Ingesting NOAA HRPT Data
The following pages will provide you with a quick tutorial on how to ingest NOAA HRPT
telemetry. Example output is provided throughout, along with links to help pages for the
functions discussed. The tutorial covers just one method of processing HRPT, not all the
available functions were used in this tutorial. For a list of HRPT functions, please see
the NOAA HRPT pages. Also, our example output will
not match yours exactly. However, the examples are close enough that you should garner
some useful information out of the tutorial. In other words: Your mileage may vary.
The topics covered are:
First, see what passes are currently on the pass disk and then ingest a NOAA pass.
To list the passes on the pass disk, type the following at the UNIX command
prompt (%):
% lspass
Example results from a site that is at UTC+1 hour:
# satel telem date day time durat lines
1 noaa-14 hrpt 1997/08/29 241 12:47:04 11:46 4241
2 noaa-14 hrpt 1997/08/29 241 14:25:44 14:03 5061
3 orbview-2 swhrpt 1998/01/22 22 20:31:25 10:47 3886
4 f-12 rtd 1997/08/29 241 10:09:05 13:55 9872
5 f-12 rtd 1997/08/29 241 11:51:04 10:21 7344
6 meteo-6 pdus 1997/08/30 242 13:01:52 03:01 629
7 f-11 rtd 1994/01/11 11 21:37:48 13:30 9582
8 gms-5 svissr 1996/09/03 247 01:31:56 24:42 9904
The next step is to ingest the pass (we’ll use pass #1), converting it from raw
format to TeraScan Data Format (TDF). This is always the first step in image processing.
To do this, we run the TeraScan function hrptin.
We want to do a quick look, where we subsample 4
times along both the length and width of the pass. This makes the processing faster and
the file size smaller. We’ll call the output quicklook.1.
Example:
% hrptin
output file(s) : char(255) ? [.] quicklook.1
hrpt_types : char( 17) ? [avhrr]
on_pass_disk : char( 3) ? [yes]
pass_number : int ( 6) ? [1] 1
channels : int ( 5) ? [1 2 3 4 5] 2 4
fix_missing : char( 3) ? [yes] n
sharpen : char( 7) ? [no] [See note A]
calibrate : char( 3) ? [yes]
temp_units : char( 10) ? [celsius]
byte_output : char( 3) ? [no]
full_report : char( 3) ? [no]
solar_corr : char( 3) ? [no]
geo_correct : char( 3) ? [no] [See note B]
delta_line : int ? [1] 4
delta_sample : int ? [1] 4
use_master : char( 3) ? [yes] n
start_time : char(15) ? [00:00:00]
num_lines : int ? [1500]
start_sample : int ? [1]
num_samples : int ? [512]
pass partition 1: noaa-14 1997/08/29 12:47:11.14
./quicklook.1.avhrr: Creating ...
avcal.coef: noaa-14 1997 217 0.131200 -5.378300 0.164700 -6.751000
avcal.coef: noaa-14 1997 259 0.131800 -5.405000 0.165700 -6.793800
avcal.coef: noaa-14 1997 241 0.131543 -5.393558 0.165271 -6.775457
line 100 ch slope intcpt space target prt average
1 0.13154 -5.39 41.0 1 245.67
2 0.16527 -6.78 41.0 2 255.19
3 -0.00165 1.64 987.8 734.6 3 237.52
4 -0.16425 158.94 992.3 390.4 4 240.31
5 -0.18250 178.28 989.4 370.6
./quicklook.1.avhrr: Actual size is 1061 lines by 512 samples
|
A. Scan lines overlap more and more toward the edges of the lines because the
pixels get taller at the edges. Setting sharpen=yes
will subtract from each pixel any contamination caused by sensor oversampling
into adjacent pixels.
B. The pixel size and shape changes along the scan line. At the edges (limbs) of
the scan swath, the pixels are about 2 km high and 6 km wide. This is because
the scanner is looking at an angle and so sees more surface area. Setting geo_correct=yes
redistributes pixels along the scan line to approximately equal 1.1 x 1.1 km;
replicates pixels near end of scan line while discarding a few near the center.
|
Creating a Master (Area of Interest)
Next, you’ll identify an area of interest to use, create a master file using the
TeraScan function master, and then process the
data again using the master you created. [The Graphical User Interface (GUI) TeraMaster also creates
masters.]
Display the ingested pass in TeraVision and pick out an area of interest. For this
example, we’ll use a center of 42.6 N and 12.3 E.
Run the TeraScan function master to create an
area of interest whose center pixel is 42.6 North and 12.3 East. The projection you choose
will be rectangular.
Example:
% master
output file : char(255) ? [Master]
projection : char( 13) ? rect
center_lat : char( 15) ? 42.6n
center_lon : char( 15) ? 12.3 E
num_lines : int ? 1000
num_samples : int ? 1000
pixel_width : real ? [1.1132]
pixel_height : real ? [1.1132]
rotate_angle : real ? [0]
move_center : char( 3) ? [no]
Do a listing of the directory to see the files you have created:
% ls
Master quicklook.1.avhrr
Note that the filename of the master you created is called Master.
This is the default filename, since you did not specify another name for the output file.
To see what the master you have created looks like, run TeraMaster and open the master
file you just created. Type tmaster& at the command line.
(Note: TeraMaster looks for master files in the default directory $PASSDIR/masters.)
Run hrptin again to ingest the same data (pass
#1) using the master you created. hrptin picks the lines and samples that
are in the master area, but does not apply the map projection [see
"Using a Master at Ingest"]. This time, you will ingest all channels at full
resolution.
Example:
% hrptin
output file(s) : char(255) ? [.]
hrpt_types : char( 17) ? [avhrr]
on_pass_disk : char( 3) ? [yes]
pass_number : int ( 6) ? [1] 1
channels : int ( 5) ? [1 2 3 4 5]
fix_missing : char( 3) ? [yes]
sharpen : char( 19) ? [no]
calibrate : char( 3) ? [yes]
temp_units : char( 10) ? [celsius]
byte_output : char( 3) ? [no]
full_report : char( 3) ? [no]
solar_corr : char( 3) ? [no]
geo_correct : char( 3) ? [no]
delta_line : int ? [1]
delta_sample : int ? [1]
use_master : char( 3) ? [yes]
master_file : char(255) ? [Master]
pass partition 1: noaa-14 1997/08/29 12:47:11.14
./n14.97241.1247.avhrr: Creating ...
avcal.coef: noaa-14 1997 217 0.131200 -5.378300 0.164700 -6.751000
avcal.coef: noaa-14 1997 259 0.131800 -5.405000 0.165700 -6.793800
avcal.coef: noaa-14 1997 241 0.131543 -5.393558 0.165271 -6.775457
line 100 ch slope intcpt space target prt average
1 0.13154 -5.39 41.0 1 245.67
2 0.16527 -6.78 41.0 2 255.19
3 -0.00165 1.64 987.8 734.6 3 237.52
4 -0.16425 158.94 992.3 390.4 4 240.31
5 -0.18250 178.28 989.4 370.6
./n14.97241.1247.avhrr: Actual size is 1219 lines by 1384 samples
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Last Update: $Date: 2001/10/04 20:24:33 $