Description
The OpticalLink object models laser-based communications between spacecraft and ground assets, including the calculation of received power, free space and atmospheric losses, signal-to-noise ratio (SNR), bit error rate (BER), and link margin. The object supports configuration of wavelength, bit rate, modulation type, transmitter and receiver hardware models, and atmospheric loss parameters. Built-in models support On-Off Keying (OOK), Pulse Position Modulation (PPM), Differential Phase Shift Keying (DPSK), and other schemes, as well as receiver types such as APDs, PINs, and coherent detectors. The OpticalLink can be used for both space-to-ground and inter-satellite optical communications and supports performance analysis under clear and degraded weather conditions. See the OpticalLink Analysis Guide for more information.
Inheritance Hierarchy: Object->OpticalLink
Available In Editions:
Engineer
Mission
Timing Precision Mode
This page describes functionality in millisecond timing precision mode. Millisecond timing precision mode is deprecated and will be removed in a future release. We recommend that you migrate your Mission Plans to nanosecond timing precision mode.
Click here to see the documentation for this object in nanosecond timing precision mode.
Name
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Description
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Attributes
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AtmosphericLossParameters
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Child object presenting an interface to the parameters affecting losses incurred by propagation through the atmosphere.
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Type: OpticalLinkAtmosphere
Access: Read-Only
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BitRate
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The bit rate of the optical link. Used in combination with modulation to compute bandwidth.
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Type: Variable
Access: Read/Write
Units: bps
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DeclaredName
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The name of the object as declared.
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Type: String
Access: Read-Only
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LPPM
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The number of sub-divisions in a pulse position modulated (PPM) signal. This parameter is used only when the ModulationType property is set to 'PPM.' The value of this parameter must be a power of 2.
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Type: Variable
Access: Read/Write
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ModulationType
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The modulation of the optical signal (affects how SNR is mapped to BER).
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Type: String
Access: Read/Write
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Name
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The name displayed for this object in output windows such as views, plots, and reports.
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Type: String
Access: Read/Write
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ObjectId
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The unique identifier for the object.
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Type: Variable
Access: Read-Only
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ObjectType
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The type of the object.
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Type: String
Access: Read-Only
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Receiver
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Child object representing the optical receiver in the optical link.
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Type: OpticalLinkReceiver
Access: Read-Only
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Transmitter
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Child object representing the optical transmitter in the optical link.
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Type: OpticalLinkTransmitter
Access: Read-Only
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Wavelength
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Wavelength in nanometers of the optical link.
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Type: Variable
Access: Read/Write
Units: nm
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Name
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Description
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ClearSavedStates
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Clears previous saved states for this object.
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ComputeBandwidthFromBitRate
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Uses the OpticalLink ModulationType property to determine the bandwidth consumed by a given bit rate.
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ComputeBERFromSNR
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Uses the OpticalLink ModulationType property to convert an SNR to a bit error rate.
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ComputeBitRateFromBandwidth
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Uses the OpticalLink ModulationType property to determine the bit rate made possible by the provided bandwidth.
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ComputeLinkMargin
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Returns the link margin in dB for the link based on the provided receiver sensitivity and model parameters provided in OpticalLink and its child objects Transmitter, Receiver, and AtmosphericLossParameters. For transmission through the atmosphere, this method computes the losses inclusive of precipitation effects (rain, snow) and atmospheric scattering. Any effect of scintillation may be accounted for separately with the help of the OpticalLink GetAtmosphericScintillationLinkDeficit and OpticalLink GetAtmosphereScintillationFadeProbability methods.
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ComputeReceivedPower
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Returns the computed power received by the receiver in dBm.
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ComputeSNRFromBER
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Uses the OpticalLink ModulationType property to convert a bit error rate to an SNR value.
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GetAtmosphericRainLoss
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Returns the loss corresponding to the current rain conditions in dB as described by the RainRate, RainFactor, RainExponent, and PrecipitationPathLength properties of the AtmosphericLossParameters child object.
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GetAtmosphericScatteringLoss
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Returns the atmospheric scattering loss in dB based on the meteorological visibility specified in the Visibility property of the AtmosphericLossParameters child object.
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GetAtmosphericScintillationFadeProbability
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Returns the probability of scintillation losses surpassing the available link margin, calculated as a function of receiver sensitivity.
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GetAtmosphericScintillationIndex
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Returns the scintillation index for a link with an earthbound terminus.
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GetAtmosphericScintillationLinkDeficit
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Returns the additional link margin required to achieve the specified scintillation fade probability.
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GetAtmosphericSnowLoss
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Returns the loss corresponding to the current snow conditions in dB as described by the SnowRate, SnowDry, and PrecipitationPathLength properties of the AtmosphericLossParameters child object.
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GetFreeSpaceLoss
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Returns the free space loss of the link in dB.
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GetFromFile
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Load the object state from the specified FreeFlyer object file.
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GetFromString
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Load the object state from the specified string.
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GetReceiverGain
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Returns the optical receiver gain in dB.
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GetTransmitterGain
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Returns the optical transmitter gain in dB.
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PutToFile
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Convert the object state to FreeFlyer object xml and write to a file.
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PutToString
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Convert the object state to FreeFlyer object xml and return as a string.
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ReferenceEquals
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Returns 1 if the argument refers to the calling object and 0 otherwise.
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Restore
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Restore an object's state from a previously saved state.
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Save
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Save the object's state so that it can be restored later.
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