Results of the Design
The necessary time-bound was
that all computation be done during the sampling interval or 0.2 ms. By examining the graphs we see that there are no
discontinuities, which would indicate timing problems. Testing also showed that
there were no timing or concureency problems.
By using a
handheld Korg guitar tuner. We saw that our tune frequencies where within 1% of
the intended value. The resolution on this device is not very good, so that is
the closest we could estimate the frequency. Our calculated accuracy is 0.5%.
There may be some RF
interference from the long wire going to the CPU. We donít think this is very
significant because it didnít disrupt our input signal. Therefore itís unlikely
we disrupted other groupsí devices.
The device is very user
friendly. The user sees which string they are tuning on the LCD, can select a
new string by pushing one of six buttons, and can see the deviation in
frequency on the five LEDs of the STK500 board.