Blue VNA Android Application User’s Manual

Version 0.9.6 Apr 16, 2016


Dan Toma - YO3GGX - yo3ggx@gmail.com


Please read the Privacy Policy first.
















Contents







Introduction

This is the User’s Guide for the Blue VNA Android only application to control Bluetooth enabled Antenna analyzers or VNAs (Vector Network Analyzers). Supported devices are the miniVNA, the miniVNA Pro Antenna Analyzers (with or without the matching Extender) and the new miniVNA Tiny, manufactured by: mRS mini Radio Solutions.





Features

The current version of the application has the following features:



Limitations

The current version of the application has the following limitations:

Operation

WARNING!!!

Use this application on your own risk. Do not expose the miniVNA or Extender to high RF fields. I cannot be held responsible for any damage caused to your VNA and/or Android device.

Starting the Application

Download and install the current version of the application from the Google Play Store onto your Android device. Search for the name “Blue VNA” or use the link from the top of this document.

If you have installed an older version of the application (0.1 to 0.4), please remove it before installing the new version. The new version has some changes in the structure, so if the previous version is not uninstalled, you will have two versions installed at the same time. There is no need to uninstall the previous version if it is greater than 0.4.

The application can start in two modes, depending on the selected connection mode:



First, select BlueVNA. Select “Always” to automatically start the application each time. To be asked each time, select “Just once”. The application will be started automatically.

NOTE: Please keep in mind, not to start the application manually if you want to use USB mode.

If you start the application for the first time or after a configuration file reset, you will get the following startup page:



Select the type of device: miniVNA: MiniVNA standard, miniVNA Pro or miniVNA Pro with Extender. Select using a gesture by sliding the picture horizontally or directly press one of the buttons: STD, PRO or EXT. You will get one of the following screens:

If you want to start application in Offline mode, press the “START” button.

Press the “CONN” button to connect to the miniVNA. The “CONN” button will disappear and depending on the connection the application will respond as follows:

USB Mode – connection will be established without any prompt;

Bluetooth or Wi-Fi modes –select between one of the two modes.

NOTE: To use Wi-Fi mode, the miniVNA must be equipped (as an add-on) with a Wi-Fi to serial interface or use a COM port redirector if installing this app inside an Android Emulator (like BlueStacks). The miniVNA’s Bluetooth is disabled when it is connected to a USB cable, even if the other end is not connected.

If using Bluetooth mode and Bluetooth is enabled on the Android smartphone/tablet, the application will start searching for nearby Bluetooth devices…

…in a few seconds, the display will list available nearby Bluetooth devices.

Select your miniVNA from the list or Offline mode not to connect to the miniVNA. The connection will be established, the virtual LED (on the “START” button) will become blue and the Bluetooth symbol will be displayed in the top left corner of the miniVNA “START” screen. If Bluetooth is not started, a prompt will appear to start turn on Bluetooth.

Press “Yes”, if you want to enable Bluetooth and search for the device or “No” to use “Offline” mode.

If Wi-Fi mode (if available) is selected, then a prompt for the IP address and port used by your miniVNA will appear.


Enter the data in the format IPaddr:port and then press OK. Connection will be established automatically, the virtual LED on the “START” button will go green and the Wi-Fi symbol will be displayed in the top left corner of the miniVNA START screen.



This is an example on how the symbol in the upper left part of the miniVNA picture will represent the connection mode (USB, Bluetooth or Wi-Fi for a miniVNA standard connected through USB:

The symbol and the virtual LED color on the “START” button will change as follows:

Symbol

Connection mode

Virtual LED color

miniVNA connected over USB

Magenta

miniVNA connected over Bluetooth

Blue

miniVNA connected over Wi-Fi

Green

No symbol

Offline mode

Cyan



When the miniVNA Pro or miniVNA Pro + Extender is selected, the startup page will look like the corresponing pictures:

miniVNA Pro miniVNA Pro + Extender

In the lower left part of the screen is the battery status (voltage). The color will change to yellow when low level and to red when critical. When red, recharging the miniVNA battery is mandatory to prevent battery damage.

To reinitialize or change connection mode because of an unsuccessful connection, long press the “CONN” button.

In the right part of the screen, information about your Android device and connected miniVNA (if any) is displayed. This can be useful to help me debug the application if an error occurs.

NOTE: Please write the information or save a screenshot of the startup screen and send it to me by email or post it on the Blue VNA Application Forum if you have a support request.

If for some reason you want to reset the connection mode or to completely reinitialize the configuration file to fix data corruption, long press on the “START” button. Select between “Connections” (only) or “Everything” (a full reset).

The blue “CONN” button will again be displayed in both cases and select the option to change the device or connection mode. To start using the application in the current mode, press the “START” button.

From now on, the application will behave in the same way for all connection modes: USB, Bluetooth or Wi-Fi. Next time the application starts, the “CONN” button will no longer be present and the last used connection will be automatically established. The only exception is in USB mode. If the application is automatically started when connected to the miniVNA over USB, the USB mode will be initiated no matter which mode was used in the previous session.

If running the application for the first time and no calibration data was previously saved, when pressing “START” you are forced to do a full calibration or to load it from a previously saved file.

Adjust Grid Settings (Mode and Transparency)

The grid looks different on different Android devices, depending on the display technology, quality or screen size. The graph grid can be adjusted according to your preferences. The grid transparency or the grid lines (between dotted or dashed can be adjusted);

If the calibration data was previously stored in the application configuration file, then immediately after pressing the “START” button on a blank graph, the grid can be configured.

NOTE: Only before any other operation (e.g., Capture, Calibration or File Load) can the grid be adjusted!

First, activate as a minimum, the buttons for: SWR, Z, RL and Phase, to display all the available horizontal grid lines.

Then, slide one finger horizontally (gesture) to toggle between dots or dashed line as in the following pictures.

Slide one finger vertically in upper direction (gesture) to decrease grid transparency or lower to increase it. The new grid settings will be saved in the configuration file and will be used at each application start.

Using the Application Menu

The application menu can be accessed in two ways:

For the first option, when pressing the menu button in the taskbar, the main menu items will be displayed.

To see the rest of the menu press “More” in the right. NOTE: Some Androids display this differently.



To access the menu at any time from the main application window press the “M” button in the left part of the screen.

The main menu items will slide to the center of the screen as buttons shown below.

Click on the menu item to select and the buttons will disappear to the left in a short animation.



Reflection (Antenna) Calibration Using the Wizard

If using the application for the first time in any mode except Offline and no calibration data was previously saved, when pressing the “START” button, select to do a new calibration or to load an existing calibration file.



For a new calibration, select the number of passes (between 1 and 5) and press the “(RE)CALIBRATE” button using the thumb wheel. It is recommend to use the maximum value (5) for best results. In this way, 5 successive data captures will average the value calculated for each step. The inherent calibration noise will be highly attenuated.

For a new calibration, as indicated on the display in the following photograph, connect the OPEN calibration reference to the DUT connector (or leave both connectors open for miniVNA standard) and then press the “OK” button.


NOTE: The calibration references should be connected with only finger strength tightness, firm, not too tight and not loose. No tools should be used to connect or remove the calibration references.



A progress message will be displayed. When the OPEN calibration is completed, remove the OPEN calibration reference from the DUT connector.




For the miniVNA Pro, connect the SHORT (0 ohm) calibration reference to the DUT connector as shown in the following photograph and press the “OK” button again.



A progress message will be displayed. When the SHORT calibration is completed, remove the SHORT calibration reference from the DUT connector. Then, connect the LOAD (50 ohm) calibration reference to the DUT connector as shown in the following photograph and press the “OK” button again.”



A progress message will be displayed. When the reflection mode calibration is completed as shown in the photograph below, remove the LOAD calibration reference from the DUT connector.



If all 3 steps completed okay, the corresponding buttons on the right side will indicate green on their virtual LEDs. In turn, press each of these buttons to see the calibration graphs for OPEN, SHORT and LOAD, which looks like the graphs in the following pictures (i.e., for miniVNA Pro). The large “R” in the background shows the miniVNA is in the reflection calibration mode.




OPEN calibration SHORT calibration LOAD calibration


Optionally, but strongly recommended, save the calibration data in a file. For this purpose press the “SAVE” button. A window will be displayed with the list of available calibration files. In the application, there is a demo calibration included named “calib.pro” that can be used in Offline mode if you don’t have (yet) a miniVNA device.

Press inside the cyan text entry box to open the virtual keyboard and then enter a name for your file without an extension.



When ready, press the “SAVE” button to save the file. A confirmation that the file was saved successfully will be displayed. To cancel the action, long press the “SAVE” button or slide the top of the box to the right (gesture) to make the window box disappear.

To load a previous saved calibration file, press the “LOAD” button, a list of available calibration files for your miniVNA model (if any) will be displayed.



Press the calibration file to load and a confirmation message that the calibration data was successfully loaded.



To cancel the operation, slide to the right the top of the box (Gesture) to make the display box disappear.


NOTE: The frequency calibration data can be added later, if you save (again) the file after a frequency calibration is performed.


To save the calibration data in the configuration file and start measuring, press the “USE” button. This will transfer operation to the Reflection mode screen. See Using Reflection Mode chapter on how to use this mode.

Transmission Calibration Using the Wizard

After the reflection calibration, go to Transmission mode by selecting “TRANSMISSION” through the application menu. See Using the Application Menu chapter. If no transmission calibration was performed before, a prompt will appear to do it now through the same wizard as in Reflection Calibration mode.

First, connect the OPEN reference to the DET connector and press the “OK” button as shown below. Reminder: Use only finger strength tightness to make connections.



When completed, remove the OPEN reference from the DUT connector. Then, connect a short 50 ohm cable between the DUT and DET connectors and press the “OK” button as shown below.


When completed, a confirmation message that the transmission calibration data was captured successfully as shown below. Press the “OK” button to hide the message. The two virtual LED buttons, under the “RUN” button, will become green to indicate that both OPEN and LOOP calibration were performed and a completed message is displayed as shown below.



Like in the Reflection Calibration mode, it is highly recommended to save/load calibration data in a file.

The graphs for the two calibration steps are shown by pressing the corresponding button. The graphs must look similar (not exact) with those presented in the following images (based on specific devices tolerances).


OPEN calibration LOOP calibration


NOTE: For both Reflection and Transmission Calibration, the vertical scale of the graph is in relative units, with no other meaning. The graph uses auto scale to better represent the trend which must be similar for miniVNAs of the same model.

The next step is to press the “USE” button to save the Transmission calibration data in the configuration file and return to the Transmission mode.


You are now ready to use your device for “real life” data captures for Reflection and Transmission modes.

Frequency calibration is not too important for the Reflection and Transmission modes, so skip it for the moment.


A similar calibration procedure applies for the miniVNA Standard, but some of the steps are not available on the standard version. If using the Extender, the same procedure applies. See the note below.


NOTE: Separate calibrations are required with and without the Extender. In order to prevent a recalibration each time, the calibration data is saved separately in the configuration file. Save both calibrations in separate files, with a distinctive name. To load the calibration data after a reset, separately load it for Pro with and without extender modes. The application prevents loading the wrong calibration, so a prompt will be shown in case of error.

Using the Main Application Screen in Reflection or Transmission Mode

The screen will look like the following images for each respective mode:


Reflection mode Transmission mode


On the left side are the scales for SWR and Loss. On the right side are the scales for Z, Rs, Xs (all in ohms) and Phase (in degrees). Phase is between -180 and 180 for the miniVNA Pro and between 0 and 180 for the miniVNA standard. Xs has an absolute value for the miniVNA standard and a signed value for miniVNA Pro. Negative value for Xs is displayed as a dashed line on the graph.


After a data capture is completed, select which graph to display using the checkboxes on the right side of the screen.

In Transmission mode, only Loss and Phase graphs can be selected for display.


When the application is started for the first time, the full available range of frequencies is selected.

The frequency range can be changed by pressing on the “FREQ” button. A window will pop up allowing directly selection of one HAM band at a time, the full range or a custom frequency range.



A long press on the “FREQ” button will reset to the full frequency range.

Long press on the “10m” button will select the CB (11 meter) band.



To enter a custom frequency range, press the “CUST” button. Another window will appear to change the minimum and maximum frequencies (in MHz).



A short press on the “CLR” button will delete the last entered digit or long press to delete everything from that field.

When ready, short press the “SET” button to use that frequency range for the next data capture. To cancel the operation, long press the “SET” button.

Changing Application Font Size

In the current version, the application font size is automatically set to an optimum value, independent on the system settings. However, to modify the font size, from the graphical menu or system extended menu select the “FONTSIZE” button. This can only be done in Reflection or Transmission mode. For the other modes an error message will appear:



In the correct menu, a screen will be shown like the following:



Slide one finger vertically (gesture) anywhere over the grayed zone (up or down) to increase or decrease the application font size. The new font size will be modified in real time, so choose the optimum size according to your preferences.

When ready, slide one finger horizontally (gesture) over the grayed zone to exit this mode through an animation. The new font size will be saved in the configuration file for further use.

At next start, the new font size value will be displayed in the information section of the startup screen.

Manual Calibration

Sometimes a recalibration for a specific mode is needed and you don’t want to use the wizard. Press on the “Cancel” button when prompted and select from corresponding button the type of calibration and then press the “RUN” button.


When ready, press the “USE” button to save the new calibration values in the configuration file.

Using Reflection Mode

To start a data capture, short press on the “RUN” button. A standard data capture begins using 1000 steps and takes about 5 seconds to complete.


The “RUN” button virtual LED becomes red during the data capture and then a short message will be displayed. At the end of the data capture the “RUN” button virtual LED will become gray again.


Long pressing the “RUN” button will start a continuous data capture. For a higher frequency sweep speed, in continuous mode only, the data capture is done with only 100 steps, enough for an estimation of the parameters.


The “RUN” button’s virtual LED will remain red during the continuous data capture and the button name will change to “STOP.”

To stop the continuous data capture, press the “STOP” button. The graph will disappear for a few seconds and a full data capture will be completed automatically with (with 1000 steps).


NOTE: The same graph can be obtained in Offline mode, if the provided demo-pro.vec file is loaded. This can be done through the FILE LOAD menu or by just pressing the “RUN” button when in Offline mode.



Press a button on the right side corresponding to a parameter to display on the graph. The corresponding graph will be displayed with the same color as the button.


Negative Xs values are displayed with a dashed line (only for miniVNA Pro).

Displaying the Vertical Marker

Slide one finger (gesture) from the top to the middle of the screen in the horizontal position to place a marker. The marker will be displayed in that position as a white dotted vertical line. A box will appear at the left lower corner. All selected parameter values will be displayed. The box can be moved anywhere on the screen by dragging it. The marker can be moved the same way.



To remove the marker repeat the same gesture as before but in opposite direction, from the middle of the screen to the top. The marker size box can be toggled between normal and full screen size by one tap on it. In full screen mode, it will look like the following image:



Finding the Frequency for the Minimum SWR

When in Reflection mode, slide your finger (gesture) from the middle to the bottom of the screen. This will toggle the display of a grayed box containing all the selected parameter values for the frequency where the SWR has a minimum value.


Besides the values for the selected parameter values, the bandwidth (Δf) for a SWR < 3:1 will be displayed too. If minSWR is > 3:1, then the bandwidth value will not be displayed.


Tapping on the box with the values will toggle between standard and full screen mode which can be useful for work outside to tune an antenna.


Reversing the gesture (middle to bottom) will close the box.


Zooming and Shifting the Graph (Frequency Axis)

Use Android’s “Multi Touch” feature to zoom the graph horizontally or to shift to the left or right, inside the limits of the captured data. By default, the capture is done with 1000 steps, so even if you zoom into the graph, the quality will be maintained. Use two fingers to touch the screen and spread them to zoom in, bring them together to zoom in.




In the following pictures, the original data capture file (top) at full frequency range and then zoomed to the interest zone (bottom) without data recapture.

Full Frequency Range


Zoomed in Frequency Range


Only when zooming, the zooming level is displayed in the lower right corner of the graph.


You can revert to the default display (no zoom, no shift) by simply sliding 3 fingers (gesture) anywhere on the display.

Extend the Display

A useful feature, especially for small screen devices, is to extend the graph to full screen. Tap the screen on the left side of the Y axis in the Loss and SWR values zone.



The buttons from the right side will disappear.



To display the buttons, tap again in the same area.

Changing the Impedance Scale

There are 3 possible scales for the impedance: 1000, 500 and 100 ohms. The default scale, the one when the application is started, is 500 ohms.


To change the scale, long press on one of the impedance buttons (Z, Rs or Xs). The scale will be changed in the following order: 500-1000-100-500….



Saving Data to a File

To save captured data, select “FILE SAVE” from the extended menu bar “More.”

A small window will appear prompting to enter the name of the file to save without the extension.



If the Smartphone/Tablet does not have a SD card, data will be saved in the internal memory. The file will be automatically created with the .vec file extension. Enter the name without the extension in the cyan data field from the top or select an existing name to override the file and then press the “SAVE” button.

To cancel the operation, slide a finger from left to right (gesture) over the “SAVE TO FILE” text on top. The window will disappear in a short animation.

Using the Smith Chart

The Smith Chart can be initiated only in Reflection mode.

There are two options to activate the Smith Chart when in Reflection mode: using the menu (press on the “SMITH CHART” button or long press the menu “M” button. The Smith Chart will appear as in the following screen:



The Smith Chart screen contains the following fields:











dot;





Note the following is possible, a full 1000 step data capture in the Online mode (press the “RUN” button), continuous capture with 100 steps (long press the “RUN” button) or use a loaded or imported data (use the “LOAD” or “IMPORT” button from the menu).

Using the Transmission Mode

To use Transmission mode, select it using one of the menus. The operation is similar to the Reflection mode. The difference is that measurements are made using two connections, one generating a signal as an input to the device under test (DUT) and the other connection as an input detector (DET) where the transmission measurement is made. Only Transmission Loss and Phase measurements are available as values.

The Transmission Loss scale is automatic. 3 steps are used for the end scale values: 30 dB, 60 dB and 90 dB. This is used to get as much dynamic range as possible without user intervention.

Taking a Screenshot

To take a screenshot of what is currently displayed, touch the screen with four fingers at the same time. A short message will confirm that the image was saved to a file.


The name of the file has the following format: miniVNA-MMDDYYHHmm.png


…where

MM is the month (01-12),

DD is the day (01-31),

YY is the year (12),

HH is the hour (01-24) and

mm is the minute (01-59).


The PNG picture is saved in the /btvna/exports folder.


Loading Data from a File

To load data from a .vec file, select “FILE LOAD” from the extended menu. A small window will appear prompting to select the file to load. Touch the desired file. Follow the same steps described in the Reflection Calibration procedure.On the left side of the screen, in the background, a vertical text showing the current VNA model being used, but only if you load a file saved for a different VNA type than the one currently selected in the startup page. The name of the loaded file is displayed in Cyan color in the upper middle part of the screen.


Exporting Data to be Used in External Applications

BlueVNA is able to export data in 3 different formats: Zplots, S1P and CSV. The file formats are shown in the following examples:

"Frequency(Hz)","Return Loss(dB)","±Phase(deg)"

1000000.000000,0.829000,128.496094

1029029.000000,1.063800,160.136719

1058058.000000,1.005100,159.609375

1087087.000000,1.005100,158.906250

Frequency(Hz),Return Loss(dB),Phase(deg),Rs,SWR,Xs,|Z|

1000000.000000,0.829000,128.496094,4.349966,14.158465,23.997530,24.388597

1029029.000000,1.063800,160.136719,4.331952,11.895669,8.718664,9.735549

1058058.000000,1.005100,159.609375,4.165849,12.390331,8.959275,9.880430

! created by BlueVNA at 11/24/2012 19:22:57

! generated using BlueVNA Android app v0.5.9.5

# MHz S MA R 50

130 0.9163369523325197 144.1483154296875

130.03003 0.9070582405335701 144.41029357910156

130.06006 0.9086618422139108 144.4204559326172

130.09009 0.9079785936809234 144.38973999023438

130.12012 0.907173630498886 144.31277465820313

NOTE: See Bibliography for more details about each format.



To export data, select “FILE EXPORT” from the main menu. A window will be displayed with a list of existing exported files including their extension.

Enter the name of the file in the cyan data field on top or select an existing file to override it.


NOTE: Selecting a different file type to export (i.e., .csv and export it in .s1p) the previous file will not be deleted, but a new file will be created using the same name but with a different extension.

Press the button corresponding to the format in which you want to export the file.

The file will be saved in the “/btvna/exports” folder.

If you want to cancel the operation slide the finger (gesture) from left to right over “EXPORT TO FILE” text on top. The window will disappear in a short animation.

Importing Data from External Applications

Blue VNA imports data only in the CSV format. The file format must be exactly the one used to export in CSV format:

CSV (extension “.csv”) and captured with 1000 steps:

Frequency(Hz),Return Loss(dB),Phase(deg),Rs,SWR,Xs,|Z|

1000000.000000,0.829000,128.496094,4.349966,14.158465,23.997530,24.388597

1029029.000000,1.063800,160.136719,4.331952,11.895669,8.718664,9.735549

1058058.000000,1.005100,159.609375,4.165849,12.390331,8.959275,9.880430

To import a CSV file, press on the corresponding menu item and then select the file from the list of available files of that format. An error message will appear if the file is not in the correct format and the import will be canceled.

This function can be useful to display data captured with another applications (i.e., to display a Smith Chart).

Using Generator Mode

miniVNA Pro without Extender

In the main Menu, press “GENERATOR” to enter the Generator mode. A screen like the following image will appear.




The basic interface provides the following components:


To set a specific parameter, short press the button and it will start flashing. The “STOP” button name will change to “STORE”. This allows changing the value using the rotary knob. The rotary knob has an acceleration feature, so rotating the knob faster will alter the rate of steps being changed.



All selected parameters are changed the same way.


When all parameters are set, press the “STORE” button to disable further editing. The button name will change back to “STOP”.


Long pressing on a parameter other than PHASE the rotary knob will be replaced by a numeric keypad.



Use a short press on the “C” button to delete the last digit or a long press to delete all digits.

Again, when ready, press “STORE”.


The generator can operate in NORMAL (manually or live) or SWEEPER mode. To toggle between the operations modes shortly press the green “MODE” button. Current mode is displayed as in the following pictures.



To operate it manually, short press on the “START” button when in NOR mode. The button will change to orange color and the button text to “SET”. At the same time, the miniVNA generator is started with the configured parameters. Any further change in the displayed values will not change the generator until the next short press on the “SET” button.



To stop the generator, press on the “STOP” button.


To operate the generator in Live (NOR) mode, long click on the “START” button. The button will change to red and the button name to “LIVE.”


Any change in the displayed values will be automatically transferred to the generator. If no changes are made, no command is transmitted to the miniVNA to prevent the inherent noise associated with the changing of the generator parameters. To stop the generator, press on the “STOP” button.


In sweeper mode the GUI will look like in the following picture:



To set the SWEEPER (SWP) parameters long press on “MODE” button when in SWP mode or press the area containing sweeper configuration data in the lower left part of the screen. An overlay will be displayed which will help you to set the parameters values as follows:

Fmin[MHz] – start frequency in MHz;

Fmax[MHz] – end frequency in MHz;

Swp Steps – number of steps for the sweeper. If empty or 0 then use 1;

Tstep[s] – duration of a step in seconds. Minimum value is 0.1s. Any empty value or below 0.1 will be automatically changed to 0.1s.

Passes – number of passes for the sweeper. This is an integer greater than 1.



After you enter all the parameters press “SET” button to save them for future use. Values are stored in the configuration file. Now you just have to press “START“ button in order to start the Sweeper. To stop it at any time, even the sweep cycle is not ended, just press on “STOP” button.

miniVNA Standard/Pro with Extender/Tiny

For a miniVNA standard or miniVNA Pro with the Extender, only one channel output (DUT for miniVNA standard and TX for Extender or Tiny) is available. The GUI will look like in the following picture in NORMAL mode.



In SWEEPER mode the GUI will look like in the following picture.



NOTE: You cannot set the output level for miniVNA Standard, Pro with Extender of Tiny.

Frequency Calibration

miniVNA Pro without Extender

To calibrate the frequency generated by the VNA that also applies to all other operation modes, select “CALIBRATE” from the extended menu when in Generator mode. The display will change as in the following image:




To calibrate, use a very well calibrated frequency meter connected to DUT (miniVNA Pro without extender or miniVNA standard) or TX (miniVNA Pro with Extender). The available frequency range is the one supported by your miniVNA model (0.1-180 MHz for miniVNA Standard, 0.1-200 MHz for Pro without Extender and 40-1500 MHz for Pro with Extender). In this example, the miniVNA will be calibrated using a 10 MHz reference.


Enter 10.000000MHz in both the “REFERENCE FREQ” and “GENERATED FREQ” and long press on the “START” button to start Live mode. Use the frequency meter to measure the generated frequency. Fine tune “GENERATED FREQ” (+ or -) using the knob until the frequency meter will show exactly 10.000000 MHz and then press the “SAVE” button.



Frequency calibration is completed. Save the frequency calibration data in a calibration file that can be used after a configuration file reset.


NOTE: If the calibrations for reflection, transmission and frequency are done first, then save it to a file, as the data for all 3 calibrations will be stored in the same file, so load just one file to recover all calibration data.

miniVNA Standard/Pro with Extender/Tiny

The GUI for frequency calibration will look like in the following picture.



Enter the reference frequency in MHz and press “OK”. Reference frequency will be displayed. Start LIVE mode and change the frequency with the tuning knob till the generator output exactly the reference frequency, then press SAVE.

The correction coefficient will be displayed and the interface will go back to generator mode.

Using Cable Mode

To enter CABLE mode, select “CABLE” from the Main Menu. A new screen appears as in the following picture:



The interface provides the following controls:

To measure a piece of 50 ohm coax with a length between 1 meter and hundreds of meters, connect one end to the DUT connector of your VNA and leave the other one open, then press the “RUN” button.



The button will become red during the first step of the data capture.



If the cable length is more than a few meters, then the process will be two steps. During the first step, an intermediate value for the cable length will be calculated using the whole available frequency range for that specific miniVNA and the “RUN” button will soon become yellow. When the measurement is finalized, the “RUN” button becomes gray again and the calculated data is displayed.




There are 2 graphs in the background. The red graph is for the Return Loss and a green one for Phase. The green graph is used to calculate cable length.


The cable Type / Velocity Factor can be changed using the upper wheel for the frequency where cable loss was measured with the lower wheel. The LENGTH and LOSS data fields will be automatically updated.

The Velocity Factor can be manually changed by pressing on the value data field. The data field becomes cyan and allows manually entry of the new Velocity Factor from the numeric keypad.



Press the “CALC” button to recalculate the cable length based on the newly entered Velocity Factor. There is no need to run a new data capture.


The cable length factor can be manually changed by pressing on the value data field. The data field becomes cyan and allows entry of the new cable length from the numeric keypad. Take care to use the current scale, feet or meters.



Press the “CALC” button to recalculate the Velocity Factor based on the newly entered cable length. There is no need to run a new capture.


NOTE: In the current version, the cable loss measurement is only approximated. Perhaps in a future version a better algorithm to provide higher precision is being considered. For higher precision for now, use the Transmission mode, but access to both ends of the cable are required.

Adding a New Cable Type

For this purpose, first run a capture for the new cable. Then, change the parameter value for the Velocity Factor and press the ‘CALC” button. A prompt will be provided to save the new cable type.



Enter the name of the new cable and press the “SAVE” button. The new cable type will be added at the end of the list. To cancel, press the “CANCEL” button. The data is saved in the application configuration file and will be available at the next application start. The value is lost in the configuration file if a reset operation is made.


Displaying miniVNA Battery Status

When in Online mode, connected to the miniVNA, its battery voltage is displayed on the screen in both Startup and the main page for Reflection and Transmission modes only).



The voltage is displayed with black characters on a colored background. The color of the background depends on the battery voltage as follows:



A fully charged battery displays a voltage of about 4.2V. The miniVNA will probably stop working if the voltage is below 3.1V.

To toggle the battery level display, press on it and the background will become semitransparent gray.


Using SM6ENG Audio Mode

The purpose of this mode is to adjust SWR to minimum without having to look at the display. One very practical use of this function is for outdoor antenna adjustments. It's hard to read a display on an Android phone in bright daylight. Further, both hands are used when adjusting an antenna. In this mode, an audio sine wave tone is heard in the speaker or earphones of the Android device. Be sure to set the device volume.


The pitch of the audio tone is dependent of the SWR reading for the selected measurement frequency. The higher the SWR, the higher audio pitch. For an SWR=1:1, the pitch is 400 Hz. For an SWR=2:1 the pitch is 1200 Hz. When the pitch is close to 5 kHz for the upper SWR of about >1:30 and this is the upper limit for this function. To obtain good audio resolution for low SWR values and still have a large dynamic range, a logarithm function is used, as illustrated in the following diagram:




When using this function, adjust for the lowest pitch and when this has been found, look at the display in order to see the actual SWR value.

The formula used for the generated frequency is the following:


f= 400 + 2657.5*log(SWR) [Hz]


To activate the SM6ENG Audio mode use the following steps:


NOTE: The SM6ENG Audio mode is also useful to locate bad connections. If the pitch of the audio tone is changed when a cable or connector is moved, then this is an indication of a bad connection.


Using XLC Mode (Experimental)

In this mode you can measure X-tals (resonance frequency and Q), inductors (inductance, Q, resonance frequency and parasite capacitance) and capacitors (capacitance, ESR, parasite inductance and resonance frequency).

NOTE: Considering the limitation of miniVNA in terms of impedances, this mode provides acceptable results only for small capacitors (< 1nF) and small inductors (< 100uH). Any feedback or suggestions for improvement are welcome.

To enter this mode press “XLC Toggle” in the graphical or in the extended menu when in any other mode. This will force the standard reflection mode with an overlay containing XLC data.



Select desired measuring mode (XTAL, L or C) from the respective buttons. Color code is used for the modes and parameters, as follows:

Connect the component to be measured to the DUT connector using shortest wires possible. I’ve built for myself a simple adapter like in the following pictures (still too big/long for very low value capacitors or inductors).



For best results try to recalibrate for OPEN, SHORT and LOAD (50ohm) with the adapter connected. Take care to use a 50ohm non-inductive resistor with as shortest leads as possible.

XTAL mode

You can measure X-tals in manual or in auto mode. In manual mode, you need to enter Fmark (Marked frequency) parameter in MHz. This is the value printed on the X-tal case. To use auto mode do not enter any Fmark value or enter 0.

The measuring is done in two passes (2 or 3 captures will be performed, depending on the X-tal quality factor) if manual mode is used or multiple passes if auto mode is used (several captures over small successive frequency ranges).

To edit Fmark value press on the value (“0.0” in the picture above). A numeric keypad will pop-up.


Enter the desired value and then press RUN button to start a measurement cycle. After 2 or 3 captures the following parameters will be displayed:

This is how the result will look for an X-tal of 4MHz.



In manual mode the resonance is searched for an interval of +/- 300KHz around Fmark frequency.

If you choose the auto mode, this may take a lot of time as the resonance frequency is searched using first brute captures over 1MHz chunks, starting with 1MHz. In this way you can find the fundamental frequency, which is not always the same as the one printed on the X-tal (which may be the 3rd harmonic).

The resonance frequency is determined by the Xs value passing through 0.


NOTE: Auto mode is limited to max. 50MHz in software.


You can switch at any moment in time to Smitchart mode for graph representation. The frequency interval is kept when you switch to normal (Reflection mode) if you want to see the full graph, not covered by the values overlay.

If you select manual mode with a Fmark value outside the X-tal resonance frequency +/- 300KHz or the X-tal is defective, you will get an error. Let’s take the example of the same 4MHz X-tal measured with a Fmark value of 2MHz.



You can remove the overlay and go back to standard Reflection mode keeping the graph (even if in Smitchart) by pressing again on the menu button “XLC Toggle”.

L mode

Select this mode by pressing L button (will go red) when in XLC mode. In this mode you can measure the following parameters of an inductance:

A 2 passes capture is done. First one, over the full available frequency range, is used to determine the auto resonance frequency. The second pass capture is done over a frequency range from 0.1MHz (minimum available for miniVNA) to 1.2*Frez, for better accuracy.

If the inductance auto resonance frequency is higher than the miniVNA maximum available frequency (200MHz for miniVNA Pro), then a single pass capture is done.

The inductance (L) is calculated at Fmark = Frez/20 from the resonance frequency using the following formula:

L=Xs/(2*π*Fmark)

The quality factor (Q) is calculated using the formula:

Q=X/R for the selected frequency range

The parasitic capacitance is calculated based on resonance frequency, using the formula:

C=1/L*(2*π*Frez)­­2

­L, C and Q graphs will be displayed in the background for the selected frequency range. As arbitrary values are used for the Y axis there is no marking. The same color code is used for the graphs.

After a capture you can activate the marker and drag it over the frequency range to read measured values based on frequency. If you run a capture with the activated marker, then a single pass capture is done and Fmark is set at the marker position.

C mode

Select this mode by pressing red C button (will go yellow) when in XLC mode. In this mode you can measure the following parameters of a capacitor:

A 2 passes capture is done. First one, over the full available frequency range, is used to determine (if possible) the auto resonance frequency. The second pass capture is done over a frequency range from 0.1MHz (minimum available for miniVNA) to 1.2*Frez, for better accuracy.

If the capacitor auto resonance frequency is higher than the miniVNA maximum available frequency (200MHz for miniVNA Pro), then a single pass capture is done.

The capacitance is calculated at Fmark = Frez/20 based on resonance frequency, using the formula:

C=-1/(2*π*Fmark*Xs)

The parasitic inductance (L) is calculated from the resonance frequency using the following formula:

L= 1/C*(2*π*Frez)­­­2

L and C graphs will be displayed in the background for the selected frequency range. As arbitrary values are used for the Y axis there is no marking. The same color code is used for the graphs.

After a capture you can activate the marker and drag it over the frequency range to read measured values based on frequency. If you run a capture with the activated marker, then a single pass capture is done and Fmark is set at the marker position.

Changing default DDS frequency (not available in Tiny mode)

To change the default DDS frequency, when you are in miniVNA Standard or Pro mode slide the finger vertically over the info box in the right part of the startup screen. The following box will be displayed:


You can enter only one of the following values for miniVNA Standard: 180, 192, 196, 400 or 1250 MHz.

You can enter only one of the following values for miniVNA Pro: 500 or 520MHz.

Using Offline Mode

The application can be used without a miniVNA device, in Offline mode. To enter the Offline mode:

When in Offline mode, the virtual LED in the left lower corner and will become Cyan.


When in the Offline mode by pressing the “RUN” button, it will automatically start the FILE LOAD routine, independent of the operation mode (REFLECTION, TRANSMISSION or CABLE). Loading previously saved file or files saved with the Windows application (in miniVNA standard mode) can be done.

Blue VNA can operate in the Offline mode in the same manner as in Live mode for all modules.



Loading an Exported File in the Zplots Application

Use the procedure described in the previous chapter to transfer exported files to a PC. Exported files are located in the “/btvna/exports” folder.



Open “ZPlots.xls” to start AC6LA Software - Zplots Excel application.

Follow the instructions provided by Dan (AC6LA) in his web page.

Zplots is an Excel application that allows exported data from VNA Blue or other sources to be plotted. Plots can be an XY axis chart, a Smith Chart or in a tabular format.

The XY axis chart can be customized with a choice of trace lines. Frequency (in MHz) is always shown on the X axis on the primary (left side) or secondary (right side) Y axis. The following data can be plotted:

Using the miniVNA Extender

Operating with the Extender is done in the same way as using a miniVNA Pro without the Extender. There are small differences that are presented below. To use the Extender mode, select the picture containing both miniVNA Pro and the Extender in the startup page.

Calibration

Use the same procedure as without the Extender and at the end save the calibration data with a relevant name, to make it easier to switch between Extender and non-Extender mode.

Main Display

When using the Extender, there is a small label (“EXT”) on the left side of the display showing the Extender is in use.


Frequency Selection

When using the Extender, the minimum and maximum frequencies for the Extender operation are limited to 40-1500 MHz, that displays a different frequency enter frame. See the image below:



The entry mode is the same as without the Extender.

Reflection, Transmission and Cable Modes

When using the Extender, there are hardware differences and limitations. The data capture in Extender mode takes longer than without the Extender. Data saved with the Extender has the same format.

Generator Mode

When using the Extender, the Generator mode has limited functionality in the current firmware version. There is only one output (TX) and there is no variable attenuator function.



The operation mode is the same as for the miniVNA standard.

Practical demonstration

A short demo of the operation is on YouTube: http://youtu.be/jY4g-aW96t0

This video shows an older version of the application (0.4) which does not support miniVNA Pro, Tiny or the Extender.

Other demo videos will be added in the future, so please subscribe to the YO3GGX channel to be informed.

Please send your feedback. Further development of the application fully depends on YOU.

Bibliography


Special thanks goes to Bertil (SM6ENG - http://www.qrz.com/db/SM6ENG) for continuous feedback on each subversion and for the idea of SM6ENG Audio mode;

Application History

Version 0.1 (Aug 5th, 2012). Initial version of the application (v0.1)

Version 0.2 (Aug 12th, 2012):





Version 0.3:



Version 0.4 (Sep 23th, 2012):


Version 0.5 (Nov 7th, 2012):



Version 0.6 (Nov 25th, 2012):



Version 0.7 (Dec 15th, 2012):





Version 0.8 (Dec 10th, 2013):



Version 0.8.1 (Dec 13th, 2013):

Version 0.8.3 (Feb 25th, 2014) – Not a public release:

Version 0.9 (Mar 10th, 2014):

Version 0.9.3 (Mar 25th, 2014):

Version 0.9.4 (Jul 3rd, 2014):

Versions 0.9.4-1 – 0.9.4-9 – Intermediary versions, included changes described for version 0.9.5

Version 0.9.5 (Jul 22nd , 2015):

Version 0.9.6 (Apr 15 , 2016):

bluevna_v0.9.6.pdf Bucharest, Apr 16, 2016 – © Dan Toma – YO3GGX – yo3ggx@gmail.com

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