An emergency information sign comprising a base substrate and an indicia layer positioned over the base substrate. A plurality of the 2T pixels may form an array, having a number of rows and a number of columns. A tunable optical filter repetitively and sequentially passes emitted light at each of the characteristic wavelengths as each particle travels through the analyzing volume and the light transmitted through the optical filter is received by single detector which provides output signals representative of each distinct wavelength of light emitted by the particle. Likewise, seed addresses can alert an e-mail provider to potential mass mailings by reporting when mail is received for ghost or non-existent accounts. In a second embodiment, the base station receives multiple RTP packets having identical information in the packet header in many fields, and selects an appropriate one among these for transmission to the mobile station, discarding the rest.