Listen a Lot, Talk a Little

I’m running my ham radio that uses the computer to do a lot of the work.

Here’s a quick run down on what you see.

First, notice there are four windows including a big, multi-section one in the upper left, a smaller one with horizontal stripes in the upper right, one with a white on black sine wave and then one hidden at the bottom center.

This is about two-thirds of what I use when “talking” BPSK-31 on the amateur radio.

The big window (upper left) is “fldigi”. It’s the main one. In the yellow area you can see parts of a conversation between hams in Venezuela (that’d be Tomas) and in Ontario Canada (Warren). I just happen to be in a spot where I can “hear” both of them. Some of the conversation is garbled because the radio frequency we were using – that’s it up in the white “Freq” box, 14070.692 (kilohertz) – was wavering in and out. (Technically speaking, what was “wavering” was the reflection of their radio signals off the bottom of the ionosphere and down to me in Arizona.)

In the middle is a light blue area with nothing inside. That’s the “to be transmitted” area. Since I was only listening to these two guys, I wasn’t sending anything. But when I’m in a conversation with someone, I type what I want to say in this area. When I click the “T/R” or “Tx »” button down near the bottom right of this area, the computer tells the radio to start transmitting and whatever I have typed, or continue to type, is sent.

This particular mode of communication uses an extremely narrow “channel”, that’s radio talk for how much space you need, and with that comes a very slow rate. The “31” part of BPSK-31 alludes to both the bandwidth and signal rate but it basically boils down to the fact that it transmits just about as fast as you can type. So while I can type-ahead some of my reply to what the other person has said, I can also add to that while the earlier part is still sending, or even let the transmitter catch up and send what I type exactly when I type it.

Down near the bottom of that first window is a dark blue area with some yellow vertical lines. That’s called the “waterfall”. It scrolls down slowly over time. Each of those yellow lines is an amateur radio station. There are five visible in this picture, one of which is very thin – that’s someone sending a pure tone while tuning up their transmitter – and another has red lines on both sides – that’s Tomas and Warren, the signals “fldigi” is decoding for me in the upper area.

In the next part, we will pull back a little and get a broader view of what’s happening in the 20 meter band: There’s a station in Cuba that wants to talk to someone.

Stay tuned for tomorrow’s episode!

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