Digirig Lite Setup Manual

Welcome to the Digirig Lite – a minimalistic USB sound card-based digital modes interface for radio communications. Thanks to its standard audio codec and versatile Push-To-Talk (PTT) options, this device offers broad compatibility across all major desktop and mobile platforms.
This manual will walk you through the setup process, helping you get on the air with popular digital modes such as FT8, JS8Call, Winlink, VARA, packet, APRS, SSTV, and beyond.

What’s Included and What’s Needed

Digirig Lite kit consists of:

1. Digirig Lite interface dongle
2. USB-C to USB-A adapter
3. Silicone dust cap doubling up as a tether for the USB adapter

Not included in the kit, but required for operation:

4. Computer, tablet or smartphone with available USB-A or USB-C connector
5. Radio transceiver
6. Digirig audio/PTT cable matching your transceiver model

Under the Hood

The ABS plastic enclosure houses the PCB with USB audio codec (CM108B) and components implementing multiple PTT methods as well as filtering and attenuation. The light from LED indicators for power (green) and PTT (red) is visible through the front side of the dongle.

Normally no hardware configuration is required, but if needed the PTT methods can be individually disabled by cutting the traces between the solder pads on the back of the PCB

Connections

Digirig Lite is connected to the computer, tablet or smartphone (computing device) using either a USB-C connector directly or through the included USB-A adapter. Other connection methods (e.g. Apple lightning, microUSB) are possible through corresponding OTG (on-the-go) adaptors which are not supplied in the Digirig Lite kit nor are guaranteed to be compatible.

The female 3.5mm TRRS socket accepts transceiver-specific Digirig audio/PTT cables with the black molding on the interface side connector. If using a combined cable with two Digirig-facing jacks, then only connect the black one leaving the colored jack unconnected. In this scenario, the recommendation is to tape over or otherwise cover the exposed contacts of the unused plug.

Transceiver Setup

Digirig “listens” and “talks” to your radio and it fully relies on your transceiver’s RF and audio performance. If you cannot establish a voice contact with a remote station, you won’t be able to set up a digital link either. Before connecting the interface, ensure you’re on the correct band and frequency, have selected the appropriate mode, and can clearly hear traffic from other stations.

For optimal performance, adjust your transceiver settings to prevent any distortion in the audio received or sent by Digirig. A good starting point is to reset your radio to its default configuration and then document any adjustments you make for future reference.

Data Port

The interface through the dedicated data port is a preferred option where available. It offers a better audio quality and keeps microphone connection available for voice contacts. Data ports are typically found in desktop and mobile radios. If you are using such connection then browse the transceiver menus for relevant settings:

• data port selection, line audio enable etc. – make sure that the data connection is enabled
• data gain, line in/out audio levels – set midway and adjust later as needed
• audio path (1200 baud vs 9600 baud) – set to match the pinout of the connected cable
• audio filtering, audio bandwidth, low/high cutoff – remove all filtering to allow as much bandwidth as available
• AGC, ALC – set to fast and adjust later as needed
• RF gain – set to value that allows you to clearly hear the digital traffic between other stations on the air
• DSP, notch, noise filters and other features – these features should not be normally applied to the data port, but a conservative choice is to first disable all features that may affect the payload and later re-enable them if proven irrelevant 
• RF power – start out low and add as needed

Mic and Speaker

Interfacing through the mic and speaker connections is a fallback option when a dedicated data port is not available. This is the only option with HTs, some budget grade mobile radios as well as with vintage desktop transceivers. Relevant transceiver settings may be:

• squelch – turn off to ensure continuous audio feed
• mic gain – set midway, adjust later as needed
• mic compression – disable compression and all other audio processing
• speaker volume – start low at 10-20% and add later as needed
• RF power – start out at low, add later as needed

System Devices

Digirig Lite is connected to a computing device, the green PWR LED should illuminate, and the system will recognize the interface as an external sound card. As a generic USB audio device, the interface does not require installation of the driver.

⚠ Unlike other Digirig models, Digirig Lite does introduce any additional devices such as a serial port or USB hub.

Windows

To confirm that Digirig Lite is correctly recognized by Windows, open Device Manager and locate two “USB Audio Device” entries under the “Audio inputs and outputs” group. Device Manager can be accessed by right-clicking the start button and selecting “Device Manager” or by launching devmgmt.msc command from the run menu.

Next proceed to the Sound section of the Control Panel by right clicking the speaker icon in the tray and selecting “Sounds”. Alternatively you can invoke it by running control.exe mmsys.cpl command. With Digirig’s sound card detected by the computer, there should now be new Playback (speaker) and Recording (microphone) entries in the corresponding tabs.

Following adjustments are recommended:

• Rename the entries from default “USB Audio Device” to “Digirig” so they can be easily recognized when listed in the ham radio apps. You can also pick a different icon purely for aesthetic reasons.
• Move “Default Device” and “Default Communication Device” designations (indicated by green checkboxes) in both playback and recording groups from Digirig devices to your computer’s internal microphone and speakers. This will prevent the system’s normal sounds and media from getting on the air and radio’s received audio from getting into your VoIP call. This is done by right-clicking the internal sound devices and selecting “Set as Default Device” and “Set as Default Communication Device”.
• Uncheck the “AGC” box in Digirig’s recording device under the “Custom” tab.
• Leave sampling rate and bit depth at the maximum values
• Make sure no effects or enhancements are turned on for any of the Digirig’s audio devices.
• Set recording and playback levels to 50% as the initial values, this will have to be revisited later (see Software Audio Settings).
• “Listen to this device” checkbox can be enabled with the default audio device selected for the initial troubleshooting. This patches the audio received by the computer to the computer’s speakers for monitoring. Uncheck it later when everything works to your satisfaction.
• In the Levels tab of Digirig Lite’s playback device leave the Microphone muted 🔇. This setting is different from the level setting in the recording device properties. Former configures the microphone feedback to the speakers and latter is responsible for Digirig’s input sensitivity.

Additionally:

• In Windows 11 edit system’s privacy settings to allow applications’ access to Digirig’s recording device (Microphone).
• Some systems may come with pre-installed software that manipulates the audio in the attempt to make voice calls sound better. Naturally, this wreaks havoc on the digital modes. Keep an eye out for any third-party utilities related to sound and make sure they stay away from Digirig’s audio.

Linux

The first step is to confirm that USB devices are detected by running lsusb or dmesg commands before and after plugging in Digirig Lite.

Next you can use alsamixer or pavucontrol to set the output sensitivity and output level of Digirig’s audio devices. While in alsamixer turn off the AGC feature to allow manual sensitivity setting.

MacOS

With Digirig plugged into a USB port, confirm that the system lists a new sound card “USB Audio Device” in Applications -> Utilities -> Audio MIDI Setup.

Move the default device assignments to your computer’s internal speaker and mic by right-clicking over corresponding entries in the list and selecting all “Use This device for …” options from the menu. This will prevent unwanted audio from getting on the air or noises from the radio getting into your VoIP call.

iOS and Android

On mobile platforms when the external sound card is plugged in, it takes over the default audio. Use the system’s volume controls to adjust the output level.

With the transceiver connected make sure the device doesn’t generate any audio other than payload for the digital modes. Things like ringtones, media, alarms can accidentally get on the air if not deactivated.

Software Settings

Depending on the digital mode you wish to operate, you will need to run a specific software application. Here are some of the popular examples:

• WSJT-X for FT8 and FT4 – contesting style minimal QSOs over weak signals protocol.
• JS8Call – conversational QSOs over weak signals protocol (keyboard-to-keyboard or store-n-forward).
• Winlink Express + VaraHF or Soundmodem for email over radio.
• FlDigi for RTTY and other legacy conversational data modes.
• MMSSTV or YONIQ for images from terrestrial stations or ISS/satellites.
• Pinpoint APRS, APRSISCE/32 or other for location reporting and messaging.
• APRSDroid – Android APRS client for exchanging position reports and messages.
• RadioMail – Winlink client for iOS.
• WoAD – Winlink client for Android devices.
• FT8 Radio – FT8 client for Android devices.
• AndFlmsg – combination of Fldigi and Flmsg for Android devices.

There are numerous setup tutorials for specific ham radio applications made available on the web and in videos including discussions in the Digirig Forum. Most of the settings are similar regardless of the interface being used. Here we’ll focus on common settings pertaining to Digirig Lite that can be expected in every application.

⚠️ Note that Digirig must be plugged in and recognized by the computer before the software is launched otherwise the devices may not be visible to the app.

Software Audio Settings

Each desktop application for digital modes will have a soundcard or audio configuration section. Reference Digirig’s recording (input) and playback (output) audio devices in the corresponding dropdowns. If you renamed the entries as discussed in OS Settings section above then the target components will be easy to recognize by “Digirig” name, otherwise look for the default “USB Audio Device” description. If there is a choice of the channels, then set input to “Mono” and output to “Left”. Use “both” if you want to activate PTT by Right output channel feeds into the internal VOX circuit (see next section).

Below are some of the examples of the audio device configuration in popular digital modes software:

For optimal results the input sensitivity and output audio levels will have to be later adjusted from their initial levels:

• Use the level slider in Digirig’s recording device (see OS Settings) to adjust the sensitivity of the received audio while monitoring the readout of the UV meter or the equivalent indicator in the software. The “listen” checkbox can be temporarily enabled in order to patch the received audio to the computer’s speakers and monitor the traffic on the air while fine tuning and troubleshooting the levels. Other factors playing into the received audio level are radio’s line audio levels, RF gain, AGC, volume knob etc. (see Transceiver Setup).
• Use the level slider in Digirig’s playback device (see OS Settings) to adjust the volume of the audio sent to the radio for transmission. Other factors playing into the received audio level is radio’s line audio level, mic gain, ALC (see Transceiver Setup) and any volume controls in the app (e.g. Pwr slider in WSJT-X).

PTT Settings

Most of the apps will try to get your data on the air. For that they’ll need to key up the radio. Digirig Lite supports several PTT options accommodating every application there is. Here are the choices in the order of preference starting from the most desirable:

• PTT via GPIO3 (also known as PTT by RA Board, C-Media PTT or PTT by HID) – The Digirig sound card chip features general-purpose control lines, one of them (GPIO3) is configured to trigger the hardware PTT line in the connected radio. This method is the preferred choice, as it provides the software with precise timing control over the transceiver’s transmission.
• PTT by tone – Several applications for digital modes offer an option for sending a PTT tone on a separate audio channel. This method allows the software to key up the radio moments before the payload is sent. If this feature is available then configure the PTT tone on Digirig’s right audio output channel and the payload to the left.
• PTT by VOX – If the payload audio is sent to both audio channels then it will key up the transceiver as well as get on the air without any support from the software. Although Digirig’s VOX implementation is highly optimized and is known to work great, consider it a fallback option for the cases when no explicit PTT methods are available. All VOX circuits have inherent latency at the beginning and hang time at the end of the payload. Timing adjustments may be needed with the software settings mentioning “delay”, “prefix”, “preamble” or similar to offset this effect.

Notes regarding RFI

Radio frequency interference (RFI) which can cause a temporary system malfunction comes in two flavors:

• RF power from the antenna nearby wirelessly induces voltages in the radio’s accessory cables
• Unbalanced and insufficiently choked antenna uses radio’s accessory cables as part of the counterpoise system

Both types of interference are especially notorious when using HTs with a directly attached antenna.

If the setup works without any problems while receiving but becomes erratic during or after the first attempt to send the power out, then the RFI is a likely reason for the problem. The symptoms may include radio getting stuck in transmission, USB dropping out, sound card errors. The effect may be different depending on RF bands, cables layout and seemingly other random factors.

To diagnose the issue, reduce the RF power to a minimum level and ideally use a dummy load. If the problem goes away, then it is definitely related to the radio frequency interference. Another method is disconnecting the transceiver-side cable moments before the transmit attempt and reconnecting it after. The software has no way of knowing if the audio cable is connected so if the previously present problem goes away in this scenario then it’s another clue that the feedback is happening via RFI.

The solution is to improve the antenna system, grounding and choking.

Troubleshooting

Approaching troubleshooting systematically can mean the difference between finding the solution in minutes and getting frustrated after hours and days of trying random things.

The areas of the concern are mostly independent of each other and can be dealt with individually in following order:

1. Soundcard detected by OS
2. Audio from radio reaches the software
3. Software is able to key up the radio
4. Audio from the software gets on the air
5. Transmission cycle completes without any system errors
6. Messages are decoded and connection completes successfully

Refer to the relevant section of this manual and the troubleshooting guide to address a specific issue and do not proceed to the next step until failure is resolved. Change one factor at-a-time taking notes of the results and restore to a default or conservative value before trying something else.

Technical support

Please refer to the community forum for any technical support except for the cases pertaining to your specific Digirig order (warranty, returns etc.). Before posting your question, check out the existing threads. Powerful tagging and search options will help you narrow the results to the relevant discussions. Additional resources include the troubleshooting guide and Digirig’s Youtube channel. There are also numerous websites, forums and videos dedicated to digital modes which can be useful especially if your issue has to do more with the radio than a specific interface.

When posting in the community forum please describe:

• your system including transceiver model, type of the computing device, OS, amateur radio software, antenna system and other accessories if relevant
• area of concern per the list in troubleshooting section above
• what troubleshooting steps you attempted and what results you got

Schematic