IM and WS Mode Level 1 Product quality update

Page 1ASAR Validation Review - ESRIN – 11-12 December 2002

IM and WS Mode Level 1 Product quality

updateIntroductionIM Mode OptimisationUpdated IMS product quality (VV & HH)Updated IMP product quality (VV & HH)Updated IMM product quality (VV & HH)Updated WSM product quality (VV & HH)Conclusions

B. RosichESA/ESRIN


IM Mode products characterised and preliminary calibrated at the ECR (September) for VV polarisation.

IM Mode optimisation peformed in October requires a revision of the product quality. Characterisation of HH polarisation also needed.

Very prelimianry verification of WSM products at the ECR for VV polsarisation. An additional change in the mode requires revision of product quality. Characterisation of HH polarisation also needed.

Introduction


IM Mode Optimisation

IM mode optimisation at instrument level- Increase the Tx. Chirp BW to 16 MHz for all swaths (17-10-02):

IM mode optimisation at processing level- Depends on product type

old BW [MHz] new BW [MHz]SS1 16 16SS2 16 16SS3 12.67 16SS4 10.79 16SS5 9.53 16SS6 8.84 16SS7 8.21 16


ASAR IMS Product charateristics

Slant range, single look complex image.

Single polarisation VV or HH. Multiple incidence angles (IS1 to IS7). Coverage from 100 Km to 56 km

Natural pixel spacing in range and azimuth. Azimuth resolution from 4 m to 5 m. Range resolution from 9 m to 18 m due to decreasing chirp bandwidth.

Elevation antenna pattern correction not applied. Range spreading loss correction not applied.

Hamming window with a=0.75 applied in azimuth and range

Processing algorithm: Range Doppler. Phase preserving.

1751, IS1


Change of processing settings & products characteristics for IMS

productsRange Processing: Full BW processed for all beams. Constant slant

range resolution from IS1 to IS7.

IMS slant range res. VV

8101214161820

1 2 3 4 5 6 7 8 9 10 11 12 13

m

IS1

IS2

IS3

IS4

IS5

IS6

IS7

IMS Slant range res. New BW. VV & HH

8.5

9

9.5

10

10.5

1 3 5 7 9 11 13 15

m

IS1...IS7

Change in quality requirements for IMS products.


Azimuth processing: No changes.

Gain settings: No changes. Complete Tx. BW used before/after the BW change. No changes in the processor gain. Same K as for data acquired before the BW change.

IMS Rel RCS (K=45.6 dB). New BW

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

0 2 4 6 8 10 12

dB new BW VV

new BW HH

IMS Absolute Calibration update


PF-

ASAR

version 3.01 & 3.02 3.03 3.01 & 3.02 3.03

IMS

OK

(Nominal quality)

OK

(Nominal quality)

OK

(Higher Rg.res)

OK

(Higher Rg.res)

Data Acquired After 17- Oct. 2002Data Acquired Between 5- Sept. & 17- Oct. 2002

IMS Product quality vs. time &

vs. PF-ASAR version


Visible az. Ambigities for HH products

- Distributed target ambig. ratio: -25.5 dB (IS5), -24 (IS4)

Point target ambiguity ratio: ~-26 dB

IMS HH Ambiguities

Ambiguity ratio requirement is –25 dB. Migth be too high for HH products over low backscattering areas.


Properties of IMP Products• Ground range detected imagery• Single polarisation (VV or HH)• Elevation antenna pattern and range

spreading loss corrections applied• Size of up to 150Mbytes with 2 byte

(16bit) amplitude pixel values• Swath widths of 100 km (IS1) to 56 km

(IS7) with azimuth extents of ~100 km• Azimuth resolution of 20.7m (4 looks of

320 Hz)• Range resolution from 21m (IS2 far

range) to 37m (IS1 near range) and ~26m for IS3 to IS7

• 12.5m by 12.5m pixels


Change of processing settings & product characteristics for IMP products

Range Processing: - Range look BW: same as before, i.e. same range resolution- Number of range looks: same as before (1). Increase in noise level

expected for the higher inc. ang. beams.

Azimuth processing:- No changes. Same number of looks (4) and same look BW.

Gain settings: - Gain adjusted to compensate the fact that the full Tx. BW is only

partially processed.- Same K as for data acquired before the BW change.


Rg.Res. - IMP new Tx.Chirp BW, VV & HH

20222426283032343638

14 19 24 29 34 39 44inc.angle [deg[

rg.r

es.

[m

]

IS1

IS4

IS5

IS6

IS7

IS1 theor.

IS4 theor.

IS5 theor.

IS6 theor.

IS7 theor.

IMP Range resolutionMeasurements demonstrate that there is no change in range resolution and values are well within the requirements for VV & HH


K - IMP new BW VV & HH

54.6

54.8

55

55.2

55.4

55.6

55.8

56

56.2

0 1 2 3 4 5 6No. of measurements

K [

dB]

IS1 VV

IS4 HH

IS5 HH

IS5 VV

IS6 VV

IS7 VV

Mean K 55.3 dBK standard dev. 0.33 dB

IMP Absolute CalibrationMeasurements demonstrate that the same absolute calibration factor applies for data acquired before and after the BW change.

Mean K 55.3 dBK stdandard dev. 0.31 dB


Az. Res. IMP VV & HH

21

21.5

22

22.5

23

0 5 10 15 20No.of measurements

az.

res.

[m

]

ISLR IMP VV & HH

-15

-14

-13

-12

-11

-10

0 5 10 15 20No. of measurements

ISL

R [

dB

]

PSLR IMP VV & HH

-20

-18

-16

-14

-12

0 5 10 15 20No. of measurements

PS

LR

[d

B]

IMP Azimuth resolution, ISLR, PSLR

- Values are within the requirements- High PSLR observed however in few cases


IMP Product quality vs. time &

vs. PF-ASAR version

PF-

ASAR

version 3.01 & 3.02 3.03 3.01 & 3.02 3.03

IMP/ IMG

OK

(Nominal quality)

Degraded Rg. Res.

but acceptable quality (IS3

to IS7)

Higher Rg. Res.

(for IS3 to IS7,

e.g.13.3 m for IS7!!)

OK

(Nominal quality)

Data Acquired Between 5- Sept. & 17- Oct. 2002 Data Acquired After 17- Oct. 2002


3354, IS5, 2 looks3354, IS5, 4 looksClear Az. Ambiguities on HH products, over low backscattering areas. Amb.ratio: -25.8 (IS5) -21.1 (IS4)

Processing only 2 looks in az.: Amb.ratio: -28 dB (IS5)

IMP HH Az. Ambiguities


IMM Product Characteristics• Ground range projected detected products• Nominal resolution < 150 m . Pixel spacing 75 m• 8 looks in azimuth, 4 looks in range. ENL > 30• Antenna pattern and range spreading loss correction applied• Data output as unsigned 16 bit• Systematic stripline processing: products as long as the complete

acquisition segment• Innovative ground range projection to keep constant incidence angle

at the center of the product (common to all stripline products)


Range Processing: - Range look BW: same as before, i.e. same range resolution- Number of range looks: 10 (5 before). ENL increase expected.- Look overlap different for different beams. Different ENL

expected.

Change of processing settings & products characteristics for IMM products

Swath rg.look BW [MHz] tot.orig.BW [MHz] tot. BW [MHz] % Overlap (10 looks)IS1 3.63 16 16 62IS2 3.02 16 16 52IS3 2.43 12.67 16 38IS4 2.11 10.79 16 27IS5 1.92 9.53 16 19IS6 1.78 8.84 16 11IS7 1.69 8.21 16 6

Azimuth processing:- No changes. Same number of looks (8) and same look BW.


BEAM

ENL before Chirp BW

change

ENL after Chirp BW

change

IS1 27 35IS2 30 NAIS3 28 NAIS4 31 70IS5 32 70IS6 34 NAIS7 27 80

IMM ENL• Measurements not available yet for all

swaths.

• No changes expected for IS1 and IS2.

•For the beams with very small look overlap, values up to 80 looks are achieved

• Initial requirement for IMM ENL was 30 looks.

• Only negative impact is throughputChange in quality requirements needed.


IMM new BW rg.res. VV & HH

120.000

130.000

140.000

150.000

160.000

170.000

15.00 20.00 25.00 30.00 35.00 40.00 45.00

inc.angle [deg]

reso

luti

on

[m

]

IS1 th.

IS4 th.

IS5 th.

IS6 th.

IS7 th

IS1

IS4

IS5

IS6

IS7

Range & Azimuth Resolution match expected theoretical values for all beams

Theoretical values ranging from 107 m (far range IS1) to 160 m (near range IS1)

IMM Spatial Resolution

IMM new Chirp BW, Az. res. , VV & HH

140

142

144

146

148

150

152

0 1 2 3 4 5

No of measurementsa

z.re

s. [

m] IS1

IS4

IS5

IS6

IS7

Theor.res.

c


K - IMM orig. BW, VV

66

68

70

72

74

76

0 5 10 15No of Measurements

dB

IS1

IS2

IS3

IS4

IS5

IS6

IS7

Mean K [dB] 70.22K standard dev.[dB] 0.33

K - IMM new BW, VV & HH

66

67

68

69

70

71

0 1 2 3 4

No of measurements

dB

IS1

IS4

IS5

IS6

IS7

Mean K [dB] 67.5K standard dev [dB] 0.56

Change of K between products with original Tx. Chirp BW and products with new full TX. Chirp BW.

IMM Absolute calibrationNo changes in processing gain. Changes in product level expected between data acquired before/after the BW change.


PF-

ASAR

version 3.01 & 3.02 3.03 3.01 & 3.02 3.03

IMM

OK

(Nominal quality)

OK

(Nominal quality)

OK

(Nominal quality, dif.K)

OK

(Higher ENL, dif.K)

Data Acquired Between 5- Sept. & 17- Oct. 2002 Data Acquired After 17- Oct. 2002

IMM Product quality vs. time &

vs. PF-ASAR version


Visible Az. Ambiguities for HH products:

• Distributed target ambig. ratio: ~-20 dB

3354 ,IS5, HH 3397,IS4, HH

IMM HH Az. Ambiguities

3354 ,IS5, HH, 4 looks

IMM reprocessing using 4 rather than 8 looks in azimuth:

• Amb. Ratio: - 24.5 dB


WSM Product characteristics

• Ground range projected detected products

• Nominal resolution < 150 m

• Swath width: 406 Km

• Pixel spacing 75 m

• ENL > 12 for all the different subswaths

• Antenna pattern and range spreading loss correction applied

• Data output as unsigned 16 bit

• Systematic stripline processing: products as long as the complete acquisition segment


Initial instrument settings (till 13-08-02) Tx.Chirp BW:

Mode timeline (pulses per burst): SS1-SS5: 50, 80, 67, 87, 74

Initial processing/product settings (version < 3.01): Rg. Look BW:

Number of range looks: 3

•Result: - Range resolution ~ 150 m and Azimimuth resolution ~90 m

- ENL: below the requirements (12) -> from 8 for SS1 to 6 for SS5

SS1 SS2 SS3 SS4 SS5range look BW [MHz] 2.66 2.05 1.77 1.61 1.5

SS1 SS2 SS3 SS4 SS5Original BW [MHz] 7.15 5.33 4.39 3.01 2.82

WSM Initial product quality


First mode optimisation at instrument level (13-08-02): IncreaseTx.Chirp BW:

SS1 SS2 SS3 SS4 SS514.75 12.86 10.48 9.54 8.78(x2) (x2.4) (x2.4) (x3) (x3)

New BW [MHz]

First WSM optimisation (I)

SS1 SS2 SS3 SS4 SS5range look BW [MHz] 2.66 2.05 1.77 1.61 1.5

New processing/product settings (version >= 3.01):Rg. Look BW:

Number of range looks: 7


Result:• Range resolution: ~ 120 m

• Azimimuth resolution: ~90 m -> High undersampling & not-square resolution

• ENL: higher than initial spec (12)

•Inter-burst ambiguities (~-21 dB) detected in high contrast scenes (already present before the BW change)

SS1 15.3SS2 15.8SS3 16.2SS4 16.1SS5 16.5

First WSM optimisation (II)


WSM 2703

Second WS mode optimisation at instrument level (30-10-02)Change of mode timeline (expect SS1):

SS1-SS5: 50, 65, 55, 71, 60

New processing settings: None. Only AUX data updated

Second WSM optimisation

Result: Removal of inter-burst ambiguities Increase of Az. Res.


WSM rg.resolution VV & HH

90

100

110

120

130

140

150

14 24 34 44

inc. anglr [deg]

rg.

res.

[m

]

SS1

SS2

SS3

SS4

SS5

WSM Az. res. VV & HH

80

90

100

110

120

3100 3300 3500 3700 3900

orbit number

az

. re

s. [

m]

Az. Res

Az.res (orig.)

WSM Final products resolution

• Nominal products are still undersampled: 1.2 in range, 1.4 in azimuth.• Resolution is almost square. Could be adjusted to be more similar in both directions.• IRF measurements performed on oversampled products of 40x40 m.


K: WSM final settings (VV & HH)

67

67.5

68

68.5

69

69.5

70

3100 3300 3500 3700 3900orbit

K [d

B]

K (HH)

K (VV)

HH VV AllMean K [dB] 68.85 68.95 68.88K Std.dev. [dB] 0.59 0.33 0.50

K (VV) from rain forest: 69.08 dB

WSM Absolute calibration update


Noise level for SS1 expected to be higher than for the other swaths.

Measured values for final settings: SS1: ~-22 dBSS2-SS5: ~-24,-25 dB

The difference in noise level between SS1 and SS2 is clearly visible in the images.

SS1 SS2

WSM Noise Equivalent 0


IM mode BW increase has resulted in an improved IMS and IMM product quality and will increase the IM InSAR performance. Products quality shall be now stable.

The BW increase shall be almost transparent for IMP products. Quality could be improved with multi-look in range.

WSM optimizations provide very good product quality. Products should be now stable.

Quality results for HH polarisation are equivalent to those for VV polarisation.

Conclusions

Documents

IM and WS Mode Level 1 Product quality update