Comtech EF Data SDM-309B - Manual (Page 185)

Remote Control SDM-309B Satellite Modem
B-B–8 MN/U-SDM309B Rev. #
4.2.7 Sweep Reacquisition
This command is used to specify time duration of the reacquisition mode. The sweep is
reduced to plus/minus 2500Hz of the last known lock point. Use of this function may
reduce reacquisition times at low data rates. To inhibit the sweep reacquisition mode set
‘sR" to 0 seconds.
Command: (xxx = 0 to 999 number of seconds)
Response: >add/SR_xxx”cr””lf”]
Status Only:
Response: >add/SR_xxx”cr””lf”]
4.2.8 Fast Acquisition Mode
This command is used to enable or disable fast acquisition and directed sweep modes of
operation.
When fast acquisition is enabled the fast acquisition algorithm (requires hardware
calibration) is used for acquisition of receive symbol rates of 128Ksps or lower.
However, if the sweep range is set to less than 50khz, acquisition will be dictated by the
directed sweep specifications and the fast acquisition algorithm will not be used.
The directed sweep functions are also available when fast acquisition is enabled.
Directed sweep provides three commands for manipulating the acquisition process.
These commands are ‘sCF_" (sweep center frequency), ‘sWR_" (sweep range), and
‘sD_" (sweep direction).
Command:
Response: >add/FAM_xxx”cr””lf”]
xxx = ON or OFF (OFF disables fast aquisition and directed sweep modes).
Status Only:
Response: >add/FAM_xxx”cr””lf”]
4.2.9 Sweep Center Frequency
This command sets the sweep center frequency. During carrier acquisition the sweep
starts at a offset which is one half the currently programmed sweep range (SWR_) from
the sweep center frequency. The direction of the offset is determined by the currently
programmed sweep direction (SD_).
The sweep center frequency may be set in the range of +25000Hz to -25000Hz.
Command:
Response: >add/SCF_xnnnnn”cr””lf”]