Table 2-2. Maximum Number of Channel Types in CSS

TM 11-5895-1123-34

b. In figure 2-5, the data is shown being patched

the 256/512 kb/s field user input requires multiple

channels.

The 256 kb/s user requires four input

through the upper units (designated No. 1) but in reality

channels and the 512 kb/s user requires eight. The

the data can be patched through the lower units

proper number of channels for the 256/512 kb/s data

(designated No. 2) or any combination of No. 1 and No.

input is selected by inserting an appropriate data card

2 units as desired or necessary.

c. The overall purpose of these units is to accept

into the multiplexer. When inserted into the multiplexer,

the 256 kb/s data card will utilize the channel position

up to 24 channels of VF, TTY, order wire (OW), and/or

where it is inserted and the next three higher numbered

digital baseband data from their appropriate processing

channels. Similarly, a 512 kb/s data card will utilize the

functions described above, and combine them into one

channel of the insertion position and the next seven

stream of data on a 70-kHz IF carrier. The 70-kHz IF

higher channels. Because the maxi mum output data

modulated carrier is the output of the CSS. This output

rate of the multiplexer is limited to 1544 kbls (1536

is patched to the Radio Subsystem (RSS) through the IF

information bits plus eight overhead

timing bits),

patch panel.

externally multiplexed data rates up to 9.9999 Mb/s (10

d. In the receive mode of operation, the modem/

Mb/s) (which is the operating limit of the modem) bypass

multiplexer processing function receives the 70-kHz IF

the multiplexer and are directly applied to the modem,

signal from the RSS, removes the stream of data from

as shown in figure 2-5. Digital data users of the 50 kb/s,

the 70-kHz IF carrier, and then separates the data

20 kb/s, and 256/512 kb/s rates are patched into

stream into 24 separate channels. The 24 channels are

channels one through twelve only, while the OW, TTY,

then patched back through the TTY, VF, OW, and/or

and 12 VF channels can be patched into any of the 24

digital baseband circuits for final preparation to be sent

available input channels. It is normal operating practice

to the field users.

to reserve one VF channel for orderwire.

The

e. To initially perform the transmit process, data is

OW is usually used as a

communication means

patched through the VF and data patch panels to the

between operators at each end of the satellite link, but

input channels of the AN/FCC-98(V) multiplexer.

may also be patched to subscribers by way of the VF

f. The multiplexer is capable of operating in four

patch panel. The dedication of one VF channel for OW

different channel modes; three, six, twelve or twenty four

may be preempted when warranted by heavy demand

at the corresponding output rates of 192, 384, 768, and

for the availability of VF channels. Table 2-2 lists the

1544 kb/s respectively. Each of the 24 avail able

maximum number of channel types that may be used in

channels can support up to 64 kb of VF or digital data.

each of the four data rate modes of the mission bit

Data rates of 20, or 50 kb/s therefore only re quire one

stream.

channel

for

each

field

user

input,

while

Table 2-2. Maximum Number of Channel Types in CSS

(Not Simultaneous)

Mission Bit Stream

192 kb/s

384 kb/s

768 kb/s

1544 kb/s

3 chan

6 chan

12 chan

24 chan

VOICE CHANNELS (includes 1 order wire

3 max.

6 max.

12 max.

14 max.

and possibly 1 FSK teletype group):

50 kb/s asynchronous

2 max.

256 kbls synchronous

1 max.

512 kb/s synchronous

1 max.

0-20 kb/s asynchronous

3 max.

4 max.

Prior to referring to table 2-3, which lists full loading

into channel 12 which contains the 512 kb/s data card

examples of the different types of traffic at the different

required by the multiplexer for this input bit rate.

data rates, the following should be noted to avoid

The 512 kb/s data card will not only utilize its own

confusion: In example K of table 2-3, it appears that the

channel (12), but also the next seven higher numbered

512 kb/ s data input is in conflict with the previous

channels (13 through 19) Therefore, although 512 db/s

statement that the signals from digital data users are

input is patched into channel 12, it overflows into

patched into channels one through twelve only In

channels 13 through 19.

actuality, he 512 kb/s data input is being patched only

2-10