Abstract: A method for Doppler scan conversion includes storing coded envelope values together with spectrum data in a memory out of a logic device with a large capacity, which increases the number of envelopes stored, reduces the use of the restricted embedded memory resources, and can also achieve the envelope switching more flexibly. If the number of envelopes is not greater than the difference between the bit width of the memory and that of the spectrum data, the increase in the number of envelopes will not increase significantly the logic resources or affect the efficiency of the system.

Abstract: A frame averaging circuit adapted for a color blood flow frame in a medical ultrasound imaging system. The frame averaging circuit comprises two sections, i.e., a recursive calculation section and a non-recursive section. The recursive calculation section employs an IIR filter in combination with a look-up table, and is adapted for dealing with the cases where no change occurs to the blood flow velocity direction. The non-recursive section compares the blood flow velocity, the energy and the energy prior to wall filtering of the color blood flow echo signal to various threshold values. Different from the recursive calculation section, the non-recursive section is employed when a change occurs to the blood flow velocity direction.