pulseIn() function problem for measure frequency

kk6682:
I want to print out the period of the signal .

which is equal to 1/50.6=0.197

Check your math as that should = 0.0197 seconds, so for one half the period (you are only measuring the positive half of the signal frequency) would be = to .009881 seconds or 9881 usec. So you are measuring about 18% fast which could be just not having an accurate signal generator or possibly noisy zero crossing detection causing an inaccurate 50% duty cycle, and you are only taking a single snap shot measurement rather then say taking a few and averaging them. I played with the pulse in command some a long while back and was not too pleased with it, as I never seemed to get real stable results on a constant frequency input, but never tracked down the cause of the variation even though I was using a good quality signal generator. Possibly millis and micros interrupts could be 'skewing' the results randomly?
Lefty

I want to know that is the value of duration equal to the length of the rise time ?

which is equal to half of the period 0.197/2.

Now the displayer just shown as 8117

Is there anything i can convert the value from 8117 to the period