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Effects of Public Safety Mobile Systems Operations on DTV and NTSC Broadcasting

This study aims to determine the required guard band spectrum to protect DTV and NTSC channels operating adjacent to Public Safety Services. The laboratory tests and results show that a guard band of 200 to 400 kHz from PS channel 63/68 is needed for coexistence.

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Effects of Public Safety Mobile Systems Operations on DTV and NTSC Broadcasting

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  1. The Effects of Public Safety Mobile Systems Operations (in TV channels 63/68) on DTV and NTSC Broadcasting in Co and Adjacent TV Channels Douglas Prendergast douglas.prendergast@crc.ca Communications Research CenterCanada

  2. Study Objective To determine the amount of guard band spectrum required to protect DTV & NTSC channels operating adjacent to Public Safety (PS) Services

  3. Outline • Background • Introduction • Laboratory Test Scenarios and Test Parameters • Laboratory Test Results • Conclusions

  4. BackgroundUS National Band Plan for Digital Wireless Services in 700 MHz Band

  5. Commercial Mobile Radio Service Spectrum, Upper 700 MHz Block

  6. Tx/Rx Allocations • Channels 60-64 inclusive - Base Station Tx. • Channels 65-69 inclusive - Control, Mobile and Portables Tx.

  7. Interim NTSC/DTV Protection from PS • Until 31 December 2006 or 85% penetration. • Based on separation distance at Grade B contour. • NTSC  40 dB or greater for CCI 0 dB for ACI • DTV  17 dB for CCI -23 dB for ACI

  8. Power and Emission Limits for 700 MHz Band - Lower PS into TV Ch. 63

  9. DTV in the Upper 700 Block • In Canada channels 63/68 are proposed for digital PS with the remaining channels in 60-69 allocated to DTV. • In the US PS will occupy 63/68 and 64/69 of the Upper UHF band with the remaining channels in 60-69 designated for Commercial Mobile Radio Services.

  10. Introduction • Canada adopted a policy to assign one DTV channel for each NTSC channel • Long Transition Time - Up to 10 years • Public Safety (PS) - requires new protected spectrum. • Channels 60 to 69 are currently allocated to DTV.

  11. Shares Upper UHF TV spectrum with PS and Harmonize with US allocation. • Reserve - Channels 63/68 only for PS, all other channels for DTV. • Study effects of PS operations in 63/68 on Co and Adjacent channel DTV and NTSC. • No commercial equipment available Laboratory Analysis based on simulated PS signals and D/U at Threshold of Visibility (TOV).

  12. Laboratory Tests and ResultsSingle/Multi-Channel Test • Single Channel Test (SCT) - Effects of single channel NB and WB PS signals on DTV and NTSC • Desired signal sensitivity • Multi-Channel Test (MCT) - To determine the effects of a typical combination of NW and WB PS signals on DTV and NTSC - (CCI and ACI).

  13. DTV/NTSC - Desired signals • DTV signal: 8-VSB MPEG-2 on channel 63 • Source: Over Canada HDTV • Analog TV Signal - NTSC channel 63 • Source: “Fifth Element” DVD

  14. Public Safety - Undesired Signals • PS signals are undesired (U) from a TV view point. • PS Voice channel - CQPSK Modulation in 6.25 kHz. • PS Data channel - QAM Modulation in 25 kHz, or 50 kHz, or 150 kHz.

  15. Spectrum Plots of the PS signal Used in the Tests

  16. Test Bed: Evaluation of Interference from the PS to TV

  17. Single Channel (25 kHz) into DTV (at TOV) and NTSC (at ITU-R 3)

  18. D/U Performance of DTV Channel 63 with PS NB/WB Interferer

  19. D/U Performance NTSC Channel 63 with PS NB/WB Interferer

  20. Test Scenarios for the Multi-Channel Tests.

  21. Multi-Channel into DTV (at TOV) and NTSC (at ITU-R 3) - Scenario F

  22. Scenario A – PS Lower Adjacent (50 kHz) into DTV and NTSC

  23. Scenario A – PS Upper Adjacent (25 kHz) into DTV and NTSC

  24. Summary of ResultsSingle Channel Tests (Co-located Tx’s.) • For PS-CCI into DTV • An average D/U of 15 dB is required except in the vicinity of the pilotand modulation carrier where about 20 dB may be required • For PS-CCI into NTSC • An average D/U of 50 dB is required except in the vicinity of the Video, Audio and Chromacarriers where more protection will be required

  25. For PS-ACI into DTV • Upper adjacent channel - 200 kHz GB provides for a D/U of - 20 dB into DTV while for the Lower adjacent channel, about 400 kHz is required. • For PS-ACI into NTSC • For both upper and lower adjacent channels about 200 kHz of guard band give a 0 dB D/U

  26. Multi-Channel Tests (Co-located Tx’s and 22 to 24 PS interferers used.) • For PS-CCI and PS-ACI signal into DTV • Similar D/U requirement as when a co-channel DTV signal is the undesired signal • For PS-CCI into NTSC • Similar D/U requirement as when a co-channel DTV signal is the undesired signal

  27. For a PS-ACI signal into NTSC • For the lower adjacent channel - Similar D/U requirements as when a adjacent-channel DTV signal is the undesired signal while about 5 dB more protection is required for the upper adjacent channel because of video carrier sensitivity.

  28. ConclusionsThe results show the following: • DTV and NTSC Television can co-exist with PS in the upper UHF band. • For this sharing arrangement a guard band of 200 to 400 kHz of from PS channel 63/68 is needed. • Protection Ratios for TV are the same as those for CCI and ACI - DTV signals, when multi-channel PS systems are implemented. • Results are based on Laboratory measurements & must be confirmed by field evaluation.

  29. Thank you ! For more information: Doug Prendergast Communications Research Center 3701 Carling Avenue Ottawa Ontario Canada K2H 8S2 Tel: (613) 949-0129 Fax: 613-990-6488 douglas.prendergast@crc.ca

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