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4.5 CW Doppler Unit EZU-CW4
4.5.1
General and board description
Composition
PCB.
Outline of PCB : This is for CW Doppler by single piece probe, and carries out
4.5.2
CW PCB circuit description
CW PCB is divided into the following 11 blocks.
1.
REFERENCE CLOCK GENERATOR (Reference clock generation circuit part)
Generates transmitting signal clock for CW and reference signal having 90
degrees different phase.
2.
TRANSMITTING CIRCUIT (Transmission circuit part)
Outputs transmitting signal clock for CW to the probe through tuning amplifier
and driver circuits.
3.
PRE AMP (First step amplification circuit part)
Tunes and amplifies the receiving signal from the single piece prove.
4.
NOTCH FILTER (Notch filter circuit part)
Deletes the carrier element, which leak into the circuit, so that the receiving
signal does not saturate with them.
5.
MIXER (Demodulation circuit part)
Detects the element of Doppler shift by mixing with the reference wave.
6.
GAIN (Gain process part)
Amplifies or attenuates Doppler signal.
7.
ANALOG WALL FILTER (High area pass filter part)
Deletes unnecessary low frequency element which is mixed into Doppler signal by
body movement.
8.
ANTI ALIASING FILTER (Anti aliasing filter part)
Deletes unnecessary high frequency element to prevent aliasing by A/D converter
described later.
9.
AD CONVERTER (AD convert part)
Converts the added receive signal to digital signal and sends to EPI P.C.B.
10. CW CONTROL (CW control part)
Controls the frequency setting for reference wave, the gain setting and other
settings.
11. LO GENERATOR (Mixing clock generate part)
Generates the clock of Mixer.
: EZU-CW4 is an option of EUB-5500 and consists of the following
1.
CW PCB
transmission and reception, demodulation and filter process of
Doppler signal.
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L1E-EA0229
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