  Observations of Interplanetary Scintillation (IPS) are an efficient
remote-sensing method to study the solar wind and inner heliosphere. From 2016
to 2018, some distinctive observations of IPS sources like 3C 286 and 3C 279
were accomplished with the Five-hundred-meter Aperture Spherical radio
Telescope (FAST), the largest single-dish telescope in the world. Due to the
270-1620 MHz wide frequency coverage of the Ultra-Wideband (UWB) receiver, one
can use both single-frequency and dual-frequency analyses to determine the
projected velocity of the solar wind. Moreover, based on the extraordinary
sensitivity owing to the large collecting surface area of FAST, we can observe
weak IPS signals. With the advantages of both the wider frequency coverage and
high sensitivity, also with our radio frequency interference (RFI) mitigation
strategy and an optimized model-fitting method developed, in this paper, we
analyze the fitting confidence intervals of the solar wind velocity, and
present some preliminary results achieved using FAST, which points to the
current FAST system being highly capable of carrying out observations of IPS
