The extended resolution package lets the user set the distance between two consecutive gates, as well as the size of these measuring gates. The basic DOP3000 automatically sets its resolution to fine mode or coarse mode depending on the maximal depth of measure selected. The present option package lets the user select any desired resolution (i.e. gate spacing) between 0.12 mm (166 ns) and 15 mm (20ms), as well as the length of these gates.

The functioning parameters that can be tuned when this package is installed are the following:

• Resolution: It is the distance between the center of two adjacent gates. Defined in nanoeconde and in mm, between 166 ns and 20ms.
• Gate depth: It is the distance measured along the US beam for which all the echoes issued from particles inisde that range are combined together in order to give a single echo value. Its value is defined by both the burst duration and the electronic bandwidth of the receiver of the DOP3000. It covers the range from 0.8 to 4 mm.
• Bust length: defined in number of periods, between 2 and 8 and can be automatically setup by the UDOP software.
• Maximum PRF value: the PRF value can be as low as 0.1 second, which allows the measurement of very low velocities.

Possible problem encountered without this package	Solution to this problem

Even if a measurement of velocity every centimeter of depth can generate a decent velocity profile in a pipe of 1 meter of diameter, it will be an insufficient spatial resolution in a pipe of a few centimeters of diameter.

This package enables not only the definition of the spacing between two adjacent gates but also each size of the gate along the US beam axis.