Rohde & Schwarz R&S ZNA Series - Page 815

GUI reference
R&S
®
ZNA
815User Manual 1178.6462.02 ─ 29
consecutive bit values. Here a repeating bit pattern 0 1 1 1 1 0 is used. By definition
the voltage levels for encoding the bits are symmetrical using +V for the ones and -V
for the zeros.
In the graphic below the blue and the red trace indicate the signals used for differential
encoding on a symmetric line. Va indicates the level directly after a transition, Vd indi-
cates the level before a transition, Vb and Vc are optionally used to specify further lev-
els after the transition.
0 1 1 1 1 0... ...
Va Vb Vc Vd
In dB the pre- and post cursors are defined as:
●
Pre Cursor = 20 log
10
( Vd / Vc )
●
Post 1 Cursor = 20 log
10
( Vb / Va )
●
Post 2 Cursor = 20 log
10
( Vc / Vb )
Simple applications of the emphasis only define the Post 1 Cursor. Use a negative
value (in dB) for increasing the amplitude of the first bit after a transition. Below an
example for Post 1 Cursor = -3dB:
The FIR filter coefficients are found by solving the equations:
c
-1
+ c
0
– c
1
– c
2
= Va
c
-1
+ c
0
+ c
1
– c
2
= Vb
c
-1
+ c
0
+ c
1
+ c
2
= Vc
-c
-1
+ c
0
+ c
1
+ c
2
= Vd
subject to the normalization condition | c
-1
| + | c
0
| + | c
1
| + | c
2
| = 1.
Applic softtool