Agilent Technologies E4428C, User Manual

Page: 208 / 700

184 Chapter 4
Basic Digital Operation
Differential Encoding
As you can see from the previous illustration, the 1st and 4th symbols, having the same data value (00),
produce the same state transition (forward 1 state). In differential encoding, symbol values do not define
location; they define the direction and distance of a
transition through the I/Q State Map.
For instructions on configuring differential encoding, see “Using Differential Encoding” on page 184 .
Using Differential Encoding
Differential encoding is a digital-encoding technique that denotes a binary value by a signal change rather
than a particular signal state. It is available for custom real-time I/Q baseband generator waveforms and
real-time I/Q baseband generator TDMA waveforms. It is not available for waveforms generated by the dual
arbitrary waveform generator.
The signal generator’s
Differential State Map
table editor enables you to modify the differential
state map associated with user-defined I/Q and user-defined FSK modulations. In this procedure, you create
a user-defined I/Q modulation and then configure, activate, and apply differential encoding to the
user-defined modulation. For more information, see
“Differential Encoding” on page 180 .
Data Value Symbol Table Offset
00
01
10
11 +1
-1
+2
+0
Data = 0011100001
{ {
{
{
{
5th Symbol 1st Symbol
3rd Symbol
4th Symbol
2nd Symbol
1st
2nd
3rd
5th
4th