Skip to main content

Sinclair Transmits OFDM in Baltimore

BALTIMORE – Wednesday, March 27 was an auspicious day for the engineers at Sinclair in Balmer.

“This morning at 3:35 a.m. Eastern Time, we lit up the greater Baltimore/Washington market with 800-plus kW ERP of DVB-T2 (OFDM) power,” Sinclair’s Mark Aitken wrote to Mark Richer, president of the Advanced Television Systems Committee, which is now at work on modernizing the broadcast television transmission standard. (Aitken is pictured at right in the forefront, with Mike Simon of Sinclair in the baseball hat; Acrodyne General Manager Andy Whiteside; and Stu Boughton of Acrodyne. Bill Soreth of Acrodyne also participated.)

For Aitken and others at Sinclair, the use of orthogonal frequency division multiplexing in the United States is a long-held conviction. Sinclair and its chief David Smith championed coded OFDM in the 1990s when the industry was preparing for the digital transition. Smith was thinking of mobile reception capabilities back then, for which COFDM was more suitable than eight-level vestigial sideband, or 8-VSB modulation. The latter nonetheless won the endorsement of the ATSC and was adopted as the U.S. transmission standard.

Sinclair has since doubled its TV station holdings to 112 stations in 61 markets, covering nearly 30 percent of the U.S. population. The company also has continued to advocate for mobile DTV, through the Open Mobile Video Coalition, and the Mobile500. Last month, it was granted an experimental license by the Federal Communications Commission to test DVB-T2—Europe’s mobile broadcast modulation standard based on OFDM. (See Doug Lung’s “Details on WNUV’s Experimental License to Test OFDM.”)

Sinclair’s inaugural DVB-T2 trial, conducted on its CW affiate signal, WNUV-TV, coincided with a call from the ATSC for proposals on its so-called “next-generation” standard, version 3.0. It is clear to the ATSC and the industry in general that the current configuration, which locks broadcasters into using the MPEG-2 compression standard. MPEG-2 was sufficient for one high-definition video signal within a 6 MHz channel (as far as CBS was concerned), or several, lower-res multicast signals. It will not, however, accommodate 4K, or Ultra-HD, nor will the standard in general support advanced features such as targeted advertising and multiplatform distribution. (See “ATSC Seeks Proposals for 3.0 Physical Layer.”)

Sinclair’s Aitken said the company would continue to participate in the ATSC’s standards activities.

“Part of that participation may intersect needs to test and evaluate various systems and technologies,” Aitken wrote. “I would like to extend to ATSC that Sinclair will make every reasonable effort to provide support for its ongoing 3.0 activities by providing for the use and access to the WNUV facility to support experimental needs…. We are committed to no specific standard or provider.”

Aitken provided a “condensed engineering summary of the facility as licensed—a parallel IOT transmitter rated at 50 kW, running at 36 kWis the RF source.”

TSID: 1409 (0x0581)
DT- LIC:Ch. 40, Baltimore, Md., Est. population 8,518,396
1,223-foot, 845 kW DA (H) (57 Mile Contour / 10,534 Sq. Mi. Area)
(36 kW TPO + 15.27 dB gain = 845 kW ERP)
1,229-foot AGL (1044237); Full Service Filter
0.75-degree Electronic Beam Tilt; Dielectric TUD-C5SP-10/36SPH-1-B
N 39° 20’ 10” (39.336), W 76° 38’ 59” (-76.65) (S) (F) Television Hill, Md.

The DVB-T2 operating parameters were as follows:
16k ext FFT
GI 1/32
64 QAM
FEC 3/4

“The configuration we operated gave us additional data band-width yielding 24.92 Mbps— 30 percent more than standard ATSC—with a [carrier-to-noise ratio] of 15.1 dB—same as ATSC—with an [modulation error ratio] of 33.5 dB… and shoulders well within specs at -53dB or better at the output of the system,” Aitken said. “We were running and receiving HD programming. For the record, it was received over-the-air with a USB T2 receiver.”

Sinclair’s experimental license was granted Feb. 15, 2013 for a six-month period.

~ Deborah D. McAdams