Tektronix TSG4100A Series User manual

Output level accuracy (IQ
modulation relative to CW)
This test checks the output level accuracy of the IQ modulation inputs
relative to continuous waveform
Required equipment
Spectrum analyzer: Tektro
nix RSA5106B
Arbitrary function generator: Tektronix AFG3252C
Two BNC
-
BNC cables
Type
-
N (male)
-
Type
-
N (male) cable
1.
Using a BNC to BNC cable, connect the AFG3252C (Channel 1)
to the Vector Modulation I input of the TSG (located on the rear
panel).
2.
Using the second BNC to BNC cable, connect the AFG3252C
(Channel 2) to the Vector Modulation Q input of the TSG
(located on the rear panel).
3.
Set the AFG3252C as follows:
a. Set phase on Channel 1 to 90, frequency to 1 MHz, and
amplitude to 1 Vp-p.
b.
Set phase on Channel 2 to zero, frequency to 1 MHz,
and amplitude to 1 Vp-p.
c. Press Phase/Delay and then Align phase in the menu.
This aligns the phase between Channel 1 and Channel 2
to obtain the quadrature input for the TSG.
4. Set the TSG as follows:
a.
Press and hold the
Preset
button to reset the
instrument.
b.
Press the
RF/LF
button to access the output settings
menu.
c. Press the Freq button on the front panel.
d.
Set the frequency to 2000 MHz (fc) using the general
knob or the number keys.
e.
Select
RF Ampt
from the menu.
f.
Set the RF amplitude to 0 dBm using the general knob
or number keys.
g.
Connect the output from the TSG to the input of the
spectrum analyzer.
h. Press the gray color Mod button on the front
panel to access the modulation parameters menu.
i. Set the Source to Ext.
j. Select RF Output from the menu to turn the RF output
to ON (text will turn blue).
5.
Set the spectrum analyzer as follows:
a. Reset the instrument.
b.
Set the center frequency to 2000 MHz and the span to
5 MHz.
c. Set markers to peak search.

d.
Write down the peak value and note it is = A for later
reference.
6. Press the Mod button on the TSG front panel to turn
modulation on. Notice that MODON indicator will appear in
yellow in the top right portion of the screen.
7. Set the MOD Type to Vector -> QAM and the Source to
External.
8. Write down the 2000 + 1 MHz amplitude level from the RSA
and note it is = B for later reference.
9. Calculate the IQ modulation value B–A. Record this value in the
test record.
10. Continue to test the modulation at each frequency listed in the
test record for the specific instrument model you are testing.
Record the results.