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Topic: HC-SR04 and Ultrasonic target direction sensor (Read 4148 times) previous topic - next topic

akkotaire

Magician, thanks I will look into that !


How fast target is moving in both left and right and toward and away?  As well as how big is the target?  How much space to mount your transmit pinger on the target?

Target would be moving to a maximum speed of 35km/h in any direction but usally the receiver unit would be following simillar speed vector.
Target is a human, so I am planning on mounting the transmitter on the head to get a 360 degree possibility of beacon.
Quote
Concerns on 45 foot distance with ultrasonic.

My budget is bigger then the 3$ a HC-SR04 cost so I could go with better ultrasound units.
Why are you concerned for a 14m distance ?

Thanks

bsod666

Correct.   

Read more how HC-SR04 works,  on-board uCPU,  that generates a pulse with a length proportional to distance, starts the sequence only after you trigger "send" pin. So , it sends a pulse and wait a response.  In your model with 3 units, one as a transmitter and two as  receivers, you would need some way to synchronize 3 units, because receivers also needs  "start" events (even it doesn't send anything - transmitting piezo removed) in order to switch in "listening" mode. You may use cheep 315 - 434 MHz radio for this.
 It would be still possible to build an "asynchronous " system, when two receivers get same "trigger" events periodically,  not necessarily the same time with transmitter. For example, transmitter pings each 1 sec a pulse. You trigger receivers also every second, but doing so signal may arrive immediately or at the end of period. It's not important, if you don't need to know a distance, just an angle. Than you get just a difference in between arriving
 Now, this guy in a link you posted, build two receivers on himself, most likely he is also did just analog part w/o special uCPU for each receiver. Your options - modify cheep HC-SR04 or solder your own.  This uCPU, that build-into HC-SR04,  does some noise measurements and keep adjustment of the comparator , so if you are not really into analog design, better to modify cheep unit.
 I'd suggest, start to experiment, have a scope?

Excuse me. How to know the signal arrived? U said to calculate difference between arriving right. Can u guide me on how to get that arrival difference values

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