Noise Level Observed

Description

It represents an observation of those acoustic parameters that estimate noise pressure levels at a certain place and time. This entity is primarily associated with the Smart City and environment vertical segments and related IoT applications. In addition it also represents a break down of the frequencies present in the sound in accordance with the ISO 3741:2010 standard frequencies of 100 Hz to 10 000 Hz one-third octave band.

Data Model

The data model is defined as shown below:

  • id : Unique identifier.

  • type : Entity type. It must be equal to NoiseLevelObserved.

  • source : A sequence of characters giving the source of the entity data.

    • Attribute type: Property. Text or URL
    • Optional
  • dataProvider : Specifies the URL to information about the provider of this information

    • Attribute type: Property. URL
    • Optional
  • dateCreated : Entity's creation timestamp.

    • Attribute type: Property. DateTime
    • Read-Only. Automatically generated.
  • dateModified : Last update timestamp of this entity.

    • Attribute type: Property. DateTime
    • Read-Only. Automatically generated.
  • location : Location of this observation represented by a GeoJSON geometry.

  • address : Civic address of this observation.

  • name : Name given to this observation.

    • Attribute type: Property. Text
    • Normative References: https://uri.etsi.org/ngsi-ld/name equivalent to name
    • Optional
  • description : Description given to this observation.

  • dateObserved : The date and time of this observation represented by an ISO8601 interval. As a workaround for the lack of support of Orion Context Broker for datetime intervals, it can be used two separate attributes: dateObservedFrom, dateObservedTo.

    • Attribute type: Property. ISO8601 interval represented as Text.
    • Optional
  • dateObservedFrom : Observation period start date and time. See dateObserved.

    • Attribute type: Property. DateTime.
    • Mandatory
  • dateObservedTo : Observation period end date and time. See dateObserved.

    • Attribute type: Property. DateTime.
    • Mandatory
  • refDevice : A reference to the device which captured this observation.

    • Attribute type: Relationship. Reference to an entity of type Device
    • Optional
  • sonometerClass : Class of sonometer (0, 1, 2) according to ANSI used for taking this observation. This attribute is useful when no device entity is associated to observations. It allows to convey, roughly, information about the precision of the measurements.

    • Attribute type: Property. Text
    • Allowed values: one of ("0", "1", "2")
    • Optional
  • frequencies : Specifies the frequencies collected from the sensor represented by the ISO 3741:2010 standard frequencies of 100 Hz to 10 000 Hz one-third octave band. The value of each frequency is the A-weighted decibel value recorded.

    • Attribute type : A StructuredObject of frequency : value pairs as defined by the ISO 3741:2010 standard where the values are represented as Numbers
    • Mandatory
  • refPointOfInterest : A reference to a point of interest associated to this observation.

    • Attribute type: Relationship. Reference to an entity of type PointOfInterest
    • Optional

Representing acoustic parameters

The number of acoustic parameters measured can vary. For each acoustic measurand there MUST be an attribute which name MUST be exactly equal to the acoustic measurand name, as follows:

  • Attribute name: Equal to the name of the measurand, for instance LAeq, LAmax. It must correspond to a term defined at http://www.acoustic-glossary.co.uk/definitions-l.htm, with the only exception that those measurands which name contains a , char, such char shall be substituted by the _ char. For instance, the measurand "LAeq,d" shall be represented by an Attribute which name shall be LAeq_d.
  • Attribute type: Property. Number
  • Attribute value: corresponds to the value for the measurand as a number expressed in decibels.
  • Attribute Metadata:

Representing weather conditions

There are two options for representing them:

  • A/ Through a linked entity of type WeatherObserved (attribute named refWeatherObserved) which will capture the associated weather conditions.
  • B/ Adding weather-related properties defined at WeatherObserved.

Representing Frequency Data

As the number of frequencies collected may vary from the ISO standard it is suggested that anything outside of this range be omitted and if frequencies within this range are missing the values are set to 0

Note: JSON Schemas are intended to capture the data type and associated constraints of the different Attributes, regardless their final representation format in NGSI(v2, LD).

Examples

Normalized Example

Normalized NGSI Response

{
    "id": "Vitoria-NoiseLevelObserved-2016-12-28T11:00:00_2016-12-28T12:00:00",
    "type": "NoiseLevelObserved",
    "location": {
        "type": "geo:json",
        "value": {
            "type": "Point",
            "coordinates": [-2.698, 42.8491]
        }
    },
    "dateObservedFrom": {
        "type": "DateTime",
        "value": "2016-12-28T11:00:00"
    },
    "dateObservedTo": {
        "type": "DateTime",
        "value": "2016-12-28T12:00:00"
    },
    "LAeq": {
        "value": 67.8,
        "metadata": {
            "description": {
                "value": "A-weighted, equivalent, sound level"
            }
        }
    },
    "LAmax": {
        "value": 94.5,
        "metadata": {
            "description": {
                "value": "A-weighted, maximum, sound level"
            }
        }
    },
    "LAS": {
        "value": 91.6,
        "metadata": {
            "description": {
                "value": "A-weighted, Slow, sound level"
            }
        }
    },
    "LAeq_d": {
        "value": 65.4,
        "metadata": {
            "description": {
                "value": "A-weighted, equivalent, day period, sound level"
            }
        }
    },
    "frequencies": {
        "value": {
            "100": 40,
            "125":  40,
            "160": 40,
            "200": 40,
            "250": 40,
            "315": 40,
            "400": 40,
            "500": 40,
            "630": 40,
            "800": 40,
            "1000": 40,
            "1250": 40,
            "1600": 40,
            "2000": 40,
            "2500": 40,
            "3150": 40,
            "4000": 40,
            "8000": 40,
            "10000": 40
        },
        "metadata": {
            "description": {
                "value": "A-weighted, frequency, sound level "
            }
        }
    }
}

key-value pairs Example

Sample uses simplified representation for data consumers ?options=keyValues

{
    "id": "Vitoria-NoiseLevelObserved-2016-12-28T11:00:00_2016-12-28T12:00:00",
    "type": "NoiseLevelObserved",
    "LAS": 91.6,
    "LAeq": 67.8,
    "LAeq_d": 65.4,
    "LAmax": 94.5,
    "dateObservedFrom": "2016-12-28T11:00:00.00Z",
    "dateObservedTo": "2016-12-28T12:00:00.00Z",
    "location": {
        "type": "Point",
        "coordinates": [-2.698, 42.8491]
    },
    "frequencies": {
        "100": 40,
        "125": 40,
        "160": 40,
        "200": 40,
        "250": 40,
        "315": 40,
        "400": 40,
        "500": 40,
        "630": 40,
        "800": 40,
        "1000": 40,
        "1250": 40,
        "1600": 40,
        "2000": 40,
        "2500": 40,
        "3150": 40,
        "4000": 40,
        "8000": 40,
        "10000": 40
    }
}

LD Example

Sample uses the NGSI-LD representation

{
    "id": "urn:ngsi-ld:NoiseLevelObserved:Vitoria-NoiseLevelObserved-2016-12-28T11:00:00_2016-12-28T12:00:00",
    "type": "NoiseLevelObserved",
    "dateObservedFrom": {
        "type": "Property",
        "value": {
            "@type": "DateTime",
            "@value": "2016-12-28T11:00:00.00Z"
        }
    },
    "LAmax": {
        "type": "Property",
        "value": 94.5
    },
    "LAeq": {
        "type": "Property",
        "value": 67.8
    },
    "dateObservedTo": {
        "type": "Property",
        "value": {
            "@type": "DateTime",
            "@value": "2016-12-28T12:00:00.00Z"
        }
    },
    "LAeq_d": {
        "type": "Property",
        "value": 65.4
    },
    "location": {
        "type": "GeoProperty",
        "value": {
            "type": "Point",
            "coordinates": [-2.698, 42.8491]
        }
    },
    "LAS": {
        "type": "Property",
        "value": 91.6
    },
    "@context": [
        "https://schema.lab.fiware.org/ld/context",
        "https://uri.etsi.org/ngsi-ld/v1/ngsi-ld-core-context.jsonld"
    ]
}

Open Issues

References