A maximum frequency detector for Doppler blood velocimeters.

The clinical information available from ultrasonic Doppler blood velocimeters may be analysed in several ways, spectral analysis probably being the best. This is, however, a relatively expensive technique when compared with the cost of commerically available Doppler velocimeters. A large part of the diagnostic information present can be obtained from the maximum blood velocity in the vessel at any one time. A relatively inexpensive analogue method of extracting this information from the Doppler signal is described, and the preliminary results obtained on signals derived from peripheral arteries are discussed.