Frequency Response Analyzer for HT6004BX
User’s Manual
2019/6/22 Euphorie
Table of Contents
1. Environment
2. Installing
4.3 Tutorial: Analyzing of RC Filter Transfer Characteristic
< Supported OS >
l Windows 8.1 32bit
l Windows 8.1 64bit (*)
l Windows 10 32bit
l Windows 10 64bit (*)
(*) These environments are tested actually.
< CPU >
More than 1 GHz. Make sure that the OS works smoothly.
< RAM >
More than 1 GB (32bit). More than 2 GB (64bit).
< Harddisk >
This software uses about 10MB. Make sure that the OS works smoothly.
1) Decompress “HT6004BX_FRA_revXXXXXX.zip” to suitable folder. Execute “HT6004BX_FRA.exe” to start the software.
*CAUTION: XXXXXX is numbers that shows build date.
This software analyzes frequency response by using Hantek USB oscilloscope 6254BD. DDS (direct digital synthesizer) generates excitation signal, transfer characteristics from CH1 (reference) to CH2 and CH3, CH4 are measured, and bode plots are displayed. In the software, software lock-in amp analyzes the amplitude and the phase of each channel very accurately. Maximum frequency is 25 MHz.
This chapter describes how to use the software.
Below picture is the window of the software.
Figure 4.1 The top window of this software
A. [Menu Bar] are used to run each command.
B. [Oscilloscope View] shows the oscilloscope screen for user to check waveforms.
C. [Bode plot] shows frequency response characteristics.
D. [Table] shows measurement conditions and results of each frequency.
E. [Status Bar] shows current settings of the oscilloscope.
Here, available menu commands are described.
4.2.1 File
1) Load Sweep Settings
The measurement conditions and results will be loaded from the CSV file selected by the user, and the loaded data will be shown in the table and the bode plot.
2) Save Sweep Settings
The measurement conditions and results shown in the table will be saved to the CSV file selected by the user.
3) Save Waveform
The waveform shown in the oscilloscope view will be saved to the CSV file selected by the user.
4.2.2 Device
1) Set Oscilloscope Parameters
The below dialog will be shown to set the oscilloscope parameters, for example, horizontal resolution, vertical resolutions of each channel, and trigger settings. However, when the frequency response is analyzing, the condition in the table will be used on a priority basis.
Figure 4.2 Oscilloscope settings
2) Set DDS Parameters
The below dialog will be shown to set frequency, amplitude and offset of DDS output signal. However, when the frequency response is analyzing, the condition in the table will be used on a priority basis.
Figure 4.3 DDS settings
3) DDS ON/OFF
DDS output will be toggled.
4.2.3 Sweep
1) Start Sweep
Measuring the frequency response will be started. After the DDS output is enabled, and then the sweep will run by changing DDS frequency along conditions in the table step by step. While the sweep is running, red line is shown at current frequency position in the bode plot.
2) Abort Sweep
The sweep will be stopped.
3) Set Sweep Points
Input box will be shown to set the number of conditions of the table. If the conditions are increased, appended conditions will be copies of the last condition.
4) Setup Average
Input box will be shown to set the count of averaging of each measurement condition. All of the conditions in the table will be affected.
5) Setup Frequency
The below dialog will be shown to set up frequency of the sweep. The user needs to set start frequency and stop frequency to fill the columns of DDS Freq. and Time/DIV in the table automatically. If Log Scale is checked, the frequencies will be decided to make equally spaced intervals in the log plot. If Optimize Frequency is checked, the DDS frequency will be adjusted to make that the number of sampled points by the oscilloscope will be integer, consequently the accuracy of software lock-in amplifier will be improved. In the usual case, please check Optimize Frequency.
Figure 4.4 Settings of frequency at the sweep
6) Setup Amplitude
Input box will be shown to set the DDS output amplitude. All of the conditions in the table will be affected.
7) Setup Offset
Input box will be shown to set the DDS offset voltage. All of the conditions in the table will be affected.
8) Setup Volt/DIV
Vertical resolution selecting dialog will be shown to set up each channel of the oscilloscope. All of the conditions in the table will be affected.
9) Optimize Volt/DIV
This command will optimize the vertical resolution of each channel of the oscilloscope. Please run this command after measuring the frequency response once. In general, measuring attenuated signal on the condition of the large vertical scale results in a decrease in accuracy, but the command can optimize the vertical scale with the information based on previous measurement results. As a result of re-measurement, more accurate data will be obtained by this optimization.
Note that the below question will be shown before the command is processed. Please confirm whether 50-ohm termination is attached to the DDS out or not, and select correctly.
Figure 4.5 Cofirmation dialog of 50-ohm termination of the DDS output
4.2.4 View
1) CH1-2，CH1-3，CH1-4
These menu are used to select channels in the bode-plot view.
2) Log Scale
Log plot and linear plot in the bode-plot view will be switched.
4.2.5 Help
1) About…
The version information of this software will be shown.
This chapter describes how to analyze transfer characteristics of easy RC-filter.
4.3.1 Connecting of RC-filter
Circuit diagram of evaluated RC-filter is shown in Figure 4.6. In this case, the circuit is built on a breadboard for easy way.
Figure 4.6 Circuit diagram of evaluated RC-filter
Actual built circuit is shown in Figure 4.7. In the figure, connection between the circuit and the oscilloscope is shown explicitly.
Figure 4.7 Actual circuit and connection to the oscilloscope
4.3.2 Flow of measurement
1) Run [Sweep] > [Sweep Points]. Enter 200 as the number of sweep points.
Figure 4.8 Input of the sweep points
2) Run [Sweep] > [Setup Frequency]. In the below
dialog, the range of the sweep frequency is set from 10 Hz to 25000000 Hz.
Note that the user also can open the dialog by double-click on the column [DDS
Freq.].
Figure 4.9 Input of the range of frequency
3) Run [Sweep] > [Setup Amplitude]. Enter 1000mV as the DDS output amplitude.
Note that the user also can open the dialog by double-click on the column [DDS Ampl.].
Figure 4.10 Input of the DDS output amplitude
4) Run [Sweep] > [Setup Volt/DIV]. In the below
dialog, Select 1V/DIV at CH1 and CH2
vertical resolution.
Note that the user also can open the dialog by double-click on the column [Volt1/DIV].
Figure 4.11 Selection of the vertical resolutions
5) Click [View] > [CH1-3] and [CH1-4] to set up the bode plot like the below figure.
Figure 4.12 Settings of the bode plot
6) Run [Sweep] > [Start Sweep] to measure the frequency response. The result of measurement is shown in the below window. In the area of high frequency, decreasing of the amplitude of CH2 causes inaccurate result.
Figure 4.13 First-time result of frequency response measurement of the RC-filter
7) Run [Sweep] > [Optimize Volt/DIV] to optimize the vertical resolution of each frequency. Select [No] in the below dialog, because the DDS output is not terminated by 50 ohm in this measurement condition.
Figure 4.14 Confirm dialog of 50 ohm termination
8) Run [Sweep] > [Start Sweep] to re-measure the frequency response. The result of measurement is shown in the below window. The vertical resolutions of oscilloscope channels are selected precisely while sweeping frequency. As a result, reliability in the high frequency area is improved as compared with first-time result. The user may confirm that the oscilloscope waveform has enough amplitude while measuring.
About cut-off frequency
In this design, 330 ohm register and 0.1 uF capacitor make low-pass filter of 4.8 kHz cut-off frequency. Practically, in this evaluation, the gain is -3.1 dB at 4328 Hz. Therefore the evaluation result is suitable, although some errors are included.
SRF (Self-resonant frequency)
The gain characteristic has the valley at 2.5MHz. This phenomenon will be caused by ESR (equivalent series inductance) of the capacitor.
Figure 4.15 Second-time result of frequency response measurement of the RC-filter
Especial flow is not required. Please delete decompressed folder described at chapter 2.