Techniques for efficient searching in asynchronous systems, such as W-CDMA, as well as multi-mode searching, are disclosed. The detector includes a first optical flow cell body and a second optical flow cell body, each having a channel therethrough that allows passage of a liquid from an inlet port to an outlet port. The estimating unit may estimate at least one aspect of an array at least based on at least one video or audio signal captured respectively by at least one of portable devices arranged in an array.