Sage 930i, Руководство по эксплуатации

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5-41 © Sage Instruments 2000
9100-2930-02 01/31/00
Sage Instruments 930i Communications Test Set
5-13 OPTION MENU #:13 PHASE & AMPLITUDE JITTER
OPTION MENU #:13, PHASE & AMPLITUDE JITTER, is only available when
Purchased Option 930i-
100, Data Tests, is installed. This feature provides the capability to measure phase and amplitude jitter
on voice frequency channels as well as transient phenomena such as phase hits, gain hits, and
dropouts.
The phase and amplitude jitter measurements are displayed under OPTION MENU #:13 and the hits
are counted with impulse noise under OPTION MENU #:11.
Phase/Amplitude jitter is a dithering of the phase which appears as phase or frequency modulation.
It is measured by sending a test tone of 1020 Hz. At the receive end, a phase locked loop establishes
a phase reference and jitter is measured relative to this reference. Phase jitter measurements are made
over a 4 Hz to 300 Hz range in two bands: 20 Hz to 300 Hz and the entire 4 Hz to 300 Hz band. Jitter
standards for data transmission are no more than 10˚ between 20 Hz and 300 Hz and 15˚ between 4
Hz and 300 Hz.
To measure phase and amplitude jitter:
1. Connect the 930i to the trunk under test.
2. Perform a Psophometric Noise measurement prior to measuring phase jitter. Excess noise can
cause what appears to be significant amounts of jitter (readings should be less than 20 dBm for
quiet terminated line).
3. Press the Option Menu function key.
4. Use the Up/Down Arrow keys to scroll through the option menus, OR select 13 using the
numeric keypad and then press the Option Menu function key. The display reads:
OPTION MENU #: 13 PHASE & AMPL JITTER
K1 K2 K3 K4
5. Press ENT or any soft key (K1-K4) to activate your selection. The 930i begins measuring phase
and amplitude jitter over the filter bandwidth of 20 Hz to 300 Hz and displays the level and
frequency of the received holding tone (usually 1004 Hz).
for example:
5.7° 2.9% 1020Hz -16.0dBm 20-300Hz
K1 K2 K3 K4
Phase jitter requires a test signal of 1004 Hz. If the actual frequency of the test tone differs by more
than
±
20 Hz from the nominal value, or is below -40 dBm in level, the 930i will indicate
INVALID TONE:
Option Menu #:
13
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