how to design an active noise control system using NI6009 USB

[mahathir]

I now try to design an active noise control system using lab view software, and NI 6009 USB for the interface...
but i dont know how to set up the Ni6009 USB with the hardware device that i use suvh as the loudspeaker and the michrophone...
any suugestion on my problem....

i realy need some information now....

can also email me at the_slayercreck@yahoo.co.uk

please please

[NI-Bongo]

Hello Mahathir,

Many microphones require IEPE excitation.  The USB 6009 cannot provide this, but you could use an external excitation source.  What type of microphone are you using?  A simple dynamic microphone will produce a signal without excitation, but typically a preamplifier would be used.  Do you know what output level and impedance you expect from your microphone?  You may also be able to use the microphone input from your PC to get the signal into LabVIEW.

The speaker cannot be driven directly with the USB 6009 as it is not an amplifier.  If you have a signal that you would like to route to the speaker, you can use an analog output to send the signal to an amplifier that could power the speaker.

If you provide a bit more detail on what you would like to do, I can help you further.

[mahathir]

Hello John,

im sorry for the late reply your email..for your information, now im using the regular michrophone, that as speech michrophone..
now im stuck at the sofware...

[mallorim]

Hi Mahathir,

So, I am unclear as to what you meant when you said that you are using a regular microphone now. Did you mean that you are using a microphone that comes standard issue on a laptop or, for example, a microphone that comes with a webcam and that can be plugged into the microphone jack at the back of your computer? Some details as to which specific mic and how you are connecting it to your PC would be helpful.

Also, you mentioned that you are stuck at software. Can I ask what software you are using and what seems to be the problem? Maybe we can give you some pointers.

As I understand active noise control systems to work, you will be reading a signal from a microphone, performing signal processing at high speeds, and then outputting from a speaker a signal that should provide deconstructive interference and nullify the noise. I might mention, like John did, that your USB-6009 is incapable of hardware timed signal generation. This means that even should you use the USB-6009 to send a signal to an amplifier that will power the speaker, it will most likely not be fast enough to work. With regards to processing speed, you may find your self too slow here too. FPGA programming, which can operate at much faster speeds, is typical for applications of this type.

Hope this information helps, Mallori M.

[mahathir]

thank you..

that mean, i cant do the systems using NI 6009?

How about if using the sound card from my laptop only?

i use michrophone that used for the speech of karaoke..he3
 
i am using lab view software,but i am beginner with this software..

so know nothing about this lab view....

[NI-Bongo]

Hi Matathir,

You would have a difficult time doing active noise control with a PC speaker and microphone because of the processing required.  A software program would not likely be fast enough to acquire a signal, process it, and output a corresponding signal in real-time.  As Mallori mentioned above, FPGAs are the way to do this because you can do all the processing in hardware, which is much faster.  Here is a link to more information on FPGAs:FPGA-Based Control: Millions of Transistors at Your Command (FAQ)

http://zone.ni.com/devzone/cda/tut/p/id/3357

Also, what would you like to achieve with your active noise control system.  These requirements would help me know better what you would like to do.

[mahathir]

   

Dear Mr Bongo,

Thanks for your advice, erm  can you explain a little bit about why  I should FPGA for the active noise control system instead using the DAQ  card as a medium in my project.

I am very appreciating your opinion….

Thanks a lot from me…

[mallorim]

Hi Mahathir,

The reason that Mr. Bongo and I suggested FPGA for your active noise control system was the fast nature of the application. Being able to record sound, process that random noise information, build a waveform, and then output that signal so as to nullify the noise- all at relatively the same instance in time- will require the speed of hardware timing. FPGA will allow you to put programming on the hardware and run from there, allowing much faster processing speeds than you could get with just your computer processor. This will provide for the near instantaneous output necessary to negate the noise.

While this speed is obviously desirable, the second issue that you are going to run into is that, as can been seen in the USB-6009 specification sheet, the device allows only software-timed updates to its digital to analog converter (DAC) of up to 150 samples per second. This means that your analog output to offset the noise will be non-deterministic, or whenever the processor gets around to it and therefore not exact, and much slower than the execution of hardware timing. In hardware timing, a counter on the DAQ card, typically with an 80 MHz timebase, clocks the samples written by the analog output. In software timing, there is no onboard output timebase, so the output is written with the timing resolution of your operating system, typically only one sample every millisecond.

I hope this explanation helps.

Regards, Mallori M.

Message Edited by Support on 12-16-2008 04:51 PM

[mahathir]

Dear Mallorim,

Thank you for your xeplaination..
i'm very2 appreciate it...