Toshiba Strata DK 280 Installation Manual page 630

H Line Coding-The DK280 RDTU
supports
Ti/DS-1 transmission of Voice and Analog
Data (using modems) using Alternate Mark
Inversion (AMI) with Zero Code Suppression
(ZCS) or Bipolar Eight Zero Substitution
(B8ZS) line coding. B8ZS provides clear
channel capability, which allows frame
information bits to carry any combination of
ones and zeros-a feature needed for Tl/DS-
1 transmission of digital DATA (DK280 does
not support transmission of digital DATA over
RDTU Tl/DS-1 at this time).
As of this writing, most Telcos provide
AMI
line coding which is adequate for DK280
RDTU voice transmission; however, B8ZS
may be required by some long distance
providers, college campus private networks,
or customer premise end to end Tl
connections. AMI and B8ZS are adequate for
DK280 Voice Tl/DS-1 transmission,
W Framing-As
of the time of this writing, D3/D4
Superframe (SF), or Type I and Extended
Superframe (ESF), or Type II Tl/DS-1 is
offered by most all local Telcos and Long
Distance Providers. Normally the local Telco
will provide SF, which is adequate for DK280
voice (and modem type data) transmission.
Long distance providers may offer either SF or
ESF.
ESF provides a more enhanced method of
error checking that SF; however, the Channel
Service Unit (CSU) must be compatible with
ESF and may cost more than a SF only CSU.
ESF circuits have the additional power of
Cyclic Redundancy Checking (CRC), which
allows end-to-end monitoring of Tl circuit
performance. ESF, Ti performance
monitoring normally requires that a person be
specially trained for this function. SF and ESF
Frame format is adequate for DK280 Voice
(and modem type data) Tl/DS-1 transmission.
8. Programs *41-3 and
-4-These programs allow
the RDTU Transmit and Receive (Volume) level to
be adjusted by changing the RDTU built-in digital
PAD value between +6 decibels (dB) and -15 dB.
Transmit and Receive levels are individually
adjustable on each RDTU (all channels will have
the same level). It is recommended to use the
initialized levels (Receive -3 dB/Transmit -6 dB)
upon initial installation. Adjust the RDTU digital
PAD as required while testing each RDTU Tl
channel.
11-6
January 1996
9. Program *42 Series-T1
Span Timing Reference
Assignments
Timing references for Ti RDTU PCBs are made
with the Program *42 series. The RDTU (Tl)
timing (or synchronization) program options
determine how the DK280 system digital voice
transmission path (time-switch) is synchronized
with the far end digital system transmission path.
For proper Tl operation, the equipment at each
end of a Tl span line must be synchronized.
The DK280 time-switch is synchronized (as slave)
to the Ti span equipment on the other end of the
Tl line by the RDTU PCB designated as the
Primary Reference in Program *42-l. When a
RDTU is connected to a Telco or Long Distance
Provider Tl span line, the RDTU in the lowest slot
number should be assigned as the Primary
Reference RDTU (x42-1, DATA = 1 FOR THIS
RDTU). If a malfunction occurs and Primary
Synchronization is lost, the DK280 automatically
switches modes and synchronizes to the Tl span
connected to the RDTU PCB designated as the
Secondary Reference (provided that there are two
RDTU PCBs installed in the DK280) (see
Figure 11-12).
If there are two RDTU PCBs installed, it is
recommended not to install the Primary and
Secondary Reference RDTU PCBs in the same
DK280 cabinet if possible (although both Primary
and Secondary Reference RDTU PCBs can be
installed in the same cabinet). The Secondary
Reference RDTU should also be connected to a
Telco or Long Distance Provider Tl span (*42-2,
Data = 2 for this RDTU).
If the equipment on the other end of the DK280 Tl
lines should synchronize to the DK280 clock
source, then blanks should be entered in Program
*42. In this case, the DK280 clock runs free and is
considered the Master Synchronization provider.
The DK280 can be assigned as the Master (free
run) clock provider if the far end equipment
connected to the RDTU Tl span is a Customer
Premise type equipment and it is not synchronized
to some other Tl provider (i.e., PBX, Channel
Bank, Key/Hybrid or other DK280). In this case
(when the Telco network is not connected), either
the DK280 RDTU span or the far end equipment
can be the Master (synchronization -clock
provider).