DIGITAL DATA WITHOUT ASSOCIATED TIMING.

T.O. 31W2-2GSC24-2

TM 11-5805-688-14-1

NAVELEX 0967-LP-545-3010

Normally, Rc is nominally equal to KRp. In cases where

Type II form are processed within the multiplexer set by

the use of one of two techniques: timing recovery or

Rc is not equal to KRp, the channel rate is adjusted

transition encoding/decoding.

Type II data to be

within the multiplexer set and processed at a rate of the

processed by the timing recovery technique must be at

form Rc = KRp. The rate adjustment process is termed

rates fitting the expression:

coarse rate conversion, and is performed completely

within the multiplexer set. Therefore, although coarse

Rc = 75 x 2n bps

rate conversion may be used, the demultiplexer's

channel output rate is the same as the multiplexer's

where

channel input rate.

Rc = channel data rate

3-21. Type-I channel input/output rates may vary from

their assigned nominal value by plus or minus 250 parts

n = an integer from 0 to 7.

per million (+250 ppm;.

The multiplexer set

automatically compensates for such rate deviations,

Rates fitting this expression are as follows:

using a process of internal bit insertion and deletion

termed stuffing. The stuffing capability enables the

Rc(bps)

multiplexer set to process channel input/outputs not

synchronous with the set or with each other. For

example, a channel input rate of 1.0 Mbps that varies

between 1.000250 and 0.999750 Mbps is properly

processed in the multiplexer set. Deviations appearing

150

in a multiplexer input channel rate are automatically

reinserted in the corresponding demultiplexer output

300

channel rate. The multiplexer is therefore considered to

be transparent to applied rate variations within

600

prescribed limits.

1200

3-22.

DIGITAL

DATA

WITHOUT

ASSOCIATED

2400

TIMING.

4800

3-23. A second form of input/output channel data

accepted and processed by the multiplexer set is digital

9600

data without timing. This data form is commonly referred

to as Type II data. When provided with Type II channel

It is also required that Type II channel data processed by

data inputs, the multiplexer accepts the incoming data

the timing recovery technique reflect a sense transition

and processes the data by means of timing signals

(1 to 0, or 0 to 1) at least once each 100 data bit times.

generated within the multiplexer. Data inputs of the

This enables the multiplexer to internally generate an

appropriately synchronized timing signal for subsequent

processing of the applied data. Type II data rates may

vary from their assigned nominal values in the same

manner as that described for Type I data rates

(paragraph 3-21).

3-6