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 typing import ClassVar

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


class ImagingSatellite(sats.ImagingSatellite):
    observation_spec: ClassVar[list[obs.Observation]] = [
        obs.OpportunityProperties(
            dict(prop="priority"),
            dict(prop="opportunity_open", norm=5700.0),
            n_ahead_observe=4,
        )
    ]
    action_spec: ClassVar[list[act.Action]] = [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()

2026-09-02 14:51:32,102 gym                            INFO       Resetting environment with seed=117868976
2026-09-02 14:51:32,104 scene.targets                  INFO       Generating 1000 targets
2026-09-02 14:51:32,163 sats.satellite.EO-1            INFO       <0.00> EO-1: Finding opportunity windows from 0.00 to 600.00 seconds
2026-09-02 14:51:32,195 sats.satellite.EO-2            INFO       <0.00> EO-2: Finding opportunity windows from 0.00 to 600.00 seconds
2026-09-02 14:51:32,224 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})

2026-09-02 14:51:32,229 gym                            INFO       <0.00> === STARTING STEP ===
2026-09-02 14:51:32,230 sats.satellite.EO-1            INFO       <0.00> EO-1: target index 3 tasked
2026-09-02 14:51:32,231 sats.satellite.EO-1            INFO       <0.00> EO-1: Target(tgt-298) tasked for imaging
2026-09-02 14:51:32,232 sats.satellite.EO-1            INFO       <0.00> EO-1: Target(tgt-298) window enabled: 280.5 to 373.2
2026-09-02 14:51:32,232 sats.satellite.EO-1            INFO       <0.00> EO-1: setting timed terminal event at 373.2
2026-09-02 14:51:32,233 sats.satellite.EO-2            INFO       <0.00> EO-2: target index 2 tasked
2026-09-02 14:51:32,234 sats.satellite.EO-2            INFO       <0.00> EO-2: Target(tgt-298) tasked for imaging
2026-09-02 14:51:32,235 sats.satellite.EO-2            INFO       <0.00> EO-2: Target(tgt-298) window enabled: 184.1 to 296.3
2026-09-02 14:51:32,235 sats.satellite.EO-2            INFO       <0.00> EO-2: setting timed terminal event at 296.3
2026-09-02 14:51:32,266 sats.satellite.EO-2            INFO       <187.00> EO-2: imaged Target(tgt-298)
2026-09-02 14:51:32,267 data.base                      INFO       <187.00> Total reward: {'EO-2': 0.4647482490566316}
2026-09-02 14:51:32,269 sats.satellite.EO-2            INFO       <187.00> EO-2: Satellite EO-2 requires retasking
2026-09-02 14:51:32,271 gym                            INFO       <187.00> Step reward: {'EO-2': 0.4647482490566316}

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})

2026-09-02 14:51:32,276 gym                            INFO       <187.00> === STARTING STEP ===
2026-09-02 14:51:32,277 sats.satellite.EO-1            INFO       <187.00> EO-1: setting timed terminal event at 202.0
2026-09-02 14:51:32,278 sats.satellite.EO-2            INFO       <187.00> EO-2: setting timed terminal event at 202.0
2026-09-02 14:51:32,281 sats.satellite.EO-1            INFO       <202.00> EO-1: timed termination at 202.0 for broadcast
2026-09-02 14:51:32,281 sats.satellite.EO-2            INFO       <202.00> EO-2: timed termination at 202.0 for broadcast
2026-09-02 14:51:32,282 data.base                      INFO       <202.00> Total reward: {}
2026-09-02 14:51:32,283 comm.communication             INFO       <202.00> Communicating data in 2 directions.
2026-09-02 14:51:32,283 comm.communication             INFO       <202.00> Optimizing data communication between all pairs of satellites
2026-09-02 14:51:32,284 sats.satellite.EO-1            INFO       <202.00> EO-1: Satellite EO-1 requires retasking
2026-09-02 14:51:32,284 sats.satellite.EO-2            INFO       <202.00> EO-2: Satellite EO-2 requires retasking
2026-09-02 14:51:32,287 gym                            INFO       <202.00> 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

2026-09-02 14:51:32,292 gym                            INFO       <202.00> === STARTING STEP ===
2026-09-02 14:51:32,293 sats.satellite.EO-1            INFO       <202.00> EO-1: target index 2 tasked
2026-09-02 14:51:32,293 sats.satellite.EO-1            INFO       <202.00> EO-1: Target(tgt-381) tasked for imaging
2026-09-02 14:51:32,294 sats.satellite.EO-1            INFO       <202.00> EO-1: Target(tgt-381) window enabled: 305.0 to 402.8
2026-09-02 14:51:32,294 sats.satellite.EO-1            INFO       <202.00> EO-1: setting timed terminal event at 402.8
2026-09-02 14:51:32,295 sats.satellite.EO-2            INFO       <202.00> EO-2: setting timed terminal event at 217.0
2026-09-02 14:51:32,299 sats.satellite.EO-2            INFO       <217.00> EO-2: timed termination at 217.0 for broadcast
2026-09-02 14:51:32,299 data.base                      INFO       <217.00> Total reward: {}
2026-09-02 14:51:32,300 comm.communication             INFO       <217.00> Communicating data in 1 direction.
2026-09-02 14:51:32,301 sats.satellite.EO-2            INFO       <217.00> EO-2: Satellite EO-2 requires retasking
2026-09-02 14:51:32,303 gym                            INFO       <217.00> Step reward: {}