sound source

[didi80]

  I am using LabVIEW 2012, yes I have look at the DAQmx examples. At the present stage I am generating the signal with the function generator and outputting through the speaker and receiving it with the microphone. Need to compare the two signals from the speaker and microphone in other to make the stable sound source.

[ThiCop]

Hello didi,

I have been Out of Office the last few days, but I would like to come back to the questions you were having.

It is not yet a 100% clear to me what you are trying to do:

- You have a non-NI 20 MHz "signal generator" that can generate sinewaves from 100Hz to 10 kHz

- This "signal generator" is connected to a speaker (Is there no amplifier in between?)

- At the other side you have a B&K microphone.

- This microphone is receiving the signal from the speaker.

Some questions from my side:

- Are you having any problems while reading out signals with your PCI-6052e?

- Do you need to generate any signals with you PCI-6052e?

- How are you currently controlling the "signal generator"?
  Is this by hand or programmatically?

- What is the end goal of this project?

  Is it to improve the stability of the existing signal generator "while it's generating"?

  Or in other words: Are you trying to create a closed loop control system?

- Are you currently measuring only the microphone output signal via the PCI-6052e?

- What do you mean exactly with "Need to compare the two signals from the speaker and microphone in other to make the stable sound source"?

Please define:

1) The signal from the microphone:

    Is this the signal the microphone output (voltage/current)?
    Or is this the signal you receive at the input of the microphone (sound wave)?

2) The signal from the speaker:
     Is this the signal the speaker produces (sound wave)?

     Or is this the signal your "signal generator" produces (voltage/current) before reaching the speaker?

[didi80]

 Hello Thicop,

Answers to your questions

It is not yet a 100% clear to me what you are trying to do:

- You have a non-NI 20 MHz "signal generator" that can generate sinewaves from 100Hz to 10 kHz

•  I am using the Basic function generator VI to generate the signal

- This "signal generator" is connected to a speaker (Is there no amplifier in between?)

• yes for the moment I am not using a power amplifier

- At the other side you have a B&K microphone.

- This microphone is receiving the signal from the speaker.

•  yes the microphone is receiving the signal from the speaker

Some questions from my side:

- Are you having any problems while reading out signals with your PCI-6052e?

• No problem reading both signals

- Do you need to generate any signals with you PCI-6052e?

- How are you currently controlling the "signal generator"?   Is this by hand or programmatically?

•  with arrary of values through the basic function generator VI

- What is the end goal of this project?

  Is it to improve the stability of the existing signal generator "while it's generating"?

  Or in other words: Are you trying to create a closed loop control system?

•  creating a closed loop control system to keep a sound pressure level constant within a distance of 1.5m

- Are you currently measuring only the microphone output signal via the PCI-6052e?

•  yes only the microphone output signal

- What do you mean exactly with "Need to compare the two signals from the speaker and microphone in other to make the stable sound source"?

•  mean to keep the sound presurre level constant. for exapmle at 80dB(-+dB) at a distance of 1.5m
•  by incresing / decreasing depending on the reading from the microphone, the signal to have a sound pressure level of 80dB at 1.5m.

Please define:

1) The signal from the microphone:

    Is this the signal the microphone output (voltage/current)?     Or is this the signal you receive at the input of the microphone (sound wave)?

•    the microphone is having a conditional amplifier which produced electrical signal (voltage)

2) The signal from the speaker:      Is this the signal the speaker produces (sound wave)?

    yes.

     Or is this the signal your "signal generator" produces (voltage/current) before reaching the speaker?

•      the speaker produces acoustic output detected by a microphone.

[ThiCop]

Hello didi,

One thing still remainsunclear:

Which device is going to create the output signal that the speaker will use?

Is this the "Agilent function generator" or is this the NI PCI-6052E card?

[NIquist]

OK, it sounds  like you're all set.  The part I didn't get is what your actual setpoint was going to be.  Now I see you're going to set up an arbitrary maximum SPL and simply limit the gain of the system (AGC).  If you make the system response time very fast you should be able to perform compression on the signal.  You could even add some filtering to the input signal and do multi-band compression for different frequency ranges.

Let us know how it works out.  Post your code if you want some feedback. 

[didi80]

Hello ThiCop,

I am going to used the NI PCI-6052E card to create the output signal to speaker.

I have already done that.

[didi80]

Using LabVIEW 2012, yes that the idea to used a AGC.

[ThiCop]

Hello didi,

Can you tell me what the goal of the "Agilent function generator" in the current application then is? 

PS: Sorry that I am still confused, but I do not see where this fits in the current application.

[didi80]

 Hello ThiCop,

I am not using the "Agilent function generator" any more in the application I have replaced

it with a Basic functional generator VI.

At the moment the difficulties is in desiging the AGC in LabVIEW.

[ThiCop]

Hello didi,

Can you post any of your code and explain where it is going wrong?