DLP-2232DAQ DLP Design Inc, DLP-2232DAQ Datasheet - Page 9

• Manufacturer Part Number: DLP-2232DAQ
• Description: Interface Modules & Development Tools USB Data Acquisition System
• Manufacturer: DLP Design Inc

Specifications of DLP-2232DAQ

• Interface Type: USB
• Data Bus Width: 12 bit
• Operating Supply Voltage: 5 V
• Product: Interface Modules
• For Use With/related Products: FT2232C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

For example: Let’s say our A/D is sampling at a rate of 4,000 samples per second and
takes 128 voltage measurements from a signal that consists of a sine wave oscillating
at 1,000Hz. If these 128 samples are number-crunched by an FFT, the result is 64
frequency domain data points or bins. Since we sampled at 4,000Hz, the maximum
frequency that can be accurately acquired is 2,000Hz; and since a single
1,000Hz- signal was present in the source, then Bin Number 32 of the output data will
hold a numeric value that is larger than all of the other bins.
There are other considerations that have been overlooked such as converting the data
in the bins to usable power spectrum data (measured in dB) and using filters on the
source data, but these items are beyond the scope of this article.
Now that we have access to frequency domain data and can detect which note is being
whistled, all that is left to do is write an application that detects when a particular note
(or a note within a specific range) has been held for a second or so and respond
accordingly. A Windows application can be downloaded from dlpdesign.com that
allows the user to set up these conditions and respond in a number of ways. (A screen
shot of the program can be seen in Figure 5. Also, as mentioned earlier, source code
for an example program that shows how to access the A/D, DAC, relays, and digital I/O
lines is available for download.
Figure 5. Whistle Detection Software
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