X C E L L E N C E I N S C I E N T I F I C A P P L I C AT I O N S
The 16 serial output links from the FPGA are grouped into four sets of four lanes, each with XAUI frame encoding. This passes to a Netlogic XAUI transceiver device onboard the digital receiver card that reserializes the four input streams to a 10.51875-
Gbps 64b/66b encoded output serial stream (Fibre Channel line rate). The four 10G transceivers drive four Finisar SFP+ optical transceivers. Each antenna has 192 (48 digitizers/antenna x 4 fibers/digitizer) singlemode fibers connecting to the central
Figure 3 – The digital receiver card samples, filters and transmits PAF receptor data to the central processing site.
site, for a total data rate of 2 Tbps. The fiber spans vary from hundreds of meters for the closest antennas up to 8 km for the farthest. BEAMFORMER DATA ROUTING Two key components of the data-routing and distribution architecture are the Vitesse 6.5-Gbps 72 x 72 crosspoint switch and the industry-standard Advanced Telecommunications Computing Architecture (ATCA) backplane. Together, these components make it possible to route individual 3.1875-Gbps serial data streams from the digital receivers directly to the appropriate beamformer card for further processing. We use discrete ROSA (receiver optical subassembly) devices to convert the 10-Gbps optical data signals from the antennas back to electrical signals, then deserialize them to four 3.1875-Gbps signals via the same XAUI transceiver device used on the digital receiver. This circuitry resides on the ATCA rear transition module, with each RTM designed to accept 12 x 10Gbps data streams. The ATCA backplane supports up to 16 cards, each with four duplex 3-Gbps data links to every other card, meaning
XC6VLX130T -1FF1156
XC6VLX240T -1FF1156 3Gbps
3Gbps
Digital Receiver FPGAs
XAUI
SFP+
Optical Fiber 10Gbps
ROSA
XAUI
Crosspoint Switch
ATCA Backplane
Beamformer FPGAs
3Gbps
ATCA RTM Board
ATCA Front Board
Figure 4 – Each antenna passes 2 Tbps of data to the beamformer, which distributes it using an ATCA backplane.
Second Quarter 2011
Xcell Journal
33