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()

2026-07-28 23:38:43,145 gym                            INFO       Resetting environment with seed=1157630489
2026-07-28 23:38:43,147 scene.targets                  INFO       Generating 1000 targets
2026-07-28 23:38:43,208 sats.satellite.EO-1            INFO       <0.00> EO-1: Finding opportunity windows from 0.00 to 600.00 seconds
2026-07-28 23:38:43,233 sats.satellite.EO-2            INFO       <0.00> EO-2: Finding opportunity windows from 0.00 to 600.00 seconds
2026-07-28 23:38:43,256 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})

2026-07-28 23:38:43,260 gym                            INFO       <0.00> === STARTING STEP ===
2026-07-28 23:38:43,261 sats.satellite.EO-1            INFO       <0.00> EO-1: target index 3 tasked
2026-07-28 23:38:43,261 sats.satellite.EO-1            INFO       <0.00> EO-1: Target(tgt-107) tasked for imaging
2026-07-28 23:38:43,262 sats.satellite.EO-1            INFO       <0.00> EO-1: Target(tgt-107) window enabled: 61.3 to 266.7
2026-07-28 23:38:43,263 sats.satellite.EO-1            INFO       <0.00> EO-1: setting timed terminal event at 266.7
2026-07-28 23:38:43,263 sats.satellite.EO-2            INFO       <0.00> EO-2: target index 2 tasked
2026-07-28 23:38:43,264 sats.satellite.EO-2            INFO       <0.00> EO-2: Target(tgt-268) tasked for imaging
2026-07-28 23:38:43,265 sats.satellite.EO-2            INFO       <0.00> EO-2: Target(tgt-268) window enabled: 60.0 to 233.7
2026-07-28 23:38:43,265 sats.satellite.EO-2            INFO       <0.00> EO-2: setting timed terminal event at 233.7
2026-07-28 23:38:43,275 sats.satellite.EO-1            INFO       <68.00> EO-1: imaged Target(tgt-107)
2026-07-28 23:38:43,276 data.base                      INFO       <68.00> Total reward: {'EO-1': 0.7067141642507594}
2026-07-28 23:38:43,277 sats.satellite.EO-1            INFO       <68.00> EO-1: Satellite EO-1 requires retasking
2026-07-28 23:38:43,280 gym                            INFO       <68.00> Step reward: {'EO-1': 0.7067141642507594}

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})

2026-07-28 23:38:43,284 gym                            INFO       <68.00> === STARTING STEP ===
2026-07-28 23:38:43,285 sats.satellite.EO-1            INFO       <68.00> EO-1: setting timed terminal event at 83.0
2026-07-28 23:38:43,286 sats.satellite.EO-2            INFO       <68.00> EO-2: setting timed terminal event at 83.0
2026-07-28 23:38:43,289 sats.satellite.EO-1            INFO       <83.00> EO-1: timed termination at 83.0 for broadcast
2026-07-28 23:38:43,290 sats.satellite.EO-2            INFO       <83.00> EO-2: timed termination at 83.0 for broadcast
2026-07-28 23:38:43,290 data.base                      INFO       <83.00> Total reward: {}
2026-07-28 23:38:43,291 comm.communication             INFO       <83.00> Communicating data in 2 directions.
2026-07-28 23:38:43,291 comm.communication             INFO       <83.00> Optimizing data communication between all pairs of satellites
2026-07-28 23:38:43,292 sats.satellite.EO-1            INFO       <83.00> EO-1: Satellite EO-1 requires retasking
2026-07-28 23:38:43,293 sats.satellite.EO-2            INFO       <83.00> EO-2: Satellite EO-2 requires retasking
2026-07-28 23:38:43,295 gym                            INFO       <83.00> 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

2026-07-28 23:38:43,299 gym                            INFO       <83.00> === STARTING STEP ===
2026-07-28 23:38:43,299 sats.satellite.EO-1            INFO       <83.00> EO-1: target index 2 tasked
2026-07-28 23:38:43,300 sats.satellite.EO-1            INFO       <83.00> EO-1: Target(tgt-476) tasked for imaging
2026-07-28 23:38:43,301 sats.satellite.EO-1            INFO       <83.00> EO-1: Target(tgt-476) window enabled: 206.8 to 345.0
2026-07-28 23:38:43,301 sats.satellite.EO-1            INFO       <83.00> EO-1: setting timed terminal event at 345.0
2026-07-28 23:38:43,302 sats.satellite.EO-2            INFO       <83.00> EO-2: setting timed terminal event at 98.0
2026-07-28 23:38:43,305 sats.satellite.EO-2            INFO       <98.00> EO-2: timed termination at 98.0 for broadcast
2026-07-28 23:38:43,306 data.base                      INFO       <98.00> Total reward: {}
2026-07-28 23:38:43,306 comm.communication             INFO       <98.00> Communicating data in 1 direction.
2026-07-28 23:38:43,307 sats.satellite.EO-2            INFO       <98.00> EO-2: Satellite EO-2 requires retasking
2026-07-28 23:38:43,309 gym                            INFO       <98.00> Step reward: {}