ACT6000 User Guide
– January 2021 Page 44 of 52
-
Power Spectral Density (with Spectrum Analyzer in High Impedance)
The PSD measurement, in
Medium
or
High Band
, can be performed in limited band by
the
Spectrum Analyzer
(not intrusive).
Set the instrument as follows:
-
dBm
or
dBm/Hz
by
F1
-
TX Off
by
F2
-
4W Bal
by
F3
-
Normal
or
MaxVal
by
F4
-
AC-Inp
by
F5
and then:
-
Vo Rif
for the best trace display
-
dB/Div
for the best vertical resolution
-
Fc (kHz)
for the Medium Band center
or
RX Band
(for one of the
High Bands
)
-
kHz/Div
for the Medium Band limit
-
Zo RTX: Z-High
- Connect (in parallel) the line to
a
-
b
points of the
RTX
connector directly for unfed lines;
- Connect (in parallel) the line to
a
-
b
points of the
RTX
connector inserting the right Probe,
“
ACT-15/6
” (for medium Band) or “
ACT-15/30
” (for High Band), for fed lines and select
“
Probe
” by
F5
.
In the figure is shown the PSD measurement (subscriber side) of the typical ADSL stream
(over POTS), in fact the line feed is shown by the little
“
Vdc
” window.
-
Return Loss with Network Analyzer
The spectral measurement of the Return Loss in any band, can be performed in limited
band by the
Network Analyzer
.
Set the Spectrum Analyzer as follows:
- dBm
by
F1
- TX SW
by
F2
- 2W +/-
(or
2W Bal
for High Band) by
F3
- Normal
by
F4
- DC-Inp
*
by
F5
and then:
- Vo Ref
to
0
- dB/Div
for the best vertical resolution
- Fc (kHz)
for the Base / Medium Band
centre or
RX Band
(
for one of the High
Bands
)
- kHz/Div
for the Medium Band limit
- Out Lev: 0.0
and
Zo RTX:
(eg.
100 Ohm
)
Connect the line to
a
-
b
points of the
RTX
connector.
The setting made as in the example shown is used to measure the Return Loss of typical
copper pairs for the transport of ADSL2+ stream, where the bandwidth is from few kHz up
to 2 MHz (approx).
The typical value of the Return Loss of a good copper line (>1 km long ..at least) is
normally over 15 dB
(see the table at the end of this paragraph).