Spectracom 9289, Instruction Manual

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Model 9289 Spectracom Corporation
NetClock/NTP Network Time Provider Instruction Manual 7-10
location). The System Modem Configuration screen (Figure 7-1) provides options to configure
the operation of the dial-out modem feature from the left-hand menu. All fields will display the
current system settings.
7.1.6 Modem Dialout
The Modem Dialout screen (Figure 7-7) is used to annotate the phone number used to obtain
the time from and to determine how often the modem will be used to retrieve the current time.
Phone Numbers:
Prefix:
The phone prefix is a number(s) that need to be dialed to reach an outside line.
Predefined:
Stores two predefined number NIST-Colorado and NIST-Hawaii. These are the
phone numbers to the National Institute of Standards and Technology modem time service.
Specified Number:
This field will take any phone number that the user would like to use to dial
out to obtain time.
Try Calling:
This field specifies how many times the dial out modem software will try to connect
to the selected phone number. Setting this field’s value to 0 will generate a warning because it
will prevent any dial out to be made in any condition, effectively disabling the modem dial out
feature.
Call Interval:
The call interval is used to manually configure how often the modem should dial-out for Time
verification calls when the unit is in the holdover mode and time synchronization is normally
derived from GPS (Secondary/Backup mode of operation) or time synchronization calls when
the modem is selected as the primary mode of operation.
To prevent a leap second occurrence from being missed and a one second error being inserted
into the NetClock, we recommend the Time Verification calls be placed less than once-per-
month. Setting the Time Verification call period to longer than once-per-month can result in a
one second error from the time a leap second is asserted by NIST until the next time
verification/time synchronization call is placed.