# Choosing ASF Data Products

The variables to be determined when requesting data from ASF and
determining its price are listed below. These variables are discussed in
some detail with reference to cost where appropriate.

[Choosing ASF Data Products 1](#choosing-asf-data-products)

[Satellite 1](#satellite)

[Location of ground station 1](#location-of-ground-station)

[Beam Modes 2](#beam-modes)

[Resolution 2](#resolution)

[Media type and Delivery 3](#media-type-and-delivery)

[Cost 3](#cost)

## Satellite

RADARSAT-1 is an advanced radar sensor called Synthetic Aperture Radar
(SAR). SAR

is a microwave instrument which sends pulsed signals to the Earth and
processes the

received reflected pulses.

## Location of ground station

Research emphasis is on the polar regions, though onboard tape recorders
will allow imaging of any region, world-wide. Data will be down linked
in real time or stored on one of the tape recorders until the spacecraft
is within range of a receiving station. Data is expected to be available
for users a few hours after the satellite passes over an area. Receiving
stations are located at Prince Albert, Saskatchewan; Gatineau, Quebec;
Tromso, Norway; and Fairbanks, Alaska.

There are additional costs (as noted below) for data acquisitions from
stations outside the ASF and McMurdo station masks.

Ground Station Transcription Times and Costs

  ------------- ------ ------------ ----------- --------- --------- ---------- ----------- ----------
  Ground        ASF    McMurdo,     Gatineau,   Prince    Tromso,   West       Singapore   China
  Station              Antarctica   Canada      Albert,   Norway    Freugh,    (CRISP)     (RSGS)
                       (MCM)        (GSS)       Canada    (TROM)    Scotland               
                                                (PASS)              (DERA)                 

  Delay Time    1 week 3 months to  2-3 months  2-3       2-3       4-6 months 3-4 months  4-6
  from                 1 year                   months    months                           months, L0
  Acquisition          depending on                                                        data
  to Orderable         date                                                                products
                                                                                           only

  FGS Cost per  NA     NA           150         150       350       350        275         250
  datatake                                                                                 
  ------------- ------ ------------ ----------- --------- --------- ---------- ----------- ----------

## Beam Modes

RADARSAT-1 offers two types of data: Standard SAR and ScanSAR.

1.  Standard SAR

All standard data are processed to a 100 km x 100 km scene. If the
actual swath is less than 100 km, such as JERS at 75 km, the remaining
pixels are 0-filled. Nominally, the full-resolution images have 12.5 m
pixel spacing and 30 m resolution, and the low-resolution images have
100 m pixel spacing and 240 m resolution. Each full-resolution image is
8192 x 8192 x 8 bits or 67 MB in size, and each low-resolution image is
1024 x 1024 x 8 bits or 1 MB in size. These image products represent how
brightly the viewed ground targets backscattered the SARs\' radar
pulses. Metadata distributed with these images allows users to compute
various other parameters, such as sigma-naught, from the pixel values.

Standard SAR has the following beam modes:

a.  Standard Beams

b.  Wide Beams

c.  Fine Resolution Beams

d.  Low Incidence

e.  High Incidence

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2.  ScanSAR

The RADARSAT-1 ScanSAR images are somewhat different. The RADARSAT-1 SAR
utilizes beam forming techniques in order to provide several different
beam modes. The modes may be capable of imaging closer to or farther
from the satellite, with finer resolution and accordingly smaller areas
or wide areas with worse resolution. The ScanSAR mode actually combines
a few of these other modes in order to obtain a very wide swath -
approximately 500 km, depending on which ScanSAR sub-mode is chosen.
Three resolutions are provided: 75, 150, and 600 meters. ASF can also
process these data to Polar Stereographic, Lambert, or UTM map
projections. Please see the documentation on [RADARSAT ScanSAR
Images](http://www.asf.alaska.edu/R1ScanSAR.pdf) for further information

Notes: 1) The data may be geocoded to a Polar Stereographic, Lambert, or
UTM projection, however, ASF User Services recommends ordering
Ungeocoded ScanSAR and using software programs to perform geocoding.

2\) There is also a terrain-corrected product which is terrain corrected
in addition to being geocoded but this product has not been validated.
ASF provides software for geocoding, and mosaicking. The terrain
correction software does not work with ScanSAR.

ScanSAR has the following beams:

a.  Wide A

b.  Wide B

c.  Narrow A

d.  Narraow B

For details on the characteristics of these different beams, see the
following websites: <http://www.asf.alaska.edu/2_3.html>,
<http://www.asf.alaska.edu/R1ScanSAR.pdf>

For suggestions on how to choose the appropriate beam mode, see
<http://www.asf.alaska.edu/R1beamChoice.pdf>.

## Resolution

The following Standard resolutions are available:

1.  Low Resolution

2.  Full Resolution

3.  Complex-Format Data-Full Scene

The following ScanSAR resolutions are available, more details at
<http://www.asf.alaska.edu/R1ScanSAR.pdf> :

1.  Low

2.  Medium

3.  Full

Notes on prices based on resolution for both Standard SAR and ScanSAR
beams are given below.

Standard Processing Prices for ERS-1, ERS-2, JERS-1, and RADARSAT-1
Standard-Beam SAR Data

  ---------------------------------------------------- ---------- -----------
  Product                                              Price      Size

  Low Resolution                                       \$2.00     1.1 MB

  Full Resolution                                      \$15.00    64.1 MB

  ERS-1, ERS-2, JERS, RADARSAT-1 Complex-Format        \$100.00   525 -- 550
  Data-Full scene                                                 MB
  ---------------------------------------------------- ---------- -----------

Processing Prices for RADARSAT-1 ScanSAR Data Products

  ------------------------------------ --------------- -------------------
  Product                              Price           Size

  Low Resolution                       \$5.00          1.6 MB

  Medium Resolution                    \$15.00         26.0 MB

  Full Resolution                      \$30.00         104.0 MB
  ------------------------------------ --------------- -------------------

## Media type and Delivery

Media can be delivered via file transfer protocol or mailed on a tape.
Prices are listed below.

> Media Price Addition

  ------------------------------------------------ ----------------------
  Type                                             Cost

  Disk Space (for files transferred via ftp)       50 per product

  Tapes:                                            

  4mm 2GB, 8mm 2.5 GB, 8mm 5GB                     1.00 per product

  Digital Linear Tape (DLT) at 20GB, 35GB          10.00 per product
  ------------------------------------------------ ----------------------

## Cost

Here is an example of the costing for a data order.

**Example 1:**

For an order of a non-foreign ground station RADARSAT-1 ScanSAR Full Res
Product, delivered via ftp:

  --------------------------------------- ----------- --------------------
  Product Processing Cost=\               30.00\      Data Credits\
  Media Cost=\                                 .50\   Data Credits\
  Total=                                  30.50       Data Credits

  --------------------------------------- ----------- --------------------

See <http://www.asf.alaska.edu/4_3_1.html> for more guidelines to
estimate costs for data acquisition.

###