Exporting Radial Metrics in SeaSondeR
This vignette demonstrates how to export radial metrics from HF-Radar spectra using the SeaSondeR package. The exported radial metrics table contains key parameters (e.g. DOAs, FOR limits, signal strengths) that can be used with tools such as Sea Display.
Example
# Set sample file paths
cs_file <- system.file("css_data/CSS_TORA_24_04_04_0700.cs", package = "SeaSondeR")
apm_file <- system.file("css_data/MeasPattern.txt", package = "SeaSondeR")
# Read the antenna pattern file to create a SeaSondeRAPM object
apm_obj <- seasonder_readSeaSondeRAPMFile(apm_file)
#> seasonder_createSeaSondeRAPM: APM object created successfully.
# Create a SeaSondeRCS object from a spectral file
cs_obj <- seasonder_createSeaSondeRCS(cs_file, seasonder_apm_object = apm_obj)
#> new_SeaSondeRCS: SeaSondeRCS object created successfully.
# Compute first-order regions and run the MUSIC algorithm if needed:
cs_obj <- seasonder_computeFORs(cs_obj, FOR_control = list(nsm = 2, fdown = 10^(10/10), flim = 10^(20/10),
noisefact = 10^(6/10), currmax = 2,
reject_distant_bragg = TRUE, reject_noise_ionospheric = FALSE,
reject_noise_ionospheric_threshold = 0))
#> seasonder_rejectDistantBraggPeakTest: First Order Rejected at range 3, peak negative_FOR. Distance Bragg test failed.
#> seasonder_rejectDistantBraggPeakTest: First Order Rejected at range 53, peak negative_FOR. Distance Bragg test failed.
#> seasonder_rejectDistantBraggPeakTest: First Order Rejected at range 54, peak negative_FOR. Distance Bragg test failed.
cs_obj <- seasonder_runMUSICInFOR(cs_obj)
#> seasonder_runMUSIC: MUSIC algorithm started.
#> seasonder_runMUSIC: MUSIC algorithm finished.
# Define a land mask (AngSeg) to remove onshore data
AngSeg <- purrr::list_c(lapply(45:61, function(i) list(c(i, 313, 360), c(i, 0, 31))))
temp_file <- tempfile(fileext = ".ruv")
# Export the radial metrics in LLUV format
radial_metrics <- seasonder_exportLLUVRadialMetrics(cs_obj,
LLUV_path = temp_file,
AngSeg = AngSeg)
# Display the first few rows of the exported radial metrics
head(radial_metrics)
#> LOND LATD VELU VELV VFLG RNGE BEAR VELO
#> 1 -8.803399 42.20252 -0.73150986 0.8124240 0 0.1870365 318 -1.0932243
#> 2 -8.803050 42.20271 0.08548836 -0.1422765 0 0.1870365 329 0.1659845
#> 3 -8.801221 42.20288 -0.04852919 -0.1587318 0 0.1870365 17 0.1659845
#> 4 -8.802199 42.20293 1.42508463 -10.1400040 0 0.1870365 352 10.2396556
#> 5 -8.804139 42.20112 10.20069064 0.8924448 0 0.1870365 265 10.2396556
#> 6 -8.810673 42.20290 -10.83519089 2.7015165 0 0.7481461 284 -11.1668954
#> HEAD SPRC SPDC MSEL MSA1 MDA1 MDA2 MEGR MPKR MOFR MP13
#> 1 138 1 332 1 318 16 1440 37.51764 0.000000 0.000000000 9.817918
#> 2 149 1 333 2 347 329 17 18.52968 1.281161 0.008196858 -10.360013
#> 3 197 1 333 3 347 329 17 18.52968 1.281161 0.008196858 -10.360013
#> 4 172 1 341 2 18 352 265 10.68098 1.255016 0.480175432 18.178391
#> 5 85 1 341 3 18 352 265 10.68098 1.255016 0.480175432 18.178391
#> 6 104 4 324 2 303 284 17 14.73077 1.888563 0.169387956 62.720131
#> MP23 MSP1 MDP1 MDP2 MSW1 MDW1 MDW2 MSR1 MDR1
#> 1 -74.77181 -94.73992 -94.11004 0.00000 88 2 0 6.030989 10797.146
#> 2 -52.03949 -93.92921 -96.44397 -97.52001 21 4 91 43.954436 3684.432
#> 3 -52.03949 -93.92921 -96.44397 -97.52001 21 4 91 43.954436 3684.432
#> 4 -77.73468 -93.13555 -94.14548 -93.15898 52 3 142 7.804122 10080.287
#> 5 -77.73468 -93.13555 -94.14548 -93.15898 52 3 142 7.804122 10080.287
#> 6 -42.53534 -93.15633 -95.86587 -98.62718 61 4 142 9.589858 3357.601
#> MDR2 MA1S MA2S MA3S MEI1 MEI2 MEI3
#> 1 0.000000 1.360982 9.018854 6.186278 5.473080e-10 1.458802e-11 5.887997e-12
#> 2 33.138962 3.853958 8.727675 7.514739 6.686443e-10 3.608504e-11 6.028202e-12
#> 3 33.138962 3.853958 8.727675 7.514739 6.686443e-10 3.608504e-11 6.028202e-12
#> 4 1.349332 5.822285 6.497650 8.659952 7.490601e-10 7.013029e-11 4.088580e-12
#> 5 1.349332 5.822285 6.497650 8.659952 7.490601e-10 7.013029e-11 4.088580e-12
#> 6 8.765369 2.744370 9.868149 8.270750 8.306654e-10 5.638981e-11 5.380048e-12
#> MDRJ PPFG PWFG
#> 1 16 9 9
#> 2 0 9 9
#> 3 0 9 9
#> 4 0 9 9
#> 5 0 9 9
#> 6 0 9 9The example above exports the radial metrics into a file (LLUV format) that can later be reviewed using visualization applications such as Sea Display.
Description of the Radial Metrics Table
Below are the columns of the exported Radial Metrics table in SeaSondeR.
| Column | Description |
|---|---|
| LOND, LATD | Longitude and latitude (decimal degrees) |
| VELU, VELV | East and north components of velocity (cm/s) |
| VFLG | Vector validity (see below) |
| RNGE | Distance from the antenna (km) |
| BEAR | Bearing of the vector (counter-clockwise from true north) |
| VELO | Radial velocity (cm/s) |
| HEAD | Velocity direction (counter-clockwise from true north) |
| SPRC | Range cell |
| SPDC | Doppler bin |
| MSEL | Selected solution (1 = single, 2 = dual 1, 3 = dual 2) |
| MSA1 | Bearing of the single solution (1440 if invalid) |
| MDA1, MDA2 | Bearing of the first and second dual solutions (1440 if invalid) |
| MEGR | Ratio of the first and second eigenvalue |
| MPKR | Signal power ratio |
| MOFR | Off-diagonal ratio |
| MP13 | Phase between antennas 1 and 3 |
| MP23 | Phase between antennas 2 and 3 |
| MSP1 | Signal power of the single solution (dB) |
| MDP1, MDP2 | Signal power of the first and second dual solutions (dB) |
| MSW1 | 3-dB width of the DOA function below the peak for the single solution |
| MDW1, MDW2 | 3-dB width of the DOA function below the peak for the first and second dual solutions |
| MSR1 | Value of DOA function at the peak of the single solution |
| MDR1 | Value of DOA function at the peak of the first dual solution |
| MDR2 | Value of DOA function at the peak of the second dual solution |
| MA1S, MA2S, MA3S | SNR of the self-spectrum of antennas 1, 2, and 3 for this Doppler bin |
| MEI1, MEI2, MEI3 | First, second, and third eigenvalue of the covariance matrix |
| MDRJ | Reason for dual-solution rejection (see below) |
| PPFG, PWFG | Flags for QARTOD tests 103 and 104 (1 = pass, 4 = fail) |
VFLG
The value is composed as a sum of powers of 2, representing a binary number where each bit indicates a specific flag.
| Value | Description |
|---|---|
| 0 | Valid vector |
| +64 | Low SNR |
| +4096 | Either PPFG or PWFG is not equal to 1 |
MDRJ
This value is also composed as a sum of powers of 2, where each bit represents a flag.
| Value | Description |
|---|---|
| 0 | Dual solution not rejected |
| +1 | P1 test failure |
| +2 | P2 test failure |
| +4 | P3 test failure |
| +8 | The angle difference between both solutions is less than 20 degrees |
| +16 | Only one peak was found in the dual solution |