DTV Channel 6 Interference to FM Band Reception

Final Report

Return to EUonline   |  Complete our TV-6 Interference Survey |
Read Doug Vernier's Analysis of the report, and what it means to your station

"The continued use of channel-six by TV stations for DTV transmissions poses a significant threat to many non-commercial educational FM stations throughout the country. " - Conclusion in an analysis of the DTV Report by Doug Vernier.

 

"National Public Radio (NPR) commissioned this study to consider the interference potential of digitally modulated television (DTV) stations assigned to DTV Channel 6 on existing public radio stations operating in the lower noncommercial FM band, Channels 201-220 (88.1-91.9 MHz). While there was considerable historical interference between NTSC television stations assigned to Channel 6 and FM stations in the noncommercial FM band, there had not been a detailed consideration of this issue during the laboratory and field testing of DTV systems...

The realities of DTV interference became evident on February 27, 1998 when low power biomedical telemetry devices using VHF television channel 9 failed to operate after WFAA-TV, Dallas began DTV broadcasting on the same channel. Several nearby hospitals experienced data loss in remote cardiac monitoring equipment. This event served as a wake-up call for the entire broadcast industry, as well as secondary and unlicensed users of broadcast spectrum to the potential of DTV interference."
-Excerpt from the Executive Summary of the report

The free Adobe Acrobat Reader is required for viewing this report; the Reader is downloadable directly from Adobe. Look for the "Get Adobe Reader" icon on the home page, and follow their instructions for the Reader installation.

With the exception of Section I of the Laboratory Test Report, the text and graphics are taken directly from data disks provided to NPR, and the printed version has been used to verify correct order and presentation. Section I of the Lab Test Report was scanned and processed in Adobe Acrobat for best file size/viewing for this Web site.

Please take a moment to complete our TV-6 Interference Survey

NPR is seeking recent information concerning the predicted interference consequences under 73.525 vs. actual interference experienced to TV-6 in specific markets. Because some NCE-FM stations may have to relocate from their existing transmission towers due to DTV start-up, any recent real-world experiences could help these stations navigate potential TV-6 interference issues. To assist in compiling and analyzing this information, we have created a short interactive web-form.
If your station operates within a TV-6 service area, and you have any experiences with the percentage of viewers actually affected with impaired reception vs. what 73.525 predicts, please complete this survey. This survey also covers what remediation efforts have proven successful with specific kinds and degrees of intereference.
NPR will make the information received available to all NCE-FMs by publication on the EUonline website.

All material is Copyright © 1998 National Public Radio. All Rights Reserved.

Final Report (13K)

Index of Laboratory Test  Reports - Section 1 (A list of the pdf files that comprise this section)

Laboratory Test Report - Section 2 (431K)

Doug Vernier's Analysis of the Report

 

Appendix                    Description (Download file size is listed in Kilobytes)
A Narrowband Noise Sensitivity Test Results (44K)
B Denon TU-380 RD Noise Floor Plot (22K)
C Pioneer Noise Floor Plot (25K)
D Panasonic Noise Floor Plot (22K)
E Delco Noise Floor Plot (27K)
F Denon TU-680 NAB Noise Floor Plot and Additional Certification Tests (49K)
G Audiovox Noise Floor Plot and Additional Certification Tests (49K)
H RF Distributions with and without Multipath (16K)
I Audio Distribution (13K)
J Test Results based on FCC Specifications prior to February 23, 1998 C1 (69K)
K Test Results based on DTV Transmitter operating out of Specification C2 (56K)
L Test Results based on Minimum DTV Out of Band Emissions C3 (56K)
M Test Results based on FCC Specifications after February 23, 1998 C4 (80K)
N Test Results based on Proposed -60 dB Emissions C5 (19K)
O Audiovox Multipath Noise Floor at 88.5 MHz and C4 Emissions (673K)
P Delco Multipath Noise Floor at 88.5 MHz and C4 Emissions (702K)
Q Audiovox Multipath Noise Floor at 90.1 MHz and C4 Emissions (652K)
R Delco Multipath Noise Floor at 90.1 MHz and C4 Emissions (679K)
S Audiovox Multipath Noise Floor at 90.9 MHz and C5 Emissions (658K)
T Delco Multipath Noise Floor at 90.9 MHz and C5 Emissions (676K)
U Emission Level Measurements (11K)
V RMS Meter and Analog to Digital Converter Calibration (12K)
W Averaged Test Results based on February 23, 1998 FCC Specifications (24K)
X Averaged Test Results based on Simulated New Technology (23K)
Y Averaged Test Results based on Defective DTV Transmitter (24K)
Z Averaged Test Results based on FCC Specifications prior to February 23, 1998 (25K)