57.
Measuring
11.On the EMC analyzer, set the center frequency to 9 kHz.
12.Set the microwave spectrum analyzer START FREQ, STOP FREQ, and RES BW as indicated in the rst row of Table
13.Press SINGLE on the microwave spectrum analyzer and wait for the sweep to nish. Press PEAK SEARCH. If the marker frequency is greater than 2.5 GHz, press PRESEL PEAK and wait for the PEAKING! message to disappear.
14.Verify that the marked signal is not the fundamental or a harmonic of the fundamental by performing the following steps:
Note that the following steps are for an HP 8566A/B microwave spectrum analyzer, the steps may be dierent if you are using another microwave spectrum analyzer.
a.Divide the marker frequency by the fundamental frequency (the EMC analyzer center frequency setting). For example, if the marker frequency is 26.5 kHz and the fundamental frequency is 9 kHz, dividing 26.5 kHz by 9 kHz yields 2.944.
b.Round the number calculated in step a the nearest whole number. In the example above, 2.944 should be rounded to 3.
c.Multiply the fundamental frequency by the number calculated in step b. Following the example, multiplying 9 kHz by 3 yields 27 kHz.
d.Calculate the dierence between the marker frequency and the frequency calculated in step c above. Continuing the example, the dierence would be 500 Hz.
e.Due to span accuracy uncertainties in the microwave spectrum analyzer, the marker frequency might not equal the actual frequency. Given the marker frequency, check if the dierence calculated in step d is within the appropriate tolerance:
For marker frequencies <5 MHz, tolerance = 6200 kHz
For marker frequencies <55 MHz, tolerance = 6750 kHz
For marker frequencies >55 MHz, tolerance = 610 MHz
f.If the dierence in step d is within the indicated tolerance, the signal in question is the fundamental signal (if the number in step b = 1) or a harmonic of the fundamental (if the number in step b >1). This response should be ignored.