Problem with number of pulse of encoder
I am using this kit for my robot https://www.parallax.com/product/570-00080. In the document, it says there are 1920 pulses for a rev with gear. I believe I have problem when measure the velocity of the motor by reading encoder. I got 28 pulse per 100 msec means 6.8 sec/rev if 1920 is a correct number. But by look at the wheel and use a time clock I get about 5 sec/rev. I wrote a small test to read the pulse only and spin the wheel manually I got about 1438 pulse/rev. So does the encoder not work as description?