Protocol analysis
R&S
®
RTO6
777
User Manual 1801.6687.02 ─ 05
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Symbol encoding is carried out via a one-dimensional (1D) PAM-3 encoder that
converts the 3-bit groups into pairs of ternary symbols. These symbols are
transmitted using three voltage levels (-1 V, 0 V and +1 V). One symbol is
transmitted in each symbol period
–
Data scrambling is carried out via a sidestream scramble to randomize the
sequence of transmitted symbols and avoid the presence of spectral lines in
the signal spectrum
PAM-3 has a higher spectral efficiency that limits the signaling bandwidth to 33.3
MHz instead of 65 MHz to 80 MHz in 1000BASE-T and 100BASE-TX such that
communication occurs in the best part of a twisted-pair channel. This in turn
improves return loss, reduces crosstalk and EMI, allows for a more aggressive
Electromagnetic Compatibility (EMC) filtering and lower cost (often lower quality)
cabling
In terms of the trigger and decoder development, multiple aspects of this protocol are
new, specifically:
●
Sidestream descrambler: Descrambles the randomized sequence of received ter-
nary symbols
●
1D PAM-3 decoder: Decodes the received ternary symbols into groups of three bits
according to a conversion chart
●
4b/3b line decoder: Decodes the groups of three bits (result of ternary pair) back to
groups of four bits of the data stream
13.18.2
100BASE-T1 configuration
13.18.2.1
100BASE-T1 configuration settings
Access: [Bus] > "100BASE-T1" > "Setup" tab
Make sure that the tab of the correct serial bus is selected.
Ethernet 100BASE-T1 (option R&S
RTO6-K560)
