electronics to be located within sensor pods 218 because the length and number of wires within each cable assembly 222 is relatively small the signal loss and required cable diameter is low enough to allow communication between sensor pods 218 and hub 212 at a level of reliability and quality not commonly associated with downhole analog signals in contrast digital communication is preferred for the link from hub 212 to the surface because of its reliability over long lengths and potential for high speed data transmission each hub 212 receives data from sensor pods 218 of upper 214 and lower 216 branches and encodes the data for communication with the surface additionally hubs 212 may also include sensors that are not contained in sensor pods 218 the types of sensors that are located within data hubs 212 typically either require complex electronics to operate do not need frequent measurements or are too expensive to place in every sensor pod 218 once data is collected in hubs 212 it is sent to the surface by a high speed communication link contained within conduit 220 where reservoir engineers are able to extrapolate information that they need additionally it is preferred but not required that every hub 212 have a fault isolator installed so that in the event of a failure of a hub 212 the remaining hubs on the circuit are not disabled an.