I've bought a DC geared motor with an optical encoder. The vendor didn't provide specification. I can read MITSUMI M25N-2R-14 2241 and 25GA-370-12V-330RPM on the motor. There are some pages on the internet about this motor with contradicting information that I can't trust. I need to find a practical method to find exact gear ratio and encoder resolution.
I took a picture of the encoder and in a CAD software measured 1 degree the angle between two lines. I'm not sure about accuracy of this method!
I use this code in Arduino:
#include <Encoder.h> Encoder myEncoder(2,3); // Best Performance 2, 3 intrupt double Position ; void setup() { Serial.begin(250000) ; Serial.println("Encoder Test.") ; } long oldPosition = -999 ; void loop() { long newPosition = myEncoder.read() ; if (newPosition != oldPosition){ oldPosition = newPosition ; Serial.println(newPosition); }} I can read data from my encoder but how can I use this data?

