HP 54750A, User Manual, Page: 140 / 478

The Digital Communications
Analysis Menus
Mask T est Menu
Standard masks The factory-installed industry-standard masks include the following:
Optical Masks Electrical Masks
STM0/OC1 STS1 Eye
STM1/OC3 STS1 Pulse
OC12 STS3 Eye
OC24 STS3 Pulse 0
STM16/OC48 STS3 Pulse 1
FC133 DS1
FC266 DS1C
FC531 DS2
FC1063 DS3
FDDI PDH 2.048 Mb
100BASE-FX PDH 8.448 Mb
GIGABIT ETHERNET PDH 34.4 Mb
PDH 139 Mb 0
PDH 139 Mb 1
Any of these masks may be recalled from memory and used to test a
waveform to a specic industry standard listed above .
Fixed-voltage masks Industry standards for PDH data rates at 2.048 Mb/s , 8.448 Mb/s , 34.368 Mb/s ,
and 139.000 Mb/s require xed-voltage masks . This means the test signal 1
and 0 voltages must fall within certain absolute limits and the mask is not
permitted to scale vertically to t the waveform.
In rmware A.02.00 and above , the HP 83480A automatically performs
xed-voltage mask tests on these rates.
There are two considerations in mask testing at these rates: the mask is
specied for a 75 ohm test impedance , and the required signal swings exceed
the HP 83480A's specied input voltage range . T o convert the HP 83480A's
input impedance to 75 ohms , use a minimum loss pad such as the HP 11852B .
T o reduce the signal level to within the input range of the HP 83480A, add an
appropriate 50 ohm xed attenuator between the minimum loss pad and the
channel input. The HP 11852B has an insertion loss of 5.7 dB , and suggested
additional attenuation values are listed in the table below .
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