{
  "$type": "site.standard.document",
  "description": "A loudspeaker (2) emits a broad band acoustic signal that is reflected around the interior of the vehicle and is received by a microphone (1). A signal signature is obtained when the vehicle is empty of people and is used as a reference. This is compared to the one obtained if an intruder enters…",
  "path": "/patents/1090661",
  "publishedAt": "2004-01-02T00:00:00.000Z",
  "site": "at://did:plc:oql6ds5vnff4ugar6rruliwd/site.standard.publication/3mn3ohu7oxx5w",
  "tags": [
    "B60R25/1009",
    "SIEMENS AG [DE]"
  ],
  "textContent": "A loudspeaker (2) emits a broad band acoustic signal that is reflected around the interior of the vehicle and is received by a microphone (1). A signal signature is obtained when the vehicle is empty of people and is used as a reference. This is compared to the one obtained if an intruder enters and an alarm is triggered.",
  "title": "Method for acoustic surveillance"
}