  We have designed and built a modern versatile research-grade instrument for
ultrasound pulse-echo probing of the elastic properties of a wide range of
materials under laboratory conditions. The heart of the instrument lies in an
AD8302 microchip: a gain and phase detector from Analog Devices, Inc. To
construct the device, we have implemented a schematic that utilizes the
homodyne principle for signal processing instead of the traditional
superheterodyne approach. This design allows one to measure phase shifts with
high precision and linearity over the entire range of $0-360^\circ$. The system
is simple in construction and usage; it makes ultrasound measurements easily
accessible to a broad range of researchers. It was tested by measuring the
temperature dependence of the ultrasound speed and attenuation in a
KTa$_{0.92}$Nb$_{0.08}$O$_{3}$ (KTN) single crystal at a frequency of $\sim$ 40
MHz. The tests were performed in the vicinity of the ferroelectric transitions
where the large variations of the speed and attenuation demand a detector with
outstanding characteristics. The described detector has a wide dynamic range
and allows for measuring in a single run over the whole temperature range of
the ferroelectric transitions, rather than just in limited intervals available
previously. Moreover, due to the wide dynamic range of the gain measurements
and high sensitivity this instrument was able to reveal previously unresolvable
features associated with the development of the ferroelectric transitions of
KTN crystals.
