A pre-amplifier circuit for connection to an antenna of a human-portable locator includes a differential amplifiermixer pair and means for allowing a common-mode \u201cphantom\u201d signal to modulate a transfer function of the differential amplifiermixer pair. An example portable audience measurement device includes a housing, a media detector in the housing to collect media exposure data, and a packaging sensor to receive an audio signal. Further, the front side cache memories connected with the channel adapters and the back side cache memories connected with the disk adapters are provided as two layered cache system. A mobility level of the communication channel may be compared to a low mobility threshold corresponding to a low mobility level. An advantage of the method and system is that it is so fast that it can be used to save time due to a lower amount of data transferredstored in scenarios like network transfer, disk or memory storage, cache storage or any other real-time applications where time plays a crucial role. Embodiments identify, during either initial screening of a UI applicant or on an ongoing basis for current recipients, those individuals who would seek to defraud UI programs by receiving improper payments.