HP 3048A Operating Manual page 189

Table 3-26. Reference Messages (2 of 7)
Cause FIRST calibration PEAK voltage at mixer input.
Action: Adjust the frequency of the source, or adjust the phase shifter to get either a
positive or negative peak voltage reading using the Marker function on the HP 3561 A.
To ensure that you have adjusted to the maximum peak setting, adjust to slightly
beyond the maximum peak and then back to it. (The peak voltage setting can also be
determined using a voltmeter or oscilloscope connected to the AUX MONITOR port on
the HP 11848A.) When the peak setting has been attained, press Proceed
When you are prompted to cause the second calibration peak, adjust to a maximum peak
of the opposite polarity using the same technique.
NOTE
For this calibration technique to be most accurate, the two signal paths to
the HP 11848A Phase Detector should be well matched (>10 dB return loss)
and the R port level should be at least 5 dB below the L port level. If you
are not able to attain a true peak setting, you will have to use a different
calibration technique.
Apply modulation to carrier. Either a double-sided spur or modulation of the same
type as is being measured.
Action: Apply the modulation type required for your measurement. Apply angle
modulation for a Phase Noise without PLL or FM discriminator measurement, or apply
amplitude modulation for an AM measurement. Ensure that the modulation is applied
at a level that will enable the HP 3048A to readily detect it above the noise of the
device-under-test. The following maximum limits should also be observed.
• Double-sided spur < - 2 0 dB
• AM < 10%(-26dB)
The offset frequency of the spur should be between 1 Hz and 50 kHz (or between 1 Hz
and 20 MHz if an RF Analyzer is configured in the system).
Apply calibration spur to carrier. A single-sided spur is expected.
Action: The spur is typically generated by combining a signal near the frequency of the
device-under-test (DUT) with the DUT output. This can be done using a power splitter or
a directional coupler.
Turn on the spur signal source and note the amplitude of the spur signal relative to the
amplitude of the DUT. The spur level should be high enough to be readily observable
above the noise of the DUT on a spectrum analyzer. The spur level should not exceed
- 2 0 dBc relative to the DUT amplitude.
Signal Source Applications 3-139