Slide 1

Barcelona Forum on Ph.D.
Research in Communications,
Electronics and Signal
Processing
21st October 2010

On-ground tests and measurements
of the Passive Advanced Unit
Synthetic Aperture (PAU-SA)
Isaac Ramos Pérez, Thesis Advisor: Adriano José Camps
Carmona


Slide 2

Outline
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Introduction and objectives
PAU-SA’s concept
Work Plan
Potential improvements for future SMOS’s
PAU-SA’s processor
PAU-SA’s assembled process
Preliminary results
Conclusions

Barcelona Forum on Ph.D. Research in Communications, Electronics and Signal Processing 2v


Slide 3

Introduction and objectives
The SMOS mission:
o Retrieve global and frequent data of Soil Moisture and
Ocean Salinity
o New kind of spaceborne Y-shaped aperture synthesis
radiometer:
MIRAS (Microwave Imaging Radiometer
by Aperture Synthesis)

o ESA Earth Explorer, Scheduled for 2010

Objective:
o Test potential improvements for future MIRAS payloads
New instrument:
o Passive Advanced Unit - Synthetic Aperture (PAU-SA)
o Award EURYI 2004 by A. Camps / Patented
Barcelona Forum on Ph.D. Research in Communications, Electronics and Signal Processing 3v


Slide 4

PAU-SA concept
PAU-RAD

PAU-GNSS-R

PAU-IR
Th,v ( , sea surface roughness , S S T , S S S )

Barcelona Forum on Ph.D. Research in Communications, Electronics and Signal Processing 4v


Slide 5

Work Plan
Study
Potential
Improvements

(Software)
Simulator

(Mechanic)
Mobile Unit
(Truck)

(Electronic)
Device & test

Assemble

Full system’s
test

2006
2007
2008

2009
2010

Barcelona Forum on Ph.D. Research in Communications, Electronics and Signal Processing 5v


Slide 6

Potential improvements for future SMOS’s
Parameter

MIRAS/SMOS

Frequency operation

L-band (1400 - 1427 MHz)

Bandwidth
Arm size
Altitude

19 MHz
4m
Global observation, LEO, orbital altitude

Antenna type

Patch antenna with V & H polarizations
(not simultaneous)

Number of antennas per arm

23

8+1 (dummy)

Number total antennas

69
0.875 
at 1400 MHz,
(21 cm)
single polarization
(1 per element)

31
0.816  at
1575.42 MHz,
(15.5 cm)
dual polarization
(2 per element)

Antenna spacing

Receiver type
Topology of the LO downconverter

Distributed LO
(groups of 6 elements)

Quantization

1 bit IF sampling depending upon the noise
uptake level
(Inside the LICEF )

I/Q conversion

Analog

Frequency response shaped
by

Analog RF filter

Power measurement system
(PMS)
Calibration by Noise
Injection
Image capabilities

Analog, using classical methods (diode)
Injection of Distributed noise
Dual-pol or full-pol (sequential)

PAU-SA

Comments

L-band (1575.42 MHz)
L1 of GPS signal
2.2 MHz
1.3 m
ground-based
Patch antenna with V &
H polarization
(simultaneous)

Same frequency both Radiometry and
GPS Reflectrometry
Spatial correlation effects are
negligible
Full-pol
(non-sequential)
Improve G matrix condition
number

Increase the alias-free field of view
Full-pol
(non-sequential)

Centralized reference clock + internal
Reduce LO leakage and correlated
LO generated in each receiver
offset
Used both
8 bits IF sub-sampling using a external
digital I/Q demodulation (8 bits)
ADC
digital Power measurement (8 bits)
Mass reduction.
Digital
Elimination phase error
Mass reduction, quasi perfect
Digital low- pass filter
matching, no temperature and aging
drifts
Mass reduction,
Digital (FPGA)
No temperature drifts
Simple calibration.
Injection of Centralized noise PRN
Calibration of non-separable errors
Full-pol
Necessary to GNSS-R applications
(non-sequential)

Barcelona Forum on Ph.D. Research in Communications, Electronics and Signal Processing 6v


Slide 7

PAU-SA processor
Source panel

Simulation
Characterization

Processing window

Antenna panel

Barcelona Forum on Ph.D. Research in Communications, Electronics and Signal Processing 7v


Slide 8

PAU-SA’s assembled process

1.3 m
Structure AutoCAD design and implementation

Mobile Unit AutoCAD design and implementation
Barcelona Forum on Ph.D. Research in Communications, Electronics and Signal Processing 8v


Slide 9

PAU-SA’s assembled process
• PAU-SA in Assemble process
• Calibration and validation test

Master clock
and buffers for
clock distribution

ADCs + FPGA
(correlations and
power estimation)

PAU-SA instrument during integration process

Barcelona Forum on Ph.D. Research in Communications, Electronics and Signal Processing 9v


Slide 10

PAU-SA’s assembled process

2008

2010

2009

2010

2010

2010

1st Barcelona Forum on Ph.D. Research in Electronic Engineering 10


Slide 11

Preliminary results

Real data: Single baseline response

Measurements at UPC anechoic chamber

Normalized correlation (I and Q)
vs. number of samples

Minimum Allan’s variance for normalized
correlations (real and imaginary parts)
for 200 s

Power variance versus number
of samples

Minimum Allan’s variance for power at
15 s → visibilities desnormalization

Barcelona Forum on Ph.D. Research in Communications, Electronics and Signal Processing 11v


Slide 12

Preliminary results
PRN Signal

Az +/- 10º,

FFT

 3s

Rectangular filter

+/- 20º

El +/- 10º,
+/- 20º

Pol H Az= 0º El= 0º

Point Source : PRN or tone
Moving the Instrument
(without control temperature)

Pol H Az= +10º El= 0º

Pol V Az= 0º El= +10º

Pol H Az= +20º El= 0º

Pol V Az= 0º El= +20º

Barcelona Forum on Ph.D. Research in Communications, Electronics and Signal Processing 12v


Slide 13

Conclusions
Long Project with different tasks:
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RF/FI Hardware designer - Digital Hardware: FPGA /PICs
Analog Hardware
- Software programmer
(Simulator)
System Assembled and tested
Director 5 PFCs (Coordination)
TEAM work, collaboration with:
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GUTMAR (Mobile Unit) Project
Funcadió Eduard Soler (Mobile Unit) Mechanic
Student designers
PAU TEAM (brainstorm meetings )
Several UPC personal

Barcelona Forum on Ph.D. Research in Communications, Electronics and Signal Processing 13v


Slide 14

Thank you for your attention

Barcelona Forum on Ph.D. Research in Communications, Electronics and Signal Processing 14v