Provided is a method for generating a preamble sequence group. An amplifying medium in free space is placed inside a Fabry-Perot cavity consisting of two reflectors. The p-GaN membrane bows upward between the pillars in order to relieve stress built up during the epitaxial growth of membrane. Said photosensitizer is produced by extracting Spirulina biomass with the aid of acetone. The bottom of the smoke detection chamber has an opening therein with a shielding arrangement thereabout open to the chamber for a photodiode detector, the opening and shielding arrangement being located between the centerline of the smoke detection chamber and the mounting arrangement in the side wall of the chamber. The Kalman filter is used both statically and dynamically.