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FPGA Ultrasonic range finder

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Conezz

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Hi all, I'm new to this.

I have a Spartan 3AN FPGA board and I'm wanting to make an extension board that does measurements of ultrasonic frequencies at 40kHz.

The range that would be desired is 5 metres.

I haven't used the ADC/DAC yet so I would like to use these for connecting the TX/RX transducers. I am wondering how to make a circuit that will interact with the ADC/DAC?

I know I will need to amplify the signal that is received but when transmitting would I need to amplify before I send as well?

If anyone could help, greatly appreciated.
 

mtwieg

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A few years back I did a SODAR project using a cyclone III. We used a DAC > Power amp > step up transformer to drive an electrostatic transducer, then a mems microphone for receive.
 

Conezz

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A few years back I did a SODAR project using a cyclone III. We used a DAC > Power amp > step up transformer to drive an electrostatic transducer, then a mems microphone for receive.
Yeh, could you give me more detail on the transmitter circuit like what components did you use? Or if you still have any kind of schematics?
 

mtwieg

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The circuitry was nothing special. Just used op amps to amplify the DAC signal to 24Vpp, which drove a step up transformer (which we made ourselves). The TX transducer was one of these:
http://www.senscomp.com/specs/600 instrument spec.pdf
and our receiver was this:
http://media.digikey.com/pdf/Data Sheets/Knowles Acoustics PDFs/SPM0404HD5-PB.PDF

We used a continuous pseudorandom noise signal rather than chirps, and ended up with a resolution of a few millimeters, with a range of several meters.
 
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petrel-fulmar

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Hello,
I reopen this topic because I would like to use the SensComp 6000 you used for your design. Mtwieg, you said that your output signal is 24Vpp but in theory, the signal could be up to 200Vpp; am I right? Also one need a 200V DC bias...

I found op amps to amplify arbitrary signal (I need to output signal up to 100KHz) between 0 and 350V (using PA78 from Apex analog) but I am unable to find proper dc dc converter to power it at 350V (Also I would like that the input voltage of my board is not higher than 24V)...
Any ideas?
If it is impossible to find such component, how did you do your step-up transformer?
Do you know how much current is needed?


thanks in advance!
 

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