R&S AFQ100A
Main Applications
1401.3078.62 2.2
E-3
Main Applications
R&S AFQ is mainly used for generating modulation signals for an RF generator to check the data taken
by a receiver. Moreover, RF generators with I/Q inputs can also be tested. Gain and phase of the two
channels I and Q can be adjusted, hence accounting for non ideal characteristics of the RF generator to
be driven. For test purposes, modulation signals are output at the digital output (option R&S AFQ-B18)
of the instrument prior to D/A-conversion.
In addition, the impairment of the digital signal is possible, delay, gain, voltage offset and phase
mismatch. Pre-distortions are useful for compensating calibration errors of the instrument to be driven.
Beyond this, the user can check the influence on the rate of successfully transmitted bits. Differences in
amplitude between the I and Q channels give rise to an offset in the constellation diagram and thus to a
narrower eye width for the modulation. Quadrature offsets can be illustrated by an I/Q vector diagram:
I
Q
Ideal modulation vector
Resulting
modulation vector
Error vector
Constellation Diagram
The main applications are:
bit error rate testing of baseband and RF devices
testing semiconductor devices which process baseband signals
testing transceivers and demodulators
developing wireless communication systems
checking how sensitive devices are with regard to impairments
adjusting I/Q RF modulators
