(j)ava (A)udio and (Re)mote (C)ontrol

A Java multiplatform application to make your transceiver available for CAT and audio transfer securely over the LAN or WAN

Version 3.0

Dan Toma - YO3GGX - yo3ggx@gmail.com


This is a very simple to use multi-platform Java application which can be used to redirect one of your computer serial ports and audio channel to an Ethernet connection. Using jAReC you are able to connect to any serial port (Computer embedded, USB/Serial adapter or Bluetooth adapter) remotely over the network along with a bi-directional audio channel (by using a special client). Some of my Android applications, are able to serially connect over Ethernet so this can be useful addition. My PocketRxTx Android application can use the secure login authentication feature to securely connect and control (CAT) your radio transceiver remotely over Internet, including audio support.


The current version of the application has the following features:

IMPORTANT!!!: When using jAReC with Pocket RxTx (free or PRO), you must ensure both pieces of software are at the same version number. To find current version, use Help > About in jAReC or short press on the application name on the startup page in Pocket RxTx.


Current version of the application has the following known limitations:


Use this application at your own risk. I cannot be held responsible for any damage caused to your system by use of this program.

Starting the application


To start the application in Windows, as long as you have previously installed the Java Runtime (from Oracle), just may simply click on the file (jAReC.jar). The following window will appear:


Using a terminal enter the following command when you are in the folder containing the program file:

java –jar jAReC.jar

NOTE: With java runtime version 9, you may get the following error:

ES2 Prism: Error - reported GLX version = 1.2

GLX version 1.3 or higher is required

If this situation occurs, run the application using the following command:

java -Dprism.order=sw -jar jAReC.jar

A window similar to this one will appear:

Mac OS

Using a terminal enter the following command when you are in the folder containing the program file:

java –jar jAReC.jar

A window similar to this one will appear:

NOTE: This application is not yet compatible with Java 9, so please use the latest available 8u version. Currently was tested with Java SE Runtime Environment 8u192 downloaded from here.

Configuring Authentication

From the Config menu select “Security”. You will get a window similar to this one (on all platforms):

Check to select/unselect authentication. Encryption is not available in the current version, only secure login authentication. Authentication is de-selected by default. Enter a secret password in the white entry field. This must be a string longer than 3 chars and cannot contain a ‘*’ char. When you are ready click “OK”.

Configuring Audio

From the Config menu select “Audio”. You will get a window similar to this one (all platforms):

You need to select Audio In and Audio Out devices to point to the audio interface required. When using this with PocketRxTx it will be the interfaces connected to the transceiver.

Check “Use Audio” and press OK.

Configuring Custom Commands for use with PocketRxTx

From the File menu select “Custom Cmd”. You will get a window similar to this one (on all platforms):

To add a new custom command, enter the command/script with the full path in the text box, then press “Add”. The command will be saved using the first available index, ‘02’ in the first available.

Use this index to assign the command in Pocket RxTx Pro, as “Command02”.

In this example, when “Command02” is executed by pressing an option button in Pocket RxTx Pro, Notepad is launched on the PC where jAReC runs.

You can select from the dropdown box any already saved custom command and edit it. When you finish editing, press “Replace”. You can delete a selected command by pressing “Delete”. When you are finished, click “Cancel” to return to the main window.

For custom command definitions that have backslash or colon in them (such as windows command line) please use “/” instead of “\” and replace “:” by “*”.

Using the main application screen

When you hover the mouse over one of the windows controls a tooltip will be displayed to better describe the function of that control.

In order to use the application, you will need to configure the following parameters:

This port will be used for CAT or CAT and PTT if you choose to control PTT through RTS or DTR signals from the same port.



Mac OS

NOTE: Please be aware that if you also wish to stream bi-directional audio, The UDP port of the same number as the selected TCP port is used, so it must also be free.

After you have configured all 3 parameters, click the START button to start listening for a network connection on the defined port. If the chosen serial port is free, then the computer will start listening on the network port and the window background will change to yellow:

The IP address of the computer will be displayed in the field “My Local IP Address” when you press the down arrow at the end of this field.

NOTE: If your computer has multiple IP addresses, only the first one is displayed.

You can now remotely connect to that socket (a socket is the pairing of IP address and TCP port, for example: When using PocketRxTx this is done in the background for you, as long as you have configured the network panel correctly in that Android App.

The application window background will be yellow when listening for remote connections.

When the remote connection is established successfully, the window background will change to green and the remote IP address will be displayed instead of local IP, as shown in the following picture:

All the parameters are now saved in the configuration file. If you close and then restart the application, the form will be automatically filled from the saved parameters, so there is no need to configure them again.

If you want that the application to automatically goes into the listening mode when started, check “Autostart”. (this is useful in an unattended situation where you are not present to press the “Start” button).

At any time, if you click on STOP button, the connection will be dropped and the window background will go back to gray.

When transmitting (PTT pressed in Pocket RxTx), the background will go red and the microphone audio level will be shown as a bar graph, in the lower part of the window.

A bargraph in the lower part of the screen is used to display audio level. The label changes from Spk (for Rx audio level) to Mic (for Tx audio level) as appropriate.

You can simultaneously start several instances of the jAReC application, one for each serial port you want to give access to through the network. For example, if you have multiple transceivers, you can start one instance if the application for each of them. The only requirement is to use different TCP port for each connection, in order to have unique network sockets.

The serial Port can be not only a local physical serial port (like the physical RS232-COM on the motherboard or a USB/Serial interface) but also a virtual COM port, for example the one created by a Bluetooth interface. You can hence use jAReC to connect to your Bluetooth serial device over the network.

The configuration file

When you first download the Java application from my web site, there is no configuration file. This is automatically created when jAReC is first run. The configuration file resides in the same folder as the jar file. You can edit the configuration file using a simple text editor (do not use a Word processing program as their formatting can render the file unusable). The filename is jsn.cfg and the format is shown below:

#Wed Sep 21 17:12:29 EET 2016

















Each parameter is self-explanatory, and correspond to the parameters entered via the GUI. The authentication/encryption password (secret) is stored as a SHA-1 hash, so there is no way to read it from the configuration file.

For any custom command definition, use “/” instead of “\” when you run jAReC on Windows and replace “:” by “*””.

Setting RTS and/or DTR lines

Some CAT interfaces require that RTS or DTR line from the COM port to be set in a high state. You can do this from the config menu.

Check the line you want to be active. This is saved in the application configuration file.

Import/Export files from Pocket RxTx

To use this function, you must first configure the network configuration between jAReC and Pocket RxTx. Click here to learn how to do it in jAReC and check the PocketRxTx documentation for the needed settings in that App.

From the File menu select “Cfg Imp/Exp”. The main application window turns cyan. This means that jAReC is waiting for commands from Pocket RxTx.

Importing from PocketRxTx

Once jAReC is waiting for files as described above, to transfer files from Pocket RxTx to the PC where jAReC is running. In the startup page of Pocket RxTx, click on the OPT button, then on EXTRA, then finally on CFG EXP. You will be prompted to confirm that jAReC is in Cfg Imp/Exp mode.

Click OK. A short message will be displayed for each transferred file. As soon as the transfer is completed, jAReC will go back in listening for connection mode (not file transfer mode). All of the transferred files will now be available in a subfolder of jAReC folder, named “configs”. If this folder does not initially exist, it is automatically created when jAReC starts.

The following files are transferred (if available on the android device):

You can now edit or backup all of the transferred files on your PC.

Exporting to PocketRxTx

To export files from the PC where jAReC is running to the Android device running Pocket RxTx, in the startup page of Pocket RxTx, click on the OPT button, then on EXTRA and then on CFG IMP. You will be prompted to confirm that jAReC is in Cfg Imp/Exp mode.

Click OK. A short message will be displayed for each transferred file. As soon as the transfer is completed, jAReC will go back in listening for connection mode (not file transfer mode).

The following type of files are transferred to the Android device (if present in the “configs” subfolder):

Using the Monitoring mode

From the File menu select “Monitor”. This function is available only when a network connection from Pocket RxTx is active (green background). When in Monitor mode, jAReC does not send any commands through to the serial porto . The background changes colour to to cyan, to indicate you are in Monitor mode. Serial data sent over the network is displayed on the screen. This mode will help you check and validate CAT command definitions in Pocket RxTx. This is especially useful when checking data when radio feedback is activated. The monitoring screen looks like the following image.

To monitor data from PocketRxTx, press one of the option buttons or tune to a specific frequency. Only the last command executed will be displayed. Let’s take for example manual tuning to 145.225MHz with an Yaesu FT-991. By default, the command is displayed in HEX format.

For the FT-991, the default CAT command definition is based on strings. From the CAT command dropdown box, you can select the display mode: Hexadecimal, Decimal, Binary or string.

We will select String in this case. The received command will be displayed now in this format;

You can save the command for future reference. Select from the Brand drop down listYaesu, from the radio FT-991 and name of the command “Set frequency to 145.225MHz”, then click on “Save”. This definition will be saved in the configuration file.

Next time this command is received, the parameters in the lower fields will be automatically displayed.

To test a feedback command, set the POLLING command in the Pocket RxTx config file for this radio model to receive feedback for only one parameter (ex. Frequency).


We will now activate feedback to PocketRxTx for a moment. This will enable us to provide the response to the CMD_READ_FREQ_VFO-A command. In the “Radio Answer” text field we enter the answer expected from the radio. Referring to the Yaesu CAT manual, we see the following:

In this case, read command received is ‘FA;’ Let’s consider that the radio returned the frequency 3.705MHz. Fill the expected answer in the Radio Answer text field and press SET, then activate feedback answering by checking the box.

Now set some other frequency in Pocket RxTx, ex. 145.225MHz and then activate feedback in PocketRxTx.

You will see how the frequency displayed in Pocket RxTx will be automatically changed to 3.705MHz. This is a way to can test individual commands that receive radio feedback.

Monitoring data is saved in a separate configuration file which is named “mon.cfg”.

An example of mon.cfg is shown below:

#Wed Jan 19 22:50:45 EET 2019





CMD46413134353232353030303B=Yaesu,FT991,Set frequency to 145.225 MHz



CMDFEFEAAE0161201FD=Icom,IC7300,Set AGC Fast


CMDFEFEAAE0161202FD=Icom,IC7300,Set AGC medium




CMDFEFEAAE0161203FD=Icom,IC7300,Set AGC Slow


Again, the format is self-explanatory. Commands are represented in HEX format.

Application history

Version 0.1 (Feb 27th, 2014). First public release of the application

Version 0.4 (Aug 20th, 2014)

- added secure authentication support - can be used only when using the PocketRxTx Android application as a network client

- added full data encryption support (experimental, buggy)

- added audio support (for the moment only in the GUI, not functional yet)

- detect network disconnection and go back to "waiting for connection" mode (yellow background)

Version 0.8 (Aug 23rd, 2015)

- added bidirectional audio support with mic level meter

- name changed to jAReC, From (j)ava (A)udio and (Re)mote (Control)

- version number set in sync with the Pocket RxTx Android application (for compatible features)

- deactivate START button when already started and STOP button when already stopped.

- changed design of and increased size of icons for security and audio settings

- auto-start function added

- reconnect to COM port and restart server if any configuration parameter changed while connected

- 128 bytes symmetric key used for password encryption (instead of 64 in the previous version)

- changes to ensure compatibility with Java 8

Version 2.0 (Jan 9th, 2018)

- added PTT support using CAT, RTS or DTR, on the same as CAT or different COM port

- added PTT timer (to limit transmission time to prevent locking the transceiver in TX if something happens with the network link)

- heartbeat to check at ~8s the link between PocketRxTx and jAReC and restart into listening mode if network link dropped.

- Added RTS/DTR power for the serial interface (eg for FT-991)

- when in Rx Mode, the bargraph changes from Mic to Spk and displays the Rx audio level

- added ability to have custom commands/scripts to run on PC triggered via the CAT command link (only with the Pro version of Pocket RxTx)

- Added Monitor mode to help with writing/debugging radio config files (monitor data to be sent/received over serial CAT)

- changed to run audio over UDP (with lower latency), using the same port number as the TCP one for CAT

- display all local IP addresses in the main window

Bugs solved:

- if using authentication on jAReC and not enabled in on PocketRxTx, CAT does not work but audio link is started.

- bidirectional audio support with mic level meter

- solved the combo box click bug

- sometimes mic level freezes to the last value even in Rx

Version 3.0 (Jan 14th, 2019)

Onlyto be used with PocketRxTx v3.x (not compatible with Pocket RxTxv2.x)

- support for PocketRxTx configuration, memories, debug log and call log files transfer (import/export)

- changed app menu format

- default mon.cfg file automatically created if not existing

- GUI controls are now disabled when in Import/Export mode

- Import/export can now be used even without a valid COM port

Bugs solved

- if you connect, then disconnect from PocketRxTx and then try to reconnect, you get an Authentication Failure.

jAReC_v3.0.pdf Bucharest, Jan 19 2019 – © Dan Toma – YO3GGX – yo3ggx@gmail.com