CD22103AD Intersil Corporation, CD22103AD Datasheet - Page 6

• Manufacturer Part Number: CD22103AD
• Description: CMOS HDB3 High Density Bipolar 3 Transcoder for 2.048/8.448Mb/s Transmission Applications
• Manufacturer: Intersil Corporation

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
2. Spaces (zeros) in the binary NRZ signal are coded as
3. Marks (ones) in the binary signal are coded alternately as
4. Strings of four spaces in the binary signal are coded
denoted B+, B-, and 0.
spaces in the HDB3 signal. For strings of four spaces,
however, special rules apply (See Item 4 below).
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).
according to the followinq rules:
NRZ - OUT DATA
73
RAIS
CRX
FIGURE 6. RECEIVER ALARM-INHIBIT-SIGNALS TIMING WAVEFORMS
AIS
+HDB3 IN
-HDB3 IN
FIGURE 7. RECEIVER ERROR-SIGNALS TIMING WAVEFORMS
CRX
ERR
FIGURE 5. CRX RECONSTRUCTION REQUIREMENTS
CKR
CRX
CD22103A
t
P
t
D
A. The first space of a string is coded as a space if the polar-
B. The second and third spaces of a string are always coded
C. The last space of a string of four is always coded as a
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.
as spaces.
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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