09.19.2008 08:00 AM
Originally featured on BroadcastEngineering.com
NCTA letter raises concerns about unlicensed white space devices
The National Cable and Telecommunications Association (NCTA) wrote the FCC Sept. 10 telling the commission it must first address three specific areas of concern to the cable TV industry before moving forward on allowing unlicensed white space devices into the TV band.
Specifically, the association pointed to the potential for interference from white space devices with TV receivers, interference with headends and interference from fixed-line use. The NCTA letter sought to draw the attention of the commission to the “significant potential for harmful interference” that would impact cable systems and subscribers without adequately addressing these issues.
(Editor’s note: Edgar Reihl, Shure director of advanced development, recently relayed an anecdotal story in a recent Sound Off interview about a member of the FCC’s Office of Engineering and Technology losing cable TV service when a prototype white space device in his home was turned on and interfered with his cable receiver.)
The letter raised several points, including:
- more than 67 million cable viewers could be affected by the outcome of the commission’s decision in the white space proceeding
- inattention to the date regarding potential disruption of customer viewing of cable programming resulting from direct pickup (DPU) interference to cable-ready DTV receivers
- the significant threat from white space devices to cable TV reception of distant over-the-air TV programming at headends
The association told the commission that “proposals for unlicensed, personal and portable devices and for fixed, licensed use of the TV bands have the potential to seriously degrade service for cable television viewers.”
While the cable association’s position does not go as far as those of those of the broadcast and wireless mic industries in opposing unlicensed device use in the TV band, it shares concerns with those industries that opening the band will jeopardize billions of dollars in existing infrastructure.
If the commission moves forward and allows white space devices into the TV band, NCTA suggested six requirements:
- Restrict the operation of portable devices to a maximum of 10mW and prohibit transmissions in the VHF channels given the high probability of direct pickup interference to TV receivers.
- Prohibit operations, at a minimum, on Channels 2-4.
- Restrict the operation of fixed devices to at least 400ft from the external walls of residential buildings.
- Prohibit operation of fixed devices in VHF channels.
- Require spectrum coordination before operation of portable devices on channels adjacent to those being received at headends.
- Of the suggested methods by which fixed and portable devices might automatically determine channel availability, it appears that auto-location (GPS or equivalent), combined with regular access to a reliable database containing geographically indexed lists of available channels, has the potential to provide the flexibility and reliability required to protect headend reception.