Chapter 3
Diphase Testing
About Diphase testing
Data Communications and Diphase Testing Manual
Page 24
21148872, Rev. 002
January 2016
About Diphase testing
Using the MSAM with a Diphase PIM, you can test multiplexors, cable spans, radio
spans, and perform end-to-end tests. Figure 4 illustrates the various access points
where you can connect the instrument to verify channel routing, cable integrity, and
communication across radio or satellite links.
Before you begin testing, be certain to review the Getting Started manual that shipped
with your instrument, and the concepts presented in
manual.
Manchester (Diphase) encoding
Manchester (Diphase) encoding ensures that there is a phase transition each time the
logic level changes. Each time the data signal is logic level 1, a high to low phase tran-
sition (
) occurs. Each time the data signal is a logic level 0, a low to high phase tran-
sition (
) occurs. See
for an illustration of a Manchester encoded bit pattern
of 101001100.
The signal level transition occurs at the half bit interval point. This signal transition helps
eliminate any DC component of the signal and provides timing recovery from the trans-
mitted signal.
Figure 4
Diphase circuit testing
Figure 5
Manchester encoding
