ONGOING DEFAULT THEME CONTEST!!!

[Llorean]

One option is to just have an icon for stereo that fades for mono (so that you see the faded version when you don't have stereo) so it appears more of a yes/no status than switching between two different things - that way you aren't trying to figure out what the "mono" icon means when you don't have stereo at all - you see instead a faded stereo icon which provides context by being faded relative to the other icons.

The trick then, of course, is coming up with an icon that's clearly "stereo" but at least you don't need a contrasting mono icon (which to me, at least, seems it could be more difficult).

[Vague Rant]

That's a workable idea as long as you're considering at the very least greyscale screens, but impossible or at least highly undesirable on monochrome screens.

[Llorean]

The "signal present" icon as presented also won't work on the mono screens (as a note - does anyone else think it looks an awful lot like the Firefox RSS icon?).

One option for the signal present icon is to always show the dot at the bottom, and show the bars when there's signal. Stereo can work a similar way, possibly. Come up with a base image that you can add to for the presence of stereo. Or of course, text is still an option.

[Vague Rant]

(as a note - does anyone else think it looks an awful lot like the Firefox RSS icon?).

Definitely, that was my first thought; I didn't know whether to think it was for DAPs with digital radio or something, just not something I associate with an analogue radio signal.

As for a degradable (i.e. works on monochrome) icon, I agree with your idea for bars dropping off when there's no signal, something like (MS Paint, not meant to be taken seriously) could easily be modified to look good in colour but be representative on all devices.

[TexasRockbox]

The RDS logo is only superficially similar. In my opinion ZincAlloy's design is clearly not a copy or based on the RDS logo.

No implication of copying was intended, it is just being noted the similarity (superficial or not) between the two might be confusing.  If RDS detection is displayed with the sort of infinity, sideways eight, two rings (whatever) and stereo is displayed with two rings that would be (in my view) too much similarity representing the respective detection.

[soap]

One option is to just have an icon for stereo that fades for mono (so that you see the faded version when you don't have stereo) so it appears more of a yes/no status than switching between two different things - that way you aren't trying to figure out what the "mono" icon means when you don't have stereo at all - you see instead a faded stereo icon which provides context by being faded relative to the other icons.

Three dots, arranged horizontally collinear, outer two "lit" while center "dim" for stereo - center "lit" while outer two dim for mono.
 

[Llorean]

That's a very space saving way to do it, but again doesn't translate well to mono screens because  the dimmed images won't be there. It does have the idea of a context-establishing dimmed image, though, which I like over all compared to two completely separate images.

[soap]

On mono screens make the dot "hollow" for unlit.

[Vague Rant]

How well understood is that imagery? I agree with Llorean that the dim/hollow image helps to make it somewhat clearer; perhaps that could be combined with the mono/stereo symbols I described above; have the channel box visible at all times, and light up each dot as necessary. This even allows for having no channels lit when there's no signal.

EDIT: e.g.:


Either the top or bottom rows depending on which conveys the information more clearly; from left to right (though I feel their strength is in this hopefully already being obvious) no channels (when radio is untuned), one channel (mono), two channels (stereo).

[soap]

Is that not pretty much what I suggested, VagueRant, except with the "addition" of an unneeded box.  (Unneeded since there will never be the extra dimension for channel placement?

[Vague Rant]

Indeed, hence my suggestion that the idea be "combined" with more identifiable imagery rather than "replaced" or some other verb which would suggest I was disagreeing with you.

The subject at hand is whether some dots sitting side by side clearly represent the concept of mono and stereo sound; as far as I know there's no established standard to that effect, so it needs to be strongly indicative of its meaning innately. For that reason I lean toward either imagery like speakers, with sound waves travelling either one direction or two, or well-known symbols for sound channels such as the box. If there's a well-known symbolic icon for mono/stereo then I'd support the use of that.

[soap]

or well-known symbols for sound channels such as the box.

I was unaware of said symbol. 

[Ezraghast]

Icons shouldn't really be used unless it's completely self-explanatory and if I saw it alternating between one ring and two rings as I scanned through the frequencies I probably wouldn't have any clue what it meant.

I don't really get that. Icons represent a thing, they don't necessarily describe it. Is the standard 'play' icon obvious to someone who has never seen it before?

[soap]

Icons shouldn't really be used unless it's completely self-explanatory and if I saw it alternating between one ring and two rings as I scanned through the frequencies I probably wouldn't have any clue what it meant.

I don't really get that. Icons represent a thing, they don't necessarily describe it. Is the standard 'play' icon obvious to someone who has never seen it before?

Today?  Likely not except for its cultural momentum.
In the context of a tape deck?  Likely many / most caught on quickly.

But that's really the point.  The play triangle did catch on, I believe in part, due to its (I can't think of the right word) its connection to our spatial cognition.

[ZincAlloy]

How well understood is that imagery? I agree with Llorean that the dim/hollow image helps to make it somewhat clearer; perhaps that could be combined with the mono/stereo symbols I described above; have the channel box visible at all times, and light up each dot as necessary. This even allows for having no channels lit when there's no signal.

EDIT: e.g.:


Either the top or bottom rows depending on which conveys the information more clearly; from left to right (though I feel their strength is in this hopefully already being obvious) no channels (when radio is untuned), one channel (mono), two channels (stereo).

I considered using these, but thought they wouldn't look good when styled like the other icons. And they show a speaker arrangement. That's cofusing. I also think that the circles are far more common. I've seen them in TV guides, on records, car radios and digital audio workstations.
Maybe we should add a greyed out ring to the mono icon to make things clearer.

As for the reception icons: An antenna icon would need to be quite large to look good in cabbie. The two other common icons that indicate reception are a number of ascending bars and the one that looks similar to the rss icon. I think the bars would look too similar to the volume icon. Furthermore I associate the other one with airwaves. It's meaning should be pretty clear on a radio screen. And it's simple. I still think it's the best icon for that job.