R&S FSQ Signal Analyzer - Rohde & Schwarz

R&S FSQ Instrument Functions
MODULATION
DEPTH
4.5.13.6 Measurement of the AM Modulation Depth
Analyzer Mode
The MODULATION DEPTH softkey switches on the measurement of the AM modulation
depth. An AM-modulated carrier is required on the screen for ensuring correct
operation.
The level value of MARKER 1 is taken as the carrier level. When this function is activated,
MARKER 2 and MARKER 3 are automatically set symmetrically to the carrier
on the adjacent peak values of the trace as delta markers and MARKER 2 is activated
for the entry.
When the position of MARKER 2 (delta) is changed, MARKER 3 (delta) is moved
symmetrically with respect to the reference marker (MARKER 1).
If the data entry is activated for MARKER 3 (MARKER 1 2 3 4 softkey), the latter can
be moved for fine adjustment irrespective of MARKER 2.
The R&S FSQ calculates the power at the marker positions from the measured levels.
The AM modulation depth is calculated from the ratio between the power values
at the reference marker and at the delta markers. When the powers of the two AM
side bands are unequal, the mean value of the two power values is used for AM
modulation depth calculation.
Measurement example
The AM modulation depth of a carrier modulated with 1 kHz is to be measured at
100 MHz.
[PRESET] The R&S FSQ is set to the default setting.
[CENTER: 100 MHz] The center frequency is set to 100 MHz.
[SPAN: 5 kHz] The span is set to 5 kHz.
[AMPT: 0 dBm] The reference level is set to 0 dBm.
[MKR FCTN] MARKER 1 is switched on and positioned at the maximum
of the displayed trace.
[MODULATION DEPTH:
1 kHz]
The measurement of the AM modulation depth is switched
on. MARKERS 2 and 3 (delta markers) are set to the adjacent
peak values of the trace and are activated for the frequency
entry.
The AM modulation depth is output in % in the marker info
field.
When 1 kHz is entered, MARKER 2 can be exactly positioned
on 1 kHz and MARKER 3 at -1 kHz from the reference
marker.
Remote command: CALC:MARK:FUNC:MDEP ON;
CALC:MARK:FUNC:MDEP:RES?
Operating Manual 1313.9681.12 - 01 4.119