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dsocPoissonChannel

Create a deep space optical communications Poisson channel

Since R2023a

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Description

The dsocPoissonChannel System object™ adds Poisson distributed noise to a signal through a deep space optical communications (DSOC) Poisson channel. The object uses the Poisson channel implementation described in section IV of the Interplanetary Network Progress report [1].

To add Poisson distributed noise to the input signal through a DSOC Poisson channel:

  1. Create the dsocPoissonChannel object and set its properties.

  2. Call the object with arguments, as if it were a function.

To learn more about how System objects work, see What Are System Objects?

Creation

Syntax

chan = dsocPoissonChannel
chan = dsocPoissonChannel(Name=Value)

Description

chan = dsocPoissonChannel creates a default DSOC Poisson channel System object.

example

chan = dsocPoissonChannel(Name=Value) sets properties using one or more optional name-value arguments. For example, dsocPoissonChannel(NumSignalPhotons=6) sets the average number of signal photons per pulsed slot to 6.

example

Properties

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Unless otherwise indicated, properties are nontunable, which means you cannot change their values after calling the object. Objects lock when you call them, and the release function unlocks them.

If a property is tunable, you can change its value at any time.

For more information on changing property values, see System Design in MATLAB Using System Objects.

Average signal photons per pulsed slot, specified as a nonnegative finite real scalar.

Data Types: double

Average background noise photons per slot, specified as nonnegative finite real scalar.

Data Types: double

Normalized timing offset, specified as a real number in the range [0, 1)

Data Types: double

Source of the random number stream, specified as "Global stream" or "mt19937ar with seed".

  • "Global stream" — The object uses the current global random number stream for Poisson distributed random number generation. In this case, the reset object function resets only the filters.

  • "mt19937ar with seed" — The object uses the mt19937ar algorithm for Poisson distributed random number generation. In this case, the reset object function resets the filters and reinitializes the random number stream to the value of Seed property.

Data Types: string | char

Initial seed of the mt19937ar random number stream generator algorithm, specified as a nonnegative integer. When you call the reset object function, it reinitializes the mt19937ar random number stream to the Seed value.

Dependencies

To enable this property, set the RandomStream property to "mt19937ar with seed".

Data Types: double | uint32

Usage

Syntax

y = chan(x)

Description

y = chan(x) adds Poisson distributed noise to the input signal x through a DSOC Poisson channel, and returns the output signal y.

Input Arguments

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Input signal, specified as an N-element binary column vector. N is the number of samples. The vector contains the modulated data, with 1 representing a laser pulse and 0 representing the absence of a laser pulse.

Data Types: double | int8 | logical

Output Arguments

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Output signal, returned as an N-element column vector. N is the number of samples. The vector contains the estimate of the photon count within each slot. y is of the same length as x.

Data Types: double

Object Functions

To use an object function, specify the System object as the first input argument. For example, to release system resources of a System object named obj, use this syntax:

release(obj)

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stepRun System object algorithm
releaseRelease resources and allow changes to System object property values and input characteristics
cloneCreate duplicate System object
isLockedDetermine if System object is in use
resetReset internal states of System object

Examples

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Open Live Script

To estimate photon count per slot at the receiver, configure a DSOC Poisson channel and pass the input signal through the channel.

Generate data.

rng("default")
symLen = 1000;
m = 6;
M = 2^m;                               % M-ary PPM
data = randi([0 M-1],symLen,1);

Create a default channel object.

chanObj = dsocPoissonChannel;

Modulate the data using the pulse position modulation (PPM) technique.

modOut = zeros(symLen*M,1);
mapIndex = (0:symLen-1)'*M + data + 1; % Mapping Index
modOut(mapIndex) = 1;

Pass the modulated data through a Poisson channel.

receivedData = chanObj(modOut);

Plot the distribution for pulsed slots.

histogram(receivedData(modOut==1))
xlabel("Slot")
ylabel("Photon Count")
title("Distribution for Pulsed Slots")

Figure contains an axes object. The axes object with title Distribution for Pulsed Slots, xlabel Slot, ylabel Photon Count contains an object of type histogram.

Open Live Script

Estimate photon counts per slot by configuring a DSOC Poisson channel and adding a timing offset to the signal.

Generate data.

rng("default")
symLen = 1000;
m = 6;
M = 2^m;                               % M-ary PPM
data = randi([0 M-1],symLen,1);

Create a DSOC Poisson channel object with these properties.

  • Average signal photons per pulsed slot — 6

  • Average noise photons per slot — 0.01

  • Normalized timing offset — 0.11

  • Source of random number stream — "mt19937ar with seed"

  • Initial seed of mt19937ar random number stream — 64

chanObj = dsocPoissonChannel(NumSignalPhotons=6,NumNoisePhotons=0.01,TimingOffset=0.11, ...
                       RandomStream="mt19937ar with seed",Seed=64);

Modulate the data using PPM.

modOut = zeros(symLen*M,1);
mapIndex = (0:symLen-1)'*M + data + 1; % Mapping Index
modOut(mapIndex) = 1;

Pass the modulated data through a Poisson channel.

receivedData = chanObj(modOut);

Plot the distribution for pulsed slots.

histogram(receivedData(modOut==1))
xlabel("Slot")
ylabel("Photon Count")
title("Distribution for Pulsed Slots")

Figure contains an axes object. The axes object with title Distribution for Pulsed Slots, xlabel Slot, ylabel Photon Count contains an object of type histogram.

References

[1] Moision, B., and J. Hamkins. "Coded Modulation for the Deep-Space Optical Channel: Serially Concatenated Pulse-Position Modulation." The Interplanetary Network Progress Report, vol. 42-161 (May 15, 2005): 1–25. https://ipnpr.jpl.nasa.gov/progress_report/42-161/161T.pdf.

[2] Quirk, Kevin J., Jonathan W. Gin, and Meera Srinivasan. "Optical PPM Synchronization for Photon Counting Receivers." In 2008 IEEE Military Communications Conference (MILCOM 2008), 1–7. San Diego, CA: IEEE, 2008. https://doi.org/10.1109/MILCOM.2008.4753054.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

Version History

Introduced in R2023a

See Also

Functions

Objects

Topics