A packer structure for grouting injects a repair liquid into a crack of a concrete structure. In the above-mentioned structure, when the second internal terminal is not bonded to an external terminal, the second internal terminal is pulled up or pulled down in accordance with a logical level of a signal input to the first internal terminal. For each target power level in the dynamic range, a control module in the transmitter configures operational settings of amplification stages of the transmitter in order to produce the output RF signal having the appropriate target power level, while consuming minimal power from the power source. It is possible that the first scan path may or may not be parallel to the second scan path, and that the first image may or may not be aligned with the second image.