typedef struct {
  int   month; /* Date for this ray; month (1-12). */
  int   day;   /* Date for this ray; day (1-31).   */
  int   year;  /* Date for this ray; year (eg. 1993). */
  int   hour;  /* Time for this ray; hour (0-23). */
  int   minute;/* Time for this ray; minute (0-59).*/
  float sec;   /* Time for this ray; second + fraction of second. */
  float unam_rng;  /* Unambiguous range. (KM). */
  float azimuth;   /* Azimuth angle. (degrees). Must be positive
                    * 0=North, 90=east, -90/270=west.
                    * This angle is the mean azimuth for the whole ray.
                    * Eg. for NSIG the beginning and end azimuths are
                    * averaged.
                    */
  int   ray_num;   /* Ray no. within elevation scan. */
  float elev;       /* Elevation angle. (degrees). */
  int   elev_num;   /* Elevation no. within volume scan. */
  
  int   range_bin1; /* Range to first gate.(meters) */
  int   gate_size;  /* Data gate size (meters)*/
  
  float  vel_res;    /* Doppler velocity resolution */
  float sweep_rate;   /* Sweep rate. Full sweeps/min. */
  
  int prf;          /* Pulse repitition frequency, in Hz. */
  int prf2;         /* Second PRF, for Sigmet dual PRF. */
  float azim_rate;  /* Sweep rate in degrees/second.*/
  float fix_angle;  /* Elevation angle for the sweep. (degrees). */
  float pitch;      /* Pitch angle. */
  float roll;       /* Roll  angle. */
  float heading;    /* Heading. */
  float pitch_rate; /* (angle/sec) */
  float roll_rate;  /* (angle/sec) */
  float heading_rate; /* (angle/sec) */
  float lat;          /* Latitude (degrees) */
  float lon;          /* Longitude (degrees) */
  int   alt;          /* Altitude (m) */
  float rvc;          /* Radial velocity correction (m/sec) */
  float vel_east;     /* Platform velocity to the east (negative for west)   (m/sec) */
  float vel_north;    /* Platform velocity to the north (negative for south) (m/sec) */
  float vel_up;       /* Platform velocity toward up (negative for down)     (m/sec) */
  float pulse_count;  /* Pulses used in a single dwell time. */
  float pulse_width; /* Pulse width (micro-sec). */
  float beam_width;  /* Beamwidth in degrees. */
  float frequency;   /* Bandwidth GHz. */
  float wavelength;  /* Wavelength. Meters. */
  float nyq_vel;    /* Nyquist velocity. m/s */
  float (*f)(Range x);       /* Data conversion function. f(x). */
  Range (*invf)(float x);    /* Data conversion function. invf(x). */
  int   nbins;               /* Number of array elements for 'Range'. */
} Ray_header;