Interference Rejection Thresholds of Consumer Digital Television Receivers Available in 2005 and 2006 March 30, 2007 Technical Research Branch Laboratory Division Office of Engineering and Technology Federal Communications Commission OET Report Prepared by: FCC/OET 07-TR-1003 Stephen R. Martin ACKNOWLEDGEMENTS The author gratefully acknowledges the following contributions to this work. Mark Hryszko of the Digital Television group of Advanced Micro Devices provided the “Muddy Waters” RF vector file (mathematically derived from an MPEG2 transport stream) that was used with the Wavetech WS2100 RF player to provide a “desired signal” for the final few tests performed for this report. John Gabrysch of the Commission’s Media Bureau set up and evaluated the performance of the Rohde and Schwarz SFU DTV signal generator and developed channel assignment files for the instrument. The work of Charles Rhodes on third-order intermodulation inspired the paired-signal tests in this project. Gary Sgrignoli of MSW provided a fast-track DTV education to prepare the author for the prequel to this project. The author thanks the following Commission employees for reviewing drafts of this document: Alan Stillwell, Rashmi Doshi, and William Hurst (Office of Engineering and Technology); Doug Miller, John Raymond, and Steve DeSena (Enforcement Bureau); Richard Engelman and Sankar Persaud (International Bureau). The author also acknowledges the support of wife, Dr. Bonnie Dorr, through many long hours spent completing this work. i TABLE OF CONTENTS EXECUTIVE SUMMARY ....................................................................................................................................... viii Tuner Type Tests .................................................................................................................................................. viii Interference Rejection Tests ....................................................................................................................................ix Interference From One Undesired Signal ................................................................................................................ix Interference From IM3-Generating Pairs of Undesired Signals ..............................................................................xi CHAPTER 1 INTRODUCTION...................................................................................................................................1 Background...............................................................................................................................................................1 Objectives .................................................................................................................................................................2 Measurement Program..............................................................................................................................................3 Overview...................................................................................................................................................................5 CHAPTER 2 SCOPE AND APPROACH................................................................................................................. 2-1 Scope of Testing ................................................................................................................................................... 2-1 Interference Rejection Testing Approach ............................................................................................................. 2-4 Presentation of Results.......................................................................................................................................... 2-6 Test Summary....................................................................................................................................................... 2-8 CHAPTER 3 TUNER TYPE TESTS ........................................................................................................................ 3-1 Tuner Topologies.................................................................................................................................................. 3-1 LO Measurement For Tuner Type Identification.................................................................................................. 3-2 Interference Rejection Tests For Tuner Type Identification................................................................................. 3-3 Summary............................................................................................................................................................... 3-4 CHAPTER 4 INTERFERENCE REJECTION REFERENCE LEVELS AND TEST METHODOLOGY .............. 4-1 Reference Levels for Interference Rejection Performance ................................................................................... 4-1 Test Setup Requirements ...................................................................................................................................... 4-3 Test Setup ............................................................................................................................................................. 4-4 Test Setup Performance ........................................................................................................................................ 4-5 Test Setup Configurations..................................................................................................................................... 4-7 CHAPTER 5 REJECTION RESULTS ON CHANNEL 30 FOR SINGLE INTERFERERS WITH FULL CHANNEL WIDTH.................................................................................................................................................. 5-1 Tests at ATSC-Specified Desired Signal Levels .................................................................................................. 5-1 Selection of a Weaker Desired Signal for Tests.................................................................................................... 5-3 Effect of Desired Signal Source............................................................................................................................ 5-5 Tests with Desired Signal at DMIN + 3 dB............................................................................................................. 5-7 Summary of Fifth-Generation Receiver Results ................................................................................................... 5-8 Earlier-Generation Receivers................................................................................................................................ 5-9 Taboo Effects and Other Observations ................................................................................................................. 5-9 CHAPTER 6 REJECTION RESULTS ON CHANNEL 51 FOR SINGLE 8-VSB INTERFERERS....................... 6-1 Tests at ATSC-Specified Desired Signal Levels .................................................................................................. 6-1 Comparison to Channel-30 Results....................................................................................................................... 6-2 CHAPTER 7 TESTS WITH DIFFERENT SIGNAL TYPES AND SOURCES ...................................................... 7-1 1-MHz Bandwidth Undesired Signal.................................................................................................................... 7-3 Desired Signal Source: SFU Versus ATSC997 ................................................................................................... 7-3 Repeat Baseline Test............................................................................................................................................. 7-5 Undesired Signal Type: 8-VSB Versus Bandlimited Gaussian Noise.................................................................7-6 Undesired Signal Type: DVB-H OFDM Versus Bandlimited Gaussian Noise ................................................... 7-7 CHAPTER 8 THEORETICAL FRAMEWORK FOR OUT-OF-CHANNEL INTERFERENCE............................ 8-1 Interference Mechanisms and Order..................................................................................................................... 8-1 Threshold of Visibility of Picture Degradation Due to Interference..................................................................... 8-2 Slopes of Log-Log Plots of D, U, and D/U........................................................................................................... 8-3 Effect of AGC....................................................................................................................................................... 8-3 Weak Signals ........................................................................................................................................................ 8-4 IM3 With Paired Signals....................................................................................................................................... 8-5 CHAPTER 9 THIRD-ORDER INTERMODULATION WITH PAIRED EQUAL-POWER INTERFERERS....... 9-1 Spectra of Third-Order Intermodulation Distortion.............................................................................................. 9-1 Channel-30 Results at Three Desired Signal Levels............................................................................................