The buried listening node. A sealed passive seismic and acoustic node that is buried once, goes silent, and reports only over a buried fibre.
Five figures size the node. Four reasons explain why a buyer trades a standing post for a buried one.
Every hour a node keeps silent watch on a chokepoint is an hour nobody stands a post there. Buried and closed over, it listens through a years-class standby on a primary lithium pack and speaks only when something crosses its threshold.
Buried and spliced, the node puts nothing into the air in any wake state or configuration. Its position comes from the survey that placed it, so there is no radio link to jam and no satellite fix to spoof.
One sealed, coupled, fibre-linked body takes a vertical geophone, a three-element bearing set or an added acoustic pressure element. The same node watches a pipeline for leaks and third-party interference without a change.
Emplaced alone, it watches one approach nobody else has eyes on. Strung node to node on a fibre trunk, a run of them is the Trembler Line CS-435, which detects, localizes and cues a person at a console.
The product specification and the systems engineering behind it, grouped the way an integration lead reads an emplaced sensor: the body, what it senses, how it reports, what powers it, how it goes into the ground and what it is.
Body and massSensingLink and reportingPower and dormancyEmplacement and environmentRole and classification
| Parameter | Value | Basis |
|---|---|---|
| Configuration | Sealed cylindrical housing, direct-buried or augered in | the product specification table |
| Housing dimensions | ~90 mm dia × ~380 mm length | design value, the product specification table |
| All-up mass | ~4.5 kg | design value, the product specification table |
| Housing material | Moulded glass-filled nylon; recycled PET for non-structural parts only | no corrosion, no galvanic couples, electrically inert |
| Seal design case | Submersion, not splash | burial below the water table is the design case |
| Structural loads | Soil overburden · frost heave · sustained hydrostatic head | the loads the case carries for its whole buried life |
| Internal protection | Electronics conformally coated and potted; desiccant with a moisture telltale | against the condensation that thermal cycling produces in any sealed volume |
| Parameter | Value | Basis |
|---|---|---|
| Sensor package | Tri-axial geophone · MEMS accelerometer · acoustic sensor | the product specification table |
| Sensing mode | Passive only: no active seismic source, no acoustic projector, no electromagnetic emitter | the payload boundary, in every variant |
| Geophone power | 0 W | a moving-coil geophone is a generator; its output is proportional to ground velocity |
| Detection range | Footsteps and digging: tens of metres; vehicles: farther, soil-dependent | the product specification table; any range figure states its soil and threat class |
| Threshold discrimination | Rejects wind, weather and passing wildlife; catches digging, footsteps, vehicles and tunnelling | the product specification table |
| Wake and report latency | Sub-second threshold trip; report to head-end under 1 s over fibre | the product specification table |
| Parameter | Value | Basis |
|---|---|---|
| Comms | Buried fibre only, node to node or direct to head-end; no radio | the product specification table |
| Emissions over the air | None, in any wake state or configuration | the product specification table |
| Fibre ports | Two: one up-line, one down-line | the daisy-chain line topology |
| Link state | Dark by default; energized only to report or to relay a neighbour's traffic | an idling optical transceiver would spend the battery |
| Reporting pattern | Wakes on threshold, classifies locally, reports once | the product specification table |
| Health data over the fibre | Battery voltage under load · coupling-spectrum snapshot · moisture telltale | the scheduled self-check, on a slow fixed cadence |
| Position reference | The install survey; no satellite receiver aboard | every node must know where it is for a line's solution |
| Parameter | Value | Basis |
|---|---|---|
| Battery chemistry | Primary lithium, long-shelf-life cell class | the product specification table |
| Standby endurance | Years-class at ultra-low duty cycle | the product specification table |
| Duty cycle | Sleep and listen; wakes on threshold | the product specification table |
| Wake-up | Analog front end on the geophone output, not a continuously sampling digital stage | the power floor between events decides how long the watch lasts |
| Line power option | Tether tap from a line supply where a node sits near a bored conduit | removes the battery constraint for anchor nodes |
| Parameter | Value | Basis |
|---|---|---|
| Emplacement method | Auger or hand-buried at a surveyed position, on the group's directional-drilling survey discipline | the product specification table |
| Emplacement modes | Hand or auger burial · trenched with the fibre on a strung line · delivered down a CS-410 bore | the three emplacement modes |
| Burial depth | 0.3–1.0 m nominal, site-dependent | design value, the product specification table |
| Coupling features | Spike or cone · base plate · full burial, compacted or grouted | seismic-practice coupling options, chosen to the ground |
| Operating temperature | −40 °C to +50 °C class | design value, the product specification table |
| Tilt at commissioning | Read from the accelerometer, static | install-time self-knowledge |
| Recovery | Dug back along its own fibre lead, or logged and left in place by decision | the product specification table |
| Parameter | Value | Basis |
|---|---|---|
| Chain role | Node of the Trembler Line CS-435 picket; also emplaced standalone as a listening post | the product specification table |
| Response scope | Physical response is CS-425, tasked on a person's decision; not this node | the product specification table |
| Payload | None: sensing electronics and battery only | the product specification table |
| Munitions classification | Passive sensing node: no warhead, no fuze, no energetic material; no offensive capability of any kind | the product specification table |
| Patent status | Patent pending | the product specification table |
| Export control | Export-controlled; international transfer subject to Canadian government permits; counsel first | the product specification table |
CS-430 is a buried instrument restated as a fleet node: a sealed body couples a passive sensor to the ground, a low-power stack sleeps behind an analog wake-up, and a normally dark fibre carries the record out.
A sealed cylindrical housing in moulded polymer, direct-buried or augered in. It is the pressure vessel, the corrosion barrier and the first element of the signal chain at once.
A tri-axial geophone and a MEMS accelerometer read ground-borne vibration, and an acoustic sensor reads what travels through air and structure. Every element listens and nothing aboard emits.
Fibre only, node to node or straight to a head-end, in a daisy-chain line. Nothing goes over the air in any wake state or configuration.
The life cycle is short to describe. The position is surveyed, the node is augered or hand-buried and seated at depth, its fibre lead is spliced into the head-end or into the next node down the chain, and the pit closes. From then on it does nothing visible for a very long time: sleep and listen, wake on a threshold, classify the event locally, report once, sleep again.
It has two lives: a listening post on its own, or one node of Trembler Line CS-435.
Every other platform in the fleet is engineered around something that moves. This one moves once, and each of the three things that replace motion in its design is harder than what it replaces.
On a Trembler Line the same buried node does three jobs at once. It is the detection element, it is a fibre relay for its neighbours, and it is the surveyed geometric reference the line's solution is computed against.
Half of the coupling subsystem is hardware and half is procedure, and a poor installation colours everything the node reports for the rest of its life.
A buried case on soil is a sprung mass. Its coupling resonance rises with the stiffness of the soil contact and falls with the mass of the node, and it has to sit well clear of the band the node listens in. Two design rules follow: seat the coupling feature in undisturbed soil, and keep the node modest in mass. Loose backfill is the classic failure, because it lowers the contact stiffness and drops the resonance into the band.
Coupling also changes with the seasons, as saturation and freeze gaps alter the contact. A drift shows up first as a shift in the ambient spectrum the node reports, long before it shows up as a missed event. Inside the case, a rigid chassis ties the sensing element straight onto the coupling feature through a short, stiff load path with no soft interface, because every compliant joint subtracts signal.
| Coupling feature | Where it suits | What it buys |
|---|---|---|
| Spike or cone | Undisturbed soil at the bottom of the hole | The simplest hand-emplaceable seating |
| Base plate | Soft or organic ground | Bearing area where a spike would sink rather than seat |
| Full burial, compacted or grouted | Permanent installations | The ground itself clamps the case |
Burial depth is 0.3–1.0 m nominal and set per site rather than read from a catalogue, and the position is surveyed before the node goes in.
The coupling feature is seated in undisturbed soil. It gives the best-controlled coupling there is, and it asks for someone to walk the line.
Node and node-to-node fibre go in on one shallow trench pass, so emplacement and network build are a single operation. It is the natural mode for a planned line on owned or permitted ground.
The node travels down a CS-410 tube bore and is emplaced at the head, with the fibre handed back out through the bore. Nothing marks the surface along the line.
Depth buys three things at once. It buys seasonal stability, because each freeze-thaw cycle reworks a seating near the surface. It buys rejection of surface noise, because wind, rain and traffic couple most strongly into the uppermost soil. And it buys concealment. Whatever the mode, every node must know where it is: a line's solution is only as good as the surveyed node positions it starts from, and the group's directional-drilling survey discipline is the one that puts each node where the survey says it goes. The bore used in the third mode is CS-410.
Deploy-and-forget is an energy claim before it is anything else, and three architectural rules carry it.
A moving-coil geophone draws nothing and puts out a signal proportional to ground velocity, so the sensor costs nothing to leave switched on for the life of the node.
The wake-up is an analog front end on the geophone output. A digital stage that never stops sampling would spend in months what the pack holds for years.
A conventional optical transceiver draws power even while idle, so the link is dark by default and energized only to report or to relay a neighbour's traffic. A neighbour's light wakes it.
The events themselves are almost free. What decides how long the watch lasts is what the node draws while it waits, so its endurance is an outcome of the electronics architecture rather than of battery size, and bigger cells cannot rescue a design that wastes power. Hold the analog wake-up and the dark fibre, and the node reaches the end of its cells' calendar life or of its seal before it reaches the end of its energy.
The pack is primary lithium of the long-shelf-life cell class, and standby endurance is years-class at an ultra-low duty cycle. Where a node sits near a bored conduit, a tether tap from a line supply removes the battery constraint altogether.
The case holds out soil pressure, groundwater, freeze-thaw and soil chemistry for a very long time, and passes ground motion to the sensor with as little colouration as it can.
Moulded glass-filled nylon is close to ideal for the duty. It does not corrode, forms no galvanic couples, is electrically inert and is mouldable on the group's own tooling. There is no radio aboard to shield, so the one property a polymer case normally costs is one this node never needs. Recycled PET is used for non-structural parts only.
Inside, the battery sits low and hard, where its inertia works for the coupling rather than against it. The electronics are conformally coated and potted against the condensation that years of thermal cycling produce in any sealed volume. A desiccant and a moisture telltale share the space, and the telltale is read over the fibre, a near-free health measure on a node nobody is going to open. The operating temperature is the −40 °C to +50 °C class.
The no-radio rule treats the link as the vulnerability, and this node is where the rule reaches its cleanest expression.
Once the fibre is spliced and the pit is closed, the node emits nothing over the air in any wake state or configuration: not a beacon, not a heartbeat, not a status ping. Nothing is sent, so there is nothing to intercept. There is no receiver to jam and no satellite fix to lose or spoof, because the node knows where it is from the survey that put it there. Two fibre ports carry the dark fibre, one up-line and one down-line, and on a line each node relays its neighbours' traffic as well as its own.
Reports go node to node or straight to a head-end: the event record when a threshold trips, and on a slow fixed cadence the battery voltage under load, a snapshot of the coupling spectrum and the moisture telltale.
No active seismic source, no acoustic projector and no electromagnetic emitter of any kind. A passive sensing node with no warhead, no fuze and no energetic material, and no offensive capability. Its output ends at data on a fibre.
What a node learns about itself at the install is part of what is bought, because coupling and position cannot be recovered afterwards.
Tilt comes free from a static read of the accelerometer at commissioning. Absolute azimuth, which the bearing variant needs, has two routes: the install-time survey where the surface is worked, and a known-source calibration thump at a surveyed point where the node went down a bore. The thump doubles as the end-to-end acceptance check on coupling, and coupling quality is accepted on the day or carried for the life of the node.
There is no link check to run. The link is a wire, and it is either spliced or it is not. In service, a threshold trip is sub-second and the report reaches the head-end in under a second over the fibre.
Footsteps and digging read at tens of metres and vehicles farther, and any range figure states its soil and threat class.
Ground-borne amplitude falls with distance twice over, by geometric spreading and again by absorption in the soil it travels through, and high frequencies die first. Source strengths span orders of magnitude between a footstep, hand digging, mechanized tunnelling and a vehicle, and a site's noise floor spans orders of magnitude again. Node spacing is therefore an output of the site survey, and a line is delivered as a surveyed, commissioned system rather than as nodes at a fixed interval. Discrimination starts at the node, where the threshold detector rejects wind, weather and passing wildlife and catches digging, footsteps, vehicles and tunnelling.
The cue a line produces goes to a person at a console, not to a machine. Where a confirmed cue calls for a physical response, that response is CS-425, sent forward on a person's decision. This node's role ends at data on a wire, and no strike authority exists in the loop for it to command.
Every variant shares the envelope, the coupling, the power stack and the link, so a new element is a change of what sits inside rather than a new node.
A single vertical-axis moving-coil geophone, the workhorse of seismic practice, drawing nothing. It hears that something is happening, and roughly how energetically.
A three-element set, geophone or low-noise MEMS accelerometer, adds polarization and a single-node bearing, so a line solves position from arrival times and bearings together. It suits anchor positions in a mixed line among single-geophone nodes.
Fitted where a node sits near a tunnel, culvert or pipeline. Seismic and acoustic channels together separate source types: an engine in a void is acoustic-strong and seismic-weak, and digging is the reverse.
Pipeline leak and third-party-interference monitoring, and slope and seismic monitoring. Leak noise and an excavator strike are the same detection problem on the same hardware.
The lines that hold in every variant, in every emplacement and for every customer.
The page this sheet specifies, and the sheets beside it in the line.
The page this sheet specifies, with the pictures and the reasoning.
The buried picket of fibre-linked listening nodes.
A first conversation needs the ground, the approach or chokepoint, and what a detection there has to set in motion.
Not an offer. Enquiries are screened, international transfer is subject to Canadian government permits taken per shipment, and all designs, systems and technologies shown are patent pending.
