The term “Doppler effect” honors Austrian physicist Christian Doppler. Doppler discovered that the distance between waves, such as sound or light, changes as an observer of the waves and the source of the waves move relative to each other.
Dopplers operate on the principle of listening to reflections of small, high frequency sound waves. These sound waves, called ultrasound, are generated by microscopic vibrations of a ceramic crystal. When ultrasound waves reflect off moving objects such as the fetal heart or blood flow, the waves are altered slightly in frequency. The Doppler then picks up these signals, processing and amplifying them so they are audible.
When choosing Doppler probes, lower frequency probes will penetrate the body deeper and will have a wider beam. Likewise, the higher frequency probes will not penetrate as deeply and will have a narrower beam. So, for listening to deeper objects such as a fetal heartbeat, a lower frequency 2 or 3 MHz probe is needed. For listening to superficial objects such as blood vessels, a higher frequency 5 or 8 MHz probe is appropriate.
Cephalon carries a lot of dopplers and their accessories, some can be found here:
The FreeDop™ from Nicolet is a cordless, portable, counter-top Doppler. With easy-to-use touch controls and a unique smart charging stand, the FreeDrop features meet the demanding requirements of users. The unique cordless probes are compact and offer c...
The ELITE hand-held Doppler available with heart rate display
Use the flat 5 MHz or pencil tip 8 MHz vascular probes to screen patients at risk for stroke, peripheral arterial disease and other occlusive vascular conditions or to monitor difficult pulses...
The Falcon product family provides a wide range of solutions for diagnosis of peripheral vascular disease. Everything you expect from an advanced state-of-the-art
PVD medical system, and much more: up to 10 independent pressure channels, 3 different...
A new generation doppler technology on the highest level of innovation in an innovative design for connecting to any external Windows©-based computer.
The Doppler-BoxTM X1 as a compact unit with tablet-PC is ideal for flexible use in the consulting room, at patient’s bedside or in operating theatre.
Multi-Dop® T digital – this means cutting edge technology in an innovative, ergonomic and compact design. A new control concept renders operating the comprehensive performance range of the Doppler-system intuitive, fast, and safe at any time and in an...
Multi-Dop® X digital has been developed to support complex applications and special function tests. The system is being used increasingly by the science and research community.
Combined with the fixations and special monitoring probes developed by DWL®, t...
