CDMA System Time Parameters
Overview
The CDMA system time is the time reference used by all IS-95/IS-2000 and IS-856 systems. It is synchronous to UTC time (Universal Coordinated Time) except for leap seconds and uses the same time origin as GPS (Global Positioning System) time. Access terminals (ATs) use the same system time, offset by the propagation delay from the AN to the AT.
The test set emulating an AN allows you to set the
CDMA System Time
,
Leap Seconds
and
IS856 Local Time Offset (hh.mm)
which are sent to the AT in the overhead messages (
Sync Message
and
SectorParameters Message
). The AT determines its local time based on these parameters. When the AT successfully synchronize its system time to the test set, the local time that is displayed on the AT's screen should be same as the
CDMA Local Time
displayed on the test set's
CDMA System Time Information
window.
The settable CDMA system time provides convenience to verify AT's time-based applications such as alarms, calendar, meeting scheduler, etc.
( Lab Application Only ) The settable CDMA system time is required by multiple test sets synchronization. For details, see Multi-unit Synchronization .
CDMA System Time Parameters and Information
-
The CDMA System Time consists of two portions:
CDMA System Time (Date)andCDMA System Time (Time)which are set from theCDMA System Time Parametersmenu when the test set is in idle state. The CDMA system time in the test set starts at what you set (or internal RTC time when shipped from the factory) and keeps going as the UTC time (Universal Coordinated Time) without leap seconds. It is shown on theCDMA System Time Informationwindow and updated every two seconds. To get a more accurate CDMA system time running in the test set, useCALL[:CELL]:CSTime:TIME? query command which has one second resolution.The
CDMA System Time (Date)can be set to any date from January 6, 1980 to January 5, 2080. TheCDMA System Time (Time)can be set to any time of the day. You can change the CDMA system time while the test set is in idle state. When setting the CDMA system time from the front panel, you can use a simple way. For example, to set the CDMA System Time to January 1, 2000 2:00 PM, you can simply enter 2000.1.1 in theCDMA System Time (Date)field and enter 14 in theCDMA System Time (Time)field. Moreover, <second> you enter in odd number will be automatically rounded up to an even number.The CDMA system time is stored in the test set's non-volatile RAM. Power-cycle, full preset and save/recall operations do not affect the ongoing CDMA system time but power cycle may cause minor uncertainty on CDMA system time. (see Operating Consideration ).
GPIB Command: CALL[:CELL]:CSTime:DATE and CALL[:CELL]:CSTime:TIME
-
Specifies the leap seconds since the start of CDMA system time. It is ranged from 0 to 255 seconds. It is used by CDMA Local Time calculation.
It is stored in the test set's non-volatile RAM and is not affected by power cycle, full preset or save/recall operations.
GPIB Command: CALL[:CELL]:CSTime:LOCal:LEAP
-
IS856 Local Time Offset (hh.mm)
Specifies the local time offset from CDMA system time. It is ranged from -17.00 to +17.00 hours. It is used by CDMA Local Time calculation.
It is stored in the test set's non-volatile RAM and is not affected by power cycle, full preset or save/recall operations.
GPIB Command: CALL[:CELL]:CSTime:LOCal:OFFSet[:SELected] or CALL[:CELL]:CSTime:LOCal:OFFSet:TA856
-
Like the CDMA system time, the CDMA local time consists of two portions:
CDMA Local Time (Date)andCDMA Local Time (Time)which are shown on theCDMA System Time Informationwindow and updated every two seconds. The CDMA local time is a calculated value which is based on the formula:CDMA Local Time = CDMA System Time (Date) + CDMA System Time (Time) - Leap Seconds + Local Time Offset
The CDMA local time is primarily used to verify the correctness of the time displayed on the AT's screen. When the AT successfully acquires and synchronizes with the test set, the time displayed on the AT's screen should be same as the
CDMA Local Time (Date)andCDMA Local Time (Time)that are shown on the test set.GPIB Command: CALL:STATus:CSTime:LOCal:DATE? and CALL:STATus:CSTime:LOCal:TIME?
Operating Consideration
-
The
CDMA System Time (Date)and theCDMA System Time (Time)are available only inActive CellorIS-856 Test Modeoperating mode. -
The
CDMA System Time (Date)and theCDMA System Time (Time)can only be set when the test set is in idle state.
Most ATs will immediately open a session with the test set once they reach the idle state upon power-up. You can close the session at any time (see Session Closing State ) and the data connection will be taken to the idle state. However, most ATs will try to immediately re-establish a session. You can prevent the AT from re-establishing a session by turning Call Limit Mode on.NOTE
- There is about +/- 1 second uncertainty on CDMA system time when any of the following actions is performed.
- Cycle power the test set.
- Perform the Channel Power Calibration, Open Loop ALC Calibration or Average Power Calibration (See Calibrating the Test Set ).
- Change the Digital Bus Path setting on the test set (See Digital Bus Information ).
- Switch the application format (for example switch between cdma2000 and 1xEV-DO applications) (see Test Application Switching ).
-
Switch the
Operating ModefromCW(withTest Signalset toAMorDSB-SC) toActive CellorIS-2000 Test Mode.
- There is about +/- 1 second uncertainty on CDMA system time when any of the following actions is performed.