m-Sequences of Different Lengths with Four-Valued Cross Correlation

{\bf Abstract.} Considered is the distribution of the cross correlation between $m$-sequences of length $2^m-1$, where $m$ is even, and $m$-sequences of shorter length $2^{m/2}-1$. The infinite family of pairs of $m$-sequences with four-valued cross correlation is constructed and the complete correlation distribution of this family is determined.