Download Packetized Broadband Correlator

Packetized Broadband Correlator
ASIAA, Institute of Astronomy and
Astrophysics, Academia Sinica
Taiwan
Homin Jiang
Mini CASPER Taiwan
Workshop 2011, Taipei
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Contents
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Concept of Packetized Correlator
F Engine
X Engine
System Backend: Initialization, transmission,
receiver
SMA Specification
Proof of Concept : Phase 1
Proof of Concept : Phase 2
Discussion
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Correlator for Array
• Many baselines.
• 2 ways. – backplane bus (typical) or
packetized
• transmission thru high speed network.
• ALMA, SMA -- backplane solution.
• PCI , ISA, or other standard buses.
• Resources concerned. ALMA solution or
Japanese Solution.
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Packetized Correlator Concept
Or by regular
Ethernet to every
ROACH board
Jason Manly
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F Engine Inside
Coarse
Delay
PFB
FFT
Fringe
Rotate
Corner
Turn
Pketize
Quantiz
Reorder
X
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F Engine Inside
Coarse
Delay
PFB
FFT
Fringe
Rotate
Quantiz
Corner
Turn
Pketize
X
Reorder
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F Engine Inside
Coarse
Delay
PFB
FFT
Fringe
Rotate
Corner
Turn
Pketize
Quantiz
Reorder
X
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X Engine Inside
F
DePack
Buffer
X
Accum
Borph
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X Engine Inside
F
DePack
Buffer
X
Accum
Borph
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System Backend : System Schematic
Init
ROACH
PowerPC
Linux
BORPH
FPGA
Start Rx
Display
ROACH Server
Computer
ROACH 2
Start Tx
ROACH n
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System Backend
Init
Start Tx
Start Rx
Display
• Software registers on ROACH FPGA addressable by
BORPH on ROACH’s Power PC embedded Linux system.
• Automated Python scripts for writing these registers.
• “start TX” command begins dumping the data in shared
BRAM of Xengine or Xvacc on separate UDP port or 10G
port.
• Receiver collects UDP packets, buffers and saves to disk.
• Multiple files generated for storage,display and debugging.
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System Backend: Init
Init
Start Tx
Start Rx
Display
• Python script run on server computer.
• Program the specified bof file one by one on separate UDP
port.
• Tests F and X engine one Roach by one Roach.
• Allows programming of any software register on the Roach
FPGA by name.
• Program the gains, accumulation, FFT shift schedule,
equalization, etc.
• Checking the timing, synchronization etc.
• Checking the UDP, 10G communication.
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System Backend: Transmit
Init
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Start Tx
Start Rx
Display
Python script run on ROACH/Linux.
Reads out data in X engine or X vacc BRAMs when full.
Data is enclosed in a timestamped packet.
Transmitted via UDP packet to server computer.
Can go thru Ethernet or 10GbE port.
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System Backend: Receiver
Init
Start Tx
Start Rx
Display
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Python script run on server computer.
Receives packets, decodes header and appends to buffer.
If header out of order, dumps as invalid.
Generates 4 files: Miriad UV, info files(n_chans, integration
length, gain etc), plot of last integration, raw data file.
• Creates HDF5 file format. “is a data model, library, and file
format for storing and managing data. It supports an
unlimited variety of datatypes, and is designed for flexible
and efficient I/O and for high volume and complex data.”
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System Backend: Display
Init
Start Tx
Start Rx
Display
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Draft Spec. of Broadband SMA Corr.
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Bandwidth : 18 GHz
Polarizations : 2
No. of Antenna : 8
Channel Resolution: 32768 channels over
the full band :500KHz spectral resolution.
FX configuration preferred
Zoom in function
ADC >= 10Gsps preferred
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Proof of Concept SMA Broaddband Correlator-phase 0
iADC 1 Gsps ADC , 8 bits
0.5 GHz
ROACH
F Engine
0.5 GHz
ROACH
F Engine
ROACH
10 GE
Switch
64 ports
X Engine
ROACH
X Engine
Ethernet
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Proof of Concept SMA Broaddband Correlator-phase 1
iADC 1 Gsps ADC , 8 bits
0.5 GHz
ROACH
0.5 GHz
F Engine
0.5 GHz
ROACH
0.5 GHz
F Engine
ROACH
10 GE
Switch
64 ports
X Engine
ROACH
X Engine
Ethernet
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Proof of Concept SMA Broadband Correlator-phase 2
5G ADC, 5 Gsps ADC , 4 bits dmux 1:8,
one polarization
2 GHz
Decimation after
PFB
ROACH
2 GHz
F Engine
2 GHz
ROACH
2 GHz
F Engine
ROACH
10 GE
Switch
64 ports
X Engine
ROACH
X Engine
Ethernet
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Discussion
• How to fit the 8x18GHz bandwidth in ROACH2 or
ROACH3 ?
• 5G ADC is not wide enough.
• 10 G Ethernet transmission would be a bottom neck ?
• The team keeps searching for higher data rate ADC.
The IF will be complicated and expensive with 5G
adc.
• Decimation after PFB ? What is the drawback of
decimation ?
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