Broadcast Communication

By default, communication occurs between all satellites that are specified by the communication method. This tutorial shows how to use two classes to configure a broadcast action that must be taken for communication to occur:

Broadcast, which gives satellites an action that enables communication from them at the end of the current step.
BroadcastCommunication, which can be combined with another communication method to limit communication from broadcasters to those satellites satisfying the requirements of the other communication method.

Configuring the Environment

For this example, a multisatellite target imaging environment will be used. The goal is to maximize the value of unique images taken. This configuration is similar to the Multi-Agent Environments example.

[1]:

from bsk_rl import sats, act, obs, scene, data, comm
from bsk_rl.sim import dyn, fsw


class ImagingSatellite(sats.ImagingSatellite):
    observation_spec = [
        obs.OpportunityProperties(
            dict(prop="priority"),
            dict(prop="opportunity_open", norm=5700.0),
            n_ahead_observe=4,
        )
    ]
    action_spec = [act.Broadcast(duration=15.0), act.Image(n_ahead_image=4)]
    dyn_type = dyn.FullFeaturedDynModel
    fsw_type = fsw.SteeringImagerFSWModel


ACTION_BROADCAST = 0
ACTION_IMAGE_0 = 1
ACTION_IMAGE_1 = 2
ACTION_IMAGE_2 = 3
ACTION_IMAGE_3 = 4

Satellite properties are set to give the satellite near-unlimited power and storage resources. To randomize some parameters in a correlated manner across satellites, a sat_arg_randomizer is set and passed to the environment. In this case, the satellites are distributed in a trivial single-plane Walker-delta constellation.

[2]:

from bsk_rl.utils.orbital import walker_delta_args

N_AGENTS = 2
sat_args = dict(
    imageAttErrorRequirement=0.01,
    imageRateErrorRequirement=0.01,
    batteryStorageCapacity=1e9,
    storedCharge_Init=1e9,
    dataStorageCapacity=1e12,
    u_max=0.4,
    K1=0.25,
    K3=3.0,
    omega_max=0.087,
    servo_Ki=5.0,
    servo_P=150 / 5,
)
sat_arg_randomizer = walker_delta_args(
    altitude=800.0, inc=60.0, n_planes=1, clustersize=N_AGENTS, clusterspacing=5.0
)

A communication type is defined that uses multidegree line-of-sight communication with broadcasting.

[3]:

class BroadcastLOS(comm.BroadcastCommunication, comm.LOSMultiCommunication):
    pass

Finally, the environment can be instantiated.

[4]:

from bsk_rl import ConstellationTasking

env = ConstellationTasking(
    satellites=[ImagingSatellite(f"EO-{i + 1}", sat_args) for i in range(N_AGENTS)],
    scenario=scene.UniformTargets(1000),
    rewarder=data.UniqueImageReward(),
    communicator=BroadcastLOS(),
    sat_arg_randomizer=sat_arg_randomizer,
    log_level="INFO",
)
_ = env.reset()

2025-10-16 18:32:36,248 gym                            INFO       Resetting environment with seed=531235560
2025-10-16 18:32:36,250 scene.targets                  INFO       Generating 1000 targets
2025-10-16 18:32:36,471 sats.satellite.EO-1            INFO       <0.00> EO-1: Finding opportunity windows from 0.00 to 600.00 seconds
2025-10-16 18:32:36,510 sats.satellite.EO-2            INFO       <0.00> EO-2: Finding opportunity windows from 0.00 to 600.00 seconds
2025-10-16 18:32:36,566 gym                            INFO       <0.00> Environment reset

In the first step, both agents are tasked with an imaging action, and one successfully images a target.

[5]:

_ = env.step({"EO-1": ACTION_IMAGE_3, "EO-2": ACTION_IMAGE_2})

2025-10-16 18:32:36,571 gym                            INFO       <0.00> === STARTING STEP ===
2025-10-16 18:32:36,572 sats.satellite.EO-1            INFO       <0.00> EO-1: target index 3 tasked
2025-10-16 18:32:36,572 sats.satellite.EO-1            INFO       <0.00> EO-1: Target(tgt-611) tasked for imaging
2025-10-16 18:32:36,573 sats.satellite.EO-1            INFO       <0.00> EO-1: Target(tgt-611) window enabled: 20.1 to 223.8
2025-10-16 18:32:36,574 sats.satellite.EO-1            INFO       <0.00> EO-1: setting timed terminal event at 223.8
2025-10-16 18:32:36,575 sats.satellite.EO-2            INFO       <0.00> EO-2: target index 2 tasked
2025-10-16 18:32:36,575 sats.satellite.EO-2            INFO       <0.00> EO-2: Target(tgt-611) tasked for imaging
2025-10-16 18:32:36,576 sats.satellite.EO-2            INFO       <0.00> EO-2: Target(tgt-611) window enabled: 0.0 to 135.8
2025-10-16 18:32:36,576 sats.satellite.EO-2            INFO       <0.00> EO-2: setting timed terminal event at 135.8
2025-10-16 18:32:36,590 sats.satellite.EO-2            INFO       <72.00> EO-2: imaged Target(tgt-611)
2025-10-16 18:32:36,591 data.base                      INFO       <72.00> Total reward: {'EO-2': 0.43128026715251633}
2025-10-16 18:32:36,592 sats.satellite.EO-2            INFO       <72.00> EO-2: Satellite EO-2 requires retasking
2025-10-16 18:32:36,595 gym                            INFO       <72.00> Step reward: {'EO-2': 0.43128026715251633}

When both select the broadcast action, data is shared in both directions. This is subject to line-of-sight availability as well as selecting the correct action.

[6]:

_ = env.step({"EO-1": ACTION_BROADCAST, "EO-2": ACTION_BROADCAST})

2025-10-16 18:32:36,599 gym                            INFO       <72.00> === STARTING STEP ===
2025-10-16 18:32:36,600 sats.satellite.EO-1            INFO       <72.00> EO-1: setting timed terminal event at 87.0
2025-10-16 18:32:36,601 sats.satellite.EO-2            INFO       <72.00> EO-2: setting timed terminal event at 87.0
2025-10-16 18:32:36,605 sats.satellite.EO-1            INFO       <87.00> EO-1: timed termination at 87.0 for broadcast
2025-10-16 18:32:36,606 sats.satellite.EO-2            INFO       <87.00> EO-2: timed termination at 87.0 for broadcast
2025-10-16 18:32:36,607 data.base                      INFO       <87.00> Total reward: {}
2025-10-16 18:32:36,607 comm.communication             INFO       <87.00> Communicating data in 2 directions.
2025-10-16 18:32:36,608 comm.communication             INFO       <87.00> Optimizing data communication between all pairs of satellites
2025-10-16 18:32:36,608 sats.satellite.EO-1            INFO       <87.00> EO-1: Satellite EO-1 requires retasking
2025-10-16 18:32:36,609 sats.satellite.EO-2            INFO       <87.00> EO-2: Satellite EO-2 requires retasking
2025-10-16 18:32:36,611 gym                            INFO       <87.00> Step reward: {}

One agent can broadcast while the others are completing a different task.

[7]:

_ = env.step({"EO-1": ACTION_IMAGE_2, "EO-2": ACTION_BROADCAST})  # Agent 1 broadcasts

2025-10-16 18:32:36,616 gym                            INFO       <87.00> === STARTING STEP ===
2025-10-16 18:32:36,617 sats.satellite.EO-1            INFO       <87.00> EO-1: target index 2 tasked
2025-10-16 18:32:36,618 sats.satellite.EO-1            INFO       <87.00> EO-1: Target(tgt-974) tasked for imaging
2025-10-16 18:32:36,619 sats.satellite.EO-1            INFO       <87.00> EO-1: Target(tgt-974) window enabled: 56.5 to 255.5
2025-10-16 18:32:36,619 sats.satellite.EO-1            INFO       <87.00> EO-1: setting timed terminal event at 255.5
2025-10-16 18:32:36,620 sats.satellite.EO-2            INFO       <87.00> EO-2: setting timed terminal event at 102.0
2025-10-16 18:32:36,623 sats.satellite.EO-2            INFO       <102.00> EO-2: timed termination at 102.0 for broadcast
2025-10-16 18:32:36,624 data.base                      INFO       <102.00> Total reward: {}
2025-10-16 18:32:36,625 comm.communication             INFO       <102.00> Communicating data in 1 direction.
2025-10-16 18:32:36,626 sats.satellite.EO-2            INFO       <102.00> EO-2: Satellite EO-2 requires retasking
2025-10-16 18:32:36,628 gym                            INFO       <102.00> Step reward: {}