1. Data transport architecture over fiber and/or copper
Francesco Simeone
INFN Sez. Roma

2. Detection Unit interface with the Optical Network…
Tower 1
Tower 5
2 fibers redundancy can be implemented at connector level
PJB
SJB 1
2 fibers allow 100% redundancy
MEOC …
SJB 18
Slow control data sent to the DUs connected to the SJB as broadcast.
Data from each DU is sent to the SJB over a different fiber using a specific color.

3. Data Transmission (1/3): Tower Backbone
Backbone architecture: optical daisy chain
“waterfall” scheme (1 B&W transceiver per node);
data rate 1.25 Gb/s (easily expandable up to 2.5 Gb/s);
accommodates up to 6 PMTs and 2 hydros per storey
high optical power budget allows cheaper connectors;
nodes are connected by backbone branches
optical and electrical branches are separated;
PRO: improved system reliability, lower cable complexity, shorter manufacture time and assembly time. 3

4. Data Transmission (1/3): Tower Backbone
Backbone architecture: optical daisy chain
“waterfall” scheme (1 B&W transceiver per node);
data rate 1.25 Gb/s (easily expandable up to 2.5 Gb/s);
accommodates up to 6 PMTs and 2 hydros per storey
high optical power budget allows cheaper connectors;
nodes are connected by backbone branches
optical and electrical branches are separated;
PRO: improved system reliability, lower cable complexity, shorter manufacture time and assembly time.
F19
F17
F15 F3 F1
F20
F18
F16 F4 F0 F2
B&W
BackBone
1 Fiber
1 color per direction 4

5. Data Transmission (2/3): BackBone Bypass
Faulty nodes can be bypassed:
use a splitter per node (10:90 ratio);
use an active switch per node (controlled by the independent power control system);
allowed by the high optical power budget available at each hop;
bypass optical loss: pass 1.1 dB and tap 10 dB;
total worst case loss 11 dB (10 nodes failure case);
transceivers with about 15 dB power link budget can be used (wide availability)
Low power transceivers electronics: <1W per floor 5

6. Data Transmission (3/3): the copper daisy chain
Copper daisy chain architecture:
stringent limitations between cable length and max data flux;
double daisy chain:
one going up, lower speed, carries the clock: the receiver recover and regenerates the clock
one going down, carrying 1.2 Gb/s data at ~50m distance
accommodates up to 6 PMTs and 2 hydros per storey;
at the DU base an electronic board transfers the flux on optical fibre (one colour) to the optical network
copper handling safer than fibre handling, with copper cheaper connectors and components
data rate on copper limited
bypassing a faulty storey not so easy as with optical backbone

7. Data Transmission (3/3): Tower JB Electronics
Odd
Back
Bone
(OBB)
400V/5V
DC/DC
converter
V-I
meter
Power Monitor & Control,
Data Mux & Demux, Floor Control
Spread Spectrum
Drivers
Opto Tx
Opto Rx
DWDM
TX/RX
Even
(EBB)
Main DC
400 V
Tower
Single
Fiber
Copper