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This reference design implements a complete 2-Port radio frequency (RF) Network Analyzer using a low-cost zero intermediate frequency (ZIF) architecture in an Arduino form factor, which is designed to plug into EVAL-ADICUP3029.
To use the software GUI, the firmware must first be loaded onto the EVAL-ADICUP3029.
After launching the software GUI. The connection window will be first shown. It lists all the available serial ports. To start using the GUI, choose the COM port of the EVAL-ADICUP3029 used. Have the baud rate set to the default, 115200, then click Connect . The connection window will automatically close after a successful connection.
First, make sure that port 1 and port 2 of the CN-0507 shield is already connected to the DUT. To perform a sweep, just click the Start Sweep button. This figure shows the magnitude plot from an open sweep with the default sweep setting values.
The default settings have it set at 25 steps, with a start frequency of 1700 MHz, and a stop frequency of 3400 MHz. This range is set because this is the frequency range that the CN-0507 can handle. The number of steps can be chosen between the available value of 25, 50, 100, 500, and 1000 steps. The expected time per sweep is indicated at the right of the steps box. The S-parameters that will be plotted may also be selected at the Sweep Settings card. It is recommended to have all the S-parameters checked since it is also possible to hide a plot by clicking its legend at the top. By default, the magnitude plot is shown. To view the phase plot, click on the Phase option at the top.
The Y-axis of the magnitude plot view can be adjusted using the Adjust Y buttons in Plot Settings located on the lower right of the GUI. Below that is the Export Plots button which will save the magnitude and phase values into a standard touchstone .S2P file.
Averaging multiple sweeps can be enabled by checking the Averaging checkbox. The Sweep Count value determines how many sweeps to average. Take note that averaging multiple sweeps will take a longer time to finish.
A calibrated sweep can also be performed by checking the Use Calibration checkbox. The appropriate calibration file must also be loaded after clicking the Choose File button. The sweep settings (start frequency, stop frequency, step size) of the calibration file must be the same with the sweep settings that will be performed. The next section discusses how to generate a calibration file.
Generating a calibration file is necessary to perform calibrated sweeps. First, click the menu button located in the upper right corner of the GUI. Select the Calibration option to open the calibration window.
The first tab, Calibration Constants, contains calibration kit constants and the sweep settings of the calibration file to be generated. These constants must be changed depending on the value of the calibration kit. A previously generated calibration file can also be loaded to fill the constants by clicking Constants→Load From File. When all the fields are filled out correctly, click the Use Calibration Constants button then go to the next tab.
The second tab, DC Offsets is used for the IQ demodulator DC offset correction. Click the Measure button to measure the DC offset voltages of the IQ demodulators. Wait for it to finish. After it is performed, go to the next tab.
The third tab, Calibrate Port 1 is for calibrating port 1. Follow the instructions shown in that tab. For reflection measurements, connect an open terminator to port 1 then click the corresponding Calibrate button. Do this again for short and 50-ohm load terminators. For the isolation measurement, connect a 50-ohm load terminator on each port then click the corresponding Calibrate button. For the through measurement, connect port 1 and port using a thru then click the corresponding Calibrate button. Do this again for port 2 on the fourth tab, Calibrate Port 2. After all of these are performed, go to the fifth tab.
The fifth tab, Save is for saving all the performed calibration measurements with the sweep settings and the calibration constants used to a single file. After the things done on the previous tabs, the badges below Port 1 Calibration and Port 2 Calibration must be Ready and color green. With this, click the Save Calibration Values to save it into a JSON file. This file can now be used to perform a calibrated sweep.
This would discuss on how the customers can make their own PC application that could communicate with the existing firmware using UART communication. This also includes the UART settings and communication protocols
The microcontroller waits for commands. The command list are listed on the table below. Once the microcontroller receives a command, it will perform what the command is supposed to do. After that, it will send back an output.
The microcontroller expects an input packet as follows: The header contains the total size of the packet and the command hex code. If the command requires an input, the next bits after the header shall contain the input parameters. For example, a cmd_normal command with 1.7 GHz start frequency, 3.4 GHz stop frequency, 68 MHz step size, and port set to Port 1. More details can be found on the image below
The general output packet of the microcontroller has the 2 bytes header, 2 byte command, command output (size depends on the command) and the 2 bytes delimeter (0xAAAA). For more details please see the image below.