When a consumer electronics device is sold in the US, especially if it has a wireless aspect, it must be tested for compliance with FCC regulations and the test results filed with the FCC (see preparing your product for FCC testing). These documents are then made available online for all to see in the Office of Engineering and Technology (OET) Laboratory Equipment Authorization System (EAS). In fact, it’s this publishing in this and other FCC databases that has led to many leaks about new product releases, some of which we’ve covered, and others we’ve been privileged enough to know about before the filings but whose breaking was forced when the documents were filed, like the Raspberry Pi 3. It turns out that there are a lot of useful things that can be accomplished by poring over FCC filings, and we’ll explore some of them.
At some point you’ve decided that you’re going to sell your wireless product (or any product with a clock that operates above 8kHz) in the United States. Good luck! You’re going to have to go through the FCC to get listed on the FCC OET EAS (Office of Engineering and Technology, Equipment Authorization System). Well… maybe.
As with everything FCC related, it’s very complicated, there are TLAs and confusing terms everywhere, and it will take you a lot longer than you’d like to figure out what it means for you. Whether you suffer through this, breeze by without a hitch, or never plan to subject yourself to this process, the FCC dance is an entertaining story so let’s dive in!
The police force in Evanston, Illinois had a problem on their hands. A mystery transmitter was blocking legal use of radio devices, car key fobs, cellphones, and other transmitters in an area of their city, and since it was also blocking 911 calls they decided to investigate it. Their first call for help went to the FCC who weren’t much use, telling them to talk to the manufacturers of the devices affected.
Eventually they approached the ARRL, the USA’s national amateur radio organisation, who sent along [Kermit Carlson, W9XA] to investigate. He fairly quickly identified the frequencies with the strongest interference and the likely spot from which it originated, and after some investigation it was traced to a recently replaced neon sign power supply. Surprisingly the supply was not replaced with a fault-free unit, its owner merely agreeing to turn it off should any further interference be reported.
The ARRL are highlighting this otherwise fairly unremarkable case to draw attention to the problem of devices appearing on the market with little or no pretence of electromagnetic compatibility compliance. In particular they are critical of the FCC’s lacklustre enforcement response in cases like this one. It’s a significant problem worldwide as huge numbers of very cheap switch-mode mains power supplies have replaced transformers in mains power applications, and in any center of population its effects can be readily seen with an HF radio in the form of a significantly raised RF noise floor. Though we have reported before on the FCC’s investigation of the noise floor problem we’d be inclined to agree with the ARRL that it is effective enforcement of EMC regulations that is key to the solution.
City of Evanston police vehicle picture, [Inventorchris] (CC BY-NC 2.0) via Flickr.
Two years ago, the FCC, with interested parties in Microsoft, Google, and many startups, created the Citizens Band Radio Service (CBRS), a rule that would open up the 3550-3650 MHz band to anyone, or any company, to create their own wireless backbone between WiFi access points. It is the wireless solution to the last-mile problem, and last year the FCC enthusiastically endorsed the creation of the CBRS.
In a recently released FCC filing, Google has announced their experimental protocol for testing the new CBRS. This isn’t fast Internet to a lamp pole on the corner of the street yet, but it lays the groundwork for how the CBRS will function, and how well it will perform.
Google will be testing the propagation and interference of transmissions in the 3.5 GHz band in places around the US. Most of the Bay Area will be covered in the tests, as well as Boulder, CO, Kansas City, Omaha, Raleigh, NC, Provo, UT, and Reston, VA. Tests will consist of a simple CW tone broadcast in the 3.5 GHz band.
The 3.5 GHz band is already allocated to shipborne navigation and military radar systems, posing an obvious problem to any wireless broadband system using this spectrum. To this end, the FCC is proposing a novel solution to the problem of coexistence between the CBRS and the military. Instead of simply banning transmissions in the spectrum, FCC Chairman Wheeler proposes, “computer systems can act like spectrum traffic cops.” A computer is able to direct the wireless traffic much more effectively than a blanket ban, and will allow better utilization of limited spectrum.
Google’s FCC filing is just for testing propagation and interference, and we have yet to hear anything about how a network built on 3.5 GHz spectrum will be laid out. One thing is for certain, though: you will not have a 3.5 GHz USB networking dongle for the same reason you don’t have a Google Fiber input on your desktop.
Last year, the Federal Communications Commission proposed a rule governing the certification of RF equipment, specifically wireless routers. This proposed rule required router manufacturers to implement security on the radio module inside these routers. Although this rule is fairly limited in scope – the regulation only covers the 5GHz U-NII bands, and only applies to the radio subsystem of a router, the law of unintended consequences reared its ugly head. The simplest way to lock down a radio module is to lock down the entire router, and this is exactly what a few large router manufacturers did. Under this rule, open source, third-party firmwares such as OpenWRT are impossible.
Now, router manufacturer TP-Link has reached an agreement with the FCC to allow third-party firmware. Under the agreement, TP-Link will pay a $200,000 fine for shipping routers that could be configured to run above the permitted power limits.
This agreement is in stark contrast to TP-Link’s earlier policy of shipping routers with signed, locked firmware, in keeping with the FCC’s rule.
This is a huge success for the entire open source movement. Instead of doing the easy thing – locking down a router’s firmware and sending it out the door – TP-Link has chosen to take a hit to their pocketbook. That’s great news for any of the dozens of projects experimenting with mesh networking, amateur radio, or any other wireless networking protocol, and imparts a massive amount of goodwill onto TP-Link.
Thanks [Maave] for the tip.
If you stand outside on a clear night, can you see the Milky Way? If you live too close to a conurbation the chances are all you’ll see are a few of the brighter stars, the full picture is only seen by those who live in isolated places. The problem is light pollution, scattered light from street lighting and other sources hiding the stars.
The view of the Milky Way is a good analogy for the state of the radio spectrum. If you turn on a radio receiver and tune to a spot between stations, you’ll find a huge amount more noise in areas of human habitation than you will if you do the same thing in the middle of the countryside. The RF noise emitted by a significant amount of cheaper modern electronics is blanketing the airwaves and is in danger of rendering some frequencies unusable.
If you have ever designed a piece of electronics to comply with regulations for sale you might now point out that the requirements for RF interference imposed by codes from the FCC, CE mark etc. are very stringent, and therefore this should not be a significant problem. The unfortunate truth is though that a huge amount of equipment is finding its way into the hands of consumers which may bear an FCC logo or a CE mark but which has plainly had its bill-of-materials cost cut to the point at which its compliance with those rules is only notional. Next to the computer on which this is being written for example is a digital TV box from a well-known online retailer which has all the appropriate marks, but blankets tens of megahertz of spectrum with RF when it is in operation. It’s not faulty but badly designed, and if you pause to imagine hundreds or thousands of such devices across your city you may begin to see the scale of the problem.
This situation has prompted the FCC Technological Advisory Council to investigate any changes to the radio noise floor to determine the scale of the problem. To this end they have posted a public notice (PDF) in which they have invited interested parties to respond with any evidence they may have.
We hope that quantifying the scale of the RF noise problem will result in some action to reduce its ill-effects. It is also to be hoped though that the response will not be an ever-tighter set of regulations but greater enforcement of those that already exist. It has become too easy to make, import, or sell equipment made with scant regard to RF emissions, and simply making the requirements tougher for those designers who make the effort to comply will not change anything.
This is the first time we’ve raised the problem of the ever-rising radio noise floor here at Hackaday. We have covered a possible solution though, if stray RF is really getting to you perhaps you’d like to move to the National Radio Quiet Zone.
Last year, the FCC introduced new regulations requiring router manufacturers to implement software security to limit the power output in specific 5GHz bands. Government regulations follow the laws of unintended consequences, and the immediate fear surrounding this new directive from the FCC was that WiFi router manufacturers would make the easiest engineering decision. These fears came true early this year when it was revealed a large router manufacturer was not following the FCC regulations to the letter by limiting the output of the radio module itself, but instead locking down the entire router.
The FCC’s rules regarding the power output of 5GHz routers was never a serious concern; the FCC is, after all, directed to keep the spectrum clean, and can force manufacturers to limit the power output of the wireless devices. The problem comes from how manufacturers implement this regulation – the easiest solution to prevent users from modifying the output of the radio module will always be preventing users from modifying the entire router. Developers don’t like it, the smart users are horrified, and even the FCC is a little flustered with the unintended consequences of its regulation.
While the easiest solution to preventing the modification of a radio module is to prevent modification to the entire router, there is another way. The folks at Imagination Technologies have come up with a virtualization scheme that allows router manufacturers to lock down the radio module per the FCC directive while still allowing the use of Open Source router firmware like OpenWrt.
A demonstration of the capabilities of this next-generation router comes from the prpl Security Working Group and uses MIPS Warrior CPUs to create multiple trusted environments. The control of the router can be handled by one secure environment, while the rest of the router firmware – OpenWrt included – can be run in an environment more conducive to Open Source firmware.
The demo of a compartmentalized, virtualized router uses a dev kit consisting of a dual-core MIPS P5600 CPU running at 1GHz, and a Realtek RTL8192 WiFi adapter plugged into the USB port. The driver for the WiFi adapter runs under a secure hypervisor, making it secure enough to pass the FCC’s muster.
This build wouldn’t be possible without hardware virtualization in microprocessors and microcontrollers. Imagination Technologies has been working on this for a while, and only a few years ago demonstrated a PIC32 with baked in virtualization.
In the video below, Imagination Technologies demonstrates a MIPS board running three virtual machines. The first machine is running OpenWrt, the second is running a WiFi driver, and the third is running third-party applications. Crashing one machine doesn’t bring down the others, and the WiFi driver is locked away in a secure environment in accordance with the FCC regulations.
While it’s hard to imagine a router based on a MIPS board that would be cheaper than the already inexpensive router SoCs found in today’s routers, this method of secure virtualization is the best way to give consumers what they deserve: an open source option for all their devices.