Microsemi SyncServer S300 User Manual page 73

available (e.g., if the hardware clock or other server associations became unreachable).
While the SyncServer's NTP daemon is synchronized to the modem association (system
peer = modem), the Sync LED on the front panel is green and the SyncServer operates as a
stratum 1 NTP server.
The REFERENCES - Modem page provides the telephone numbers of several established time
services. The user can edit or replace these with the number of any compatible dial-up time
service (same protocols, time code, and time scale). Microsemi recommends that users out-
side the United States, Japan, and Germany determine whether a local timekeeping author-
ity offers a compatible dial-up time service.
After the modem association has been created, the user can influence how often the modem
calls the time service by modifying the Minimum Poll Interval (default 00:02:08, in hh/m-
m/ss format) and Maximum Poll Interval (default 18:12:16, in hh/mm/ss format) on the NTP
- Config page. The interval between calls starts out close to the Minimum Poll Interval and
gradually increases to the Maximum Poll Interval over a day or so. Decreasing the Max-
imum Poll Interval improves timing accuracy, but also increases the frequency of phone calls.
Note: All communication and service charges are the responsibility of the user.
The user can determine the highest acceptable value for the Maximum Poll Interval by mul-
tiplying it with the estimated drift rate of the oscillator (given on the TIMING - Holdover page).
For example, on a SyncServer equipped with a TCXO oscillator, the default Maximum Poll
Interval, 18:12:16, translates into approximately 0.76 days or approximately 14 ms of drift
between synchronizations. This value may be acceptable for network timing applications, but
should be considered if more precise timing is required, particularly from the timing outputs
from the rear panel.
Note: The settings on the TIMING - Holdover page do not apply to the modem association, they
only apply to the Hardware Clock Input References.
Modem Configuration
Dial Configuration:
Tone Dial (ATDT): (Factory Default) Configures the modem for "touch tone" dialing, com-
n
mon throughout the world.
Pulse Dial (ATDP): Configures the modem for pulse "rotary telephone" dialing, still used in
n
selected regions of the world.
None (User Dial Command): Makes AT commands available in the Dial-Up Time Reference
n
Phone Number(s) fields. Phone numbers must be preceded by a valid AT command. Some
potentially useful AT modem commands for getting an outside line from a PBX system:
AT X0 establishes blind dialing and dials 0, common in Japan.
n
AT X9 establishes blind dialing and dials 9, common in USA.
n
Note: Leave a space between T and X in the preceding commands.
Modem Pre-Test
The user can test a number by entering a number in the Test Number field and clicking the
TEST MODEM button. If successful, "Modem Connected to Test Number" appears in small text
997-01520-02 Rev. F1..........................................................................
REFERENCES - Modem
Page 73