AMSS Level-1A Users Guide

2.3 AMSS Level-1A Users Guide

Introduction
AMSS Instrument Summary
2.1 AMSS Specifications
2.2 AMSS Spectral Bands
AMSS Data Calibration
3.1 Visible/Near-Infrared Band Calibration
3.2 Temperature Correction of Visible/Near-Infrared Bands
3.3 Near-Infrared/Short Wave Infrared Calibration
3.4 Thermal Infrared Band Calibration
AMSS Data Geolocation
Structure and Contents of AMSS level-1A Data

1. Introduction

The Airborne Multi-Spectral Scanner (AMSS) is a scanning spectrometer which flies on a Beechcraft-200 aircraft and provides spectral information similar to that which will be provided by the Global Imager (GLI) scheduled to be launched on the ADEOS-II platform in 1999.

The AMSS spectrometer acquires high spatial resolution imagery in the range of 0.40 to 12.45 microns. Total of 59 spectral bands are available in this range. AMSS Record and Processing System was configured for each mission to record a pre-selected group of 46 signal No. in 14-bit resolution.

The AMSS spectrometer is mated to a scanner sub-assembly which collects image data with an IFOV of 2.5 mrad, giving a ground resolution of 5 meters in 54 spectral bands and IFOV of 5.0 mrad, giving a ground resolution of 10 meters in 5 spectral bands from 2000 meters altitude , and a cross track scan width of +/- 40 degrees.

2. AMSS Instrument Summary

2.1 AMSS Specifications

(1) AMSS Instrument/Platform Specifications

Wavelength Range /Center Wavelength	Bandwidth	IFOV	SNR,NEDT, at 50% albedo, 300k
400 - 800 nm	10-30 nm (variable)	2.5*1.25 mrad	23000-500
800 - 890 nm	10-30 nm (variable)	2.5*1.25 mrad	6000-1300
890 - 1000 nm	10-30 nm (variable)	2.5*1.25 mrad	1200-100
1050 nm	20 nm	5.0 mrad	120
1240 nm	20 nm	5.0 mrad	80
1650 nm	200nm	5.0 mrad	420
2215 nm	270nm	5.0 mrad	80
3.715 nm	0.33um	5.0 mrad	0.15
7.5 um	0.5 um	2.5 mrad	0.15
8.30 um	0.5 um	2.5 mrad	0.11
10.85 um	1.0 um	2.5 mrad	0.07
11.95 um	1.0 um	2.5 mrad	0.08

(2) AMSS Instrument/Platform Specifications

System Parameters	Scanning Method	Conical Scan
	Scan Rate	41.6 Hz
	Swath angle	+/-40 deg
	Dispersion Method	0.4-1.0 micrometer: 2grating
	Dispersion Method	1.0-12 micrometer: filter
	Instrument Mass	200 Kg
	Instrument Size	846568533(mm)
Data Processing	Quantization	14 bit
	Recording Media	1 VLDS
	Data Rate	4 MByte/s
	Max. No. of bands to be recorded	46
Flight Parameters	Platform	Beechcraft-200 aircraft
	Flight Altitude	1000 - 8000 m
	Ground Speed	150 kt
Visible Calibration	Integrating sphere on the ground
Infrared Calibration	Two black bodies on board

2.2 AMSS Spectral Bands

AMSS has a capability of recording information of 46 No. in 50 visible and infrared spectral band regions at 12-bit resolution.
Offered below is the spectral band configuration for Sakata (96June), Fuji (96Aug) , Chiba (96Dec), Rikubetu (97Feb), Bihoro (97Feb)..
(All values are in microns)

Detecter No. Center of Wavelength Band Width

d1 405.3 5.5

d2 412.6 9.9

d3 425.2 8.6

d4 433.3 10

d5 442.3 9

d6 451.7 7

d7 463.2 8.8

d8 472.1 9.9

d9 481.1 9.4

d10 489.6 8.9

d11 510.5 7.8

d12 522.8 9.2

d13 531.5 9.5

d14 538.9 8.3

d15 545.4 9

d16 553.2 8.7

d17 561.3 7.8

d18 580.4 8.5

d19 587.2 8

d20 593.5 7.2

d21 615 11.8

d22 627.3 10.1

d23 636.2 10.5

d24 644.5 8.1

d25 651.2 9.5

d26

d27 675.7 8.9

d28

d29 693 10.2

d30 713 10.8

d31 721.4 9.7

d32 732.3 10.7

d33 740.6 9.7

d34 750 9.4

d35 757.7 9.5

d36

d37 773 10.2

d38

d39

d40

d41 668.1 9.3

d42 683.4 10.3

d43 765.6 10.6

d44 784.2 13.4

d45 800.9 12.6

d46 829.4 13.6

d47 848.1 20.6

d48 866 15.5

d49 900.3 19.3

d50 943.7 or 941.3 14.3

d51 1,050.8 16.1

d52 1,239.8 20.5

d53 1,631.8 217.5

d54 2,233 198.3

d55 3,716 0.34

d56 7,482 0.53

d57 8,246 0.56

d58 10,764 1.01

d59 11,959 1.08

The AMSS data system has a capacity of recording 46 spectral bands at 14-bit resolution. This required unique instrument configurations for each Field Experiment.

3. AMSS Data Calibration

3.1 Visible/Near-Infrared Band Calibration (Detector No. 1 - 51)

Calibration coefficients for the AMSS visible (- < 0.7 um) and near-infrared (0.7 um <- < 1.1 um) bands are derived from integrating spheres used pre and/or post flight The transformation from digital count to radiance is defined by

Radiance =Gain * (Count -Offset)

where,


     Radiance = computed radiance (W/m2/sr/um)

     Count = recorded count

     Gain = No. gaint, determined for each band

     Offset = Offset count, determined for each band

The radiance units are Watts per square meter per steradian per micron (W m-2 sr-1 um-1). Integrating sphere calibrations may be carried out once during a AMSS flight experiment.

3.2 Temperature Correction of Visible/Near-Infrared Bands

Not Conducted. Planned in next year Field Experiment. .

3.3 Near-Infrared Bands/Short Wave Infrared Calibration (Detector No. 52 - 54)

Calibration data for the AMSS infrared (IR) bands (1.1<- <3.7 um) are obtained used pre and/or post flight from blackbody sources under following conditions.

Detector No. 52: 450 degrees C
Detector No. 53: 350 degrees C
Detector No. 54: 200 degrees C

The equivalent Planck radiances for the blackbodies (assuming unit emissivity) are computed using a sensor weighted integral of the Planck function.
The transformation from digital count to radiance is defined by

Radiance =Gain * (Count -Offset)

where,


     Radiance = computed radiance (W/m2/sr/um)

     Count = recorded count

     Gain = No. gain, determined for each band

     Offset = Offset count, determined for each band

3.4 Thermal Infrared Band Calibration (Detector No. 55 - 59)

Calibration data for the AMSS infrared (IR) bands (- > 3.7 um) are obtained used pre and/or post flight from low temperature calibration blackbody sources. The calibration data is obtained using the second (warm) blackbody is maintained at a higher temperature of 0,10, 20, 30, 40, 50, 60, 70, and 75 degrees centigrade.

The transformation from digital count will be derived from recurrence formula using Calibration Table as follows.

temperature : 0,10, 20, 30, 40, 50, 60, 70,
digital count : D0, D10, D20, D30, D40, D50, D60, D70

4. AMSS Data Geolocation Data

Navigation data onboard the Beechcraft-200 is recorded by an FDS (GPS and Gyro). This FDS has a dedicated tape recorder, which is separate from the AMSS tape recorder.
This data was unpacked and formatted , and distributed as a separate file along with the AMSS data.
In the INS recording system, aircraft position and attitude were updated every 1 seconds.

1.	col. 2-8 (7 byte):	Internal Time (hh:mm:ss.d )
2.	col. 9-14 (6 byte):	GPS Time (hh:mm:ss.d )
3.	col. 15-21 (7 byte):	GPS Latitude (N/S, ddmm.mm)
4.	col. 22-29 (8 byte):	GPS Longitude (E/W, dddmm.mm)
5.	col. 30-30 (1 byte):	GPS Status(-: Normal, A: Not Recieving, 0: malfunction)
6.	col. 31-35 (5 byte):	Atmospheric Pressure Hight (+/-, m)
7.	col. 35-38 (3 byte):	Speed (km/sec)
8.	col. 39-39 (1 byte):	Rolling Direction (L: Left, R: Right Wing Downward)
9.	col. 40-42 (3 byte):	Rolling Angle (dd.d degrees)
A.	col. 43-43 (1 byte):	Pitching Direction (+: Head upward, -: Head Downwrd
B.	col. 44-46 (3 byte):	Pitching Angle (dd.d degrees)

4. Structure and Contents of AMSS LEVEL-1A Data

AMSS data in this CDROM are stored in Band interleaved format (BIL) and compressed by GNU tool of gzip.

AMSS line byte data size is :
2 (byte/pixel) * 1024 (pixel/line) * 46 (band)= 94,208 byte/line

data order is:

Line 1 (94,208 byte): (p1, r1),(p2,r1),(p3, r1),.....(p1024, r1),(p1,r2),(p2, r2),......(p1024, r46).
Line 12 (94,208 byte): (p1, r1),(p2,r1),(p3, r1),.....(p1024, r1),(p1,r2),(p2, r2),......(p1024, r46).
.......
Line n (94,208 byte): (p1, r1),(p2,r1),(p3, r1),.....(p1024, r1),(p1,r2),(p2, r2),......(p1024, r46).

where the symbol of r1, r2, ...., r46 is Record Sequence defined in Configulation Tabel in each directory and the symbol of p1, p2, ..., p46 is pixcel No.

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