Saturday, November 19, 2016

A bit to much

While working on a 12 bits analog to digital converter in the scope I did some math about the need for 12 bits. Since we use 200 values of the opto sensor over a frequency range of 1650hz.
This means 1650 / 200= 8.25Hz steps.
What is the just-noticeable difference in frequencies for a human ear?
Below 500 Hz, the JND is about 3 Hz for sine waves above 1000 Hz the JND is about 0.6%, 10Hz at the highest pitch of Kedok. So I need to get more values while a shooter is on the target card. I will rewrite the sensor code in Kedok to get a software range of 1000 steps over the target card. 1650 / 1000= 1.65Hz steps.
At this moment im testing with a ADS1015 Analog to Digital converter in the scope. With the internal AD converter (10 bits) of Kedok I can get a resolution of 200 steps over the target. I hope I can get it to 400 with the new converter. 1650/400= 4.125 Hz steps.

Lots of coding ahead :)

Ref: Wiki about Just-noticeable difference