Comtech EF Data SDM-100A - Manual (Page 185)

SDM-100A Satellite Modem Options
Rev. 0 B–3
The ASYNC interface PCB also provides its own Doppler buffer, which has a maximum
depth of 32 ms at the highest terrestrial data rate. Buffer fill status can be checked in the
monitor menu on the front panel of the modem. Depth selection and centering of the
buffer are provided in the CONFIG INTERFACE menu.
The AUPC function allows each of two modems that are in a closed link to control the
output of the other modem. In order for this feature to function, both modems must have
their AUPC options enabled. These options are:
AUPC Enable Enables the AUPC to function locally.
Nominal Power Output power level. Can be used for problem conditions, if chosen.
Minimum Power Sets minimum output power to be used.
Maximum Power Sets maximum output power to be used.
Target Noise Desired E
b
/N
0
of the local modem.
Tracking Rate Sets speed at which modems will adjust to output power.
Local CL Action Defines action that local modem will take if it loses carrier
(Maximum, Minimum, or Hold).
Remote CL Action Defines action that local modem will take if remote modem reports
carrier loss (Maximum, Minimum, or Hold).
LINK
MODEM A MODEM B
With AUPC enabled on both modems A and B, as in the above illustration, if modem A
loses carrier:
1. Modem A will set its output power as specified by Local CL Action. This will be
Maximum, Minimum, or Hold.
2. Modem A will then send a “lost carrier” command to modem B.
3. Modem B will set its output power as specified by its Remote CL Action. This
will either be Maximum, Minimum, or Hold.