Module: simpleTransmitter

Executive Summary

This module provides first-order modeling of data downlinking from a simple transmitter at a fixed baud rate. Specifically, the transmitter reads a DataStorageStatusMsgPayload from the storage unit it is subscribed to, searches for the data buffer with the maximum amount of data, and downlinks a packet of data at a fixed baud rate. The transmitter writes out a DataNodeUsageMsgPayload describing the data name and baud rate of the data it wants to downlink.

For more information on how to set up and use this module, see the simple data system example: scenarioDataDemo

Module Assumptions and Limitations

This module makes no additional assumptions outside of those already made in the Module: dataNodeBase base class.

Message Connection Descriptions

This module uses the input and output messages of the Module: dataNodeBase base class, plus an additional DataStorageStatusMsgPayload input message subscribed to and read in customRead() method.

Module I/O Messages

Msg Variable Name

Msg Type




vector of data storage input messages. These are set using the addStorageUnitToTransmitter method

User Guide

This module inherits the user guide from the Module: dataNodeBase base class, but there are several key differences from other Module: dataNodeBase child classes:

  • Unlike other child classes of Module: dataNodeBase, this module does not require a user to set a nodeDataName

  • The nodeBaudRate variable should be set to a negative value in order to remove data from the storage unit.

  • The user must specify a packetSize variable (negative value) in addition to the nodeBaudRate variable

  • The user must specify the number of buffers numBuffers variable so the transmitter knows how many buffers to search through

  • The user must specify the storage unit the transmitter should subscribe to using the addStorageUnitToTransmitter()` method

To set up this module users must create a SimpleTransmitter instance:

transmitter = simpleTransmitter.SimpleTransmitter()
transmitter.ModelTag = "transmitter"

Set the nodeBaudRate, packetSize, and numBuffers variables:

transmitter.nodeBaudRate = -16000. # baud
transmitter.packetSize = -1E6 # bits
transmitter.numBuffers = 2

The next step is to attach one or more DataStorageStatusMsgPayload instances to it using the addStorageUnitToTransmitter() method:

transmitter.addStorageUnitToTransmitter("msg name")

The final step is to specify the output message name and add the model to task:

transmitter.nodeDataOutMsgName = "TransmitterMsg"
scenarioSim.AddModelToTask(taskName, transmitter)

Follow the Module: partitionedStorageUnit or Module: simpleStorageUnit instructions to add the transmitter to a storage unit.

For more information on how to set up and use this module, see the simple data system example: scenarioDataDemo

class SimpleTransmitter : public DataNodeBase
#include <simpleTransmitter.h>

simple data transmitter class

Public Functions


Constructor, which sets the default nodeDataOut to zero.

void addStorageUnitToTransmitter(Message<DataStorageStatusMsgPayload> *tmpStorageUnitMsg)

Adds a dataStorageStatusMsgPayload to be accessed by transmitter.


tmpStorageUnitMsg – A spacecraft state message name.



Public Members

double packetSize

Size of packet to downklink (bytes)

int numBuffers

Number of buffers the transmitter can access.

int currentIndex

Current partition that the transmitter is downlinking a packet for.

std::vector<ReadFunctor<DataStorageStatusMsgPayload>> storageUnitInMsgs

Vector of data node input message names.

std::vector<DataStorageStatusMsgPayload> storageUnitMsgs

local copies of input messages

BSKLogger bskLogger

class variable

Private Functions

void evaluateDataModel(DataNodeUsageMsgPayload *dataUsageMsg, double currentTime)

Loads the nodeDataOut attribute into the dataUsageSimMessage instance.

bool customReadMessages()
int getMaxIndex()

Private Members

double packetTransmitted

Amount of packet downlinked (bytes)

double currentTimestep

Current timestep tracked for data packet integration.

double previousTime

Previous timestep tracked for data packet integration.