post-correlation interference mitigation
DESCRIPTION
Post-Correlation Interference Mitigation. M. Kesteven & R. Sault Australia Telescope National Facility [email protected]. IUCAF – Bonn, March, 2001. Post-Correlation RFI excision. Overview of the scheme Application 1 - Single Dish Application 2 - Synthesis Array Problems/Limitations - PowerPoint PPT PresentationTRANSCRIPT
Post-Correlation Interference Mitigation
M. Kesteven & R. Sault
Australia Telescope National Facility [email protected]
IUCAF – Bonn, March, 2001
Post-Correlation RFI excision
Overview of the scheme Application 1 - Single Dish Application 2 - Synthesis Array Problems/Limitations Comparison with Adaptive Filters Parametric Filter - Glonass excision
Features
A Post-Correlation equivalent to an Adaptive Filter Applicable to Single Dish observations Applicable to Synthesis Array observations Performance comparable to the Adaptive Filter Can be implemented with current hardware
Adaptive Filter (schematic)
Post-Correlation Filter
Reference antenna
Parkes 64m
Single Dish - Autocorrelation
The Reference Antenna
Post-Correlation - Features
Tolerant to small number of sampler bits Tolerant to multi-pathing interference Tolerant to significant delays between the reference
and the astronomy antenna Tolerant to offset between the array tracking centre
and the interference location Only one reference antenna required even for an array
filter
Post-Correlation Filter
Before and after spectra
ATCA - 1503 MHz; 4 MHz BW
Before and after images
ARRAY - notes
Require one Reference Antenna + conversion chain Require Additional Correlator resources. Equivalent to
adding one extra antenna to the array. Enjoys all the flexibility of the observatory correlator Makes no assumption as to similarity between antennas
of the array. Interference may enter via different sidelobes in different antennas.
The corrections are based on the correlator output – therefore works with few-bit samplers.
Glonass Excision
Glonass Excision
Glonass excision
Post-Correlation - Theory
),(),(
),(),(),(
tfgtfV
VtfItfgtfV
rref
skyrfiaast
The correction spectrum Vc(f) is given by:
),(
),(),( *
RRvis
RBvisRAvisVc
dttfIfgdttfItfg
dttfVtfVt
RAvis rAa
),()(~ ),(),( Requires
),(.),(1
),(
: where
*
Post-Correlation Filter
OK is pathing-multibut ... (f)any in interferer oneonly
coupling; theofn descriptio adequatean is g(f) closure... -
... {g} yingslowly var -
:requires This
)f(I)f(g~)f(I)f(g
)R,R(Cross
)R,B(Cross).R,A(Cross)f(Corr
)f(I)f(g)f(V
)f,(V)f(I)f(g)f(V
*yx
*yxxx
RR
A,skyAA
Synthesis Array Filtering
Synthesis Array Filtering
Cleaned spectrum