Moss S, Bennett D
J Biomed Eng. 1979 Jan;1(1):5-11. doi: 10.1016/0141-5425(79)90004-9.
The Parks Model 806 Doppler blood velocity meter was shown to have a linear voltage output with respect to input frequencies of up to 5kHz. It was linear and accurate to velocities of 70 cms-1 at angles of 50 degrees and 60 degrees to the flow, on a steady flow rig, and shown to have a linear frequency response to 9Hz. A combined pulse echo and Doppler transducer system has been developed allowing quantitation of arterial peak velocity.