According to RFC 6928, the SRTT is only calculated with the formula
SRTT <- (1 - alpha) * SRTT + alpha * R'
after two RTT measurements have been made. After the first measurement, SRTT is initilized to the value of this first measurement, ie. SRTT <- R'
.
You were close, according to the RFC alpha SHOULD
be 1/8 (= 0.125).
Note, in RFC's, SHOULD
means "there may exist valid reasons in particular circumstances to ignore a particular item, but the full implications must be understood and carefully weighed before choosing a different course." (RFC 2119)
TCP
.it was on wikipedia..i had just assumeda = 0.1