A limited value range is defined for obtaining approximated integer cosine transform coefficients. In one such connection, the user is afforded enhanced directory assistance upon a user command in the form of an out-of-band signaling message, e. The shaft journal is axially secured. An elongated sleeve being axially slidably mounted over the in-line housing covers the in-line housing. The controlling includes detecting an optical power level of the output probe signals and controlling at least one of an optical gain difference between the two arms and an optical phase difference between the two arms in accordance with a detected optical power level of the probe output signal.