Changes between Version 1 and Version 2 of DUNEFiberMultiplexing

Timestamp:

May 3, 2016, 10:46:31 AM (8 years ago)

Author:

Eric Hazen

Comment:

--

DUNEFiberMultiplexing

@@ +1 @@
+
+== Data Formats ==
+
+On pages 4, 5 of the [http://ohm.bu.edu/~hazen/DUNE/COLDATA/Draft%20COLDATA%20Specification_v4.pdf COLDATA spec] (v4) 
+there is a 56-word (16-bit words) format described for transmission in two links at "~1.2Gb/s".  One frame is sent each 500ns exactly in response to a "convert" command from the timing system.  There are no details (yet) specified on how the data is divided between the two links.
+
+56 words with 8b10b encoding is 1120 bits.  Half per link is 560 bits which takes 467ns to send at 1.2Gb/s.
+
+At 1.2Gb/s one can send 30 words of 16 bits (8b10b encoded).
+For four channels (half the data) there are 24+1 words of ADC data and header bits.  This leaves
+only 5 words for header etc.  
+
+Currently the protocol consists of the following (16-bit words):
+
+|| 1 || Start of Frame ||
+|| 2 || Checksum ||
+|| 3 || Timestamp ||
+|| 4 || Errors ||
+|| 5 || Spare 1 ||
+|| 6 || Spare 2 ||
+|| 7 || ADC header S1-S4 ||
+|| 8 || ADC header S5-S8 ||
+|| 9..32 || ADC data S1-S4 ||
+|| 33..56 || ADC data S5-S8 ||
+
+Constructing two independent blocks to transmit on the two 1.2Gb/s links is challenging.
 
 
-For one 10kT TPC:
+== For one 10kT TPC: ==
 
 One APA (analog plane assembly) has 2560 readout channels (20 readout boards, 128 channels each).
@@ -11 +37 @@
 Fibers to surface:  96 strands (duplex or simplex?) with 64 devoted to DAQ.
 
-
-
 * Multiple channels on one fiber using WDM (wavelength division multiplexing).  [http://www.transmode.com/en/technologies/wdm-the-transmode-way/wdm-the-transmode-way-html/2-wdm-networking-technologies  Useful article] from some vendor
 * CWDM 10G XFP seem to be ~ $150