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()

2026-03-09 19:07:57,025 gym                            INFO       Resetting environment with seed=2756621361
2026-03-09 19:07:57,027 scene.targets                  INFO       Generating 1000 targets
2026-03-09 19:07:57,146 sats.satellite.EO-1            INFO       <0.00> EO-1: Finding opportunity windows from 0.00 to 600.00 seconds
2026-03-09 19:07:57,191 sats.satellite.EO-2            INFO       <0.00> EO-2: Finding opportunity windows from 0.00 to 600.00 seconds
2026-03-09 19:07:57,236 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})

2026-03-09 19:07:57,242 gym                            INFO       <0.00> === STARTING STEP ===
2026-03-09 19:07:57,243 sats.satellite.EO-1            INFO       <0.00> EO-1: target index 3 tasked
2026-03-09 19:07:57,243 sats.satellite.EO-1            INFO       <0.00> EO-1: Target(tgt-978) tasked for imaging
2026-03-09 19:07:57,244 sats.satellite.EO-1            INFO       <0.00> EO-1: Target(tgt-978) window enabled: 67.4 to 156.4
2026-03-09 19:07:57,244 sats.satellite.EO-1            INFO       <0.00> EO-1: setting timed terminal event at 156.4
2026-03-09 19:07:57,245 sats.satellite.EO-2            INFO       <0.00> EO-2: target index 2 tasked
2026-03-09 19:07:57,246 sats.satellite.EO-2            INFO       <0.00> EO-2: Target(tgt-978) tasked for imaging
2026-03-09 19:07:57,247 sats.satellite.EO-2            INFO       <0.00> EO-2: Target(tgt-978) window enabled: 0.0 to 78.9
2026-03-09 19:07:57,247 sats.satellite.EO-2            INFO       <0.00> EO-2: setting timed terminal event at 78.9
2026-03-09 19:07:57,258 sats.satellite.EO-2            INFO       <48.00> EO-2: imaged Target(tgt-978)
2026-03-09 19:07:57,259 data.base                      INFO       <48.00> Total reward: {'EO-2': 0.8024112609456648}
2026-03-09 19:07:57,260 sats.satellite.EO-2            INFO       <48.00> EO-2: Satellite EO-2 requires retasking
2026-03-09 19:07:57,263 gym                            INFO       <48.00> Step reward: {'EO-2': 0.8024112609456648}

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})

2026-03-09 19:07:57,268 gym                            INFO       <48.00> === STARTING STEP ===
2026-03-09 19:07:57,268 sats.satellite.EO-1            INFO       <48.00> EO-1: setting timed terminal event at 63.0
2026-03-09 19:07:57,270 sats.satellite.EO-2            INFO       <48.00> EO-2: setting timed terminal event at 63.0
2026-03-09 19:07:57,275 sats.satellite.EO-1            INFO       <63.00> EO-1: timed termination at 63.0 for broadcast
2026-03-09 19:07:57,275 sats.satellite.EO-2            INFO       <63.00> EO-2: timed termination at 63.0 for broadcast
2026-03-09 19:07:57,276 data.base                      INFO       <63.00> Total reward: {}
2026-03-09 19:07:57,277 comm.communication             INFO       <63.00> Communicating data in 2 directions.
2026-03-09 19:07:57,278 comm.communication             INFO       <63.00> Optimizing data communication between all pairs of satellites
2026-03-09 19:07:57,278 sats.satellite.EO-1            INFO       <63.00> EO-1: Satellite EO-1 requires retasking
2026-03-09 19:07:57,279 sats.satellite.EO-2            INFO       <63.00> EO-2: Satellite EO-2 requires retasking
2026-03-09 19:07:57,281 gym                            INFO       <63.00> 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

2026-03-09 19:07:57,287 gym                            INFO       <63.00> === STARTING STEP ===
2026-03-09 19:07:57,288 sats.satellite.EO-1            INFO       <63.00> EO-1: target index 2 tasked
2026-03-09 19:07:57,289 sats.satellite.EO-1            INFO       <63.00> EO-1: Target(tgt-394) tasked for imaging
2026-03-09 19:07:57,289 sats.satellite.EO-1            INFO       <63.00> EO-1: Target(tgt-394) window enabled: 17.9 to 217.7
2026-03-09 19:07:57,290 sats.satellite.EO-1            INFO       <63.00> EO-1: setting timed terminal event at 217.7
2026-03-09 19:07:57,291 sats.satellite.EO-2            INFO       <63.00> EO-2: setting timed terminal event at 78.0
2026-03-09 19:07:57,295 sats.satellite.EO-2            INFO       <78.00> EO-2: timed termination at 78.0 for broadcast
2026-03-09 19:07:57,296 data.base                      INFO       <78.00> Total reward: {}
2026-03-09 19:07:57,297 comm.communication             INFO       <78.00> Communicating data in 1 direction.
2026-03-09 19:07:57,297 sats.satellite.EO-2            INFO       <78.00> EO-2: Satellite EO-2 requires retasking
2026-03-09 19:07:57,300 gym                            INFO       <78.00> Step reward: {}