Analog modulations
R&S
®
SMA100B
93User Manual 1178.3834.02 ─ 09
Remote command:
[:SOURce<hw>]:AM:DEPTh:SUM on page 566
Ratio Path2/Path1 ← AM settings
Sets the deviaton ratio of the signal depth for path 2 to path 1 in per cent when using
combined sources.
Using external LF signals, the R&S SMA100B indicates the Sensitivity per Volts for the
input signal.
In conjunction with the deviation mode, you can set the depth of both paths independ-
ently or coupled.
●
Deviation Mode > Uncoupled
Enables you to set the Depth or Sensitivity of both paths independently.
●
Deviation Mode > Fixed Ratio
Couples the ratio of the two paths as follows.
– Changing the ratio path2/path1 adjusts the depth of both path2. The depth of
path1 remains the same
– Changing the depth of one path adjusts the depth of the other accordingly. The
ratio path2/path1 remains the same.
Remote command:
[:SOURce<hw>]:AM:RATio on page 567
5.4.3 Chirp modulation
Option: see Chapter 5.1, "Required options", on page 81.
About chirp modulation
Chirp modulation is used in radar technique to achieve pulse compression. Pulse com-
pression increases the sensitivity and resolution of radar systems by modifying trans-
mitted pulses to improve their auto-correlation properties. To chirp the radar signal is
one way of accomplishing pulse compression. A chirp is a signal with increasing or
decreasing frequency over time.
The R&S SMA100B always couples the chirp modulation with the pulse modulation. It
generates the modulation signals for FM and pulse modulator, and synchronizes the
signals internally. The internal pulse generator signal is the modulation source for the
pulse modulator, and the internal LF generator signal is the signal source for the fre-
quency modulation. Normal FM mode is used. Using an external modulation signals is
not possible for chirp modulation.
The following graph shows the FM demodulated signal of chirped pulses with a chirp
bandwidth of 80 MHz and a pulse width of 80 µs. Chirp direction is up.
Modulation settings
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