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Linksys WRT Routers Won't Block Open Source Firmware, Despite FCC Rules (arstechnica.com)
The FCC requires all manufacturers to prevent users from having any direct ability to change RF parameters (frequency limits, output power, country codes, etc). The easiest way for a router manufacturer to comply with FCC's guideline is to block the open source router firmware -- which is what TP-Link has been doing. But thankfully, at least one router manufacturer doesn't think blocking the firmware is the right way to go about it. Ars Technica reports: Linksys has been collaborating with chipmaker Marvell and the makers of OpenWrt to make sure its latest WRT routers can comply with the new rules without blocking open source firmware, company officials told Ars. Linksys' effort stands in contrast with TP-Link, which said it would entirely prevent loading of open source firmware on its routers to satisfy the new Federal Communications Commission requirements. "They're named WRT... it's almost our responsibility to the open source community," Linksys router product manager Vince La Duca told Ars. Cybersecurity experts have urged the router manufacturers to not block open source firmware.
The FCC rules do not mandate, either directly or indirectly, that OS firmware be blocked.
Which was already explained in the Summary.
I know this is /. and nobody reads TFA, but you could at least read a little bit past the title and at least read the summary.
A title has limited number of words and characters: "despide FCC rulins" is as mush as the author managed to cram into it.
And the FCC *IS* causing most manufacturer to lock their firmware. FCC doesnt madante litteraly against opensource and user-upgradeable firmware, but the ruling is strict. No unlawful signal shall be emitted by a device. Under no circumstances.
- Either a manufacturer has to jump through some complex hoops to find a solution which both open and user accessible (following the spirit of the GPL license used by some component. And litteraly following GPLv3) AND at the same time prevent the end-user from emitting signals that fiolated FCC rules (e.g.: emitting on a EU-only frequency in USA).
- Or the manufacturer could just lock everything in a box, and only let cryptographically-signed firmwares in, and call it a day. (and hope no GPLv3 got violated in the process).
Nearly every constructor goes for the latter. Only LinkSys Fritz and a few other go for the former
"Sufficiently advanced satire is indistinguishable from reality." - [Tips: 1DrYakQDKCQ6y52z6QbnkxHXAocMZJE61o ]
Don't be deceived, it's still possible to flash custom firmware on a TP-Link device even after all their work. You can find more information via search on the openwrt forum.
All this on a $79 router.
"Science will win because it works." - Stephen Hawking
The "open" 5 GHz band spans from 5030 - 5835 MHz. Right smack dab in the middle of it at 5600 MHz is terminal doppler weather radar. That's one of the radars used to make the pretty rainfall pics you see on the news reports. More crucially, airports use it to detect wind shear conditions which have brought down several airliners in the past.
The problem is, because it's doppler radar, the frequency shift of the radar signal is crucially important, not just the return signal strength. So the FCC has carved out a band from 5250 - 5730 MHz and declared it DFS - dynamic frequency selection. Equipment can use these open frequencies, but if they do they have to monitor to see if weather radar is being used, and immediately shift to a different frequency outside this band if they detect weather radar.
A few routers do implement this frequency shifting. The vast majority simply block out those frequencies in their firmware (which is why your 5 GHz channel selection is limited to channels 36-48 and 149-165). But most third party firmwares are made in countries which don't have airports with TDWR radar (in fact most U.S. airports don't yet), so their governing agencies don't restrict these frequencies, so the firmware authors make no effort to limit use of these frequencies. Loading the third party firmware onto a router in the U.S.allows your router to spam these frequencies indiscriminately, leading to TDWR possibly being unable to detect wind shear or detecting it later than it could have without the interference, possibly causing another airliner to crash.
Excellent explanation. Visually, devices that interfere with TDWR displays appear as a wedge that is several degrees wide. The wedge obscures everything from the center of the display to the edge. Here's an example:
http://fpvlab.com/forums/attachment.php?attachmentid=69438&d=1452686140