Frequency Offset Mode Operation; Differences Between Internal And External R-Channel Inputs - Agilent Technologies 8719D User Manual

Frequency Offset Mode Operation

Frequency offset measurements do not begin until all of the frequency offset mode parameters
are set. These include the following:
Start and Stop IF Frequencies
n
n
Up Converter / Down Converter
n
n
The Lo frequency for frequency offset mode must be set to the same value as the external Lo
source. The offset frequency between the analyzer source and receiver will be set to this value.
When frequency offset mode operation begins, the receiver locks onto the entered IF signal
frequencies and then offsets the source frequency required to produce the IF. Therefore, since
it is the analyzer receiver that controls the source, it is only necessary to set the start and stop
frequencies from the receiver.

Differences Between Internal and External R-Channel Inputs

Due to internal losses in the analyzer's test set, the power measured internally at the
R-Channel is 16 dE3 lower than that of the source. To compensate for these losses, the traces
associated with the R-Channel have been offset 16 dB higher. As a result, power measured
actual value. If power meter calibration is not used, this offset in power must be accounted for
with a receiver calibration before performing measurements
The following steps can be performed to observe this offset in power.
1. The default source output power of the standard HP 8719D/20D is too high for the
R-channel input. To reduce the source output power level to 0 dRm, press:
Since the default source output power of the HP 8722D is below 0 dBm, no
Note
reduction in source output power is required for this procedure.
Setting the power range to manual prevents the internal source attenuator from switching
when changing power levels If you choose a different power range, the R-channel offset
compensation and R-channel measurement changes by the amount of the attenuator setting.
2. Connect the analyzer source output, port 1, directly to the to the R-channel input as shown
in Figure 3-3.
To prevent connector damage, use an adapter (HP part number 1250-1462) as a
Caution
connector saver for R CHANNEL IN.
3 4 M a k i n g M i x e r M e a s u r e m e n t s ( O p t i o n 0 8 8