They seem fairly coherent to me...
And then he read the Signature rules and realized that a consumer-grade vehicle's autopilot runs over one in six pedestrians... which could be completely fixed by the manufacturer spending 500 yen on a better camera system and ripping out the atmosphere sensor. Damned atmosphere sensor must have killed more people than Stalin...
*Reads over the Signature rules (presuming you refer to Sensor Tests on page 171 of SR4A, only place the "master index" refers to for signatures)*
That doesn't make them less coherent, just completely impractical. I'll agree that if you actually use the Signature modifiers, your going to kill a lot of people. Ignore the Signature modifiers (or adjust to suit, if that's your preference).
If you want to go a step further, use a little handwavium and treat vehicle sensors as operating under the same concepts as metahuman perception (if it's not hiding, you can detect it).
Yes, the sensor software does make this more complicated, but you can take heart that your GM will rule most sensors to be "personal electronics" with a Device Rating of 3, so without program options, you can only run 3 of them at any one time on any one sensor, and they only work up to rating 3.
Problem there is that sensors don't exist in a vacuum. You want a hidden camera, you've got to pin it to an RFID tag, which then becomes "your device". There are larger sensor banks as well, but my point is that a camera isn't an object so much as an "upgrade" for a package. But, if you consider it a 3/3 node, I've got to wonder why I bother buying a commlink..
A peripheral device is a Matrix-capable appliance or piece of equip- ment that is wireless (or in some cases wired) but is not intended to be used for full-blown Matrix interfacing and processing. Security cameras, stoves, ear buds, medkits, firearms, children’s toys, doorbells, showers, biomonitors, cyberware, make-up kits, vehicles, coffee makers, store displays, electronic paper, drones, light switches, and many, many other items are all peripheral devices in Shadowrun.
Peripheral devices have no persona firmware, and are usually just smart enough to serve their function, although many have unused processing power. Such devices also often offer significant storage space in unused memory.
Reading through that, I get "all electronics are matrix capable" and "if it's a peripheral device, no personas can run on it". Which would be why you bother with that commlink.
Further reading:
There are far too many electronics in the world of Shadowrun for a gamemaster to keep track of their individual Matrix attributes. Instead, each device is simply given a Device rating. Unless it has been customized or changed in some way, assume that each of the Matrix attributes listed above for a particular device equals its Device rating.
Looking at the "Sample Devices Table" on the same page, "Standard Personal Electronics" (such as a hand held camera) are Device Rating 3, with no persona firmware, so they're a Response = System = Firewall = Signal 3 node that can't host a persona.
Sensor RFID tags are one option, though reading over their rules, they seem pretty limited, sending you an alert when whatever specified object/person/environment triggers a pre-set condition. Nothing about retrans of the actual data feed. Which fits RFID tag common sense.
On the other hand, you also have micro (note, it doesn't say "drone", it's not intended to, since you also have the micro camera, pg 332), hand-held, or mounted sensors. All of which are independent devices from Drones, vehicles, and RFID.
A micro sensor, such as the classic button-camera, is a Capacity 1, signal 2, DR 3 camera (Rating 1), per the above.
A security camera is a mounted sensor package (Capacity 5, Signal 4, DR 4). Since it has extra capacity, you can stick a MAD scanner, microphone, and maybe 1 or 2 other toys in there.
The advantage to the RFID route is that it will alert you when something important happens, whereas you have to monitor the micro-camera. After all, no pilot (unless you purchase one separately) means no dog-brain to inform you of something important happening.
