--- /dev/null
+#ifndef LEVEL2_H
+#define LEVEL2_H
+
+/* http://www.ncdc.noaa.gov/oa/radar/leveliidoc.html */
+typedef struct {
+ /* 24 bytes */
+ char version[4];
+ char unknown0[16];
+ char station[4];
+} __attribute__ ((packed)) level2_header_t;
+
+typedef struct {
+ /**
+ * Channel Terminal Manager:
+ *
+ * Archive II (the data tape) is a copy of messages or data packets
+ * prepared for transmission from the RDA to the RPG. CTM information
+ * is attached to a message or data packet for checking data integrity
+ * during the transmission process and is of no importance to the base
+ * data (omit or read past these bytes).
+ */
+ short ctm[6]; // ignore
+
+ /**
+ * Message Header:
+ *
+ * This information is used to identify either base data or one of
+ * thirteen types of messages that may follow in bytes 28 - 2431. This
+ * header includes the information indicated below:
+ */
+ // Message size in halfwords measure from this halfword to the end of
+ // record.
+ unsigned short size;
+
+ // Channel ID:
+ // 0 = Non-Redundant Site
+ // 1 = Redundant Site Channel 1
+ // 2 = Redundant Site Channel 2
+ unsigned char id;
+
+ // Message type, where:
+ // 1 = DIGITAL RADAR DATA (This message may contain a combination of
+ // either reflectivity, aliased velocity, or spectrum width)
+ // 2 = RDA STATUS DATA.
+ // 3 = PERFORMANCE/MAINTENANCE DATA.
+ // 4 = CONSOLE MESSAGE - RDA TO RPG.
+ // 5 = MAINTENANCE LOG DATA.
+ // 6 = RDA CONTROL COMMANDS.
+ // 7 = VOLUME COVERAGE PATTERN.
+ // 8 = CLUTTER CENSOR ZONES.
+ // 9 = REQUEST FOR DATA.
+ // 10 = CONSOLE MESSAGE - RPG TO RDA.
+ // 11 = LOOP BACK TEST - RDA TO RPG.
+ // 12 = LOOP BACK TEST - RPG TO RDA.
+ // 13 = CLUTTER FILTER BYPASS MAP - RDA to RPG.
+ // 14 = EDITED CLUTTER FILTER BYPASS MAP - RPG to RDA.
+ unsigned char type;
+
+ // I.D. Sequence = 0 to 7FFF, then roll over back to 0.
+ unsigned short seq;
+
+ // Modified Julian date starting from 1/1/70
+ unsigned short gen_date;
+
+ // Generation time of messages in milliseconds of day past midnight
+ // (UTC). This time may be different than time listed in halfwords
+ // 15-16 defined below.
+ unsigned int gen_time;
+
+ // Number of message segments. Messages larger than message size
+ // (halfword 7 defined above) are segmented and recorded in separate
+ // data packets.
+ unsigned short num_seg;
+
+ // Message segment number.
+ unsigned short seg;
+
+ /**
+ * Digital Radar Data Header:
+ *
+ * This information describes the date, time, azimuth, elevation, and
+ * type of base data included in the radial. This header includes the
+ * following information:
+ */
+ // Collection time for this radial in milliseconds of the day from
+ // midnight (UTC).
+ unsigned int coll_time;
+
+ // Modified Julian date referenced from 1/1/70.
+ unsigned short coll_date;
+
+ // Unambiguous range (scaled: Value/10. = KM).
+ unsigned short range;
+
+ // Azimuth angle (coded: [Value/8.]*[180./4096.] = DEG). An azimuth of
+ // "0 degrees" points to true north while "90 degrees" points east.
+ // Rotation is always clockwise as viewed from above the radar.
+ unsigned short angle;
+
+ // Radial number within the elevation scan.
+ unsigned short radial;
+
+ // Radial status where:
+ // 0 = START OF NEW ELEVATION.
+ // 1 = INTERMEDIATE RADIAL.
+ // 2 = END OF ELEVATION.
+ // 3 = BEGINNING OF VOLUME SCAN.
+ // 4 = END OF VOLUME SCAN.
+ unsigned short rad_status;
+
+ // Elevation angle (coded:[Value/8.]*[180./4096.] = DEG). An elevation
+ // of "0 degree" is parallel to the pedestal base while "90 degrees" is
+ // perpendicular to the pedestal base.
+ unsigned short elev_angle;
+
+ // RDA elevation number within the volume scan.
+ unsigned short elev_num;
+
+ // Range to first gate of reflectivity data (METERS). Range may be
+ // negative to account for system delays in transmitter and/or receiver
+ // components.
+ short first_refl;
+
+ // Range to first gate of Doppler data. Doppler data - velocity and
+ // spectrum width (METERS). Range may be negative to account for
+ // system delays in transmitter and/or receiver components.
+ short first_dopp;
+
+ // Reflectivity data gate size (METERS).
+ unsigned short refl_size;
+
+ // Doppler data gate size (METERS).
+ unsigned short dopp_size;
+
+ // Number of reflectivity gates.
+ unsigned short num_refl_gate;
+
+ // Number of velocity and/or spectrum width data gates.
+ unsigned short num_dopp_gate;
+
+ // Sector number within cut.
+ unsigned short sector;
+
+ // System gain calibration constant (dB biased).
+ float gain;
+
+ // Reflectivity data pointer (byte # from the start of digital radar
+ // data message header). This pointer locates the beginning of
+ // reflectivity data.
+ unsigned short refl_ptr;
+
+ // Velocity data pointer (byte # from the start of digital radar data
+ // message header). This pointer locates beginning of velocity data.
+ unsigned short vel_ptr;
+
+ // Spectrum-width pointer (byte # from the start of digital radar data
+ // message header). This pointer locates beginning of spectrum-width
+ // data.
+ unsigned short spec_ptr;
+
+ // Doppler velocity resolution.
+ // Value of: 2 = 0.5 m/s
+ // 4 = 1.0
+ unsigned short dopp_res;
+
+ // Volume coverage pattern.
+ // Value of: 11 = 16 elev. scans/ 5 mins.
+ // 21 = 11 elev. scans/ 6 mins.
+ // 31 = 8 elev. scans/ 10 mins.
+ // 32 = 7 elev. scans/ 10 mins.
+ unsigned short pattern;
+
+ // Unused. Reserved for V&V Simulator.
+ short vv_sim[4];
+
+ // Reflectivity data pointer for Archive II playback. Archive II
+ // playback pointer used exclusively by RDA.
+ unsigned short refl_ptr_rda;
+
+ // Velocity data pointer for Archive II playback. Archive II playback
+ // pointer used exclusively by RDA.
+ unsigned short vel_ptr_rda;
+
+ // Spectrum-width data pointer for Archive II playback. Archive II
+ // playback pointer used exclusively by RDA.
+ unsigned short spec_ptr_rda;
+
+ // Nyquist velocity (scaled: Value/100. = M/S).
+ unsigned short nyquist;
+
+ // Atmospheric attenuation factor (scaled: [Value/1000. = dB/KM]).
+ unsigned short atten;
+
+ // Threshold parameter for minimum difference in echo power between two
+ // resolution volumes for them not to be labeled range ambiguous
+ // (i.e.,overlaid) [Value/10. = Watts].
+ short thresh;
+
+ // Unused.
+ short unused0[17];
+
+ /**
+ * Base Data:
+ *
+ * This information includes the three base data moments; reflectivity,
+ * velocity and spectrum width. Depending on the collection method, up
+ * to three base data moments may exist in this section of the packet.
+ * (For this example, only reflectivity is present.) Base data is coded
+ * and placed in a single byte and is archived in the following format:
+ */
+ // A bit confsued by these docs.
+ // Note: Need to check size field to get correct size.
+ unsigned char data[2300];
+
+ // Reflectivity data (0 - 460 gates) (coded: [((Value-2)/2.)-32. =
+ // dBZ], for Value of 0 or 1 see note below).
+ //unsigned char refl[460];
+
+ // Doppler velocity data (coded: for doppler velocity resolution of 0.5
+ // M/S, [((Value-2)/2.)-63.5 = M/S]; for doppler resolution of 1.0 M/S,
+ // [(Value-2)-127.] = M/S], for Value of 0 or 1 see note below), (0 -
+ // 92 gates). Starting data location depends on length of the
+ // reflectivity field, stop location depends on length of the velocity
+ // field. Velocity data is range unambiguous out to 230 KM.
+ //unsigned char vel[920];
+
+ // Doppler spectrum width (coded: [((Value - 2)/2.)-63.5 = M/S], for
+ // Value of 0 or 1 see note below), (0 - 920 gates). Starting data
+ // location depends on length of the reflectivity and velocity fields,
+ // stop location depends on length of the spectrum width field.
+ // Spectrum width is range unambiguous out to 230 KM.
+ //unsigned char spec[920];
+
+ // Four bytes of trailer characters referred to the Frame Check
+ // Sequence (FCS) follow the data. In cases where the three moments are
+ // not all present or the number of gates for each moment have been
+ // reduced, the record is padded out to a constant size of 1216
+ // halfwords (2432 bytes) following the trailer characters.
+ unsigned int fcs;
+} __attribute__ ((packed)) level2_packet_t;
+
+#endif
projects / grits / blobdiff