Update on myDAQ acoustics – myBAT

This week we had hoped to receive the PCB quickly but it had taken 3 days to be built. However whilst we waited we started on our final design in which we wanted to shift the captured signals via hardware.  After talking with our supervisor, we decided against this and decided to shift the signals via software (labVIEW).  We wanted to shift via hardware rather than software initially because we thought the myDAQ’s were limited to 20 kHz.  Afterwards we found out that labVIEW can sample the input at 200 k samples per second which meant that the actual limit is 100 kHz, this is because when digitalise an analogue input the sampling rate has to be at least twice the maximum frequency.

In order to maximize the frequency bandwidth we have to design an Anti-Aliasing (AA) Filter, we designed this on software called FilterLab.  The screenshot shown below is our AA Filter.  We started working on our PCB and have completed soldering all components.  Our next aim is to start testing on the PCB and w would also like to connect a function generator to the myDAQ through the AA Filter and then simulate a signal.

Some pictures are shown below:

This is a screenshot of our Anti-Aliasing Filter which we created on FilterLab. 

Note: the design from FilterLab uses very precise resistor values. The simulation in Multisim uses randomised resistor values. As a result of that the AA filter is not as good as it should be. We will work on it and try to improve the filtering.

This is a picture of the PCB for all the components and PCB’s for the microphones

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Once we had our PCB’s, we had to first solder all our surface mount components.  The completed task is shown below.

This is a picture of the PCB with all the components soldered.  However as you can see in the centre of the PCB, the last chip we need hasn’t arrived yet.

This picture shows the microphone soldered onto the PCB.