Published: TV Technology magazine

Issue: 23 March 98



Dallas Hospitals Feels the Growing Pains of DTV   

Broadcasters Mull over the Safety Issue After DTV Transmission Interferes With Biomedical Equipment



by Joe Fedele



DALLAS 

  Friday afternoon, Feb. 27, was a big day at WFAA-TV in Dallas as the ABC affiliate put the first non-experimental 

VHF digital channel in the United States on the air. But the jubilation at WFAA-DT was somewhat short-lived as sta-

tion management ceased operation of its Channel 9 DTV transmitter because of a frantic call from an area hospital.

  It seemed that the DTV transmissions were interfering with at least 60 wireless heart monitors used at Baylor Univer-

sity Medical Center (BUMC). Located less than 20 miles from the WFAA transmission tower (see fig.), BUMC is the 

second-largest tertiary care private nonprofit hospital in North America.

  Biomedical telemetry devices permit patients to move freely about in hospitals while being continually monitored by 

health care providers. The devices include heart, blood pressure and respiration monitors used by patients in their re-

covery. 

  Since no digital sets were in use in WFAA’s market, station management decided to cease its DTV operations until 

BUMC could replace the monitoring equipment. The hospital plans to spend about $200,0000 installing new heart 

monitors and related equipment. The station then resumed DTV operations on the morning of March 6, with BUMC 

back on-line as well.



ONGOING PROBLEMS

  But the interference problems did not stop there. Within the hour the station received a call from Dallas Methodist 

Hospital, where 48 patient monitors suddenly ceased functioning when WFAA-DT signed back on. Methodist Hospital 

is closer to the WFAA transmitter site than BUMC. Again, the station ceased its DTV operations.

  Coincidentally, only four days prior to the commencement of WFAA’s DTV transmissions, a TV Technology article 

warned that such incidents were a possibility. In the Feb. 23 article titled “FCC 

Proposes New Spectrum Use,” it was revealed how these devices were authorized for use by the FCC, despite the op-

position of the Society of Broadcast Engineers (SBE), the Public Broadcasting System (PBS), and several other broad-

cast and health organizations.

  By far the most impassioned arguments came from the SBE, which stated in its comments that “potentially life-

critical biomedical telemetry has no place as a bottom-of-the-food-chain device.” 

  Dane Ericksen, a professional engineer with Hammett and Edison, a San Francisco-based consulting firm and the 

chairman of the SBE FCC Liaison Committee, strongly opposed the commission’s decision to allow biomedical de-

vices on broadcast channels. 

  Ericksen stated that “ironically, I don’t think that WFAA-DT’s use of DTV on Channel 9 was the problem per se [but 

rather] the real problem, I suspect, is any high-power use of Channel 9 in the Dallas area, whether NTSC or DTV.” 

  He explained that under the old NTSC rules, the presence of Channel 8 in the Dallas market precluded the use of 

Channel 9 in the same area. Thus, medical telemetry use of Channel 9 worked without any problems. “But as soon as 

WFAA-DT fired up on Channel 9, bingo, interference was caused.”



SET IN MOTION

  Now, with the first major DTV interruption incident on record, many fear that the FCC decision may have set in mo-

tion a string of similar events. Ericksen agreed, saying that “what’s scary is that similar incidents might well occur all 

over the county as previously precluded N+1 or N-1 [adjacent] channels come into use for DTV.”

  And, as hospitals begin to shift their operations to non-DTV channels, similar incidents from wireless microphones 

and other communications devices could become more prevalent, he said. 

  Wayne Kube, engineering technical manager at WFAA, was taken aback by the magnitude of the problem. Com-

menting that he was not surprised at how invasive the interference was, Kube was “surprised at the amount of 

[biomedical] equipment out there in that frequency band.” 

  Like many broadcasters and engineers, Kube was not aware of the widespread use of biomedical equipment on the 

television broadcast band. “We did know about wireless microphones, wireless intercoms, etc., in the broadcast band 

and we’re dealing with that,” he continued. “But we had no idea about the hospital usage.” 

  With both of the hospitals well within the NTSC city grade contour of WFAA, it is not surprising to Kube that the 

interference was so strong, seeing that biomedical monitors operate at very low- power levels. “The DTV transmission 

fills the 6 MHz spectrum very completely,” he said. “That signal would appear as a powerful noise source to the te-

lemetry receivers at the hospital.”

  And those problems can only get worse. “We are operating at 7 kW ERP from a two-bay Channel 9 batwing antenna, 

[which is] located 900 feet above ground. About May 1, we will begin operating at 18.5 kW ERP about 1,600 feet 

above ground from the same site.”

  What can broadcasters do about the interference problem? “Hopefully, the publicity and knowledge that [the broad-

cast and medical industry] are gaining from this will help the next stations that go on the air,” Kube said. “I would 

suggest that chief engineers contact the biomedical engineering departments at their local medical facilities to let them 

know of possible problems.”

  But Ericksen is looking at a different approach to resolve the issue. “This incident could conceivably provide grounds 

for an SBE Petition for Rule Making asking the commission to undo its recent October 1997 decision in ET Docket 

95-177,” he said, which approved use of biomedical devices on broadcast channels. “But since more than 30 days have 

elapsed since the Report & Order was released, I believe that it is probably too late for a Reconsideration Petition.”

  Another issue that has not yet been readily discussed is possible legal ramifications. “When will the first ‘wrongful 

death’ lawsuit get filed,” Ericksen asked.   In today’s hyper-litigious society, it is conceivable that broadcasters could 

be dragged into court, at considerable expense, even though hospitals bear the full responsibility for operating on the 

broadcast spectrum. n

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