04-13-2012 03:19 PM
Good evening Everyone. I have a problem. I'm currently a student and i'm doing a project on sonar devices. I'm currently performing a project where I will have a remote control boat in a tub. My partner has built a devicethat could send a signal pusle underwater. This signal pulse will reflect off the boat and hit a hydrophone I have connected to USB NI-4431. I will in display this signal, Filter all of the noise componets out of the signal, then I am to write a lab view program that determines the distance from the the sonar to the Hydrophone in which I have the USB NI 4431. Also I am to determine the velcotiy of the object as well. I have all ready written a program that determines distance but I dont think that it is right. I have to take into account the many signal refections from the air -water interface as well as the reflections from the bottom of the tank. I have an idea of how to do this but I would like to ask what fucntions in labview can I use to calualte the distance of this obeject to the Hydrophone know ing that there may be many refections from the Sonar to the Hydrophone.. this is the file I have so far , but it is not correct.
04-16-2012 05:22 PM
First, are you working with the Sound and Vibration Toolkit? In terms of what you can use in LabVIEW to analyze your noisy signal, the best solutions lie in the "Sound and Vibration Toolkkit." This contains functions specifically developed for analyzing and processing sound signals.
If your question is about what functions in LabVIEW will allow you to apply various filters to your data, you're already successfully located the Filter Express VI, which is a useful tool.
In terms of which filters would be best for your application, that's something you'd have to do some research on. However, if you have a specific type of filtering you're trying to figure out how to apply, I'll be happy to help you.
What exactly is it about your current VI that seems to not be working?
04-16-2012 05:37 PM
This is what I'm trying to do. I have a tank that is 8 feet 10 inches long filled with water. A remote control boat will be placed in the tank. I have a hydrophone on the other end of the tank. I also built a device which can send a ping( Signal) to the the remote control boat. This signal will bounce off the boat , bounce of the surface of the tank, and air-water interface the top of the water in tank and eventually hit the Hydrophone where it can be seen. I will have the Hydrophone connected to the NI-4431 so it will capture this noisy signal. I want to find the distance of the Remote control boat at different intervals in the tank. The program I have doesn't work for that. So I'm really asking for advice on where to begin because I know what I need to do but I don't know how to program it being that I'm new to labview.
04-17-2012 06:37 PM
I understand your overall test - in fact, it sounds like quite a neat application. However, I'm not going to be able to recommend a type of filtering that will be best for your application, nor will I be able to tell you how best to isolate your signals.
What I can tell you is how to select a filter or implement your isolation method in LabVIEW. If you can tell me the kind of filtering you'd like to use, or any mathematical formulas you'd like to apply to your data for scaling purposes, I'll be happy to answer specific questions about how to go about this.
So, what type of filtering are you looking to apply to your signal? If you know the domain in which you'd like to analyze it (Time, Frequency, or Order), this will also help us narrow down which functions will be best suited (including those in the Sound and Vibration Toolkit). If you'd like to separate frequencies, it's likely you'll want to be in the frequency domain and can use an FFT. Some basic information on using FFTs can be found here:
Windowing - Optimizing FFTs Using Window Functions: http://zone.ni.com/devzone/cda/tut/p/id/4844
You can also find an overview of some basic signal conditioning functions can be found here:
Advanced Built-in Analysis and Signal Processing in LabVIEW http://www.ni.com/labview/whatis/analysis/
So, selecting the appropriate form of filtering is up to you. After you've made this selection, I can the help you implement it in LabVIEW.
Thanks, Tunmac! I look forward to hearing from you.
04-23-2012 05:38 PM
Okay I feel as though I'm getting there. I'm able to hear the the nosie in the channel even the sonar but im not able to determine the distance from the oject. here is what I have
04-24-2012 10:40 AM
It looks like you've made a lot of good progress - and I see that you've implemented the FIR filter in your "Filter" Express VI.
In order to accurately determine distance, you need to relate the time that a signal was sent by your partner's sonar device to the time that your hydrophone measures it. How is your partner's device triggered? What is the device, exactly? It it simply turned on and ran continously, or is it activated "per-ping?"
If you can connect the sonar generator to the 4431, you can use the "Multi-Function-Synch AI-AO-Ext Trigger" in the LabVIEW example finder (in LabVIEW>>Help>>Find Examples...). This example shows how to synchronize an output task (potentially your sonar device) to your input task (your signal measurement).
04-24-2012 10:54 AM
The device is actually is a speaker that is enclosed in a half of inch eletrical PVC pipe. The Ping is sent from a windows application and the Hyrdophone is connected to the 4431 as well as the sonar system. The Sonar sends continuouly at 0.08secs . Cant seem to find the application u mentioned . where is it in Labview examples finder.
04-25-2012 07:02 PM
My apologies - the example is called "...AI-AO-Ext Dig Trigger" it is attached. However, since you are using a standard speaker, this may not work for your application.
You can use the "Play Sound File.vi" function to trigger your sounds through LabVIEW rather than through windows - this may make it easier to coordinate your test. In terms of synchronizing the acquisition, I will have to do some research and get back to you tomorrow. Can you give me any more information about your hydrophone? (Model/maker, etc?)