Extended Header Example

For shipboard systems, additional information for each ray can be stored in an extended header in the ingest file.

To display the extended header, use the -data:xhdr option.

$ rays -data:xhdr -terse -if:DRY020418160516. | more
Reading file: /usr/iris_data/ingest/DRY020418041055.01Xhdr

The extended header includes time recorded to the nearest millisecond.

Starting at range 0.00 km (bin 1), bin step: 0.30 km
# 0 Az: 359.80, 0.55 El: 0.42, 0.42 Size: 1 4:11:08.055

The extended header shows the antenna azimuth and elevation, the platform pitch, roll, and heading, and the derivatives of these values in degrees/second:

Az: 350.95 El: 0.40 Pitch: -0.13 Roll: -1.10 Head: 346.79
Vel: 18.72 deg/s 0.04 0.70 359.82 359.82

The extended header information is recorded from a serial data stream transmitted from RCP. Typically this is configured to transmit updates at a maximum speed of about 20 times per second. Because rays can be recorded at up to 40 rays per second, and because of pipeline delays in the serial data, the extended header azimuth can lag the actual azimuth by up to several degrees. Normally, the platform motion period is slower.

Tr: 2.29 El_or: 0.31 Lat: 1#section#45.5'N Long:138#section#
2.8'E Alt: 14
Cor: 3.59 Age: 291 Vel: 3.69 m/s 0.00 -0.17

Tr

Training angle, which is the pedestal relative azimuth of the pedestal.

El_or

Pedestal relative elevation angle.

Cor

Velocity correction (meters/second). Applied to velocity data to correct for platform motion.

Age

Time in milliseconds since this update arrived from RCP.

Vel

Platform position and motion. Altitude is in meters, and motions are in meters/second.