Archive for the ‘FM Broadcasting’ Category

The emergence of FM broadcast interference to 700 MHz LTE

Thursday, June 27th, 2013

The law firm of Fletcher, Heald & Hildreth has a post that’s unsettling to engineers such as I who don’t expect very different radio technologies on very different frequencies to interfere with one another.

It seems that 700 MHz base station receivers have become so sensitive they’re susceptible to 8th-order harmonic interference from FM broadcast stations. This is the case even though the FM transmitters meet FCC emission requirements. LTE receivers have become better than the FCC’s Rules.

The lawyers make several good arguments in support of the broadcasters. Unfortunately for the FM stations, Section 73.317(a) of the FCC’s Rules, which governs FM emissions, includes this provision: “. . . should harmful interference to other authorized stations occur, the licensee shall correct the problem promptly or cease operation.” We’re not lawyers, but that seems to be an overarching broad requirement that, until now, hasn’t been much of a concern.

These cases of interference are now being handled on an ad hoc basis, with some encouraging cooperation between broadcasters and the mobile industry. As mobile broadband receivers continue to improve and become even more sensitive, however, they will be even more susceptible to interference from FM harmonics. This should be looked at more formally by the FCC, perhaps in an inquiry or in a rulemaking proceeding.

 

Experimental Radio Applications at the FCC

Sunday, February 5th, 2012

This summarizes a selection from 215 applications for the Experimental Radio Service received by the FCC during October, November, and December 2011. These are related to AM broadcasting, FM broadcasting, spread spectrum on HF and VHF, unmanned aerial vehicle control, electronic warfare support, small satellites, white space technology, video production, managed access, TV interference, RFID, and radar.  The descriptions are listed in order of the lowest frequency found in the application.

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Experimental Radio Applications at the FCC

Wednesday, April 13th, 2011

This summarizes a selection of applications for the Experimental Radio Service received by the FCC during March 2011. These are related to VHF propagation, satellite communications, TV white space, military communications, radar, software defined radio, aircraft broadband services, adaptive networks, peer-to-peer networks, intermodulation testing, unmanned aircraft systems, maritime broadband communications, border surveillance, target acquisition, and millimeter wave propagation.  The applications are sorted by frequency.

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Experimental Radio Applications at the FCC

Monday, January 3rd, 2011

This summarizes a selection of applications for the Experimental Radio Service received by the FCC during December 2010. These are related to FM broadcasting, Positive Train Control, TV white space, mobile satellite terminals, GSM, UMTS, through-the-wall surveillance radar, troposcatter communications, millimeter-wave propagation, flight test telemetry, Doppler weather radar, and air-to-air military radar.

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