[South Florida DX Association] What's With Knobs, Anyway?

[Bill Marx]

>From The ARRL Contest Update...


CONVERSATION
What's With Knobs, Anyway?

Somewhat lost in all the hue and cry about software-defined radio (SDR), CW 
decoding, and robotic contest stations is the gradual change of a radio's 
"front panel in the mind". As technology changes the way a radio operates, 
so, too will it change the way we interact with the radio and even the way 
we think about the radio spectrum and signals that occupy it.

For example, the first radio receiver we owned strongly colors our 
imaginations. Depending on whether that first receiver had a dial whose 
numbers increased clockwise or counterclockwise, you may imagine signals 
higher in frequency as being to the "left" or "right" of your signal. My 
first rig was an HW-16, so I turned the tuning knob clockwise to make the 
frequency increase and the dial rotated counterclockwise. To this day, 
signals higher in frequency I imagine as being off to my left. All four 
combinations of knob turning and dial direction exist somewhere in 
historical radios, so there are probably four populations of us that think 
about the spectrum in different ways.

Even deeper, almost all HF operators rotate a circular knob to tune the 
radio. Keyboard frequency entry is possible, but not commonly. What this 
means is that we think of the spectrum as a linear object. To get from 
frequency to frequency, we have to visit all of the intervening frequencies 
sequentially. Oh sure, we can hop around, but our basic conception is of a 
big ruler with the various frequencies ticked off along it.

These basic concepts have held sway since the 1920's. Radios have knobs. A 
big one changes the frequency (to the left or right) and little ones change 
the characteristics of the signals received. The model is very, very hard to 
change. Yet it is changing.

What if a ham learned to use a radio without using a tuning knob - like VHF 
FM users do? Perhaps they were trained in the military or commercial 
channelized services and don't think of the spectrum as continuous, but 
rather discrete, disconnected channels. How do they imagine their radios - 
as directionless lists of frequencies or users?

The new types of displays that are becoming common - especially the 
waterfall - have the potential to erode the linear model's dominance. The 
Digipan PSK31 display simultaneously shows all the contacts within its 
received bandwidth - in parallel! SDR displays can show an entire band and 
when coupled with Skimmer software, the station call signs, too. Freed from 
the linear model, operators are free to simply "click around the band", 
instead of tuning from one station to the next.

What does that mean for hams and radio in general? This reminds me of an old 
joke: When the horse was asked, "When you walk, do you move both legs on one 
side or the diagonally opposing legs, front and back?" The horse thought for 
a minute and said, "I'll never walk again!" This can get awfully deep when 
our goal is simply to fool around on the radio, but it does have 
implications.

Someday soon, a developer will release a radio display that doesn't need a 
knob or keypad at all. The operator-cum-user will enter a visual world in 
which signals appear in different colors, different sounds, in different 
directions. They may be spikes, icons, photos, patterns - anything that 
contains the necessary information for us to accomplish our goals of using 
the radio. Perhaps you'll even be able to see other stations that are 
"tuning". This will be a brave new world of radio, enabling a whole new way 
of interacting with the RF spectrum. It won't be long before operators will 
be asking, "What was with the knobs, anyway?"

73, Ward N0AX