Persistent Unattended Sensing Supporting Formation-Based Layered Protection

Executive Summary

Brigade and battalion formations in large-scale combat operations operate inside an increasingly
compressed adversary ISR-to-effects cycle. At the National Training Center, small UAS were highly visible
and operationally consequential. They were also only the most visible expression of a broader multi-domain
adversary ISR architecture that exploited the electromagnetic spectrum, cyber effects, electronic
reconnaissance, human observation, and pattern analysis to shape the battlespace against the brigade. The
resulting problem is not a sensing shortfall alone. It is a decision timeline mismatch in which adversary
ISR-enabled targeting cycles outpace brigade-level detection, orientation, decision, and response.

A persistent unattended sensing layer helps restore decision time by extending detection forward and in
depth. Unattended ground sensors using seismic, acoustic, and magnetic sensing can be emplaced as passive
tripwires along likely adversary ISR approaches, maneuver corridors, command post approaches, logistics
routes, and previously occupied positions. Their operational value comes from detecting activity in the
physical environment, including ground vehicles, personnel, aircraft, and UAS, and converting those
detections into actionable cues for existing ISR, EW, fires, force protection, and C2 workflows. The purpose
is not to replace airborne ISR, radars, electronic warfare, cameras, patrols, or command-and-control
systems. The purpose is to cue those systems earlier, reduce blind periods during displacement, and preserve
situational awareness when formations cannot afford to remain fixed.

This concept aligns directly with Formation-Based Layered Protection by supporting C2 compatibility,
scalable employment, low-signature operation, event-driven reporting, and integration with existing
operational workflows. A distributed unattended sensing architecture helps formations reduce the signature
of the sensing layer itself, complicate adversary characterization, cue action before engagement, and
preserve awareness through displacement or attack. Its purpose is not to create another isolated sensor feed,
but to provide a low-signature detection layer that feeds existing decision processes.

Operational Problem

In current LSCO conditions, formations are not vulnerable simply because adversaries possess
sensors. They are vulnerable because the adversary can observe, characterize, target, and engage
faster than the friendly formation can recognize the threat, orient to its implications, decide on a
response, and preserve continuity of command and control. In the language of layered protection,
the adversary is not merely trying to see the formation. It is trying to understand what it has found,
identify critical capabilities, assets, and activities, and converge effects against them. Small UAS,
forward observers, electronic reconnaissance, cyber-enabled targeting, electromagnetic sensing,
and rapid fires create a condition in which a detected command post, logistics node, fires element,
or support area may have only limited time before engagement or disruption.

The central operational problem is the loss of decision time. Brigade formations are being detected,
characterized, and targeted by a broader adversary ISR enterprise before they can respond
effectively. This forces displacement, degrades command and control, and pushes commanders
into a reactive cycle. Platform-based ISR remains valuable, but it is intermittent, weather-

dependent, tasking-constrained, and increasingly vulnerable in contested airspace. Active
detection systems provide important capability, but they may also contribute to electromagnetic
signature, power demand, and operator workload. Sensors tied directly to maneuver units often
move with the formation, creating gaps at the exact moment sensing continuity is most needed.

This creates a harsh operational tradeoff: a formation can stay in place and maintain sensing
alignment, or it can displace and survive. Neither option is sufficient by itself. A brigade that
survives displacement but loses awareness remains shaped by the enemy. It becomes reactive,
repositioning after threat detection rather than acting during the adversary’s search,
characterization, and targeting phases. The practical requirement is not simply to detect more. The
requirement is to gain enough early indication to act before adversary target confirmation, while
preserving awareness as command posts, sustainment nodes, fires elements, and retransmission
sites displace to survive.

When a persistent layer is absent, displacement creates predictable blind periods. Warning is lost,
ISR coverage becomes misaligned, and commanders are forced back into reactive movement after
the adversary has already begun to observe, characterize, and target the formation. Without
forward indication of adversary ISR activity and associated ground movement, units cannot act
prior to target confirmation and cannot effectively disrupt the adversary kill chain before fires or
other effects are delivered.

Tactical Employment Requirement

Brigade and battalion operations in this environment occur across large areas, under constant
pressure from adversary ISR, UAS, long-range fires, electronic warfare, cyber effects, and
degraded communications. Command posts must reduce signature, displace frequently, and
operate for limited periods before moving again. Logistics nodes, retransmission sites, assembly
areas, and fires positions face similar pressure. The cumulative effect is a formation that must
sense, decide, move, communicate, and fight while its own systems are being observed and
targeted.

Existing systems remain essential, but each is finite. Airborne ISR has limited dwell time and may
be unavailable due to air defense, weather, airspace prioritization, or competing collection
requirements. Radars and active systems provide valuable detection, but they may create signature,
require power, require deliberate positioning, and compete for bandwidth and operator attention.
Patrols and reconnaissance elements provide judgment and context, but cannot continuously
occupy every likely approach, observation point, or named area of interest. Cameras and towers
are useful where infrastructure exists, but they do not solve the problem of mobile formations
operating across depth.

A passive unattended sensing layer provides a different signature profile in two ways. First, the
sensor layer itself is designed to avoid detection through small nodes, limited visual presence,
passive sensing, camouflage or concealment options, and event-based reporting rather than
continuous high-bandwidth collection. Second, by cueing higher-signature systems only when
relevant activity is detected, the sensing layer helps the formation reduce unnecessary exposure
from continuously operating radars, cameras, patrols, or other active systems.

The operational requirement is a sensing layer that persists through displacement while imposing
minimal signature of its own. Formations need an unattended layer that remains in place when
units move, reports by exception, and continues to collect operationally relevant detections across
time and terrain. This requirement becomes most acute during displacement, when the formation
is vulnerable, C2 is shifting, and traditional ISR coverage may be degraded, misaligned, or
temporarily unavailable.

A persistent unattended layer also changes the commander’s relationship with terrain.
Displacement no longer has to mean a complete reset of the sensing plan. Formations can build a
sensing architecture over time. Some sensors are recovered and reseeded. Others are deliberately
left behind to continue reporting from previously occupied positions, likely enemy observation
areas, UAS approach corridors, suspected launch or control areas, electronic reconnaissance
positions, and ground mobility routes. In this way, the sensing layer accumulates operational
context rather than disappearing every time the formation moves.

Role of Persistent Detection

Persistent unattended sensing should be employed as a detection and cueing layer, not as a
standalone surveillance solution. Unattended ground sensors using seismic, acoustic, and magnetic
modalities can function as passive tripwires that detect activity associated with personnel
movement, vehicle movement, aircraft, and Class 1 UAS activity. Because the sensors are small,
passive, unattended, and capable of being concealed or camouflaged, they support the “Avoid
Being Seen” aspect of layered protection at the sensing-layer level while also enabling the
formation to use higher-signature systems more selectively.

This matters because adversary ISR does not exist only in the air or in the electromagnetic
spectrum. It is supported by people, vehicles, launch teams, control teams, observers, security
elements, logistics nodes, and displacement patterns that must move through terrain. The system’s
value is operational rather than merely technical. It gives commanders earlier indicators that
relevant activity is occurring in terrain they cannot continuously patrol, watch, or occupy.

In operational terms, a distributed UGS field using seismic, acoustic, and magnetic sensing can
provide early indicators across multiple threat behaviors:

• UAS activity approaching a command post, support node, fires position, or
retransmission site.
• Dismounted movement near a retransmission site, logistics area, assembly area, or
observation point.
• Vehicle movement along a mobility corridor, suspected launch or control area,
observation area, or electronic reconnaissance position.
• Pattern changes around previously occupied positions after friendly displacement.
• Tamper or disturbance indicators suggesting adversary clearance, probing, exploitation,

or route sanitization.

The value does not come from any single sensor providing complete certainty. It comes from
distributed placement, overlap, and correlation over time. Multiple event detections can help
identify direction of travel, recurring routes, probable origin areas, anomalous activity, and
emerging patterns. This directly supports the “Avoid Being Understood” challenge by helping
commanders recognize how the adversary is probing, observing, and characterizing friendly
activity. That information can then cue EW, ISR, patrols, fires cells, force protection elements,
cyber/EW coordination, or command post displacement decisions.

Unattended sensing should be understood as a cueing and correlation layer, not as a standalone
source of certainty. Detection performance depends on terrain, emplacement quality, target type,
background noise, weather, communications availability, and the density and geometry of the
sensor field. The greatest operational value comes from correlated events across multiple sensors
over time, especially when those events are fused with ISR, EW, patrol reporting, and current
intelligence.

Persistent detection also reduces the burden on scarce ISR assets. Instead of using airborne ISR to
search broad areas with limited dwell time, the sensing layer identifies high-probability locations
and time windows. This allows commanders to employ limited assets more deliberately, increasing
the likelihood that ISR is focused on the right place at the right time.

Integration with Existing Systems

The sensing layer must be integrated into existing C2 workflows, not treated as a separate watch floor.
Reports should be event-driven, geolocated, and machine-readable, reducing cognitive burden on operators.
The operational purpose is to generate actionable cues, not continuous raw data streams.

At the formation level, the workflow should remain straightforward:

1. Sensors detect relevant seismic, acoustic, or magnetic events.
2. Events are reported as alerts rather than continuous raw streams.
3. Alerts populate OmniWatch, TAK/COP, or another operational display.
4. The watch team or fires/ISR cell correlates alerts against named areas of interest, current
displacement plans, adversary ISR indicators, UAS threat reporting, EW activity, and
ISR availability.
5. The formation cues the appropriate response, such as EW activation, repositioning, patrol
dispatch, ISR retasking, camera confirmation, fires planning, or force protection action.

At minimum, alerts should include time, location, sensor identity, detection modality, event type or
classification, confidence where available, and enough metadata to support correlation in TAK/COP or
other C2 systems.

This is where unattended sensing supports layered protection. It does not make the brigade invisible. It

helps the brigade detect adversary sensing and support activity earlier, understand likely threat direction
and origin, and act before adversary target confirmation is complete. In practical terms, it supports “Avoid
Being Struck” by creating opportunities to cue EW, ISR, fires, movement, and force protection action before
the adversary closes the ISR-to-effects cycle.

The architecture should also support intermittent and degraded communications. A hybrid approach can use
terrestrial relay where available and satellite-enabled nodes where isolated or denied conditions prevent
reliable local relay. The key requirement is not constant high-bandwidth connectivity. It is the reliable
movement of event data into existing command-and-control systems quickly enough to support commander
decision cycles.

Notional Employment Concept

A brigade employs unattended ground sensors as a distributed detection screen in depth. Sensor placement
is not uniform. It is weighted toward terrain, adversary behavior, friendly vulnerability, and operational
decision points.

To ground the notional employment discussion in a fielded capability, the following concept uses McQ
Ranger as a representative UGS system that combines seismic, acoustic, and magnetic sensing in an
unattended sensor form factor. Product-specific references are limited to areas where they support realistic
planning assumptions, such as sensor quantities, communications options, and employment concepts.

A notional brigade employment package could include approximately 120 to 180 Ranger Tactical sensors
for dense terrestrial sensing in areas where relay infrastructure can be supported, and 20 to 40 Ranger Global
sensors for isolated, denied, or leave-behind coverage. Supporting terrestrial communications may include
12 to 20 Base Station Repeaters, depending on terrain, line of sight, and network geometry. These quantities
are not intended to imply continuous coverage of the entire brigade area. They are planning estimates for
selected NAIs, high-risk approaches, likely adversary ISR support areas, command post approaches,
retransmission sites, mobility corridors, and leave-behind coverage. Final quantities should be adjusted by
terrain, mission duration, threat density, communications availability, and acceptable risk.

At battalion level, a practical package may be smaller: 24 to 48 sensors focused on the battalion command
post, logistics release points, retransmission sites, likely adversary ISR approaches, UAS approach
corridors, suspected launch/control areas, and two or three high-risk mobility routes. A company team or
security element may employ 6 to 12 sensors for local early warning around a temporary position, hide site,
support-by-fire location, or mission support node.

Spacing should reflect the target, terrain, and purpose of the sensor belt. For UAS acoustic cueing and
broader adversary ISR support activity along likely approaches, 200 to 250 meter spacing can provide
overlapping detection along critical approaches. For vehicle movement along rural mobility corridors,
wider spacing may be acceptable where seismic detection of heavy or tracked movement is the primary
concern. For command post approaches, retransmission sites, suspected launch/control areas, and electronic
reconnaissance positions, denser clusters provide better correlation and direction-of-travel assessment.

A representative brigade layout could include:

• Forward adversary ISR approach belts: 40 to 60 sensors along likely UAS ingress routes,
ridgelines, draws, observation approaches, suspected launch/control areas, and electronic
reconnaissance positions.
• Command post and support node screens: 30 to 50 sensors around the main CP, tactical
CP, sustainment nodes, retransmission locations, artillery positions, and other critical
capabilities, assets, and activities.
• Mobility corridor monitoring: 30 to 50 sensors along MSRs, bypasses, choke points, and
likely adversary reconnaissance, launch-team, or displacement routes.
• Leave-behind coverage: 20 to 40 sensors deliberately left near vacated positions, likely
enemy exploitation routes, and terrain the brigade expects the adversary to observe,
exploit, or reuse.

The employment principle is straightforward: recover and reseed selected sensors as the formation moves,
while deliberately leaving others in place to maintain continuity. The sensing layer should accumulate
across phases rather than reset every time the brigade displaces

Example Employment Scenario

A brigade combat team is operating in open and broken terrain with intermittent urban areas, canalized
routes, and limited overhead cover. The adversary uses a layered ISR approach to locate command posts,
retransmission sites, artillery positions, and logistics nodes before engaging them with indirect fires or other
effects. Class 1 UAS are the most visible part of the threat, but the brigade also faces electronic
reconnaissance, electromagnetic sensing, cyber-enabled disruption, human observation, and pattern
analysis. The brigade has already displaced its main command post twice in 36 hours. Each move preserved
survivability but degraded ISR alignment and delayed the brigade’s ability to understand adversary
reconnaissance patterns.

Before the next displacement, the brigade S2, S3, protection cell, cyber/electromagnetic activities staff, and
signal section identify likely adversary ISR approaches based on previous UAS sightings, electronic
reconnaissance indicators, terrain masking, suspected launch or control locations, ground movement
patterns, and observed fires timing. UGS are emplaced in three belts. The first belt covers likely UAS
approach corridors and observation approaches forward of the command post area. The second covers
ground approaches to retransmission sites, logistics nodes, suspected launch/control locations, and likely
electronic reconnaissance positions. The third is left behind around the previous command post location to
detect adversary exploitation after displacement.

Sensors are placed by maneuver and reconnaissance elements during routine movement, with selected
satellite-enabled UGS nodes used where terrestrial relay is not reliable. Alerts are routed into the brigade’s
COP and monitored by the protection cell and current operations section. The system does not stream
continuous video or raw acoustic data. It reports events.

At 0230, three sensors along a forward approach belt report acoustic detections consistent with small UAS
activity, while a nearby cluster reports seismic detections of light vehicle movement near a suspected control
or observation area. The detections occur in sequence, indicating movement toward the brigade support
area. The combined pattern increases confidence that the UAS activity is part of a broader reconnaissance
effort rather than an isolated overflight.

The alert appears in the COP and cues the electronic warfare section to orient toward the likely approach.
A nearby camera system is slewed to a probable crossing point, while the brigade retasks a short-duration
ISR asset toward the suspected launch or control area. Several minutes later, another sensor cluster reports
additional ground movement near the same suspected control or observation area. The pattern suggests a
small launch, control, reconnaissance, or security element repositioning after UAS employment.
The brigade does not treat the sensor report as a target by itself. Instead, the report narrows the search area,
focuses ISR, supports EW orientation, and gives the fires cell a probable named area of interest. EW effects
are applied against the UAS control link while the brigade initiates a limited displacement of the support
node most likely to be observed.

The practical outcome is not perfect protection. The important change is timing. The brigade acts during
the adversary’s search and characterization phase rather than after target confirmation. The support node
displaces before fires arrive. The ISR asset focuses on a high-probability launch/control area rather than
searching broadly. The left-behind sensors continue reporting activity around the abandoned command post
location, confirming that the adversary is still observing and probing the old position. This preserves
awareness after displacement and supports the survivability problem set by helping the formation remain
operationally coherent after moving to survive.

Operational Impact

Persistent unattended sensing improves the formation’s ability to manage time, attention, and
scarce assets. It extends awareness into terrain that cannot be continuously patrolled or watched
by airborne ISR. It provides early warning without requiring the brigade to keep active systems
continuously emitting. It reduces operator burden by reporting events rather than producing

continuous raw feeds. It supports pattern-of-life development by accumulating detections over
hours and days, not only during ISR collection windows.
At the tactical level, this supports targeted response. Patrols can be sent to likely routes rather than
broad search areas. EW can be oriented toward likely UAS approaches, suspected control
locations, or electronic reconnaissance positions. ISR can be cued to probable launch/control areas,
observation points, and mobility corridors. Fires planners can build named areas of interest from
repeated movement patterns. Commanders can displace based on warning indicators rather than
waiting for confirmed observation.

At the operational level, the benefit is continuity. A formation that must move to survive should
not be forced to become blind every time it displaces. A leave-behind sensing layer preserves
awareness across displacement, monitors vacated terrain, and helps identify adversary adaptation.
The survivability contribution is also architectural. A distributed sensing layer does not depend on
a single platform, tower, aircraft, or command post. If individual sensors are discovered, destroyed,
displaced, or lost, the remaining field can continue to report. This makes the formation less
dependent on any single collection asset and helps preserve awareness after displacement, attack,
or communications degradation.

This supports multiple layered protection effects:

• Avoid being seen by employing a small, passive, concealable sensing layer and by
enabling earlier displacement, selective activation of higher-signature systems, and more
disciplined signature management.
• Avoid being understood by detecting adversary ISR support activity, reconnaissance
patterns, and movement around friendly positions, decoys, vacated sites, and likely
observation areas.
• Avoid being struck by cueing EW, ISR, fires, force protection action, and movement
before the adversary closes the ISR-to-effects cycle.
• Survive if hit or attacked by preserving combat power, maintaining awareness after
displacement, and preventing the formation from becoming blind after it moves to
survive.

Conclusion

Formation-Based Layered Protection requires more than concealment, more than active defense, and more
than additional ISR sorties. Brigade and battalion formations need ways to preserve decision time under
adversary ISR-enabled targeting pressure, including UAS, electronic reconnaissance, electromagnetic
sensing, cyber effects, and human observation. Persistent unattended sensing provides one practical layer
in that architecture.

A representative implementation such as McQ Ranger, employed as a passive seismic, acoustic, and
magnetic UGS capability, can extend awareness across time and terrain, cue existing ISR and C2 systems,
and maintain sensing continuity through displacement. Its contribution is consistent with the layered

protection logic of reducing friendly signature, complicating adversary understanding, acting before
engagement, and preserving combat power after movement or attack. This does not eliminate the need for
camouflage, deception, EW, air defense, patrols, radars, or disciplined signature management. It makes
those systems more effective by giving commanders earlier, more focused indicators.

In LSCO, formations cannot always remain still, cannot always emit, and cannot always rely on continuous
ISR. A persistent unattended sensing layer helps them move without forfeiting awareness, act before target
confirmation, and disrupt the adversary kill chain before fires or other effects are delivered.