Aim of the study:
The use of acoustic Doppler current profilers (ADCP) is becoming more popular. When considering to use different equipment, the question arises as to whether there are any differences in measuring with ADCP that works at different frequencies. Therefore, we evaluated and compared three ADCPs that operate at different frequencies: 2,000 kHz, 1,500 kHz, and 600 kHz under field conditions

Material and methods:
We measured five times in a transverse section of 100 m wide and 7 m depth, the following parameters: (1) components of velocity flow, (2) depth, (3) transverse distance among vectors, (4) total distance and (5) geographic position of each vector.

Results and conclusions:
Our results showed that the velocity magnitudes were low in margin areas, while high in the center. To 5.0 m depth, the 2,000 kHz ADCP, keeps a homogeneous velocity distribution in comparison with other equipment. Also, we found from the statistical and graphic analysis that flow measurements did not differ by more than 5%.Nevertheless, our review of velocities showed significant differences between ADCPs. High frequency means more data detail but less deep range, particularity in zones with high sediments concentration. Low frequency means less data detail, but a more deep range. Furthermore, our findings suggest that measurements in rivers got field results, which sometimes are entirely different from the laboratory