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Using Arduino => General Electronics => Topic started by: bordeaux270993 on Jul 07, 2016, 10:02 am

Title: Ultrasonic Waves
Post by: bordeaux270993 on Jul 07, 2016, 10:02 am
Hello,

First, sorry for my poor english.

I would like to use an ultrasonic Transmeitter/Receiver separatly. I mean i don't want a transceiver like this one: SRF05.

I would like to plug a transmitter (400ST120 for instance) on ONE Arduino and a receiver (400SR120) on an SECOND Arduino.

My question is: how do i connect them to the arduino. And how did i manage to send a wave and to receive it?

My second question: Will i need amplifier pass Band filter or other electronics component?


Thanks for helping me, i hope i make myself understood.

Yours faithfully.
Title: Re: Ultrasonic Waves
Post by: OldSteve on Jul 07, 2016, 10:44 am
On the transmitter side, you need to provide a signal at 40kHz. Preferably at a voltage higher than 5V for maximum range. (The 400ST120 is rated for 20Vrms, (56.6Vp-p).)

On the receiving side you need an amplifier and band-pass filter or tone decoder etc. as you say.

Using these transducers is not trivial, but a Google search will reveal plenty of potential circuits.
Title: Re: Ultrasonic Waves
Post by: bordeaux270993 on Jul 07, 2016, 11:16 am
Ok i understand but i am not pretty sure to know how handle it.

I find a publication where they use this transmeitter and receiver. i have a picture of a circuits, but there

is a lot of component and i am not sure they are all useful. The picture of the circuit is attach. I'm not

really good in analogic electronics, can you tell me what you think about it and if it i have to go with this

for the realisation of my project.


I want to use it with an arduino so i am not sure that i can provide more than 5V, will it be a problem?

Thanks for helping me.
Title: Re: Ultrasonic Waves
Post by: OldSteve on Jul 07, 2016, 11:25 am
I can't help further. I have no idea how well that circuit will perform. Ideally you need to build it as a test circuit, maybe on a breadboard, and see how it performs.

Regarding driving the TX transducer with 5V, again, I don't have the answer. You probably won't get much range.
Ideally, you should make a driver stage powered by a higher voltage, then use a timer or PWM on the Arduino to generate the 40kHz waveform.
Title: Re: Ultrasonic Waves
Post by: Whandall on Jul 07, 2016, 11:38 am
I would like to use an ultrasonic Transmeitter/Receiver separatly.
Please explain how you want to use such an arrangement.

What are you trying to achieve?

Merely bedazzling bats would not need a receiver.
Title: Re: Ultrasonic Waves
Post by: bordeaux270993 on Jul 07, 2016, 11:39 am
Ok! Thanks anyway. I think it will be more difficult than i was expected!

I will do my best thanks for the information.
Title: Re: Ultrasonic Waves
Post by: Whandall on Jul 07, 2016, 11:50 am
I think it will be more difficult than i was expected!
What is 'it' ?
Title: Re: Ultrasonic Waves
Post by: bordeaux270993 on Jul 07, 2016, 11:56 am
I want to get the position of an object which is in movement. This object (i will call it O1) will be holding

an US transmeitter and a RF tranceiver. On the ceil i will set up many US receiver (R1) with a main

receiver with a RF tranceiver (R2).


O1 send a RF wave which is received by R2. As soon as R2 receive it, it replies an ACK answer and start a timer.

When O1 receive the ACK answer, it sends an US wave. Each time an R1 receives the US wave, it sends

a pulse to R2 which record the time and then compute the distance between R1 and O1.

Then the position is computed with trilateration.
Title: Re: Ultrasonic Waves
Post by: bordeaux270993 on Jul 07, 2016, 12:11 pm
On the first part of the project's development, i don't need the maximum range,  two meters will be enougth.
Title: Re: Ultrasonic Waves
Post by: Whandall on Jul 07, 2016, 12:34 pm
This will be more difficult than you expect. IMHO
Title: Re: Ultrasonic Waves
Post by: bordeaux270993 on Jul 07, 2016, 01:39 pm
I know i have two month for make it functional. i love challenged even if it's scared me!

I take all the advice you have, especially with this topic ( how to use a US wave!), the rest i know how to manage it.
Title: Re: Ultrasonic Waves
Post by: rosemerry on Jul 07, 2016, 04:13 pm
are you from france ?
Title: Re: Ultrasonic Waves
Post by: bordeaux270993 on Jul 07, 2016, 04:37 pm
Yes! Why i have such a bad english?  :o

I saw on an old topic that there are transmeitter/receiver with amplification filtration and all this staff

already embedded with the transmeitter/receiver. But i don't find any of them on the web!

Can any one provide me a name of such transmeitter receiver?


And another question: Do you think i can use a transciever like this :http://www.robot-electronics.co.uk/htm/srf04tech.htm

I mean use two of them and make the transmeitter from the first one communicate with de receiver of the second one?

Thanks!
Title: Re: Ultrasonic Waves
Post by: rosemerry on Jul 07, 2016, 04:44 pm
Yes! Why i have such a bad english?  :o

I saw on an old topic that there are transmeitter/receiver with amplification filtration and all this staff

already embedded with the transmeitter/receiver. But i don't find any of them on the web!

Can any one provide me a name of such transmeitter receiver?


And another question: Do you think i can use a transciever like this :http://www.robot-electronics.co.uk/htm/srf04tech.htm

I mean use two of them and make the transmeitter from the first one communicate with de receiver of the second one?

Thanks!
j'aime l'idee de projet , mais je n'admire pas la methode avec laquelle tu veut le faire , qu'est ce que tu veux apprendre a travers ca ? . en+ je croie qu'on peut mieu te comprendre si tu publie dans la section francaise de forum arduino .
Title: Re: Ultrasonic Waves
Post by: bordeaux270993 on Jul 07, 2016, 04:58 pm
Je ne savais pas qu'il y avais une section fran├žaise ! autant pour moi.
Title: Re: Ultrasonic Waves
Post by: MrMark on Jul 07, 2016, 05:38 pm
In this thread (Using HCSR 04 for communications (http://forum.arduino.cc/index.php?topic=390144.0;nowap)) I posted some comments about my experiments in communications via ultrasound that you might find of interest.  The issue I see with what you've proposed is that there will be echos from any transmit device that will greatly confuse the interpretation of the received signal at any site.

At least two approaches come to mind.  First would be to perform signal processing on the received signal prior to detection to determine and remove the channel characteristics (the echos).  This would require far more processing power than a typical microcontroller and non-trivial mathematics. 

A second approach that might be workable is to have a known station-dependent delay on each of your receivers that allows the echos from any previous transmission to die out prior to responding.  For example R1 might, upon hearing a pulse, disable listening for 100 milliseconds and respond after 10 milliseconds.  R2 would do the same except it responds after 20 milliseconds and so forth.  T1 then calculates the round trip time to R1 as the time the first pulse is received in the window 10 to 20 milliseconds after its transmission minus 10 milliseconds, and so forth . . .
Title: Re: Ultrasonic Waves
Post by: allanhurst on Jul 08, 2016, 12:46 am
Hi ..

 Why not do the whole thing with ultrasound? You' need a transmitter/receiver for each of your units, so a premade shield may be appropriate. Code the central transmitter to send an address  such that each outstaton only responds to it's own address . Then time that return.... then on to the next....  ie polling...

The coding could be as simple as morse - made of short/long pulses. Say every transmission signal consists of (eg)  8 pulses of short or long - that allow you to address each of the outstations .
The gap between pulses is big enough for echoes to die away.

Say that the master station always always starts with ( say ) 3 longs and never uses 3 successive longs elsewhere in the signal, and the outstations always respond with a signal  starting with 3 shorts and never use 3 successive longs or shorts elsewhere . That means that outstations don't respond to other outstations and the start of the signal can't be confused with a part of a signal . Leave a decent gap between signals to avoid confusion.


The other 5 pulses contain the station addresses.

The outstations don't respond until they have heard all 8 pulses. The master station knows that the end of the 8 pulses is when to start timing. The start of each pulse is the timing reference - the end may be confused by echoes.

Extend as appropriate.
 
Ce n'est pas facile.... .  Mais c'est possible!

regards

Allan

Title: Re: Ultrasonic Waves
Post by: MrMark on Jul 08, 2016, 09:43 pm
The coding could be as simple as Morse - made of short/long pulses. Say every transmission signal consists of (eg)  8 pulses of short or long - that allow you to address each of the outstations.
The general outline you've presented makes sense, but I think using pulse width ala Morse code is going to be problematic for several reasons.  

One is that multipath echoes may overlap the direct path signal making it appear longer than the intended transmission.  Second, if one uses the HC-SR04 electronics, it only detects the leading edge of the pulse and ignores what follows.   Finally, the piezo transducers are resonant at the transmit frequency (~40 kHz for HC-SR04) so they have an exponentially decaying tail after the driving signal is stopped, thus there's not a clean transmission termination, even if one were operating in an anechoic environment.

Some variant of pulse position modulation is probably dictated by the physical constraints of the problem.  My conclusion in the thread linked in the earlier post was that one could get something on the order of 100 bits per second out of an HC-SR04 based ultrasonic communication system so the position updates for the original poster's scenario are likely to be some small fraction of that.
Title: Re: Ultrasonic Waves
Post by: allanhurst on Jul 09, 2016, 01:34 am
That's ok - all echoes arrive AFTER the direct path  pulse, so if you time on the leading edge you're OK. Also works  for slow decay at the end. Note I also suggested waiting enough time between pulses for echoes to die away.

regards

Allan

ps the same problems would apply using a radio backlink.
Title: Re: Ultrasonic Waves
Post by: bordeaux270993 on Aug 09, 2016, 09:49 am
Exellent, i wasn't expecting so much answer around here since i switch to the french forum. Thanks guys i will try what you told me if one day my components arrived! (it's been 3weeks since i ordered i'm becoming crasy and i am running out of time! )

I checked the other post, very helpful, i'am just scared that i won't h
Title: Re: Ultrasonic Waves
Post by: bordeaux270993 on Aug 09, 2016, 10:08 am
have enough time!

Thanks any way both of you.

Best regards.
Title: Re: Ultrasonic Waves
Post by: MarkT on Aug 09, 2016, 01:28 pm
The good news is that the point-to-point range ought to be at least twice the reflected wave range, a
consequence of geometry and the lack of absorption from a surface half-way.

The bad news is you need a good RX tuned amplifier to get performance.

You can easily get 10V pk-pk by driving the transducer in a bridge configuration - two output
pins in anti-phase, which is 4 times the transmitted power compared to 5V pk-pk from a single
pin drive.

The transmitter you quote is piezo so can be driven from an Arduino pin via a 150 ohm resistor (piezos
are capacitive loads and need current limiting).
Title: Re: Ultrasonic Waves
Post by: allanhurst on Aug 12, 2016, 10:59 pm
The receive transducer is already highly tuned to it's resonant frequency, so that should do most of the filtering by itself.

regards

Allan.
Title: Re: Ultrasonic Waves
Post by: allanhurst on Aug 14, 2016, 10:19 am
2 quick points..

1/  ( MarkT) the range will be the square of a simple reflective system as it's working as a transponder.  Just like radar the path loss will be inverse 4th for reflection, inverse square for each direct path.

2/ ( bordeaux270993) I'd be very interested to hear how well this works out - could you let us know?

regards

Allan.