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Nexrad.js
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Nexrad.js
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class Level2Record {
static REFLECTIVITY = 1;
static VELOCITY_HI = 2;
static VELOCITY_LOW = 4;
static SPECTRUM_WIDTH = 3;
static DOPPLER_RESOLUTION_LOW_CODE = 4;
static HORIZONTAL_BEAM_WIDTH = 1.5;
static REFLECTIVITY_HIGH = 5;
static VELOCITY_HIGH = 6;
static SPECTRUM_WIDTH_HIGH = 7;
static DIFF_REFLECTIVITY_HIGH = 8;
static DIFF_PHASE = 9;
static CORRELATION_COEFFICIENT = 10;
static MISSING_DATA = 1;
static BELOW_THRESHOLD = 0;
static FILE_HEADER_SIZE = 24;
static #CTM_HEADER_SIZE = 12;
static #MESSAGE_HEADER_SIZE = 28;
static #RADAR_DATA_SIZE = 2432;
recno; // record number within the file
message_offset; // offset of start of message
hasReflectData;
hasDopplerData;
hasHighResREFData;
hasHighResVELData;
hasHighResSWData;
hasHighResZDRData;
hasHighResPHIData;
hasHighResRHOData;
// message header
message_size;
id_channel;
message_type;
id_sequence;
mess_julian_date;
mess_msecs;
seg_count;
seg_number;
// radar data header
data_msecs;
data_julian_date;
unamb_range;
azimuth_ang;
radial_num; // radial number within the elevation - starts with one
radial_status;
elevation_ang;
elevation_num;
reflect_first_gate; // distance to first reflectivity gate (m)
reflect_gate_size; // reflectivity gate size (m)
reflect_gate_count; // number of reflectivity gates
doppler_first_gate; // distance to first reflectivity gate (m)
doppler_gate_size; // reflectivity gate size (m)
doppler_gate_count; // number of reflectivity gates
cut;
calibration; // system gain calibration constant (db biased)
resolution; // doppler velocity resolution
vcp; // volume coverage pattern
nyquist_vel; // nyquist velocity
attenuation; // atmospheric attenuation factor
threshold; // threshold parameter for minimum difference
ref_snr_threshold; // reflectivity signal to noise threshold
vel_snr_threshold;
sw_snr_threshold;
zdrHR_snr_threshold;
phiHR_snr_threshold;
rhoHR_snr_threshold;
ref_rf_threshold; // reflectivity range folding threshold
vel_rf_threshold;
sw_ref_threshold;
zdrHR_rf_threshold;
phiHR_rf_threshold;
rhoHR_rf_threshold;
#reflect_offset; // reflectivity data pointer (byte number from start of message)
#velocity_offset; // velocity data pointer (byte number from start of message)
#spectWidth_offset; // spectrum-width data pointer (byte number from start of message)
// new addition for message type 31
rlength;
id;
azimuth;
compressIdx;
sp;
ars;
rs;
elevation;
rsbs;
aim;
dcount;
dbp1;
dbp2;
dbp3;
dbp4;
dbp5;
dbp6;
dbp7;
dbp8;
dbp9;
reflectHR_gate_count;
velocityHR_gate_count;
spectrumHR_gate_count;
reflectHR_scale;
velocityHR_scale;
spectrumHR_scale;
zdrHR_scale;
phiHR_scale;
rhoHR_scale;
reflectHR_addoffset;
velocityHR_addoffset;
spectrumHR_addoffset;
zdrHR_addoffset;
phiHR_addoffset;
rhoHR_addoffset;
reflectHR_offset;
velocityHR_offset;
spectrumHR_offset;
zdrHR_offset;
phiHR_offset;
rhoHR_offset;
zdrHR_gate_count;
phiHR_gate_count;
rhoHR_gate_count;
reflectHR_gate_size;
velocityHR_gate_size;
spectrumHR_gate_size;
zdrHR_gate_size;
phiHR_gate_size;
rhoHR_gate_size;
reflectHR_first_gate;
velocityHR_first_gate;
spectrumHR_first_gate;
zdrHR_first_gate;
phiHR_first_gate;
rhoHR_first_gate;
static getDatatypeName(datatype) {
switch (datatype) {
case this.REFLECTIVITY:
return 'Reflectivity';
case this.VELOCITY_HI:
case this.VELOCITY_LOW:
return 'RadialVelocity';
case this.SPECTRUM_WIDTH:
return 'SpectrumWidth';
case this.REFLECTIVITY_HIGH:
return 'Reflectivity_HI';
case this.VELOCITY_HIGH:
return 'RadialVelocity_HI';
case this.SPECTRUM_WIDTH_HIGH:
return 'SpectrumWidth_HI';
case this.DIFF_REFLECTIVITY_HIGH:
return 'Reflectivity_DIFF';
case this.DIFF_PHASE:
return 'Phase';
case this.CORRELATION_COEFFICIENT:
return 'RHO';
default:
throw new Error('Illegal Argument');
}
}
static getDatatypeUnits(datatype) {
switch (datatype) {
case this.REFLECTIVITY:
case this.REFLECTIVITY_HIGH:
case this.DIFF_REFLECTIVITY_HIGH:
return 'dBz';
case this.VELOCITY_HI:
case this.VELOCITY_LOW:
case this.SPECTRUM_WIDTH:
case this.VELOCITY_HIGH:
case this.SPECTRUM_WIDTH_HIGH:
return 'm/s';
case this.DIFF_PHASE:
return 'deg';
case this.CORRELATION_COEFFICIENT:
return 'N/A';
default:
throw new Error('Illegal Argument');
}
}
getDatatypeSNRThreshold(datatype) {
switch (datatype) {
case this.REFLECTIVITY_HIGH:
return this.ref_snr_threshold;
case this.VELOCITY_HIGH:
return this.vel_snr_threshold;
case this.SPECTRUM_WIDTH_HIGH:
return this.sw_snr_threshold;
case this.DIFF_REFLECTIVITY_HIGH:
return this.zdrHR_snr_threshold;
case this.DIFF_PHASE:
return this.phiHR_snr_threshold;
case this.CORRELATION_COEFFICIENT:
return this.rhoHR_snr_threshold;
default:
throw new Error('Illegal Argument');
}
}
getDatatypeRangeFoldingThreshold(datatype) {
switch (datatype) {
case this.REFLECTIVITY_HIGH:
return this.ref_rf_threshold;
case this.VELOCITY_HIGH:
return this.vel_rf_threshold;
case this.SPECTRUM_WIDTH_HIGH:
return this.sw_ref_threshold;
case this.REFLECTIVITY:
case this.VELOCITY_LOW:
case this.VELOCITY_HI:
case this.SPECTRUM_WIDTH:
return this.threshold;
case this.DIFF_REFLECTIVITY_HIGH:
return this.zdrHR_rf_threshold;
default:
throw new Error('Illegal Argument');
}
}
getDatatypeScaleFactor(datatype) {
switch (datatype) {
case this.REFLECTIVITY:
case this.VELOCITY_HI:
case this.SPECTRUM_WIDTH:
return 0.5;
case this.VELOCITY_LOW:
return 1.0;
case this.REFLECTIVITY_HIGH:
return 1 / this.reflectHR_scale;
case this.VELOCITY_HIGH:
return 1 / this.velocityHR_scale;
case this.SPECTRUM_WIDTH_HIGH:
return 1 / this.spectrumHR_scale;
case this.DIFF_REFLECTIVITY_HIGH:
return 1.0 / this.phiHR_scale;
case this.CORRELATION_COEFFICIENT:
return 1.0 / this.rhoHR_scale;
default:
throw new Error('Illegal Argument');
}
}
getDatatypeAddOffset(datatype) {
switch (datatype) {
case this.REFLECTIVITY:
return -33.0;
case this.VELOCITY_LOW:
return -129.0;
case this.VELOCITY_HI:
case this.SPECTRUM_WIDTH:
return -64.5;
case this.REFLECTIVITY_HIGH:
return this.reflectHR_addoffset * (-1) / this.reflectHR_scale;
case this.VELOCITY_HIGH:
return this.velocityHR_addoffset * (-1) / this.velocityHR_scale;
case this.SPECTRUM_WIDTH_HIGH:
return this.spectrumHR_addoffset * (-1) / this.spectrumHR_scale;
case this.DIFF_REFLECTIVITY_HIGH:
return this.zdrHR_addoffset * (-1) / this.zdrHR_scale;
case this.DIFF_PHASE:
return this.phiHR_addoffset * (-1) / this.phiHR_scale;
case this.CORRELATION_COEFFICIENT:
return this.rhoHR_addoffset * (-1) / this.rhoHR_scale;
default:
throw new Error('Illegal Argument');
}
}
static getMessageTypeName(code) {
switch (code) {
case 1:
return 'digital radar data';
case 2:
return 'RDA status data';
case 3:
return 'performance/maintainence data';
case 4:
return 'console message - RDA to RPG';
case 5:
return 'maintainence log data';
case 6:
return 'RDA control commands';
case 7:
return 'volume coverage pattern';
case 8:
return 'clutter censor zones';
case 9:
return 'request for data';
case 10:
return 'console message - RPG to RDA';
case 11:
return 'loop back test - RDA to RPG';
case 12:
return 'loop back test -RPG to RDA';
case 13:
return 'clutter filter bypass map - RDA to RPG';
case 14:
return 'edited clutter filter bypass map - RDA to RPG';
case 15:
return 'Notchwidth Map';
case 18:
return 'RDA Adaptation data';
case 31:
return 'Digital Radar Data Generic Format';
default:
return `unknown ${ code }`;
}
}
static getRadialStatusName(code) {
switch (code) {
case 0:
return 'start of new elevation';
case 1:
return 'intermediate radial';
case 2:
return 'end of elevation';
case 3:
return 'begin volume scan';
case 4:
return 'end volume scan';
default:
return `unknown ${ code }`;
}
}
static getVolumeCoveragePatternName(code) {
switch (code) {
case 11:
return '16 elevation scans every 5 minutes';
case 12:
return '14 elevation scans every 4.1 minutes';
case 21:
return '11 elevation scans every 6 minutes';
case 31:
return '8 elevation scans every 10 minutes';
case 32:
return '7 elevation scans every 10 minutes';
case 121:
return '9 elevations, 20 scans every 5 minutes';
case 211:
return '14 elevations, 16 scans every 5 minutes';
case 212:
return '14 elevations, 17 scans every 4 minutes';
case 221:
return '9 elevations, 11 scans every 5 minutes';
default:
return `unknown ${ code }`;
}
}
static getDate(julianDays, msecs) {
return new Date((julianDays - 1) * 24 * 3600 * 1000 + Number(msecs));
}
static factory(din, record, message_offset31) {
try {
const offset = record * Level2Record.#RADAR_DATA_SIZE + Level2Record.FILE_HEADER_SIZE + message_offset31;
if (offset >= din.length()) {
return null;
} else {
return new Level2Record(din, record, message_offset31);
}
} catch (e) {
throw e;
}
}
constructor(din, record, message_offset31) {
try {
this.recno = record;
this.message_offset = record * Level2Record.#RADAR_DATA_SIZE + Level2Record.FILE_HEADER_SIZE + message_offset31;
console.log(din.readInt32LE(0));
} catch (e) {
throw e;
}
}
}
exports.Level2Record = Level2Record;