BNL, Upton, New York, USA
ORNL, Oak Ridge, Tennessee, USA
ORNL RAD, Oak Ridge, Tennessee, USA
Detector events at User Facilities require real-time fast transport of large data sets. Since construction, the SNS user facility successfully transported data using an in-house solution based on Channel Link LVDS point-to-point data protocol. Data transport solutions developed more recently have higher speed and more robustness; however, the significant hardware infrastructure investment limits migration to them. Compared to newer solutions the existing SNS LVDS data transport uses only parity error detection and LVDS frame error detection. The used channel link is DC coupled, and thus sensitive to noise from the electrical environment since it is difficult to maintain the same LVDS common reference potential over an extensive system of electronic boards in detector array networks. The SNS existing Channel Link* uses LVDS for data transport with clock of about 40 MHz and a mixture of parallel and serial data transport. The 7 bits per twisted pair in each clock cycle are transported over three pairs of Cat7 cable. The maximum data rate is about 840 Mbps per cat7 cable. The DS90CR217 or DS90CR218 and SN65LVDS32BD components are used with shielded Cat7 cabling in transporting LVDS data. Here we discuss noise mitigation methods to improve data transport within the existing as build infrastructure. We consider the role of shielding, ground loops, as well as specifically the use of toric ferrite insolation transformer for rf noise filtering.
* K. Vodopivec et al., "High Throughput Data Acquisition with EPICS", 16th ICALEPCS, 2017, Barcelona Spain, doi: 10.18429/JACoW-ICALEPCS2017-TUBPA05
