As the LBA Antenna Turns

In a breakthrough action, the Federal Communications Commission today authorized digital television stations to use DTS technology. In a move aimed to remedy coverage problems in the analog to digital transition, the FCC has now permitted DTV stations to supplement their tall tower transmissions with low power outliers, or abandon the tall towers for a network of low height, lower power transmitters.

A DTV “distributed transmission system” (“DTS”) employs multiple synchronized transmitters spread around a station’s service area, rather than the current single transmitter approach. Each transmitter broadcasts the station’s DTV signal on the same channel. Due to the synchronization of the transmitted signals, DTV receivers treat the multiple signals as reflections or “ghosts” and use “adaptive equalizer” circuitry to cancel or combine them to produce a single signal. DTS is also referred to as DTT, for distributed transmission technologies and as DTx, for distributed transmitters.

DTS can enable service to areas that a single-transmitter station fails to reach due to obstructions that block the signal coming from the single-transmitter site. The technology provides more uniform signal levels throughout a station’s  service area, making indoor reception more reliable. Also, multiple DTS operating at a lower power than a single transmitter achieve the same coverage while reducing interference to neighboring licensees.

A full text of the FCC action may be found at the FCC website. Key points of the FCC action were as follows:

• A DTS service area was defined as being comparable to that of a station’s single transmitter facility. A new “Table of Distances” was set out to implement this policy.
• Waivers would be permitted for a station to use DTS to enable it to continue to serve its existing analog viewers who would otherwise lose service as a result of its transition to digital service.
• DTS transmitters must be located within either the DTV station’s Table of Distances area or its authorized service area.
• The multiple transmitters of a DTS network are afforded primary regulatory status within the areas that such DTS transmitters are authorized to serve.
• DTS stations are subject to the Part 73 licensing and technical rules that apply to DTV single-transmitter stations.
• DTS proposals will be evaluated using the same interference standard adopted for DTV stations’ and the root-sum-square (“RSS”) method of calculating interference from multiple DTS transmitters will be used.
• A licensee of multiple digital Class A TV, digital LPTV, and/or digital TV translator station may operate through interconnected single frequency DTS networks. Each station in the network must be separately licensed.
• We approve on an experimental basis the Use of DTS technologies by a single digital Class A TV, digital LPTV or digital TV translator station can be approved on an experimental basis within its authorized service area.

LBA can supply full support for the DTS network engineering and deployment. LBA also offers the Kathrein MSK-200 Digital Signal Analyzer with advanced capabilities for the synchronization and signal quality control of DTS networks.

For engineering support, contact Jerry Brown at 252.757.0279 or via email. For information on the MSK-200 and other LBA test equipment for television, contact Paulo Fernandes at 252.757.0279 or via email.

Among recent AM antenna systems to use the new LBA VC-1 Vacuum RF Relay is a seven tower 50 KW directional at KYES in St. Cloud, Minnesota. KYES is a new Catholic community talk radio service of The Throw Fire Project.

In addition to two phasor cabinets, the complex system includes two open panel ATU’s and five weatherproof cabinet ATU’s. The use of LBA VC-1 master and slave vacuum RF contactors has permitted more compact and logical layout of the phasing equipment without sacrifice of serviceability.

The military-grade vacuum RF switch elements are rated for over 500 years of trouble free operation! Traditional contactors are lucky to operate for a few years without repair and maintenance.

Shown here is John George, VP of Sales for LBA Technology with a KYES 50,000 watt antenna tuning unit. The uncluttered appearance of the RF switching elements is clearly seen. John says that there is one thing missing – no more earth shaking bang of RF contactors operating. The LBA VC-1 RF contactors are totally silent!

Contact Paulo Fernandes to learn more about LBA antenna equipment and RF vacuum contactors at 252-757-0279 or via email.