CD22103A Datasheet, PDF (6/7 Pages) Intersil Corporation – CMOS HDB3 High Density Bipolar 3 Transcoder for 2.048/8.448Mb/s Transmission Applications

CD22103A
CKR
50%
τ
τ
CRX
t_P t_D
50%
FIGURE 5. CRX RECONSTRUCTION REQUIREMENTS
CRX
NRZ - OUT DATA
RAIS
AIS
FIGURE 6. RECEIVER ALARM-INHIBIT-SIGNALS TIMING WAVEFORMS
CRX
+HDB3 IN
-HDB3 IN
ERR
FIGURE 7. RECEIVER ERROR-SIGNALS TIMING WAVEFORMS
Definition of HDB3 Code Used in CD22103A HDB3
Transcoder (As Per CCITRT G703 Annex
Recommendations) and Error Detection
Coding Of A Binary Signal Into An HDB3 Signal Is Done
According To The Following Rules:
1. HDB3 signal is pseudoternary; the three states are
denoted B+, B-, and 0.
2. Spaces (zeros) in the binary NRZ signal are coded as
spaces in the HDB3 signal. For strings of four spaces,
however, special rules apply (See Item 4 below).
3. Marks (ones) in the binary signal are coded alternately as
B+ and B- in the HDB3 signal (alternate mark inversion).
Violations of the rule of alternate mark inversion are intro-
duced when coding strings of four spaces (See Item 4
below).
4. Strings of four spaces in the binary signal are coded
according to the followinq rules:
A. The first space of a string is coded as a space if the polar-
ity of the preceding mark of the HDB3 signal has a polarity
opposite to the preceding violation and is not a violation by
itself; it is coded as a mark, i.e., not a violation (i.e., B+ or
B-), if the preceding mark of the HDB3 signal has the same
polarity as that of the preceding violation or is by itself a
violation.
This rule ensures that successive violations are of alter-
nate polarity so that no DC component is introduced.
B. The second and third spaces of a string are always coded
as spaces.
C. The last space of a string of four is always coded as a
mark, the polarity of which is such that it violates the rule of
alternate mark inversion. Such violations are denoted V+
or V- according to their polarity.
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