Radio Interface Setup

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Radio Interface Setup

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Radio Interface Setup

Created by Jeffrey Kopcak – K8JTK Updated 11/18/2015 Page 3 of 29

Introduction

This document will demonstrate basic setup of a radio interface device in the Windows Sound Control Panel to use with Ham Radio Sound Card digital modes. Programs include: Ham Radio Deluxe DM780, MMSSTV, Fldigi, wsjtx, FreeDV, Easypal. In addition, it will demonstrate how to record digital

transmissions and play them back.

This is written with the beginner in mind and many concepts outlined step-by-step. It will provide direction for further experimentation on your own or on the net and direction for troubleshooting. The SignaLink USB was used but these instructions can be adopted for similar devices. Those using other methods may find the settings and techniques useful.

It is important to note: plugging the same device into a different USB port will be recognized as a new device by the system. This means the audio settings will need to be re-configured. In addition, the audio device settings in the digital mode program may need to be re-configured as well.

Prepared for The Lake Erie Amateur Radio Association’s Digital Net (http://www.leara.org/).

Program versions

Windows 7 – 64 bit Audacity 2.0.6

Resources

Still having trouble after using this tutorial? Read through the product manual and support documentation. Below are links for popular devices.

Specific instructions can be found online typically by searching: [name of application] [radio interface device]. Example: Fldigi SignaLink USB.

SignaLink

Homepage: http://www.tigertronics.com/

General support, operating tips, manuals, and modifications (all models): http://www.tigertronics.com/sl_suprt.htm

SL USB troubleshooting: http://www.tigertronics.com/slusbts.htm

Rigblaster

Homepage: http://www.westmountainradio.com/

Knowledge base: http://www.westmountainradio.com/knowledge_base.php

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Radio Interface Setup

Configuration

Playback settings

This will adjust the audio path from the computer to the radio. Click the Start button.

Click Control Panel.

If Control Panel is in Category mode, first click Hardware and Sound. Click Sound.

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Radio Interface Setup

Created by Jeffrey Kopcak – K8JTK Updated 11/18/2015 Page 5 of 29 Click the main sound card device.

Click Set Default.

Notes:

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Radio Interface Setup

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Radio Interface Setup

Created by Jeffrey Kopcak – K8JTK Updated 11/18/2015 Page 7 of 29 Click the Levels tab.

Set the Speakers level to 50.

Notes:

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Radio Interface Setup

Click the Enhancements tab. Check Disable all enhancements.

Notes:

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Radio Interface Setup

Created by Jeffrey Kopcak – K8JTK Updated 11/18/2015 Page 9 of 29 Click the Advanced tab.

Under Default Format, select 16 bit, 48000 Hz. Click OK.

Notes:

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Radio Interface Setup

Recording settings

This will adjust the audio path from the radio to the computer. If not in the Sound control panel, click the Start button. Click Control Panel.

If Control Panel is in Category mode, first click Hardware and Sound. Click Sound.

Click the Recording tab.

If the radio interface device (USB Audio CODEC for SignaLink) has a green check next to it, this indicates it is the default audio device. DO NOT use the radio interface as the default Windows audio device. The radio interface will be selected in the settings of the digital application.

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Radio Interface Setup

Created by Jeffrey Kopcak – K8JTK Updated 11/18/2015 Page 11 of 29 Click the main sound card device.

Click Set Default.

Notes:

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Radio Interface Setup

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Radio Interface Setup

Created by Jeffrey Kopcak – K8JTK Updated 11/18/2015 Page 13 of 29 Click the Levels tab.

Set the Microphone level to 50.

Notes:

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Radio Interface Setup

Click the Advanced tab.

Under Default Format, select 1 channel, 16 bit, 48000 Hz. Click OK.

Notes:

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Radio Interface Setup

Testing and troubleshooting

This section will cover methods, techniques, and tips for testing your audio setup and ability to send and receive using your digital program. Not covered will be usage of a specific program. For usage

information please go back to the website and download the instructions for that specific program.

Transmit

Tune the interface connected radio to an unused or simplex frequency. Use a dummy load or reduce power to the lowest setting. Setting the Time-Out-Timer in the radio to 10 minutes serves a couple purposes: it is the maximum length of time one can send a simplex transmission and not properly identify. If the radio times-out, it is immediately known a proper ID must be sent and the transmission length is way too long for a Ham Radio transmission. However, a 3 minute time-out-timer is more reasonable on an FM repeater and good for initial practice to get a sense of transmission lengths. Turn

off all audio adjustments like EQ and compression.

One thing that trips up beginners the most: when you are transmitting digital, in most cases, you will not hear any tones or audio. This is normal. You have to rely on your radio to indicate it is transmitting and an external source (HT, another station) to verify audio levels and/or reception. For a repeater net, tune the handheld to the input frequency of the repeater which is the frequency your computer connected radio will be transmitting. Base station radios usually have an audio indicator of some kind but it may only function in certain modes. You will need to understand your radio to know how it functions. To begin, tune an HT and the computer connected radio to the same frequency.

Open the Sound Control Panel to the playback settings.

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Radio Interface Setup

When the application is sending a transmission:

 The application will generate audio output and raise the level meter next to the radio interface device to about half (shown above).

 The radio should be transmitting.

 Digital audio should be heard on the handheld radio.

 The audio should sound clean and not distorted. You’re ready to transmit! If no audio is heard or the radio is not transmitting:

 Check for a PTT or TX indicator light on the radio interface. Does it light when sending the transmission?

 Adjust the TX level on the radio interface.  Check the program audio input/output settings.

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Radio Interface Setup

Receive

Testing receive is a little harder to do. You will need another amateur station, preferably one with a known working setup that can transmit the same mode and frequency. Then test two-way digital communications. Alternatively, having another local computer, radio interface, and radio will work too.

Note: If you plan to leave your station in monitor mode, that is leave the radio on and application

running (decoding satellite passes for example), remember to disable “Auto Power Off” features in the radio and sleep/power saving features of the computer.

Tune the interface connected radio to an unused or simplex frequency. Have the other station do the same. Turn off all radio audio adjustments like EQ, filters, and noise blankers.

Open the Sound Control Panel to the recording settings.

Depending on configuration, the radio likely feeds open squelch audio to the radio interface. This is depicted above with a peaking level meter next to the interface device. Peaking here is not as important because open squelch audio is much louder than a modulated signal.

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Radio Interface Setup

Have the other station send a test transmission.

When receiving a transmission:

 Receiving a signal should produce an overall audio level of about half (shown above).

 The application will have some indication of receiving/decoding in progress. This depends on the program.

 If the message was successfully received, you’re ready to receive! If the message was not successfully received:

 Adjust the RX level on the interface.

 Check the program audio input/output settings.

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Radio Interface Setup

Recording with Audacity

Some week you can’t make the net, but you still want to receive the messages passed on the net or there is an event taking place and you want to record the transmissions. There are a couple options. Leave the digital application running on your computer in receive mode. Transmissions made will be picked up and decoded by the program for later review. Disadvantages: if the net decides to change programs and/or modes, particularly ones that don’t transmit an ID and require manual intervention won’t be recorded. Leaving more than one monitoring program running doesn’t always work because one application can take “exclusive” control over the recording device, bumping out the other program. Conversations taking place on the net explaining modes or information about the content would not be recorded.

A second option is to record the net using a sound recording program and play it back into the appropriate digital program at a later time. This is also known as Time shifting. This method works great for monitoring the net.

Do not start the digital program in addition to the recording program. Disable “Auto Power Off” features in the radio and sleep/power saving features of the computer. Re-enable when done. Download Audacity (free, all platforms): http://audacity.sourceforge.net/download/

You will need the administrator password to install if you are running as a standard user. Install with the default options.

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Radio Interface Setup

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Radio Interface Setup

Recording settings

For Recording Device, select the radio interface device.

For Recording Channels, select 1 (Mono) Recording.

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Radio Interface Setup

level.

Click Record.

When completed, click Stop.

Notes:

 These files can be very large at approximately 610MB/hr even in temporary storage.

Record all received and transmitted audio

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Radio Interface Setup

Timer recording

Begin a recording at a specified time.

Setup Audacity as instructed in the “Recording settings” section. Click Transport.

Click Timer Record.

Set the Start Date and Time.

Set the End Date and Time or the end time will be calculated based on Duration. Click OK.

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Radio Interface Setup

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Saving

When the recording is complete, it can be played immediately or saved by clicking File. Click Save Project.

Click OK on the warning message. Give the project a name.

Click Save.

Notes:

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Radio Interface Setup

Playback

Go into the Recording Sound Control Panel.

There should be a Stereo Mix, Mono Mix, or Wave option from your main sound card. This depends on the sound driver. If nothing similar is seen, right-click in the recording box and click Show Disabled

Devices. Then right-click the appropriate device and click Enable.

In the digital application, select the mix device for the input. Remember to change it back to the radio interface device when done.

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Radio Interface Setup

Created by Jeffrey Kopcak – K8JTK Updated 11/18/2015 Page 27 of 29 In Audacity, open the project if it is not already.

For Playback Device, select the speakers of the main sound card.

For Playback Volume, select 0.50. A tooltip will appear while clicking and dragging indicating volume level.

Click Play.

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Radio Interface Setup

 Selecting Speakers will allow the recording to be outputted to the speakers. In addition, this feeds audio back into the “mix” recording device where it is picked up and decoded by the digital program as it is being played back.

 Decoding issues: disable all audio processing including Enhancements in the Sound Control Panel. Default Format on the Advanced tab should be 48000 Hz (1 channel for the radio interface, the rest don’t matter). Verify these for all sound devices used in this setup.

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Radio Interface Setup

Sound card clock calibration

This concept goes above and beyond the Digital Net but is important when operating some digital modes.

All sound cards are not 100% accurate in their sampling rates. In normal audio sound applications, this tends not to matter. Digital modes like MFSK, SSTV, and Olivia require an accurate sound card clock. Other modes are more forgiving like MT63 and PSK. A difference can be calculated between the stated sample rate and actual sample rate of the card. Experiencing one or more un-calibrated sound cards results in decoding errors or little to no decoding of a strong signal.

Some programs can ‘auto correct’ on receive. The results are often ‘best guess’ and not always correct. “Auto Slant” in MMSSTV is an example. Those who commonly operate those modes will want

transmitting stations to calibrate their sound card.

Each program has its own method for doing this. Here are common examples:

SSTV: http://www.wb9kmw.com/WB9KMW/sstv_files/tutorial/That_Pesky_Slant.pdf. I prefer this method:

Radio Interface Setup

Radio Interface Setup

Radio Interface Setup

Table of Contents

Radio Interface Setup

Introduction

Program versions

Resources

Radio Interface Setup

Configuration

Playback settings

Radio Interface Setup

Radio Interface Setup

Radio Interface Setup

Radio Interface Setup

Radio Interface Setup

Radio Interface Setup

Recording settings

Radio Interface Setup

Radio Interface Setup

Radio Interface Setup

Radio Interface Setup

Radio Interface Setup

Testing and troubleshooting

Transmit

Radio Interface Setup

Radio Interface Setup

Receive

Radio Interface Setup

Radio Interface Setup

Recording with Audacity

Radio Interface Setup

Radio Interface Setup

Recording settings

Radio Interface Setup

Record all received and transmitted audio

Radio Interface Setup

Timer recording

Radio Interface Setup

Radio Interface Setup

Saving

Radio Interface Setup

Playback

Radio Interface Setup

Radio Interface Setup

Radio Interface Setup

Sound card clock calibration