R&S ZVB - Page 334

R&S
®
ZVA / R&S
®
ZVB / R&S
®
ZVT GUI Reference
Channel Menu
Operating Manual 1145.1084.12 – 30 319
 Mixer 1 and Mixer 2 (if present) select the frequency of the signal with automatic frequency
definition, see background information below.
Conversion formulas
The output signal (IF signal) of each mixer can be at the sum or at the difference of the RF and LO input
frequencies.
 IF = RF – LO means that the RF signal is down-converted (upper sideband). The analyzer
automatically switches to IF = LO – RF if the LO frequency is above the RF input frequency.
 IF = LO – RF means that the LO signal is down-converted (lower sideband). The analyzer
automatically switches to IF = RF – LO if the RF input frequency is above the LO frequency.
 IF = RF + LO means that the RF input signal is up-converted (upper sideband).
To perform measurements at different mixer output frequencies (e.g. to analyze the isolation for IF = RF or
higher-order mixing products), use option R&S ZVA-K4, Arbitrary Generator and Receiver Frequencies.
The basic formulas described above are adjusted to the mixer measurement settings:
 If the RF or one of the LO signals is in Auto mode (instead of IF), the formulas above are
automatically converted. Example: LO 1 in Auto mode, down-conversion (lower sideband) --> LO
1 = IF + RF.
 If two mixer stages are present, the conversion formulas are applied twice; see Test Setup with
Two Mixers.
In a frequency sweep where one of the input frequencies varies over a definite range, the second swept
signal (e.g. the IF signal) also covers a frequency range of the same width. An error message is displayed
if the converted frequency exceeds the maximum frequency range of the analyzer.
Remote control:
[SENSe<Ch>:]FREQuency:CONVersion:MIXer:RFMultiplier
[SENSe<Ch>:]FREQuency:CONVersion:MIXer:LOMultiplier<Stg>
[SENSe<Ch>:]FREQuency:CONVersion:MIXer:FUNDamental
[SENSe<Ch>:]FREQuency:CONVersion:MIXer:MFFixed
[SENSe<Ch>:]FREQuency:CONVersion:MIXer:TFRequency
[SENSe<Ch>:]FREQuency:STARt etc.
RF Image Frequencies
Mixers in general convert two different RF frequencies to the same IF frequency. The second RF
frequency (or frequency band) is referred to as image frequency (RF
image
). The image frequencies depend
on the conversion mode of the mixer (see Conversion formulas):
 IF = RF + LO (up-conversion, upper sideband): RF
image
= RF + 2*LO. RF
image
is always positive
and > RF. RF
image
never falls below the minimum frequency of the analyzer but may exceed its
maximum frequency.
 IF = RF – LO (down-conversion, upper sideband): RF
image
= 2*LO – RF or RF
image
= RF – 2*LO,
whichever is positive. For RF = 2*LO, RF
image
= 0. RF can fall below the minimum frequency of the
analyzer or exceed its maximum frequency.
 IF = LO – RF (down-conversion, lower sideband): RF
image
= 2*LO – RF. RF
image
is always positive
and > IF. RF
image
never falls below the minimum frequency of the analyzer but may exceed its
maximum frequency.
If RF
image
exceeds the analyzer's frequency range, an error message is displayed.