Can I monitor a VarAC QSO of others? Sure you can!

A VARA modem can operate in either Ready-To-Connect mode or Listening (Monitoring) mode.

If you want to stay available for incoming connections while also monitoring the frequency for ongoing VARA activity (such as active VARA QSOs), you’ll need to run a separate VARA modem instance in Monitor mode.

Want to know how? Open the VarAC Settings, go to the “VARA” tab, and under “VARA Monitor Path”, click the small (?) icon for more information.

I’ve heard some operators say they can’t accurately monitor ongoing VARA traffic. So let’s take a moment to dig into why that happens.

VARA is an ARQ mode, which means you either receive data 100% accurately (thanks to CRC error correction) — or you don’t receive it at all. It’s very similar in that sense to Pactor or Packet.

When two stations have a strong, stable link (for example, around +2 dB SNR) and switch to High Speed mode (say, Level 5), their connection works great between them. But if you’re receiving that same transmission at –10 dB SNR, you’ll likely fail to decode most of it. Too many bytes get lost to noise, and the CRC can’t correct the message.

It’s the same idea as trying to copy a high-speed Pactor 4 signal — it may sound strong to your ear, but the signal-to-noise ratio might still be too low for your modem to decode the data correctly.

In non-ARQ modes like RTTY or PSK, missing a few characters still allows you to make sense of the message. But with ARQ, every byte in a packet must be received (within certain limits) to reconstruct the message. If even a few bytes are missing, the entire packet is discarded.

As a result, you’ll usually decode more packets at lower VARA speeds than at higher ones. Just because you can hear a signal — even clearly — doesn’t mean your modem can successfully decode all the data within it.

Here’s a real example from my monitor screen on the Calling Frequency. You can spot several interesting elements in it.