December 30, 2020

Using UZ7HO for Winlink (Updated!)

While there are several ways to access the Winlink system, some are easier than others. One way is to use a "software" TNC (terminal node controller). A TNC is basically a modem for a radio and was originally a piece of hardware. It converted data into tones that could be transmitted to another radio and eventually decoded back into text. But today, even relatively modest microprocessors are fast enough to use software as a means of encoding and decoding tones for radios. In fact, while some will still certainly argue the point, tests have shown that software TNCs can outperform hardware TNCs for many applications including packet radio. 

Software TNCs use a computer's sound card to listen for and play tones to and from the radio. Many modern desktop radios come with USB soundcard built in, which means all you need to use them is a USB cable connected to your computer and some software.

One of the software packages currently available is written by UZ7HO and is simply called, "Soundmodem". (On the website, the file is called The is a different program and not what you are looking for.) It has been around for many years but the programmer recently released an updated version which make it even better. Previously, you had to use VOX (voice activated control, or in this case tone activated control) so your radio would automatically switch back and forth between receiving and transmitting. Switching back and forth is called the PTT (or push-to-talk) function. (Another option was to use a Signalink which provides a soundcard and PTT functions.

However, the newest version of Soundmodem includes a new feature that allows you to automatically control most popular desktop radios. Simply download the file from the UZ7HO's website, unzip it and place the files in the same folder as Soundmodem. Then, in the Settings menu, under Devices, you'll see a section called "PTT Port". Choose "CAT" for computer automated and hit Apply. You'll get an error which will be followed by a "Advanced Settings" where you can choose your radio, port, speed and other options. It worked very well with my IC-7100 and really make Soundmodem even more useful!

It's really a longer story, but to use UZ7HO, you simply install the Winlink software and then configure it to use the KISS port on UZ7HO. Then in Soundmodem, make sure to enable the KISS Interface so the two programs can talk to each other.