_distance)
Serial.print("Distance: ");
Serial.println(" cm");
Serial.println("Distance to short");
Serial.println("Distance to long");


By the way, i am using HC-SR04 sensors

This will not work, stop trying.

Same post here;

do you know, if there are alternative sensors on the market, which make this possible?

I know, there are systems that can accomplish it, but I can not give you links.
Many newer systems use cameras.

Like here:

Not sure I understand the OP's project, but maybe the following project of mine is in the ballpark:

I had two Arduinos and called one the "master" and the other a "slave." The master has a NRF24L01 radio and an unmodified HC-SR04. The slave has a NRF24L01 radio and a modified HC-SR04.

The slave's HC-SR04 was modified by unsoldering its transmit transducer.

I used the NewPing library.

The system operates like this:

The "master" radio transmits a packet, triggers its HC-SR04 using, waits "x" seconds, repeats. (The master does not use the value that returns.)

The "slave" waits for a radio packet from the master. When the slave's radio receives a packet, it triggers its HC-SR04 using, reports the distance on an LCD (which will be half the distance between the master and slave), and then waits for another packet.

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