Ceyear 4051 Series, User Manual

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8. Specifications and test methods
8.5 Performance characteristics test
654
1) Connect the frequency standard output to the 10 MHz input of the signal generator according to Fig. 8.2 to
provide reference frequency for the synthesized signal generator with the external frequency standard.
Connect the low frequency output of the synthesized signal generator to the input interface of the 4051
signal/spectrum analyzer (if no frequency standard is available, optional signal generator with frequency
of high stability can be used).
2) The 4051 analyzer to be tested, the synthesized generator and the frequency standard are preheated for
predetermined time.
3) Set the output frequency of the synthesized signal generator as the upper frequency limit of the analyzer to
be tested and the output power as -10 dBm.
4) Reset 4051, set the frequency span as 100 kHz, press Peak Search and turn on Delta Count.
5) Record marker count measurement results in B1 of the Auxiliary Form of Performance Characteristics of
4051 Series Signal/Spectrum Analyzer (hereinafter referred to as the ―4051 Auxiliary Form‖).
Fig. 8.2 Schematic diagram of frequency reference test
d) Test records and data processing
6) Calculate the frequency reference accuracy with formula (6).
Where f refers to the 4051 marker count measurement value (Hz);
f
0
refers to the nominal frequency value of the synthesized signal generator (Hz).
7) Record the frequency reference accuracy calculation results in the 4051 Record Sheet. The aging rate, the
temperature stability and the standard accuracy will be obtained via measurement standards from batch
spot checks.
8.5.1.1.4 Residual frequency modulation
a) Test items
The residual frequency modulation refers to the short-term frequency instability inherent to the local
frequency signal without any modulation input. In general, it refers to the peak value or peak-to-peak value of
frequency jitter during a set time interval of set test bandwidth.
For the analyzer, any instability of LO system is transferred to the IF byinputting a stable sinewave signal to
the analyzer and setting the analyzer at zero frequency bandwidth. Measure the amplitude offset of the signal
at the 10 Hz resolution frequency sideband. The frequency offset (also known as the residual frequency
modulation) can be obtained by multiplying the amplitude offset with the slope of the 10 Hz filter slop.