Link

Link analysis object belonging to Transmitter

Since R2021a

Description

The Link object defines a link analysis object belonging to Transmitter.

Creation

You can create a Link object using the link object function of the Transmitter or Receiver objects.

Properties

Sequence — Transmitter or receiver ID

vector of positive numbers

You can set this property only when calling Link. After you call Link, this property is read-only.

Transmitter or receiver ID, specified as a vector of positive numbers.

LineWidth — Visual width of link line

1 (default) | scalar in the range (0 10]

Visual width of link line in pixels, specified as a scalar in the range (0 10].

The line width cannot be thinner than the width of a pixel. If you set the line width to a value that is less than the width of a pixel on your system, the line displays as one pixel wide.

LineColor — Color of link line

[0 1 0] (default) | RGB triplet | string scalar of color name | character vector of color name

Color of the link line, specified as an RGB triplet, a hexadecimal color code, a color name, or a short name.

For a custom color, specify an RGB triplet or a hexadecimal color code.

• An RGB triplet is a three-element row vector whose elements specify the intensities of the red, green, and blue components of the color. The intensities must be in the range [0,1], for example, [0.4 0.6 0.7].

• A hexadecimal color code is a string scalar or character vector that starts with a hash symbol (#) followed by three or six hexadecimal digits, which can range from 0 to F. The values are not case sensitive. Therefore, the color codes "#FF8800", "#ff8800", "#F80", and "#f80" are equivalent.

Alternatively, you can specify some common colors by name. This table lists the named color options, the equivalent RGB triplets, and hexadecimal color codes.

Color Name	Short Name	RGB Triplet	Hexadecimal Color Code	Appearance
"red"	"r"	[1 0 0]	"#FF0000"
"green"	"g"	[0 1 0]	"#00FF00"
"blue"	"b"	[0 0 1]	"#0000FF"
"cyan"	"c"	[0 1 1]	"#00FFFF"
"magenta"	"m"	[1 0 1]	"#FF00FF"
"yellow"	"y"	[1 1 0]	"#FFFF00"
"black"	"k"	[0 0 0]	"#000000"
"white"	"w"	[1 1 1]	"#FFFFFF"
"none"	Not applicable	Not applicable	Not applicable	No color

Here are the RGB triplets and hexadecimal color codes for the default colors MATLAB^® uses in many types of plots.

RGB Triplet	Hexadecimal Color Code	Appearance
[0 0.4470 0.7410]	"#0072BD"
[0.8500 0.3250 0.0980]	"#D95319"
[0.9290 0.6940 0.1250]	"#EDB120"
[0.4940 0.1840 0.5560]	"#7E2F8E"
[0.4660 0.6740 0.1880]	"#77AC30"
[0.3010 0.7450 0.9330]	"#4DBEEE"
[0.6350 0.0780 0.1840]	"#A2142F"

Example: 'blue'

Example: [0 0 1]

Example: '#0000FF'

Object Functions

ebno	Eb/No at final node of link
linkPercentage	Percentage of time when link between first and last node in link analysis is closed
linkIntervals	Intervals during which link is closed
linkStatus	Status of link closure between first and last node
show	Show object in satellite scenario viewer
sigstrength	Calculate received signal strength at last node of link
hide	Hide satellite scenario entity from viewer

Examples

Determine Times of Availability for Satellite Link Between Two Ground Stations

Create a satellite scenario object.

startTime = datetime(2020,11,25,0,0,0);
stopTime = startTime + days(1);
sampleTime = 60;                                     % seconds
sc = satelliteScenario(startTime,stopTime,sampleTime)

sc = 
  satelliteScenario with properties:

         StartTime: 25-Nov-2020
          StopTime: 26-Nov-2020
        SampleTime: 60
      AutoSimulate: 1
        Satellites: [1×0 matlabshared.satellitescenario.Satellite]
    GroundStations: [1×0 matlabshared.satellitescenario.GroundStation]
           Viewers: [0×0 matlabshared.satellitescenario.Viewer]
          AutoShow: 1

Add a satellite to the scenario.

semiMajorAxis = 10000000;                                                                  % meters
eccentricity = 0;
inclination = 60;                                                                          % degrees
rightAscensionOfAscendingNode = 0;                                                         % degrees
argumentOfPeriapsis = 0;                                                                   % degrees
trueAnomaly = 0;                                                                           % degrees
sat = satellite(sc,semiMajorAxis,eccentricity,inclination,rightAscensionOfAscendingNode, ...
        argumentOfPeriapsis,trueAnomaly,Name="Satellite");

Add gimbals to the satellite. These gimbals enable the satellite receiver antenna to steer to the first ground station, and its transmitter antenna to steer to the second ground station.

gimbalrxSat = gimbal(sat);
gimbaltxSat = gimbal(sat);

Add a receiver to the first gimbal of the satellite.

gainToNoiseTemperatureRatio = 5;                                                        % dB/K
systemLoss = 3;                                                                         % dB
rxSat = receiver(gimbalrxSat,Name="Satellite Receiver",GainToNoiseTemperatureRatio= ...
    gainToNoiseTemperatureRatio,SystemLoss=systemLoss)

rxSat = 
  Receiver with properties:

                           Name:  Satellite Receiver
                             ID:  4
               MountingLocation:  [0; 0; 0] meters
                 MountingAngles:  [0; 0; 0] degrees
                        Antenna:  [1x1 satcom.satellitescenario.GaussianAntenna]
                     SystemLoss:  3 decibels
                PreReceiverLoss:  3 decibels
    GainToNoiseTemperatureRatio:  5 decibels/Kelvin
                   RequiredEbNo:  10 decibels

Add a transmitter to the second gimbal of the satellite.

frequency = 27e9;                                                                     % Hz
power = 20;                                                                           % dBW
bitRate = 20;                                                                         % Mbps
systemLoss = 3;                                                                       % dB
txSat = transmitter(gimbaltxSat,Name="Satellite Transmitter",Frequency=frequency, ...
    power=power,BitRate=bitRate,SystemLoss=systemLoss)

txSat = 
  Transmitter with properties:

                Name:  Satellite Transmitter
                  ID:  5
    MountingLocation:  [0; 0; 0] meters
      MountingAngles:  [0; 0; 0] degrees
             Antenna:  [1x1 satcom.satellitescenario.GaussianAntenna]
          SystemLoss:  3 decibels
           Frequency:  2.7e+10 Hertz
             BitRate:  20 Mbps
               Power:  20 decibel-watts
               Links:  [1x0 satcom.satellitescenario.Link]

Specify the antenna specifications of the repeater.

dishDiameter = 0.5;                                                                    % meters
apertureEfficiency = 0.5;
gaussianAntenna(txSat,DishDiameter=dishDiameter,ApertureEfficiency=apertureEfficiency);
gaussianAntenna(rxSat,DishDiameter=dishDiameter,ApertureEfficiency=apertureEfficiency);

Add two ground stations to the scenario.

gs1 = groundStation(sc,Name="Ground Station 1");
latitude = 52.2294963;                                              % degrees
longitude = 0.1487094;                                              % degrees
gs2 = groundStation(sc,latitude,longitude,Name="Ground Station 2");

Point gimbals of the satellite towards the two ground stations for the simulation duration.

pointAt(gimbaltxSat,gs2);
pointAt(gimbalrxSat,gs1);

Add gimbals to the ground stations. These gimbals enable the ground station antennas to steer towards the satellite.

gimbalgs1 = gimbal(gs1);
gimbalgs2 = gimbal(gs2);

Add a transmitter to ground station gs1.

frequency = 30e9;                                                                          % Hz
power = 40;                                                                                % dBW
bitRate = 20;                                                                              % Mbps
txGs1 = transmitter(gimbalgs1,Name="Ground Station 1 Transmitter",Frequency=frequency, ...
        Power=power,BitRate=bitRate);

Add a receiver to ground station gs2.

requiredEbNo = 14;                                                                     % dB
rxGs2 = receiver(gimbalgs2,Name="Ground Station 2 Receiver",RequiredEbNo=requiredEbNo);

Define the antenna specifications of the ground stations.

dishDiameter = 5;                                % meters
gaussianAntenna(txGs1,DishDiameter=dishDiameter);
gaussianAntenna(rxGs2,DishDiameter=dishDiameter);

Point gimbals of the ground stations towards the satellite for the simulation duration.

pointAt(gimbalgs1,sat);
pointAt(gimbalgs2,sat);

Add link analysis to transmitter txGs1.

lnk = link(txGs1,rxSat,txSat,rxGs2)

lnk = 
  Link with properties:

    Sequence:  [10 4 5 11]
    LineWidth:  2
    LineColor:  [0.3922 0.8314 0.0745]

Determine the times when ground station gs1 can send data to ground station gs2 via the satellite.

linkIntervals(lnk)

ans=4×8 table
                Source                          Target               IntervalNumber         StartTime                EndTime           Duration    StartOrbit    EndOrbit
    ______________________________    ___________________________    ______________    ____________________    ____________________    ________    __________    ________

    "Ground Station 1 Transmitter"    "Ground Station 2 Receiver"          1           25-Nov-2020 00:21:00    25-Nov-2020 00:40:00      1140         NaN          NaN   
    "Ground Station 1 Transmitter"    "Ground Station 2 Receiver"          2           25-Nov-2020 03:19:00    25-Nov-2020 03:36:00      1020         NaN          NaN   
    "Ground Station 1 Transmitter"    "Ground Station 2 Receiver"          3           25-Nov-2020 06:15:00    25-Nov-2020 06:36:00      1260         NaN          NaN   
    "Ground Station 1 Transmitter"    "Ground Station 2 Receiver"          4           25-Nov-2020 22:20:00    25-Nov-2020 22:38:00      1080         NaN          NaN   

Visualize the link by using the Satellite Scenario Viewer.

play(sc);

Determine Change in Link and Link Intervals

The example shows a scenario where the link and link intervals change with the change in inclination of the satellite.

startTime = datetime(2024,6,1,0,0,0);
stopTime = startTime + hours(4);
sampleTime = 60;% seconds
sc = satelliteScenario(startTime,stopTime,sampleTime);

Add satellite 1 to the scenario and a transmitter to it.

sat1 = satellite(sc,10e6,0,0,0,0,0,Name="Satellite 1");
txSat1 = transmitter(sat1,Name="Satellite 1 Transmitter");

Add satellite 2 to the scenario and a receiver to it.

sat2= satellite(sc,10e6,0,0,10,0,0,Name="Satellite 2");
rxSat2 = receiver(sat2,Name="Satellite 2 Receiver"); 

Add a ground station to the scenario.

latitude = 49.8728; % degrees
longitude = 8.6512; % degrees
gs = groundStation(sc,latitude,longitude,Name="Ground Station");

Point the two satellite at the ground station.

pointAt(sat1,gs)
pointAt(sat2,gs)

Add gimbals to the ground station.

gimbalrxGs = gimbal(gs);
gimbaltxGs = gimbal(gs);

Add transmitter and receiver to the ground station.

rxGs = receiver(gimbalrxGs,Name="Ground Station Receiver");
txGs = transmitter(gimbaltxGs,Name="Ground Station Transmitter");

Point ground station transmitter and receiver to the satellite.

pointAt(gimbalrxGs,sat1)
pointAt(gimbaltxGs,sat2)

Calculate the link between the ground station and satellites.

lnk1 = link(txSat1,rxGs,txGs,rxSat2)

lnk1 = 
  Link with properties:

    Sequence:  [2 8 9 4]
    LineWidth:  2
    LineColor:  [0.3922 0.8314 0.0745]

Find the link intervals.

linkIntervals(lnk1)

ans=1×8 table
             Source                      Target            IntervalNumber         StartTime                EndTime           Duration    StartOrbit    EndOrbit
    _________________________    ______________________    ______________    ____________________    ____________________    ________    __________    ________

    "Satellite 1 Transmitter"    "Satellite 2 Receiver"          1           01-Jun-2024 02:10:00    01-Jun-2024 02:14:00      240           1            1    

Link interval from lnk1 shows that a valid link exists from satellit1 to satellite2 going through the ground station for a period of 7560 seconds.

Update the scenario so that satellites are pointing at each other.

pointAt(sat1,sat2)
pointAt(sat2,sat1)

Calculate the link interval for lnk1 with the updated scenario.

linkIntervals(lnk1)

ans =

  0×8 empty table

    Source    Target    IntervalNumber    StartTime    EndTime    Duration    StartOrbit    EndOrbit
    ______    ______    ______________    _________    _______    ________    __________    ________

The linkInterval from lnk1 shows no intervals exist for the duration of the scenario as the ground station is no longer pointed at by either satellite antenna.

Create a new link object, lnk2, from satellite 1 directly to satellite 2

lnk2 = link(txSat1,rxSat2)

lnk2 = 
  Link with properties:

    Sequence:  [2 4]
    LineWidth:  2
    LineColor:  [0.3922 0.8314 0.0745]

Calculate the link interval for lnk2 in the updated scenario.

linkIntervals(lnk2)

ans=1×8 table
             Source                      Target            IntervalNumber     StartTime           EndTime           Duration    StartOrbit    EndOrbit
    _________________________    ______________________    ______________    ___________    ____________________    ________    __________    ________

    "Satellite 1 Transmitter"    "Satellite 2 Receiver"          1           01-Jun-2024    01-Jun-2024 04:00:00     14400          1            2    

Shows a link interval over the entire scenario because the satellites are pointed at each other for the entire scenario

Version History

Introduced in R2021a

R2022b: sigstrength object function added to the object

You can now compute the received signal strength at the last node of the link using sigstrength object function.