Chapter 5
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Measurement Definition
Measurement Parameter Definition
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by the read channel IC’s detector. Filter equalization modifies the data sample so that they
cluster around the target values, zero, positive and negative value. The length of time delay
(tap) determines the impulse response of the equalizer. The output signal of the analog
filter is quantized using an ADC (analog to digital converter), the digitized data is then
equalized for partial response.
The Detector is used to detect the entire sequence bits at a time as it receives data sample,
it doesn’t decode immediately whether the sample is ‘1’ or ‘0’ in the original write data.
Instead, it compares sequences of samples with sequences of possible samples. It then uses
a comparator to determine what an entire sequence of data bits should be. After detection,
the read channel decodes the data into the original user data sequence. Figure 5-18, “Read
Signal Flow,” illustrates a typical signal flow coming from the read head.
Figure 5-18
Read Signal Flow
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