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()

2026-10-09 20:35:00,216 gym                            INFO       Resetting environment with seed=985553703
2026-10-09 20:35:00,217 scene.targets                  INFO       Generating 1000 targets
2026-10-09 20:35:00,300 sats.satellite.EO_1            INFO       <0.00> EO_1: Finding opportunity windows from 0.00 to 600.00 seconds
2026-10-09 20:35:00,319 sats.satellite.EO_2            INFO       <0.00> EO_2: Finding opportunity windows from 0.00 to 600.00 seconds
2026-10-09 20:35:00,337 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})

2026-10-09 20:35:00,341 gym                            INFO       <0.00> === STARTING STEP ===
2026-10-09 20:35:00,342 sats.satellite.EO_1            INFO       <0.00> EO_1: target index 3 tasked
2026-10-09 20:35:00,342 sats.satellite.EO_1            INFO       <0.00> EO_1: Target(tgt-322) tasked for imaging
2026-10-09 20:35:00,343 sats.satellite.EO_1            INFO       <0.00> EO_1: Target(tgt-322) window enabled: 0.0 to 97.1
2026-10-09 20:35:00,343 sats.satellite.EO_1            INFO       <0.00> EO_1: setting timed terminal event at 97.1
2026-10-09 20:35:00,344 sats.satellite.EO_2            INFO       <0.00> EO_2: target index 2 tasked
2026-10-09 20:35:00,344 sats.satellite.EO_2            INFO       <0.00> EO_2: Target(tgt-72) tasked for imaging
2026-10-09 20:35:00,344 sats.satellite.EO_2            INFO       <0.00> EO_2: Target(tgt-72) window enabled: 4.6 to 83.8
2026-10-09 20:35:00,345 sats.satellite.EO_2            INFO       <0.00> EO_2: setting timed terminal event at 83.8
2026-10-09 20:35:00,353 sats.satellite.EO_2            INFO       <84.00> EO_2: imaged Target(tgt-72)
2026-10-09 20:35:00,354 sats.satellite.EO_2            INFO       <84.00> EO_2: timed termination at 83.8 for Target(tgt-72) window
2026-10-09 20:35:00,354 data.base                      INFO       <84.00> Total reward: {'EO_2': 0.8255532307189261}
2026-10-09 20:35:00,355 sats.satellite.EO_2            INFO       <84.00> EO_2: Satellite EO_2 requires retasking
2026-10-09 20:35:00,357 gym                            INFO       <84.00> Step reward: {'EO_2': 0.8255532307189261}

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})

2026-10-09 20:35:00,361 gym                            INFO       <84.00> === STARTING STEP ===
2026-10-09 20:35:00,361 sats.satellite.EO_1            INFO       <84.00> EO_1: setting timed terminal event at 99.0
2026-10-09 20:35:00,362 sats.satellite.EO_2            INFO       <84.00> EO_2: setting timed terminal event at 99.0
2026-10-09 20:35:00,363 sats.satellite.EO_1            INFO       <85.00> EO_1: imaged Target(tgt-322)
2026-10-09 20:35:00,363 data.base                      INFO       <85.00> Total reward: {'EO_1': 0.7152066973958792}
2026-10-09 20:35:00,364 comm.communication             INFO       <85.00> Communicating data in 2 directions.
2026-10-09 20:35:00,365 comm.communication             INFO       <85.00> Optimizing data communication between all pairs of satellites
2026-10-09 20:35:00,365 sats.satellite.EO_1            INFO       <85.00> EO_1: Satellite EO_1 requires retasking
2026-10-09 20:35:00,366 gym                            INFO       <85.00> Step reward: {'EO_1': 0.7152066973958792}

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

2026-10-09 20:35:00,370 gym                            INFO       <85.00> === STARTING STEP ===
2026-10-09 20:35:00,370 sats.satellite.EO_1            INFO       <85.00> EO_1: target index 2 tasked
2026-10-09 20:35:00,370 sats.satellite.EO_1            INFO       <85.00> EO_1: Target(tgt-622) tasked for imaging
2026-10-09 20:35:00,371 sats.satellite.EO_1            INFO       <85.00> EO_1: Target(tgt-622) window enabled: 165.7 to 206.1
2026-10-09 20:35:00,371 sats.satellite.EO_1            INFO       <85.00> EO_1: setting timed terminal event at 206.1
2026-10-09 20:35:00,372 sats.satellite.EO_2            INFO       <85.00> EO_2: setting timed terminal event at 100.0
2026-10-09 20:35:00,374 sats.satellite.EO_2            INFO       <100.00> EO_2: timed termination at 100.0 for broadcast
2026-10-09 20:35:00,374 data.base                      INFO       <100.00> Total reward: {}
2026-10-09 20:35:00,375 comm.communication             INFO       <100.00> Communicating data in 1 direction.
2026-10-09 20:35:00,375 sats.satellite.EO_2            INFO       <100.00> EO_2: Satellite EO_2 requires retasking
2026-10-09 20:35:00,377 gym                            INFO       <100.00> Step reward: {}