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OM20 Universal Outdoor Modem
Example 1:
User Data Rate:
In-Band Rate:
Control Ratio:
Minimum In-Band = (1,024,000 * 7)/((7 + 1) * 250) = 3,584
Slot Bits = (1,024,000 * (7 * 10))/(19,200 * (7 + 1)) = 466
Actual Ratio = (466 + 10)/466 = 1.021
Example 2:
User Data Rate:
In-Band Rate:
Control Ratio:
4.15.5 SCC Overhead Channel Setup
1.
Set the Framing Mode (located under Mod and Demod Data Menus) to SCC.
After doing this, two new menus will appear to the right of the Framing Menu, for
both the Mod and Demod. The new menus will be:
SCC CTL RATIO
SCC INBAND RATE
2.
Set the desired SCC control ratio:
SCC CTL RATIO {1/1, 1/2, 1/3, 1/4, 1/5, 1/6, 1/7}
This allows the user to simulate the framing used by the Satellite Control
Channel Option (Pass-Thru Mode only). The SCC CTL RATIO is the ratio of
overhead in-band data to synchronizing words.
3.
Set the desired SCC in-band rate:
SCC INBAND RATE {300 to 115200}
This allows the user to request the rate of in-band data for the overhead channel.
This sets the overhead amount only. The actual amount of data that can be
passed through the overhead channel will be set under "ES Baud Rate" (see
Step 6 below).
4.
Under the Interface > General menus, locate the TX ASYNC MODE (menu).
5.
Under the TX ASYNC MODE Menu, set the desired ES Interface type:
ES INTERFACE {RS-232, RS-485}
This allows the user to select the interface type.
6.
Under TX ASYNC MODE Menu, set the desired baud rate for the ASYNC Port
(J17). This will be the baud rate that will pass through the overhead channel:
ES BAUD RATE {150 - 115200}
TM116 – Rev. 1.2
1,024,000 bps
19,200 bps
1 to 7
6,312,000 bps
19,200 bps
1 to 7
Theory of Operation
(less than In-Band Rate)
4-24
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