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()

2026-01-05 18:30:33,854 gym                            INFO       Resetting environment with seed=2591099293
2026-01-05 18:30:33,856 scene.targets                  INFO       Generating 1000 targets
2026-01-05 18:30:33,989 sats.satellite.EO-1            INFO       <0.00> EO-1: Finding opportunity windows from 0.00 to 600.00 seconds
2026-01-05 18:30:34,027 sats.satellite.EO-2            INFO       <0.00> EO-2: Finding opportunity windows from 0.00 to 600.00 seconds
2026-01-05 18:30:34,074 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})

2026-01-05 18:30:34,079 gym                            INFO       <0.00> === STARTING STEP ===
2026-01-05 18:30:34,080 sats.satellite.EO-1            INFO       <0.00> EO-1: target index 3 tasked
2026-01-05 18:30:34,080 sats.satellite.EO-1            INFO       <0.00> EO-1: Target(tgt-632) tasked for imaging
2026-01-05 18:30:34,082 sats.satellite.EO-1            INFO       <0.00> EO-1: Target(tgt-632) window enabled: 0.0 to 69.4
2026-01-05 18:30:34,083 sats.satellite.EO-1            INFO       <0.00> EO-1: setting timed terminal event at 69.4
2026-01-05 18:30:34,085 sats.satellite.EO-2            INFO       <0.00> EO-2: target index 2 tasked
2026-01-05 18:30:34,085 sats.satellite.EO-2            INFO       <0.00> EO-2: Target(tgt-392) tasked for imaging
2026-01-05 18:30:34,086 sats.satellite.EO-2            INFO       <0.00> EO-2: Target(tgt-392) window enabled: 21.8 to 208.4
2026-01-05 18:30:34,086 sats.satellite.EO-2            INFO       <0.00> EO-2: setting timed terminal event at 208.4
2026-01-05 18:30:34,100 sats.satellite.EO-1            INFO       <70.00> EO-1: timed termination at 69.4 for Target(tgt-632) window
2026-01-05 18:30:34,101 data.base                      INFO       <70.00> Total reward: {}
2026-01-05 18:30:34,103 sats.satellite.EO-1            INFO       <70.00> EO-1: Satellite EO-1 requires retasking
2026-01-05 18:30:34,106 gym                            INFO       <70.00> Step reward: {}

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})

2026-01-05 18:30:34,111 gym                            INFO       <70.00> === STARTING STEP ===
2026-01-05 18:30:34,111 sats.satellite.EO-1            INFO       <70.00> EO-1: setting timed terminal event at 85.0
2026-01-05 18:30:34,112 sats.satellite.EO-2            INFO       <70.00> EO-2: setting timed terminal event at 85.0
2026-01-05 18:30:34,115 sats.satellite.EO-2            INFO       <75.00> EO-2: imaged Target(tgt-392)
2026-01-05 18:30:34,115 data.base                      INFO       <75.00> Total reward: {'EO-2': 0.8468178503369524}
2026-01-05 18:30:34,116 comm.communication             INFO       <75.00> Communicating data in 2 directions.
2026-01-05 18:30:34,117 comm.communication             INFO       <75.00> Optimizing data communication between all pairs of satellites
2026-01-05 18:30:34,117 sats.satellite.EO-2            INFO       <75.00> EO-2: Satellite EO-2 requires retasking
2026-01-05 18:30:34,120 gym                            INFO       <75.00> Step reward: {'EO-2': 0.8468178503369524}

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

2026-01-05 18:30:34,125 gym                            INFO       <75.00> === STARTING STEP ===
2026-01-05 18:30:34,126 sats.satellite.EO-1            INFO       <75.00> EO-1: target index 2 tasked
2026-01-05 18:30:34,127 sats.satellite.EO-1            INFO       <75.00> EO-1: Target(tgt-321) tasked for imaging
2026-01-05 18:30:34,127 sats.satellite.EO-1            INFO       <75.00> EO-1: Target(tgt-321) window enabled: 148.6 to 333.0
2026-01-05 18:30:34,128 sats.satellite.EO-1            INFO       <75.00> EO-1: setting timed terminal event at 333.0
2026-01-05 18:30:34,129 sats.satellite.EO-2            INFO       <75.00> EO-2: setting timed terminal event at 90.0
2026-01-05 18:30:34,133 sats.satellite.EO-2            INFO       <90.00> EO-2: timed termination at 90.0 for broadcast
2026-01-05 18:30:34,134 data.base                      INFO       <90.00> Total reward: {}
2026-01-05 18:30:34,135 comm.communication             INFO       <90.00> Communicating data in 1 direction.
2026-01-05 18:30:34,135 sats.satellite.EO-2            INFO       <90.00> EO-2: Satellite EO-2 requires retasking
2026-01-05 18:30:34,138 gym                            INFO       <90.00> Step reward: {}