Encoders - how to tell PPR

Can anyone help me with some information as to how to tell the PPR on
an encoder without any specifications? I recently bought some surplus
servo motors with encoders, but there are absoltely no specifications
on it.

I do not have a scope. Can someone recommend any simple circuit I
could put togeteher to read in through the parallel port and get a
count?


Thank you
Tom Csibor