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Spirent KB Article
Doc ID: FAQ14628
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Positioning Application: What is the ephemeris / almanac update (upload) interval and can you change it?
PosApp (SimGEN / SimREPLAYplus / SimREPLAY)
Where applicable, default ephemeris / almanac upload intervals are specified in the satellite constellation file
To view the default value and/or set a new value:-
In the scenario tree locate the 'constellation' required
Double-click to open the corresponding 'signal sources file', e.g. [GPS constellation-->GPS signal sources file]
For GPS a default of 12 hourly uploads is used and you modify this using the settings found in the [Signal control-->Upload details] page
For GLONASS a default of 30 minute uploads is used for Ephemeris and 12 hourly uploads is used for Almanac. You modify this using the
- “Ephemeris update interval” setting in the [General] page
- settings found in the [Signal control-->Upload details] page.
NOTE: this control will also schedule additional Ephemeris uploads if not a multiple of the "Ephemeris update interval"
For Galileo a default of 10 minute uploads is used and you modify this using the settings found in the [Uplink control] page
For WAAS / EGNOS / MSAS a default of 10 minute uploads (every 2 messages, with a message rate of every 5 minutes) is used and you modify this using the
- "GEO navigation message (9)" setting in the [Message output control] page
- "GEO navigation update" setting in the [Signal control-->For all satellites-->General] page
For IRNSS a default of 2 hourly uploads is used for ephemeris only and you modifiy this by creating your own schedule using settings found in the [Signal control-->Status control] page.
- Almanac is only uploaded once, at the start of the scenario
Further details are available in the relevant section of the SimGEN user manual,
For BeiDou and QZSS there is currently no equivalent, manual control of ephemeris/almanac uploads / updates.
Instead, the following are applied automatically
BeiDou uploads occur every 1 hour
QZSS uploads ephemeris every 1 hour (almanac is only uploaded once, at the start of the scenario)
For CAPS navigation data is always read from file so the idea of uploads does not apply in this case.
Even if the broadcast nav data file 'describes' an upload, the simulated RF signal (satellite orbit) will not change
Product : SimREPLAYplus,SimREPLAY,SimGEN,PosApp