any example VI of filtering real signal in Pocket PC

[student G]

Hi there

currently i am using CF-6004 to do DAQ of signals and using LabVIEW PDA module 7.1. So i am now trying to accomplish filtering of real time signal but there is no example in filtering of signal.Is there any example to do a bandpass filter using the range of lower cut off frequency 35hz and upper cutoff frequency 1khz. Thanks

Gab

[Elijah_K]

There are several shipping examples that are included in the LabVIEW example finder (Help >> Find Examples) under the Analyzing and Processing Signals >> Filtering and Conditioning category. 

If you're working on the block diagram of a VI included in a PDA Module project, it will only show you VIs that are compatible with PDA - it seems that almost all of them are still there, including the express VI, which can be found on the functions palette under express >> signal analysis.

Hope this helps - let me know if you have any other questions!

[student G]

Hi there

Thanks for your respond and have help me solve my problem. I have another question, is it possible that while recording sound, it can do some filtering process? Is there any example VI on filtering sound while recording? Thanks

Gabriel

[Elijah_K]

So you want to acquire sound and filter it on your PDA?  Are you acquiring it through the CF-6004 card, or through the PDA's hardware? 

You should be able to do both.  To get sound through the PDA's hardware, use SI Config.vi to configure a task.  You can connect the task ID out to SI Start.VI to begin sending sound into a buffer.  Use SI Read.VI to get the data from the buffer.

The example finder has sample code for recording sound from a PDA's mic.  You can find it by searching for the keyword, "sound."  The title is, "Record Sound - Pocket PC.vi"

Let me know if you have any questions. 

[student G]

hi there

if i want the sound to be directly passing through the cf-6004 card and not the pda mic, is there a way to do it?

gab

[Elijah_K]

student G,

You'll be able to do it since the CF-6004 can acquire up to 200kS/s and sound is generally sampled at around 44kS.  It'll just be a normal analog input, and you probably won't need to do any signal conditioning.  Is their a particular reason why you're wanting to use the DAQ card instead of the PDA's built in mircophone?  What are you wanting to do with the acquired sound?

[student G]

hi there

what i am trying to achive is to get a heart sound from my signal conditioning circuit and my own microphone. so the example vi found in the labview is using the pda internal microphone and not using my microphone. so is there any example  VI of using external microphone instead of internal pda microphone?

[Jennifer O]

Hi Student G,

You will want to start with one of the DAQmx Base examples for Continuous Acquisition.  You can then pass the signal to a filter of your choice.  You will need to pass the signal values, the sampling frequency and the cutoff value(s). 

The CF-6004 will return the sound in terms of voltage.  Typically sound is converted to 8 or 16 bits.  The CF-6004 is a 14 bit device.  You can take the actual signal value and divide by the input range (maximum expected voltage) to get a percentage of range.  You can then multiply by 32767 to convert to a 16 bit representation (-32768 < x < 32767).  You can then feed this value to the mono 16 bit input of the Sound Write Wave File function as shown in the Record Sound example for using the built-in microphone.

Hopefully this helps,

Jennifer O.
Applications Engineer
National Instruments