DEMULTIPLEXER COMMON ELECTRONICS.

T.O. 31W2-2GSC24-2

TM 11-5805-688-14-1

NAVELEX 0967-LP-545-3010

five channels. Similarly, the value 3 is entered in the

3-45.

SUPPLEMENTAL

CONFIGURATION

PORTS (K) block for each channel. This completes

CONSIDERATIONS.

preparation of sheet 3 of the configuration worksheets

for the example shown in figure 3-4.

3-46. The preceding discussions relative to configuration

of the multiplexer set have considered its application to

3-43. DEMULTIPLEXER COMMON ELECTRONICS.

be within an overall communications system. Because

all elements of such a system must operate in a fully

3-44. Sheet 4 of the configuration worksheets (figure 3-

compatible manner, key factors such as output rate (Ro),

8) is prepared to enable setup of the demultiplexer

port rate (Rp), and port strapping assignments for a

common electronics section.

As shown in the

given multiplexer are fixed by overall system

configuration example in figure 3-4, the demultiplexer

requirements and are not subject to selection by the

input rate (Ro) is 1.536 Mbps; the value 1536000 is

individual multiplexer set user.

In such system

therefore entered in the INPUT RATE (Ro) BPS block.

applications, the configuration of a selected multiplexer

Assuming no phase reversals in the transmission link

set may be less than optimum in terms of input/output

from the far-end multiplexer, the DATA N and TIMING

efficiency, while overall system efficiency is in fact

N blocks are each marked with an X, indicating

optimized. Efficiency here is defined as the proper

normal. Since the 1.536-Mbps input is assumed for this

processing of all applied channel inputs while

example to come from a 75-ohm driver, an X is entered

maintaining the lowest possible output rate (Ro). There

in the INTFC 75 block. A link error rate environment of

are undoubtedly some applications, however, in which

one error per hundred bits (1/100) is considered

one or more factors of a multiplexer set's configuration

acceptable for this example; however, it is desired to

are left to user selection. In these situations, the user

indicate by an alarm when the error rate exceeds this

should strive to maximize overall input/output efficiency

value, and therefore an X is entered in the ERROR

while continuing to properly process all applied channel

RATE THRESHOLD 10-2 block. Port rate and port

inputs.

assignment entries are made, based on the example in

figure 3-4; accordingly, the value 96000 is entered in the

3-47. The user must consider two primary sources of

PORT RATE (Rp) BPS block, and the number 15 is

inefficiency when configuring the multiplexer set. The

entered in the PORTS IN USE (N) block. PORT A

first source of multiplexer set inefficiency relates to the

blocks 1, 4, 7, 10, and 13 are each marked with an X,

fact that regardless of configuration, one port is always

indicating active, and PORT S blocks 2, 3, 5, 6, 8, 9, 11,

used for overhead servicing. Since this port occurs at

12, 14, and 15 are each marked with an X, indicating

the same port rate (Rp) as all other ports, its contribution

strapped.

This completes preparation of the four

to inefficiency can be minimized by selection of the

configuration worksheets for the multiplexer set

lowest possible port rate consistent with proper

configuration shown in figures 3-5 through 3-8.

processing of the applied channel inputs. With a fixed

set of input rates to be processed, reductions in port rate

will necessarily require an increase in the

3-22