1. What presence of life means
Presence of life detection answers one question about a space you cannot see into. Is there a living person in there? Federal research programs use the same phrase for the same question. They ask it for responders facing a closed door, a smoky hallway or a collapsed structure.
It is a narrower question than it sounds. It is not who is there or what they look like or what they are doing. It is whether someone is there and how sure the answer is. A narrow question is what makes the answer useful. It is also what keeps it from becoming surveillance.
2. What it can tell you
On Vantage every room can come back with these answers. Each one carries its own confidence.
- Presence. Occupied, clear or honestly unknown for every room.
- Movement. Whether each person found is moving or still. When someone moves from one room to another the change is shown and logged with the time.
- Breathing when conditions allow. A breathing rate for a still person. It is shown only when the read is confident.
- Count. How many people are in each room. When the number cannot be pinned down you get a range.
- Confidence. How sure each answer is. A strong read and a weak one never look the same.
Readings keep updating while a session is open. The through wall detection capabilities page shows each answer in a real situation.
3. What it cannot tell you
The limits matter as much as the answers. A presence of life reading cannot tell you any of these things.
- Who someone is. Vantage never identifies anyone. It only tells you that someone is there.
- What the room or the person looks like. It produces no images.
- What anyone is saying. It records no sound or speech.
- What someone intends or whether they are armed. Movement is not intent. A reading is not a threat assessment.
- How badly someone is hurt. Breathing tells you someone is alive. It is not a medical assessment.
- Whether it is a person or a large animal. Large animals can read as occupants.
- That a room it cannot read is empty. A no read means unknown. Unknown is treated as occupied.
4. Why a no read is never a clear
The most important idea here is the gap between not finding someone and finding no one.
A clear is a claim. It says no one is detected with high confidence. A no read is an admission. It says the room could not be read so nothing is known about it. Some conditions can stop a reading from forming at all. Dense concrete, steel and deep debris are the most common. If a system quietly turned those rooms into clears it would be guessing. Its guesses would look exactly like its answers.
The worst answer a system could give.
It costs time and not a life.
Being wrong costs far more one way than the other. So the safe design is lopsided on purpose. When the evidence is weak Vantage moves a room toward low confidence or no read and never toward clear. It is tuned to report no read long before it would risk a false clear. Even a confident clear is a lower priority and not a cleared room. Crews still search and clear every room.
The limits of through wall sensing page lists the conditions that lead to a no read and what to do in each.
5. Reading the confidence
Every answer comes with a confidence. A few habits make it easy to use.
- High confidence occupied. Plan or search for that room first.
- Low confidence. Probably someone but the evidence is weak. Treat the room as occupied.
- A count shown as a range. The number cannot be pinned down. This often happens in a crowded room. Treat it as a range and not a total.
- A new building. Expect more low and no reads at first. Every structure is different so Vantage starts cautious in a new one.
Weak evidence lowers a state and never raises one. Thresholds are set per deployment with your team.
6. Breathing when conditions allow
Breathing is the answer that matters most for a person who cannot move. It is also the hardest one to confirm. It needs time and calm conditions. Heavy movement nearby makes it harder. Machinery, fans, moving water and other crews all count.
That is why Vantage shows a breathing rate only when conditions allow and the read is confident. It says so when it cannot confirm one. A still person with no confirmed breathing is not an empty room. Wait for the confirm or treat the room as occupied.
7. Using a reading in a decision
A presence of life reading is a lead and not a conclusion. It tells a team where to look first and what to expect. It does not finish the job.
- In rescue it ranks the rooms for primary search. Every room is still searched and a no read is searched by hand. See the search and rescue guide.
- In law enforcement it informs the entry plan. A reading never clears a room and unknown is treated as occupied. No reading should be the only basis for a decision to use force. See through wall sensing for law enforcement.
8. The rules around it
In the United States whether someone is inside a home is exactly the kind of detail the Fourth Amendment protects. Other countries set their own rules. In Kyllo v. United States the Supreme Court held that using a device not in general public use to learn details inside a home is a search when those details could not otherwise be learned without going in. Without a warrant it is presumptively unreasonable.
So on Vantage no session opens without a recorded lawful basis. The basis is one of four: a warrant, written consent, an emergency or training. A named supervisor confirms it. Every reading lands in a sealed record that cannot be edited. The through wall sensing governance model sets out every control. Which basis applies is for your agency and its counsel to decide. This guide is not legal advice.
9. Public sources
The descriptions below are our own short summaries. Read the originals for the full picture.
- Detection of Presence of Life (DePLife) Prototype Operational Field Assessment Report. DHS Science and Technology Directorate (2023). Police officers and firefighters tested a prototype in the field. They said missed detections and false alarms did the most to lower their trust in it. They asked for better detection of people who are not moving. The report covers a different product. We cite it for what responders said they need.
- Through-the-Wall Sensors for Law Enforcement: Market Survey. National Institute of Justice (2012). NCJ 240729. A federal survey written to help agencies understand what these tools could and could not do. It was based on what manufacturers reported at the time.
- Kyllo v. United States, 533 U.S. 27 (2001). The Supreme Court decision on using technology to learn what is inside a home.
