the cvn real time correlator zhang xiuzhong, chen zhong shanghai astronomical observatory china
DESCRIPTION
The CVN Real Time Correlator Zhang Xiuzhong, Chen Zhong Shanghai Astronomical Observatory China 4th e-VLBI Workshop Sydney 2005.7. Outline : VLBI Stations in China The 5 station Real Time Correlator Some results of Real Time Correlator Mark5 connection The Future plan. - PowerPoint PPT PresentationTRANSCRIPT
The CVN Real Time Correlator
Zhang Xiuzhong, Chen Zhong
Shanghai Astronomical Observatory China4th e-VLBI Workshop
Sydney 2005.7
Outline :
VLBI Stations in China
The 5 station Real Time Correlator
Some results of Real Time Correlator
Mark5 connection
The Future plan
VLBI Stations in China
1 Gbps from station to Urmuqi
New station - 2006
A New Correlator
2006New station - 2006
Fiber in late 2005 – plan 1 Gbps
Main Specification of Chinese VLBI stations
Name Location Antenna diameter
(m)
Band
(GHz)
VLBI
Terminal
Network Connect
(Data Rate)
Available
Sheshan Near Shanghai
25 0.3, 1.6, 2.3, 5.0, 8.4, 22
VLBA, MKIV,S2,
MKV
No (1) 1987
Nanshan Near Urumqi
25 0.3, 1.6, 2.3, 5.0, 8.4, 22
MKIV, K4, MKV
2Mbps (2) 1994
Mobile VLBI
Kunming 3 2.3, 8.4 S2, MKIV 2Mbps (2) 1999
Kunming Kunming 40 2.3, 8.4 MKIV, MKV 2Mbps (2) 2006
Miyun Near Beijing
50 2.3, 8.4 MKIV, MKV No (2) 2006
(1) 100Mbps data rate network connect will be created before end of 2005
(2) 10Mbps data rate network connect will be upgrade before end of 2006
Nanshan (Urumqi) at sunrise
Seshan (Shanghai)
Main Characteristics :
1. 5 Stations
2. date rate: 0 - 256Msamples/s, 1 or 2 bits/sample
3. IFs: 8. (16 MHz / IF, may be expanded to 0.5GHz/IF)
4. Integration Time: 10 ms – 2 hours
5. data format: VLBA、MKIII、MKIV 、 VSI
6. data source : Disk Array, Network
7. Functions: Fringe searcher, Phase Cal
8. Output: via net and disk files ( in FITS format)
CVN Real Time Correlator
Architecture of Correlator(Chinese Lunar Project)
MKV
MKV
MKV
MKV
MKV
PBD
PBD
PBD
PBD
PBD
PBI
PBI
PBI
PBI
PBI
FFT &
MAC
LTA(PC)
CCC(PC with 32 users RS232)
MCCSystem Clock, Start/Stop control
Cal Fringe & FSTC
PCAL
net
net
net
net
netRS232
RS232
RS232
RS232
7300A
7300A
7300A
7300A
7300A
7300A/RS232
5 Station8Ch
7300A
BENEFITS:
Fringe Finder
Phase Calibration
10Mbps data streamfrom network
256Mpbs data stream from Disk Array
Hard Disk Array Storage
RS232
2Bit,8Ch
RS232
Data Stream & PBI
PC/AD7300AMKV
MKV
MKV
MKV
MKV PC/AD7300A
PC/AD7300A
PC/AD7300A
PC/AD7300A
Ch0 ~ Ch8
32 Tracks
32 Tracks32 Tracks32 Tracks
32 Tracks
32 Tracks
32 Tracks
PBI&
CROSS STITCH
Control Unit RS232
CLK
Delay Control
Delay Control
Delay Control
Delay Control
Delay Control
NET
NET
NET
NET
NET
Diagram of PBIDISK
ARRAYFIFO IN
CROSS SWITCH
FIFO OUT64 bits deep
FAN OUT1:4, 1:2, 1:11 or 2 bits
PARITY & CRC Check
IRQCLK
DATATrack data
DATA
Valid IF data
Ready
IF data
Clock
MCU 131ms TIC
RS232
New Frame
EN_SYNC
IRQ = FIFO_IN_not_FULLReady = FIFO_OUT_not_empty * data_validy *SyncSync = New Frame * EN_Sync
FFT Module
Two Parameter 40-Bit Fixed PT Model
Generator/Sample rate
Two Parameter 20-Bit Fixed PT Model
Generator/Sample rate
20-Bit Ramp Generator/62.5ns
Fringe Stopping
16Bit/Sample
FFT16 Bit fix-point
1024 point
FSTCFractinalSampleTime
Correction
Delay Model
Data from PBI1~2Bit/ch5 Stations
WindowFunction
MAC
The Advantages• The correlator has fringe searcher and P-cal access function.
• The PC-based disk array(CVNHD) will be used as the playback system for correlator. There are maximal 4GB memory should be mounted in these PCs. The 4GB memory could take on a huge FIFO, to smooth the data stream from disk array and from network. The commercial PC board AD7300A is used in these PCs, as a high data rate interface between PC memory and playback interface. The data rate of interface is 10Mbps for real time correlation and 256Mbps for post correlation. The data streams are controled by playback interface.
• The FFT and MAC logics of one channel of 5 stations could be configured in one FPGA chip. Compared with old hardware correlator, this design could reduce many connect cables and will increase the system reliability.
Virtex-II FPGA chips
PBD(CVNHD)
Some Results of Real Time Correlator
The Fringe of the SH-UR
Baseline TC-1 observation with
Integration time of 4 seconds
The Fringe of the SH-UR
Baseline TC-1 observation
with Integration time of
62.5 ms
MKV Connection
• Transfer Mode :MKV to PBD transfer through network MKV command : disk2net, in2net Net protocol : tcp/udp, tcp prefered
• PBD(CVNHD) Command : net2mem, mem2card Net protocol : tcp/udp, tcp prefered
MARK5A CVNHD
Network 10M/100Mbps
TCP/UDP
7300A
PBI
Transfer mode in Low rate Network Connection
• Mark5A Disk FIFO Mode(Need more tests)
A special ‘disk-FIFO’ mode use a Mark 5 scratch disk pack as the FIFO buffer in the case network transfer rates are slow. It is suitable for the low network transfer rate (10Mbps) for chinese Lunar Project .
• Make data in FIFO Disk Pack usable for playback after experiments is to be done in the future.
MKV – PBD – Correlator
Formater
SS Disk
I/O Board
Mark5A
AD 7300A Card
Disk2net
In2net
PBD
CVNHD
Correlator
Mark5A to PBD Transfer Through Network
Shared Memory
PBD Data Flow
Initial shared memory
Initial a socket to Mark5A
Save socket data to shared memory
Initial 7300A Card
Output data stored in shared memory to 7300A
Net2mem Mem2card
Shared Memory
Buffer[i] Empty?
Initial shared memory
Buffer[i] Full?
Yes Yes
Buffer[i+1] Buffer[i+1]
Waiting Singal Waiting Singal
No No
Test Results
• MK5 – PBD in 100Mbps network
Network transfer rate>50Mbps
peak rate~100Mbps
• MK5 – PBD – 7300A –PBI
A/D 7300A : TRIG_DO_CLK_10M_ACK, 32bits
Average speed 250kbps, controled by PBI
The Future plan
1. MKV connection via network
2. Network creation
3. System auto-operation software
developement
The network connect
Urumuqi
Kunming
Miyun
SheShan
City Network Connect
Real Time Corellator100Mbps/1G
35KM firbe Data Process Center in SHAO
Thank you