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Chapter 3 71
Performance Tests
AVERAGE NOISE LEVEL TEST
Performance Tests
For 11970V: 5, 0, GHz
For 11970W:
7, 5, GHz
10.Record the center frequency in Table 3-8.
11.Set the power meter CAL FACTOR to the value shown on the sensor calibration label
for the center frequency indicated on the spectrum analyzer.
12.Set the signal generator output to produce a CW signal near the center of the spectrum
analyzer display. Next, set the signal generator output power level to produce a reading
of approximately -10 dBm on the power meter. Record the power meter reading in Table
3-8. (When testing the 11970V or W, re-zero the power meter for each measurement.)
13.Subtract the coupling factor for the directional coupler from the power meter reading,
then add the power meter correction factor (dB) to the power meter reading. Record this
corrected power reading in Table 3-8.
Corrected Power Reading = Power Meter Reading - Coupling Factor + Power Meter
Correction Factor.
For example:
(-10.03 dBm) - 9.82 dB + 0.73 = -19.1 dBm
14.On the 8566A/B, press
MARKER, PEAK SEARCH, then MKR→REF LVL. Record the marker
amplitude in Table 3-8.
15.Move the marker to the displayed noise floor, or turn off the CW signal, and record the
marker amplitude in Table 3-8. (Some sources may have excessive wide band noise when
the RF signal is turned off, so that the noise floor must be measured with the signal left
on.)
NOTE Step 15 requires a signal source with a wide band phase noise characteristic
that is at least 6 dB better than the measured average noise level.
16.The Average Noise Level is calculated as follows:
Average Noise Level = Corrected Power Reading (step 13) - Marker Amplitude (step 14)
+ Marker Amplitude (step 15) - Measurement Bandwidth Correction Factor
11970K, A, Q and U Bandwidth Correction = 10log(l00kHz/ 1 kHz)
11970V and W Bandwidth Correction = 10log(3MHz/ 1 kHz)
For example:
Average Noise Level = (-19.1 dBm) - (-32.3 dBm) + (-77.7 dBm) - 34.77 dB = - 99.3
dBm
17.Enter the calculated value in Table 3-8.
The Average Noise Level must be less than:
-110 dBm (for the 11970K)
-108 dBm (for the 11970A)