Clock
The Clock attribute of a Satellite object lets you set spacecraft clock parameters and define those clock parameters that are to be simulated/estimated. Currently this clock attribute is only used in the modeling of 1W Doppler, TDRS 3L Doppler, DSN 1W TCP, and DSN 1W Doppler measurements.
Settings | |
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Parameter | Description |
Enabled | Enables the use/simulation/estimation of clock parameters. Other clock parameters are only exposed when Enabled is set to true. |
Estimate | Defines the clock parameters to be simulated/estimated. See table below. |
ClockControls | See table below. |
ClockUncertainty | See table below. |
OrbitClockCorrelations | 6x3 matrix defining initial orbit/clock cross correlations. Orbit is {R, I, C, Rdot, Idot, Cdot}.. Clock is {phase, frequency, aging} |
Estimate
The following combinations of clock parameters can be simulated/estimated:
- {phase, frequency} (the default)
- {phase, frequency, aging}
- {frequency}
- {frequency, aging}
Estimate | |
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Parameter | Description |
Phase | = true, enables clock phase |
Freq | = true, enables clock fractional frequency |
Aging | = true , enables clock aging |
Clock Controls
The following are the clock controls properties:
ClockControls Properties | |
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Property | Description |
PhaseBias | Clock phase (time) offset estimate at state creation time . |
FreqBias | Clock frequency offset estimate at state creation time. This is a fractional frequency, units are sec/sec. |
AgingBias | Clock aging offset estimate at state creation time. |
A0 | Frequency-modulated (FM) clock white noise statistic. |
Aminus1 | FM clock flicker noise statistic (not currently modeled). |
Aminus2 | FM clock random walk statistic. |
AgingWN | FM clock drift statistic. |
Clock Uncertainty
The following are the clock uncertainty properties:
ClockUncertainty Properties | |
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Property | Description |
Phase_sigma | Uncertainty associated with the phase bias estimate at the initial filter time. Used to initialize the covariance. |
Freq_sigma | Uncertainty associated with the frequency bias estimate at the initial filter time. Used to initialize the covariance. |
Aging_sigma | Uncertainty associated with the aging bias estimate at the initial filter time. Used to initialize the covariance. |
PhaseFreq_correlation PhaseAging_correlation FreqAging_correlation | Cross-correlations among the above attributes. |