Rohde & Schwarz SME02 - Simultaneous Modulation; Alternate Switching off of Modulations; Table 2-2 Status Messages in the Case of a Deviation

SME Modulation Sources
1038.6002.02 2.51 E-13
The external modulation signal must show a voltage of V
s
= 1 V (V
eff
= 0.707 V) in order to maintain the
modulation depth or deviation indicated. Deviations of more than ±3 % are signaled in the status line by
means of the following messages (cf. table 2-2).
Table 2-2 Status messages in the case of a deviation from the rated value at the external modulation
input
Message Deviation
EXT1-HIGH Voltage at EXT1 too high
EXT1-LOW Voltage at EXT1 too low
EXT2-HIGH Voltage at EXT2 too high
EXT2-LOW Voltage at EXT2 too low
EXT-HI/HI Voltage at EXT1 and EXT2 too high
EXT-LO/LO Voltage at EXT1 and EXT2 too low
EXT-HI/LO Voltage at EXT1 too high and EXT2 too low
EXT-LO/HI Voltage at EXT1 too low and EXT2 too high
2.6.1.1 Simultaneous Modulation
Basically, every combination of AM, FM, pulse modulation and a digital modulation (GMSK, GFSK,
QPSK, FSK, FFSK or 4FSK) is possible. Instead of FM, phase modulation (PM) can be switched on as
well. There are only restrictions for modulations of the same kind and for the multiple use of the 2nd LF
generator (cf. table 2-3).
Two-tone AM is possible by simultaneously switching on the external and internal source.
Two-tone FM or two-tone PM is possible by simultaneously switching on FM1 and FM2 or PM1 and
PM2. For FM1 and FM2 (PM1 and PM2) separate deviations can be set and separate sources switched
on.
Note: With two-tone modulation please observe that the set deviation or modulation depth is valid for
one signal and the sum deviation or sum modulation depth is determined by adding both
signals. This results in overmodulation if the maximal value for deviation or modulation depth is
exceeded.
2.6.1.2 Alternate Switching Off of Modulations
Due to the multiple use of some functional modules in the instrument some modulations cannot be set
at the same time (cf. table 2-3). In the case of manual control, incompatible modulations deactivate one
another, a short-time warning is displayed in the status line.
Note: The IEC-bus control according to SCPI forbids the mutual influence of types of modulation on
one another. In the case of remote control, an error message is outputted when the attempt is
made to switch on incompatible types of modulation (cf. annex B).