Method and apparatus for determining flow characteristics of a medium in a pipeline

An apparatus for determining at least one flow characteristic of an essentially laminarly flowing, gaseous or liquid medium in a pipeline, comprising:

• at least one modulation element, placed in a pipeline produces at least in the case that the medium is flowing with a velocity different from zero, at least temporarily, a change in density of the medium in the vicinity of said at least one modulation element;
• at least one mechanically oscillatable unit is placed in the pipeline spaced from said at least one modulation element which executes resonant oscillations;
• and;
• at least one electronics unit, is associated with said at least one mechanically oscillatable unit, which receives mechanical oscillations of said at least one mechanically oscillatable unit and converts these into an electrical, received signal, whereas:
• the received signal is sensitive to the density change;
• and,
• which said at least electronics unit determines the at least one flow characteristic of the medium from a reaction of the received signal of said at least one mechanically oscillatable unit to the density change.