First, I'm assuming the decker has a satellite link to keep his distance-based noise to -5.
There doesn't seem to be anything about how much distance a matrix perception can cover. Here's the relevant quote:
You can automatically spot the icons of devices that are not running silent within 100 meters of your physical location... no matter where you are in the Matrix. Beyond this distance, you need to make a matrix perception test to find a specific icon.
- Core, 235
So in other words, it doesn't actually matter where your persona is, you still need matrix perception to spot any icon that's further than 100m away from your body / device. RAW seems to say that you need to spend an action to spot each individual icon. (I'd personally let each hit spot one non-silent icon, though.) This all goes out the window if, and only if, you're on a host with the stuff you're trying to perceive.
However, there doesn't seem to be any limit on how much distance a matrix perception can cover.
RAW also seems to say that you can only look for details on one icon per action.
So, with your examples:
- They need to use matrix perception to spot icons in the first place, even though their persona is right there. But the good news is you can use it to perceive stuff as far away as you want... somehow.
- Once spotted, RAW implies that each matrix perception can only provide details about one icon at a time. (But if you had to use it just to spot a non-silent icon, then you probably had enough hits to find out whether it's playing a music file or not.)
-- Since there's somehow no limit, it doesn't matter if the gun icon is 101 meters away or 1100, your matrix perception can still spot a non-silent icon that you're
specifically looking for (you just take a distance-based noise penalty depending on how far away it turns out to be).
I know this doesn't make a lick of sense, but that's what raw seems to say.
Someone,
please, correct me if I'm wrong. I really want to be wrong this time.