S3302 series spectrum analyzers have 9 models, and various measurement functions such as spectrum measurement analysis, field strength measurement, occupied bandwidth measurement, channel power measurement, adjacent channel power measurement, tune listening and IQ capture. With options for interference analysis, AM-FM-PM signal demodulation analysis and USB power measurement, the RF signal parameters such as the frequency and amplitude can be measured. The functional block diagram of S3302 series spectrum analyzer is shown below:
System hardware can be divided into the frequency conversion module, frequency synthesizer board, IF control board, CPU board, display, keyboard, battery, etc.
The microwave frequency conversion module includes two parts: 60dB program-controlled step attenuator and switch filtering and frequency conversion part. The attenuation value of the program-controlled step attenuator is automatically associated according to the reference level or manually set by the user to provide the appropriate mixer level. The switch filtering and frequency conversion part is used for band filtering and frequency conversion of RF input signals and output of IF signals to the IF control board.
The IF control board is used for filtering IF signal input of the frequency conversion module. Gain control is implemented based on bands so as to adjust the amplitude of AD sample signals and finally output differential digital signals to FPGA after AD conversion, so as to achieve the functions of digital down-conversion, IF filtering, video filtering, etc.
The CPU board includes the power conversion and management circuit, interface and display circuit, FPGA/CPLD control and digital signal processing circuit and ARM core module, and is used for DC/DC conversion and operation management of the power supply of the whole instrument, digital signal processing, logic circuit control, etc. Finally, digital signals in the sweep curve, spectrogram and other forms, as test results are transmitted to the LCD display.
The frequency synthesizer board has the function of providing 10MHz reference input/output for the outside, with the internal reference ring output signal as the LO frequency reference, and also providing high-stability clock signals for AD sampling and FPGA. The LO generation circuit is used for providing LO signals for the mixer in the microwave MMW frequency conversion module, and related to the hardware sweeping speed, phase noise, sideband emission and other indicators of the whole instrument.