SUPPLEMENTAL CONFIGURATION CONSIDERATIONS.

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TM 11-5805-688-14-1

NAVELEX 0967-LP-545-3010

total number of ports used. The second major source of

channel data is doubled from 15 to 30, requiring a total of

31 ports in this configuration. Output rate (Ro) is again

multiplexer set inefficiency occurs when the set of input

the product of port rate and total port count, or 4 kbps x

channel rates to be processed is from a mixture of rate

31 = 124 kbps. Note that this output rate is 4 kbps lower

families. Since the port rate (Rp) selected for a given

than the 128 kbps required in the first example. The

configuration is applied to all ports, processing of

overall efficiency of configuration B in figure 3-9 is

channel input rates not of the family to which the port

expressed as:

rate is related will necessarily induce inefficiency by

requiring the use of coarse rate conversion.

(48 x 2) + (8 x 3) X 100 = 96.77

Inefficiencies resulting from the processing of inputs

124

percent.

from multiple-rate families can be minimized by selection

of a port rate related to the predominant family.

The efficiency difference of 3.02 percent between the

two examples illustrates the importance of processing

3-48. The following paragraphs provide brief discussions

applied inputs at the lowest possible port rate consistent

and examples regarding reduction of inefficiencies

with the number of ports available.

resulting from the above-mentioned sources.

3-51. Configurations A and B of figure 3-10 show the

3-49. In examining the effects upon overall input/output

effects of processing mixed input rate families upon

efficiency resulting from port rate (Rp) selection, consider

overall input/output efficiency.

the example depicted in configuration A of figure 3-9.

Five input channels at rates of 48, 48, 8, 8, and 8 kbps

3-52. Three rate families frequency encountered in

are applied to the multiplexer's channel inputs. A port

digital communications applications are the 8000N,

rate ( ) equal to the lowest input rate of 8 kps is selected.

600N, and C x 75 x 2n The values selected for N, C,

This requires the use of six ports for each of the 48-kbps

and n in these families are positive integers.

inputs (48/8 = 6) and one port (8/8 = 1) for each of the 8-

Configuration A of figure 3-10 depicts a multiplexer set in

kbps inputs. The total number of ports used, including

which rates from all three families are processed: input

the overhead port, is 16. This satisfies the requirements

channels 1 and 2 of the 8000N family, where N equals 1;

that the number of ports assigned to all channels (N) be

channel 3 is of the 600N family, where N equals 10; and

equal to or greater than 15. Output rate is simply the

channel 4 is of the C x 75 x 2n family, where C equals 23

product of Rp and the total number of ports, or 8 kbps x

and n equals 3.

16 = 128 kbps. Expressed as a percentage, overall

efficiency for the example shown is expressed as:

3-53. Representing two of the four channels applied, the

8000N family is predominant. Based on the previously

(48 x 2) + (8 x 3) X 100 = 93.75

128

percent.

established rule that mixed rate families should be

processed with a port rate related to the predominant

3-50. As shown in configuration B of figure 3-9, the

family, a port rate (Rp) of 2 kbps is used in the example

channel inputs remain unchanged from the previous

depicted in configuration A of figure 3-10.The 2kbps rate

example, but the port rate (Rp) is reduced from 8 kbps to

is a

4 kbps. The number of ports required to process the

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