fccIt has become increasingly popular to install bi-directional amplifiers (BDA’s) and distributed antenna systems (DAS’s) to overcome problems of cellular and other wireless coverage within buildings. Properly engineered, and coordinated with the cell cos being retransmitted these can greatly help in overcoming building problems.

However, these systems are readily available, and are increasingly being installed without the needed planning and coordination. This can cause real interference problems to wireless licensees – and bring FCC wrath upon the user!

In this case, a movie studio found itself in the FCC cross hairs for installing an unauthorized BDA that ran amok.

On January 29, 2010, in response to an interference complaint from   T-Mobile on the frequency 1892.0 MHz in Culver City, California, agents from the Los Angeles FCC Office located the interfering signal to a bi-directional amplifier (“BDA”) installed on the roof of Sony Studios – Stage-6 – in Culver City. Sony subsequently acknowledged operation of the BDA in question.

T-Mobile has a license to provide PCS services on 1892.0 MHz in the Culver City area. The FCC concluded that operation of the Sony transmitter (BDA) was subject to the licensing requirements under Section 24.11 of the Commission’s Rules, which applies to PCS licensees like T-Mobile. In addition, they notified Sony that transmitters in the PCS radio service must have received an equipment authorization prior to use. Furthermore, a licensee’s authority to install a BDA does not, without further authorization from the licensee, permit a subscriber to install a BDA. In response to an inquiry from a Los Angeles agent, T-Mobile reported that it did not provide Sony authorization to install a BDA.

The FCC ordered Sony to cease use of the system immediately, and to provide the Commission evidence of FCC Rules conformance before turning it back on, under penalty of prospective fines if not done.

Unintended radio frequency interference is an increasing problem in our world that is becoming more and more dependent on wireless systems. LBA has considerable expertise available for troubleshooting and correcting communication system interference. If you need assistance, please contact Mike Britner for an immediate assessment of your problem.

About The Author

LBA Group, Inc. has 50 years of experience in providing RF asset solutions and risk management for industrial and telecommunications infrastructure assets. The group is comprised of LBA Technology, a leading manufacturer and integrator of radio frequency systems, lightning protection and EMC equipment for broadcast, industrial and government users worldwide; the professional consultancy Lawrence Behr Associates and LBA University, providing on-site and online professional training. The companies are based in Greenville, N.C., USA.

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