ntia-sensor.sigmf-ext.md

ntia-sensor extension v1.0.0

The ntia-sensor namespace provides metadata to describe RF sensors.

ntia-sensor is fully compliant with the SigMF specification and conventions.

1 Global

ntia-sensor extends the Global with the following name/value pairs:

name	required	type	unit	description
sensor	false	Sensor	N/A	Describes the sensor model components. This object is RECOMMENDED.
calibration_datetime	false	datetime	ISO-8601	Time of last calibration. RECOMMENDED.

1.1 Sensor Object

Sensor definition follows a simplified hardware model composed of the following elements: antenna, preselector, signal analyzer, and computer. The antenna converts electromagnetic energy to a voltage. The preselector can provide local calibration signals, RF filtering to protect from strong out-of-band signals, and low-noise amplification to improve sensitivity. The signal analyzer (e.g., software defined radio) provides tuning, down conversion, sampling, and digital signal processing. Sensor implementations are not required to have each component, but metadata SHOULD specify the presence, model numbers, and operational parameters associated with each.

Sensor has the following properties:

name	required	type	unit	description
id	true	string	N/A	Unique logical ID for the sensor.
sensor_spec	false	HardwareSpec	N/A	Metadata to describe/specify the sensor.
antenna	false	Antenna	N/A	Metadata to describe/specify the antenna.
preselector	false	Preselector	N/A	Metadata to describe/specify the preselector.
signal_analyzer	false	SignalAnalyzer	N/A	Metadata to describe/specify the signal analyzer.
computer_spec	false	HardwareSpec	N/A	Metadata to describe/specify the onboard computer.
mobile	false	boolean	N/A	Defines whether the sensor is mobile.
location	false	Location	N/A	Specifies the location, speed, and bearing of the Sensor.
environment	false	Environment	N/A	Specifies the environment surrounding the Sensor.

1.2 SignalAnalyzer Object

SignalAnalyzer the following properties:

name	required	type	unit	description
sigan_spec	false	HardwareSpec	N/A	Metadata to describe/specify the signal analyzer.
frequency_low	false	double	Hz	Low frequency of operational range of the signal analyzer.
frequency_high	false	double	Hz	High frequency of operational range of the signal analyzer.
noise_figure	false	double	dB	Noise figure of the signal analyzer.
max_power	false	double	dBm	Maximum input power of the signal analyzer.
a2d_bits	false	integer	bits	Number of bits in A/D converter.

1.3 Preselector Object

Preselector has the following properties:

name	required	type	unit	description
preselector_spec	false	HardwareSpec	N/A	Metadata to describe/specify the preselector.
cal_sources	false	CalSource[]	N/A	Metadata to describe/specify the preselector calibration source.
amplifiers	false	Amplifier[]	N/A	Metadata to describe/specify the preselector low noise amplifiers.
filters	false	Filter[]	N/A	Metadata to describe the preselector RF filters.
rf_paths	false	RFPath[]	N/A	Metadata that describes preselector RF paths.

1.4 CalSource Object

CalSource has the following properties:

name	required	type	unit	description
cal_source_spec	false	HardwareSpec	N/A	Metadata to describe the calibration source specification.
type	false	string	N/A	Type of the calibration source.
enr	false	double	dB	Excess noise ratio.

1.5 Amplifier Object

Amplifier has the following properties:

name	required	type	unit	description
amplifier_spec	false	HardwareSpec	N/A	Metadata to describe the amplifier specification.
gain	false	double	dB	Gain of the low noise amplifier.
noise_figure	false	double	dB	Noise figure of the low noise amplifier.
max_power	false	double	dB	Maximum power of the low noise amplifier.

1.6 Filter Object

Filter has the following properties:

name	required	type	unit	description
filter_spec	false	HardwareSpec	N/A	Metadata to describe/specify the filter specification.
frequency_low_passband	false	double	Hz	Low frequency of filter 1 dB passband.
frequency_high_passband	false	double	Hz	High frequency of filter 1 dB passband.
frequency_low_stopband	false	double	Hz	Low frequency of filter 60 dB stopband.
frequency_high_stopband	false	double	Hz	High frequency of filter 60 dB stopband.

1.7 RFPath Object

RFPath has the following properties:

name	required	type	unit	description
name	false	string	N/A	Descriptive name for the RFPath.
cal_source_id	true	string	N/A	ID of the calibration source.
filter_id	true	string	N/A	ID of the filter.
amplifier_id	true	string	N/A	ID of the amplifier.

2 Captures

ntia-sensor does not provide additional keys to Captures.

3 Annotations

ntia-sensor defines the following segments that extend ntia-core.

3.1 SensorAnnotation Segment

SensorAnnotation has the following properties:

name	required	type	unit	description
rf_path_index	false	integer	N/A	Index of the RFPath object.
overload	false	boolean	N/A	Indicator of sensor overload.
attenuation_setting_sigan	false	double	dB	Attenuation setting of the signal analyzer.
gain_setting_sigan	false	double	dB	Gain setting of the signal analyzer.
gps_nmea	false	string	NMEA	NMEA message from GPS receiver.

3.2 CalibrationAnnotation Segment

CalibrationAnnotation has the following properties:

name	required	type	unit	description
gain_sigan	false	double	N/A	Gain of signal analyzer (may differ with signal analyzer gain setting).
noise_figure_sigan	false	double	dB	Noise figure of signal analyzer.
1db_compression_point_sigan	false	double	dBm	Maximum input of signal analyzer.
enbw_sigan	false	double	Hz	Equivalent noise bandwidth of signal analyzer.
gain_preselector	false	double	dB	Gain of sensor preselector.
noise_figure_sensor	false	double	dB	Noise figure of sensor.
1db_compression_point_sensor	false	double	dBm	Maximum input of sensor.
enbw_sensor	false	double	Hz	Equivalent noise bandwidth of sensor.
mean_noise_power_sensor	false	double	Defined in mean_noise_power_units	Mean noise power density of sensor.
mean_noise_power_units	false	string	N/A	The units of the mean_noise_power
mean_noise_power_reference	false	string	N/A	Reference source for the mean_noise_power, e.g., "signal analyzer input", "preselector input", "antenna terminal"
temperature	false	double	celsius	The temperature during calibration.

4 Example

4.1 Sensor Global Object and Annotations

{
  "global" : {
    "core:datatype" : "rf32_le",
    "core:sample_rate" : 2.8E7,
    "core:description" : "Radar data captured off the coast of San Francisco",
    "core:extensions" : {
      "ntia-algorithm" : "v1.0.0",
      "ntia-sensor" : "v1.0.0",
      "ntia-environment" : "v1.0.0",
      "ntia-location" : "v1.0.0"
    },
    "ntia-sensor:sensor" : {
      "id" : "192.168.1.53",
      "sensor_spec" : {
        "id" : "bh-5",
        "model" : "bassethound",
        "version" : "v1.0.0",
        "description" : ""
      },
      "antenna" : {
        "antenna_spec" : {
          "model" : "ARA BSB-26",
          "description" : "RF antenna ideally suited for reception of signals on the horizon for nautical and broadband surveillance applications"
        },
        "type" : "Omni-directional",
        "frequency_low" : 2.0E9,
        "frequency_high" : 6.0E9,
        "gain" : 0.0,
        "polarization" : "Slant",
        "cross_polar_discrimination" : 13.0,
        "horizontal_beamwidth" : 360.0,
        "vertical_beamwidth" : 68.38,
        "voltage_standing_wave_ratio" : 2.0,
        "cable_loss" : 0.79,
        "steerable" : false
      },
      "preselector" : {
        "cal_sources" : [ {
          "cal_source_spec" : {
            "id" : "37501",
            "model" : "Mercury Systems NS36B-1",
            "supplemental_information" : "https://www.everythingrf.com/products/noise-sources/mercury-systems/608-220-ns346b-1"
          },
          "type" : "Calibrated noise source",
          "enr" : "14.53 dB"
        } ],
        "filters" : [ {
          "filter_spec" : {
            "id" : "13FV40-00014, SN 6",
            "model" : "K&L 13FV40-3550/U200-o/o",
            "supplemental_information" : "http://www.klfilterwizard.com/klfwpart.aspx?FWS=1112001&PN=13FV40-3550%2fU200-O%2fO"
          },
          "frequency_low_passband" : 3.43E9,
          "frequency_high_passband" : 3.67E9,
          "frequency_low_stopband" : 3.39E9,
          "frequency_high_stopband" : 3.71E9
        }, { } ],
        "amplifiers" : [ {
          "amplifier_spec" : {
            "id" : "1904044",
            "model" : "MITEQ AFS3-02000400-30-25P-6",
            "supplemental_information" : "https://nardamiteq.com/docs/MITEQ_Amplifier-AFS.JS_c41.pdf"
          },
          "gain" : 32.85,
          "noise_figure" : 2.59,
          "max_power" : 13.0
        } ],
        "rf_paths" : [ {
          "name" : "Path 1",
          "cal_source_id" : "37501",
          "filter_id" : "13FV40-00014, SN 6",
          "amplifier_id" : "1904044"
        }, {
          "name" : "Bypass",
          "cal_source_id" : "37501"
        } ]
      },
      "signal_analyzer" : {
        "sigan_spec" : {
          "id" : "502725",
          "model" : "Keysight N6841A",
          "supplemental_information" : "https://www.keysight.com/us/en/assets/7018-02113/data-sheets/5990-3839.pdf"
        },
        "frequency_low" : 2.0E7,
        "frequency_high" : 6.0E9,
        "noise_figure" : 20.0,
        "max_power" : 20.0,
        "a2d_bits" : 14
      },
      "computer_spec" : {
        "id" : "MC 9",
        "description" : "Custom computer with Intel i7 processor, MSI motherboard, 16 GB of Ram and running Windows 7"
      },
      "location" : {
        "x" : -122.5309,
        "y" : 37.8204,
        "z" : 51.3522,
        "speed" : 0.0,
        "description" : "On a tower in Point Bonita, near San Francisco"
      },
      "environment" : {
        "category" : "Outside. Coastal."
      }
    },
    "ntia-location:coordinate_system" : {
      "coordinate_system_type" : "CoordinateSystem",
      "id" : "WGS_84",
      "elevation_ref" : "MSL",
      "elevation_unit" : "meter"
    },
    "ntia-sensor:calibration_datetime" : "2018-01-01T10:49:58.236Z",
    "ntia-core:measurement" : {
      "domain" : "Frequency",
      "measurement_type" : "Scan",
      "time_start" : "2018-01-01T07:59:42.792Z",
      "time_stop" : "2018-01-01T08:00:37.792Z",
      "frequency_tuned_low" : 3.45940625E9,
      "frequency_tuned_high" : 3.65190625E9,
      "frequency_tuned_step" : 1.925E7, 
      "classification" : "UNCLASSIFIED"
    }
  },
  "captures" : [ {
    "core:sample_start" : 0,
    "core:frequency" : 3.5501875E9,
    "core:datetime" : "2018-01-01T07:59:42.792Z"
  } ],
  "annotations" : [ {
    "ntia-core:annotation_type" : "FrequencyDomainDetection",
    "core:sample_start" : 0,
    "core:sample_count" : 458,
    "core:comment" : "",
    "ntia-algorithm:detector" : "fft_max_power",
    "ntia-algorithm:number_of_ffts" : 10,
    "ntia-algorithm:number_of_samples_in_fft" : 50,
    "ntia-algorithm:window" : "Gauss-top",
    "ntia-algorithm:equivalent_noise_bandwidth" : 962500.0,
    "ntia-algorithm:frequency_start" : 3.45021875E9,
    "ntia-algorithm:frequency_stop" : 3.65015625E9,
    "ntia-algorithm:frequency_step" : 437500.0
  }, {
    "ntia-core:annotation_type" : "CalibrationAnnotation",
    "core:sample_start" : 0,
    "core:sample_count" : 458,
    "core:comment" : " Calibration is done every 6 hours.",
    "ntia-sensor:gain_preselector" : 27.241,
    "ntia-sensor:noise_figure_sensor" : 7.638,
    "ntia-sensor:enbw_sensor" : 962500.0000000001,
    "ntia-sensor:mean_noise_power_sensor" : -94.28774890829693,
    "ntia-sensor:temperature" : 14.611,
    "ntia-sensor:mean_noise_power_units" : "dBm"
  }, {
    "ntia-core:annotation_type" : "SensorAnnotation",
    "core:sample_start" : 0,
    "core:sample_count" : 458,
    "ntia-sensor:rf_path_index" : 0,
    "ntia-sensor:overload" : false,
    "ntia-sensor:attenuation_setting_sigan" : 3.0
  } ]
}