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.
# 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.
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) |
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 |
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 |