Switched-Mode PSU Jams Communications

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The ARRL have successfully helped Police in Evanston, Illinois to pin down the source of strange RF interference to vehicle car fobs signals and cell phones 

The Police Department contacted the ARRL Lab, after an apparent interference source began plaguing wireless vehicle key fobs, cell phones, and other wireless electronics. Key fob owners found they could not open or start their vehicles remotely until their vehicles were towed at least a block away, nor were they able to call for help on their cell phones when problems occurred.

“This situation is indicative of what can happen as a result of insufficient FCC enforcement, especially with regard to electrical noise and non-compliant consumer devices. ”
— ARRL Lab EMC Specialist Mike Gruber, W1MG

The police turned to ARRL after an unsuccessful approach to the FCC. The FCC considered key fob malfunctions a problem for vehicle manufacturers, although the interference was affecting not just key fobs but cell phones, which are a licensed radio service. 

Evanston authorities worried that a serious situation could develop if someone were unable to call the emergency services, putting public safety at risk. They also were concerned that the RFI could be intentional and indicate some nefarious or illegal activity. Given the seriousness of this situation, Gruber contacted Central Division Director Kermit Carlson, W9XA, to ask if he could look into the matter.

Carlson employed a Radar Engineers 240A Noise Signature Receiver and UHF Yagi antenna to survey the affected block. Since key fobs typically operate at around 315 MHz and 433 MHz, he looked on both frequencies. The survey identified several noise sources in the affected block, but in particular a strong signal in the middle of the block. The interference source turned out to be a recently replaced neon sign switching-mode power supply, which was generating a substantial signal within the on-street parking area just across the sidewalk, between 8 and 40 feet from the sign.

“This situation demonstrates the electromagnetic compatibility problems that are evolving in an atmosphere of non-compliant, unintentional RF-emitting devices,”
— Central Division Director Kermit Carlson, W9XA

Carlson called the Evanston case “a particularly alarming example of radio interference,” especially since local authorities considered it a public safety matter. 

Full ARRL Story - http://www.arrl.org/news/amateur-radio-sleuthing-pins-down-source-of-strange-rf-interference

US Air Force to Improve HF Communications

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The US Air Force is working on plans to improve HF radio propagation by releasing ionised gas in the upper atmosphere using a fleet of micro satellites 

As well as increasing the range of radio signals, the USAF says it wants to smooth out the effects of solar winds, which can knock out GPS, and also investigate the possibility of blocking communication from enemy satellites.

There are at least two major challenges. One is building a plasma generator small enough to fit on a CubeSat – roughly 10 centimetres cubed. Then there’s the problem of controlling exactly how the plasma will disperse once it is released.

Full Story - https://www.newscientist.com/article/2100382-us-air-force-wants-to-plasma-bomb-the-sky-using-tiny-satellites/

Symbol Rate Discussion Open Until October

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Due to not being published in The Federal Register, the Notice of Proposed Rule Making (NPRM) in WT Docket 16-239, the FCC proposed to revise the Amateur Service Part 97 rules in response to the ARRL's so-called 'Symbol Rate' Petition for Rule Making (RM-11708) will be open for consultation until at least October 2016.

ARRL had asked the FCC to change the Part 97 rules to delete the symbol rate limits in Part 97.307(f) and replace them with a maximum bandwidth for data emissions of 2.8 kHz on amateur frequencies below 29.7 MHz.

In its NPRM, the FCC proposed to eliminate the current baud rate limitations for data emissions, consistent with ARRL's Petition, but it declined to propose a bandwidth limitation for data emissions in the MF and HF bands to replace the baud rate limitations.

The ARRL plans to comment in the proceeding

The NPRM can be found on the web in PDF format - http://transition.fcc.gov/Daily_Releases/Daily_Business/2016/db0728/FCC-16-96A1.pdf