Basic Information On Running Applications; Measurement; Typifying Line Parameters - Wavetek ANT-20 Operating Manual

ANT-20 NEXT
2

Basic information on running applications

2.1

Measurement

There are two basic types of measurement:
• Monitoring (only involves ANT-20 RX)
• Line measurement with loop back at far end (involves TX and RX)
Each measurement takes place in two stages:
• Setting up the ANT-20 and determining the type of item under test
• Performing optional quality measurements such as long-term BERT, G.826/M.2100, intrinsic
jitter test, MTJ, etc.
The generator section of the ANT-20 is not involved when the device is set for "Monitoring". The
item under test is typified using the received signal only. It is not possible to check whether the
path being measured is clock or pattern transparent. It is also not possible to perform tolerance
to jitter measurements and alarm sensor tests.
2.1.1

Typifying line parameters

Inputs and outputs
The ANT-20 automatically sets the correct TX outputs and RX inputs (balanced, coaxial or
optical) during the first stage. This eliminates one of the most common causes of error in
manual measurements.
If the selected application allows measurements on PMP levels or measurements using the
built-in equalizer of the ANT-20, these parameters will also be automatically set to their optimum
settings.
Once the correct RX settings and a corresponding TX setting have been found for the ANT-20,
a check is made to determine if the line is looped back at the far end. The program determines
if the data transmitted by the ANT-20 generator can be transmitted to the ANT-20 generator.
Frame structure
The "ANT-20 NEXT" software automatically sets PCM31 or PCM31CRC frames for those line
types where these frames are expected. An unframed signal is used for all subsequent
measurements if it is detected that the line is transparent to signal structure.
Clock type
The clock type is an important criterion for typifying a 2 Mbit/s communications line.
A basic distinction is made between "clock-transparent" and "re-timing".
The "ANT-20 NEXT" software first determines the type of line. The ANT-20 is then automatically
set correctly for subsequent measurements.
To determine the line type, the TX signal of the ANT-20 (setting: TX clock internal) is offset by
10 ppm and the received clock signal measured.
If the received clock is also offset by 10 ppm, the line is "clock-transparent".
If no offset is present in the received clock signal, the line operates with "re-timing".
SA-2
ANT-20SE
Standard Applications