Image Processing Reference
In-Depth Information
left-hand side of the broken line. Amplitude of negative-output becomes small on the right-
hand side of a broken line, and it becomes large on the left-hand side of the broken line.
This result shows that each system works correctly. Moreover, it shows that the waveform
and response time at the turning point of sign (near the DC) have a difference among the
systems. As these causes, performance differences, such as the response characteristic and
delay time, can be considered.
Amplitud e
I-channel
Q-channel
(a) input signal
Amplitud e
forward
reverse
(b) output signa l of the Hilbert transform system
Amplitud e
forward
reverse
(c) output signal of the complex FIR system
Amplitud e
forward
reverse
(d) output signal of the complex IIR system
Amplitud e
forward
reverse
(e) output signa l of the FFT/IFFT system
Amplitud e
forward
reverse
(f) output signal of the modulation/demodulation system
Amplitud e
for w ard
reverse
(g) output signal of the phase-shift system
Time (ck)
Fig. 7. Chirp wave responses
3.3 Comparison of time-delay and calculation load
The response is important for blood vessel detection, and the time-delay estimates it. The
simulation result of the time-delay is shown in Fig. 8. They are response waveforms of the
sinusoidal-waveform that changes discontinuously. Solid line and dotted line are I-signal
and Q-signal in Fig. 8(a). Amplitude and frequency are changing near the 50ck. The solid
lines of Fig. 8(b) and Fig. 8(c) are positive-output waveforms, and dotted lines are negative-
output waveforms. The output waveform of the complex FIR system of Fig. 8 (b) changed
from a turning point of the input shown with the dashed line after 64ck (time shown with
the chain line among Fig. 8(b)), and is stable gradually. The output waveform of the
complex IIR system of Fig. 8(c) is stable from the turning point after 8ck (time shown with
the chain line among Fig. 8(c)).
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