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Chapter X Working Principles and Key Technologies
of Instrument
Section 1 Overall Working Principle
and Hardware Function Block Diagram
The S5105D/E/F series microwave analyzer, a multifunctional multi-parameter test instrument, is
equipped with numerous functions such as spectrum analyzer, vector network analyzer, cable and
cable and antenna analyzer, vector voltage and power measurement, frequency measurement and
signal generation, etc. In addition, in terms of the overall hardware implementation plan, this analyzer
focuses on the design concept of modularization and platform generalization, fully utilizes the existing
technical foundation and determines the block diagram of implementation plan of the final project as
shown in Figure 1, including the 20 GHz excitation signal source module and 20 GHz local
oscillator source module, signal separation and frequency conversion module, spectrum receiver
module, intermediate frequency processing module, cpu module and other four-frequency super-
heterodyne sweep spectrum analyzer. The block diagram of the entire instrument is shown in Figure 10-
1.
Both the excitation signal source and the local oscillator signal source use a single phase-locked loop
method to generate a microwave signal of 30 kHz to 20 GHz. On the one hand, the multi-channel
receiving component is responsible for dividing the excitation signal of the 30 k - 20 GHz signal into two
paths by doubling frequency, power adjustment, and switching power. Among them, one path will the test
port 1 via port 1 directional coupler, and the other path will reach the port 2 via the port 2 coupler; on the
other hand, the multi-channel receiving component is responsible for dividing the 30k - 20GHz local
oscillator signal into 4 channels and sending them to the local oscillator end of the 4-way mixer; the
frequency of test signal is converted to the intermediate frequency signal that can be processed by the
instrument and then output to the intermediate frequency processing circuit for further processing.
The spectrum input signal enters the microwave frequency conversion component or 26.5 GHz
spectrum receiver board for three consecutive down-conversions to an intermediate frequency of 33.75
MHz, and then three intermediate frequency signals are amplified, anti-aliased, and A/D converted to
digital signals on the intermediate frequency processing board. In the FPGA, digital down conversion,
intermediate frequency filtering, video filtering, video detection and other processing are performed. The
FPGA finally sends the processing result to the main CPU and displays it on the screen.
Section 2 Key Technologies
Compared with the previous hand-held instruments, the Instrument features more testing functions and
higher technical indicators, uses numerous technologies such as advanced microelectronic technology,
signal processing technology, computer technology and testing technology, and innovates
high-frequency printed circuit board technology and broadband miniaturization directional separation
technology, broadband microwave component integration technology, FPGA-based multi-channel
parallel digital intermediate frequency technology, high-density digital-analog hybrid circuit technology
and other key technologies, thus ensuring excellent overall performance.
