The carrier harmonic is then band-pass filtered and frequency divided to recover the carrier frequency . ( This may be followed by a PLL . ) Multiply-filter-divide is an example of open-loop carrier recovery, which is favored in burst transactions since the acquisition time is typically shorter than for close-loop synchronizers.
32.
However, the radiation dose needed to achieve this resolution is lethal to small animals, and a 50 �m spatial resolution is a better representation of the limits of micro-CT . It is also decent in terms of image acquisition times, which can be in the range of minutes for small animals.
33.
At present, SPDM achieves 16 frames / sec with an effective resolution of 10 nm in 2D ( object plane ); approximately 2000 such frames are combined with SMI data ( ca . 10 sec acquisition time ) to achieve a three-dimensional image of highest resolution ( effective optical 3D resolution ca . 40-50 nm ).
34.
Consider a single pulse sequence consisting of ( 1 ) an excitation pulse with flip angle \ theta _ E, ( 2 ) the recording of the time domain signal ( Free induction decay, FID ) for a duration known as acquisition time a _ t, and ( 3 ) a delay until the next excitation pulse ( here called interpulse delay d _ 1 ).
