Comtech EF Data SDM-9000 - Manual (Page 90)

Operation SDM-9000 Satellite Modem
4–16 Rev. 4
BUFFER SIZE This configuration function is used to set the size of the buffer.
On entry, the current buffer length is displayed. Press [
↑
] or [
↓
] to
select the desired buffer size. The buffer size will be displayed in
ms. The user may choose from 2 to 32 ms, in increments of 2 ms,
or 0 (bypass). Press [ENTER] to execute the change.
Note: This menu is only available when the buffer is installed.
BUFFER CENTER This configuration function is used to center the buffer. Press
[ENTER] twice to center the plesiochronous buffer.
Note: This menu is only available when the buffer is installed.
RX CLOCK PHASE Programs the RX clock phase to:
•
Normal
•
Invert
On entry, the current status of the RX clock is displayed. Press [
←
]
or [
→
] to select Normal or Inverted. Press [ENTER] to execute the
change.
Note: This menu is only available for the ECL, PECL, or
MIL-STD-188 interface.
B-BAND LOOPBACK
(Test Mode
Configuration Option) Programs the modem for baseband loopback operation.
When baseband loopback is turned on, the data and timing signals
are hard-wired (via relays) from the demodulator to the modulator
on the modem side of the interface. The DTE baseband signals are
also looped back from the TX data and clock to RX data and clock
on the customer side of the interface. This is a bi-directional
loopback of the baseband data. Refer to Figure 4-19 for a block
diagram of baseband loopback operation.
On entry, the current status is displayed. Press [
←
] or [
→
] to select
ON or OFF. Press [ENTER] to execute the change.
Notes:
1. If baseband loopback is turned on, the buffer clock will be
programmed for RX satellite.
2. When baseband loopback is turned off, the previous buffer
clock selection will be programmed back.
INTERFC LOOPBACK
(Test Mode
Configuration Option) Programs the modem for interface loopback operation. When
interface loopback is turned on, data is looped back at the modem
side of the interface. This is a bi-directional loopback of the data
after the baseband data has had the overhead added. Refer to
Figure 4-20 for a block diagram of interface loopback operation.
On entry, the current status is displayed. Press [
←
] or [
→
] to select
ON or OFF. Press [ENTER] to execute the change.
LOOP TIMING Programs the send timing output reference clocking to the satellite
clock. Refer to Figures 4-21 and 4-22 for the interface clocking
diagram.
On entry, the current status is displayed. Press [
←
] or [
→
] to select
ON or OFF. Press [ENTER] to execute the change.
Note: This menu is only available with the ECL, PECL, or
MIL-STD-188 interface.