Cable_NN1 systems_NN2 can_VM handle_VVI 750_MC MHz_NNU of_IO bandwidth_NN1 ,_, with_IW hundreds_NNO2 of_IO channels_NN2 ,_, video_NN1 on_II demand_NN1 ,_, telephone_VV0 services_NN2 ,_, broadband_JJ Internet_NN1 access_NN1 and_CC interactive_JJ programming_NN1 guides_NN2 vying_VVG for_IF carriage_NN1 ._. 
But_CCB even_RR the_AT most_RGT advanced_JJ cable_NN1 systems_NN2 offer_VV0 only_RR about_RG a_AT1 dozen_NNO high-definition_JJ channels_NN2 to_II their_APPGE customers_NN2 today_RT ._. 
Why_RRQ is_VBZ that_DD1 the_AT case_NN1 ?_? 
The_AT biggest_JJT hog_NN1 is_VBZ analog_NN1 TV_NN1 channels_NN2 ,_, which_DDQ cable_VV0 operators_NN2 must_VM continue_VVI to_TO carry_VVI well_RR past_II 2009_MC ,_, according_II21 to_II22 CableLabs_NP2 ,_, the_AT research_NN1 and_CC development_NN1 arm_NN1 of_IO the_AT cable_NN1 TV_NN1 industry_NN1 ._. 
Those_DD2 linear_JJ (_( continually_RR transmitting_VVG ,_, one-way-only_JJ )_) analog_VV0 channels_NN2 occupy_VV0 as_RG much_DA1 as_CSA 550_MC MHz_NNU of_IO the_AT coaxial_JJ cable_NN1 entering_VVG homes_NN2 ._. 
Cable_NN1 companies_NN2 can_VM not_XX deep-six_MC all_DB their_APPGE analog_NN1 channels_NN2 and_CC move_VV0 everything_PN1 into_II the_AT bandwidth-efficient_JJ digital_JJ realm_NN1 because_II21 of_II22 the_AT legacy_NN1 of_IO cable-ready_JJ TVs_NP1 ._. 
Millions_NNO2 of_IO viewers_NN2 plug_VV0 the_AT cable_NN1 directly_RR into_II the_AT analog_NN1 tuners_NN2 on_II their_APPGE old_JJ tubes_NN2 ._. 
Digital_JJ cable_NN1 boxes_NN2 leased_VVN by_II subscribers_NN2 do_VD0 bypass_VVI the_AT tuners_NN2 in_II their_APPGE TVs_NP1 ._. 
So_RR cable_VV0 operators_NN2 are_VBR faced_VVN with_IW the_AT costs_NN2 of_IO offering_VVG a_AT1 box_NN1 to_II everyone_PN1 or_CC multiple_JJ boxes_NN2 to_II households_NN2 that_CST have_VH0 several_DA2 TVs_NP1 ._. 
Or_CC another_DD1 option_NN1 is_VBZ that_CST the_AT companies_NN2 may_VM simply_RR wait_VVI well_RR into_II the_AT next_MD decade_NNT1 ,_, when_CS sufficient_JJ numbers_NN2 of_IO viewers_NN2 will_VM have_VHI finally_RR replaced_VVN their_APPGE long-lasting_JJ analog_NN1 sets_VVZ with_IW ones_NN2 containing_VVG DTV_NP1 tuners_NN2 as_II31 well_II32 as_II33 other_JJ so-called_JJ conditional-access_JJ systems_NN2 ,_, such_II21 as_II22 credit-card-size_JJ CableCARDs_NP2 or_CC their_APPGE software-only_JJ counterparts_NN2 ._. 
One_MC1 way_NN1 to_TO manage_VVI the_AT pipeline_NN1 problem_NN1 is_VBZ to_TO adjust_VVI the_AT transmission_NN1 techniques_NN2 ._. 
Cable_NN1 operators_NN2 have_VH0 begun_VVN employing_VVG a_AT1 modified_JJ system_NN1 architecture_NN1 called_VVN switched_JJ broadcasting_NN1 (_( also_RR known_VVN as_II switched_VVN digital_JJ video_NN1 )_) ._. 
A_AT1 hybrid_JJ fiber_NN1 coaxial_JJ cable_NN1 system_NN1 brings_VVZ an_AT1 optical_JJ fiber_NN1 trunk_NN1 with_IW seemingly_RR limitless_JJ bandwidth_NN1 to_II a_AT1 neighborhood_NN1 ,_, but_CCB then_RT branches_VVZ to_II coaxial_JJ cable_NN1 ,_, with_IW its_APPGE 750-MHz_JJ limitation_NN1 ,_, for_IF the_AT last_MD leg_NN1 ,_, serving_VVG 300_MC to_II 500_MC homes_NN2 on_II a_AT1 node_NN1 that_CST loops_NN2 from_II the_AT fiber_NN1 ._. 
Conventional_JJ signal_NN1 distribution_NN1 carries_VVZ every_AT1 channel_NN1 in_II parallel_NN1 into_II each_DD1 home_NN1 ,_, so_CS21 that_CS22 a_AT1 parent_NN1 might_VM be_VBI tuning_VVG into_II ESPN-HD_NP1 in_II one_MC1 room_NN1 while_CS a_AT1 child_NN1 enjoys_VVZ MHD_NP1 (_( the_AT high-def_JJ sibling_NN1 of_IO MTV_NP1 )_) in_II her_APPGE room_NN1 ._. 
At_II any_DD particular_JJ time_NNT1 ,_, though_CS ,_, nobody_PN1 is_VBZ watching_VVG most_DAT of_IO the_AT channels_NN2 on_II the_AT node_NN1 ._. 
The_AT new_JJ way_NN1 is_VBZ to_TO stream_VVI only_RR the_AT channels_NN2 that_CST tuners_NN2 on_II that_DD1 node_NN1 have_VH0 requested_VVN at_II that_DD1 moment_NN1 ._. 
The_AT beauty_NN1 of_IO the_AT system_NN1 is_VBZ that_DD1 node_NN1 bandwidth_NN1 ,_, which_DDQ was_VBDZ once_RR allocated_VVN equally_RR to_II popular_JJ and_CC hardly_RR watched_VVD channels_NN2 alike_RR ,_, can_VM now_RT be_VBI freed_VVN up_RP to_TO make_VVI room_NN1 for_IF more_RGR high-definition_JJ channels_NN2 as_CSA needed_VVN --_JJ because_CS most_DAT people_NN are_VBR likely_JJ to_TO be_VBI choosing_VVG from_II among_II the_AT same_DA popular_JJ channels_NN2 rather_II21 than_II22 from_II obscure_JJ options_NN2 ._. 
Part_NN1 of_IO the_AT reason_NN1 the_AT cable_NN1 industry_NN1 is_VBZ now_RT talking_VVG about_II a_AT1 hybrid_JJ fiber-coaxial_JJ system_NN1 is_VBZ increasing_JJ competition_NN1 from_II the_AT telephone_NN1 companies_NN2 Verizon_NP1 and_CC AT_II &T,;_NULL which_DDQ have_VH0 begun_VVN rolling_VVG out_RP fiber_NN1 to_II homes_NN2 (_( or_CC groups_NN2 of_IO homes_NN2 )_) in_II select_JJ communities_NN2 ._. 
In_II a_AT1 couple_NN1 of_IO years_NNT2 many_DA2 more_DAR households_NN2 are_VBR expected_VVN to_TO be_VBI able_JK to_TO get_VVI TV_NN1 service_NN1 from_II their_APPGE "_" phone_NN1 "_" company_NN1 ._. 
Unlike_JJ cable_NN1 's_GE fiefdoms_NN2 ,_, Direct_JJ Broadcast_NN1 Satellite_NN1 (_( DBS_NP1 )_) companies_NN2 (_( DirecTV_NP1 and_CC DISH_NN1 Network_NN1 )_) operate_VV0 nationally_RR and_CC have_VH0 been_VBN digitally_RR efficient_JJ all_DB along_RP ._. 
Every_AT1 subscriber_NN1 uses_VVZ an_AT1 external_JJ tuner/decoder_NN1 to_TO receive_VVI channels_NN2 ,_, bypassing_VVG the_AT TV_NN1 tuner_NN1 ._. 
But_CCB DBS_NP1 faces_VVZ its_APPGE own_DA bandwidth_NN1 constraints_NN2 as_CSA channels_NN2 overall_RR have_VH0 proliferated_VVN ,_, the_AT number_NN1 of_IO network_NN1 HDTV_NP1 affiliates_NN2 has_VHZ swelled_VVN ,_, and_CC subscribers_NN2 have_VH0 increasingly_RR had_VHN their_APPGE local_JJ channels_NN2 beamed_VVN to_II them_PPHO2 by_II satellite_NN1 ._. 
DBS_NP1 has_VHZ been_VBN coping_VVG in_II three_MC ways_NN2 ._. 
First_MD ,_, it_PPH1 has_VHZ added_VVN satellites_NN2 ._. 
Subscribers_NN2 using_VVG older_JJR equipment_NN1 who_PNQS want_VV0 to_TO get_VVI more_RGR recently_RR added_JJ channels_NN2 may_VM need_VVI to_TO buy_VVI another_DD1 dish_NN1 or_CC replace_VV0 a_AT1 round_JJ dish_NN1 with_IW an_AT1 elliptical_JJ one_PN1 so_RR they_PPHS2 can_VM receive_VVI signals_NN2 from_II more_DAR than_CSN one_MC1 position_NN1 in_II the_AT sky_NN1 ._. 
Second_MD ,_, it_PPH1 has_VHZ increased_VVN the_AT use_NN1 of_IO spot_NN1 beams_NN2 as_II a_AT1 way_NN1 to_TO make_VVI the_AT most_DAT of_IO the_AT available_JJ frequencies_NN2 ._. 
Instead_II21 of_II22 raining_VVG down_RP identical_JJ bits_NN2 on_II the_AT entire_JJ continent_NN1 ,_, a_AT1 spot_NN1 beam_NN1 narrowly_RR focuses_VVZ channels_NN2 meant_VVN for_IF a_AT1 particular_JJ metropolitan_JJ area_NN1 ._. 
Other_JJ spot_NN1 beams_NN2 are_VBR pointed_VVN at_II other_JJ cities_NN2 ._. 
Although_CS there_EX is_VBZ redundancy_NN1 transmitting_VVG Grey_NP1 's_GE Anatomy_NN1 on_II each_DD1 spot_NN1 beam_NN1 ,_, the_AT technology_NN1 helps_VVZ to_TO preserve_VVI a_AT1 network_NN1 like_II ABC_NP1 's_GE affiliate_NN1 system_NN1 ,_, because_CS local_JJ commercials_NN2 and_CC programs_NN2 are_VBR contained_VVN in_II the_AT signal_NN1 just_RR as_CSA they_PPHS2 are_VBR if_CS the_AT viewer_NN1 received_VVD the_AT program_NN1 over_II the_AT air_NN1 or_CC by_II cable_NN1 ._. 
Last_MD ,_, satellite_NN1 systems_NN2 are_VBR changing_VVG over_RP from_II the_AT MPEG-2_MC compression_NN1 scheme_NN1 to_II MPEG-4_MC ,_, which_DDQ accommodates_VVZ about_RG twice_RR as_RG many_DA2 channels_NN2 ;_; viewers_NN2 may_VM need_VVI to_TO replace_VVI their_APPGE set-top_JJ box_NN1 with_IW one_PN1 that_CST can_VM decompress_VVI MPEG-4_MC ._. 
MPEG-4_MC coding_NN1 is_VBZ more_RGR efficient_JJ because_CS various_JJ objects_NN2 in_II the_AT same_DA scene_NN1 can_VM be_VBI scaled_VVN for_IF different_JJ levels_NN2 of_IO spatial_JJ detail_NN1 ._. 
For_REX21 example_REX22 ,_, the_AT full_JJ resolution_NN1 for_IF an_AT1 important_JJ foreground_NN1 object_NN1 ,_, such_II21 as_II22 a_AT1 football_NN1 ,_, can_VM be_VBI maintained_VVN ,_, whereas_CS a_AT1 less_RGR important_JJ object_NN1 ,_, such_II21 as_II22 a_AT1 group_NN1 of_IO fans_NN2 in_II the_AT background_NN1 ,_, can_VM be_VBI updated_VVN at_II a_AT1 lower_JJR rate_NN1 ._. 
The_AT concept_NN1 is_VBZ similar_JJ to_II the_AT perceptual_JJ coding_NN1 technique_NN1 used_VVN for_IF MP3_FO audio_JJ compression_NN1 ,_, in_II which_DDQ ,_, at_II a_AT1 particular_JJ moment_NN1 ,_, one_MC1 instrument_NN1 masks_VVZ another_DD1 ;_; the_AT encoding_JJ process_NN1 discards_NN2 what_DDQ is_VBZ imperceptible_JJ anyway_RR to_TO save_VVI bits_NN2 and_CC consume_VVI less_DAR bandwidth_NN1 ._. 
The_AT Last_MD Leap_NN1 No_RRQV31 matter_RRQV32 how_RRQV33 the_AT signal_NN1 arrives_VVZ ,_, consumers_NN2 who_PNQS want_VV0 to_TO record_VVI their_APPGE shows_NN2 may_VM have_VHI one_PN1 more_RGR digital_JJ hurdle_NN1 after_II the_AT transition_NN1 ._. 
A_ZZ1 VCR_NP1 's_GE analog-only_JJ tuner_NN1 will_VM no_RR longer_RRR be_VBI able_JK to_TO record_VVI over-the-air_JJ TV_NN1 channels_NN2 ,_, although_CS it_PPH1 may_VM be_VBI compatible_JJ with_IW analog_NN1 channels_NN2 still_RR being_VBG carried_VVN on_RP cable_NN1 ._. 
Cable_NN1 and_CC satellite_NN1 subscribers_NN2 are_VBR more_RGR likely_JJ to_TO lease_VVI or_CC buy_VVI a_AT1 high-definition-capable_JJ set-top_JJ box_NN1 with_IW a_AT1 built-in_JJ hard_JJ drive_NN1 to_TO record_VVI programs_NN2 at_II the_AT highest_JJT resolution_NN1 ._. 
Alternatives_NN2 include_VV0 CableCARD_NP1 hard-drive_JJ recorders_NN2 such_II21 as_II22 a_AT1 new_JJ high-def_JJ model_NN1 from_II TiVo_NP1 ,_, HDTV_NP1 sets_VVZ with_IW built-in_JJ hard_JJ drives_NN2 ,_, and_CC --_JJ if_CS viewers_NN2 want_VV0 to_TO play_VVI their_APPGE old_JJ VHS_NP1 cassettes_NN2 in_II the_AT same_DA device_NN1 --_NN1 DVHS_NP1 machines_NN2 that_CST can_VM also_RR record_VVI over-the-air_JJ HDTV_NP1 programs_NN2 ._. 
Of_RR21 course_RR22 ,_, occurrences_NN2 of_IO digital-picture_JJ losses_NN2 and_CC the_AT inconvenience_NN1 of_IO getting_VVG new_JJ set-top_JJ boxes_NN2 are_VBR worth_II putting_VVG up_RP with_IW ,_, HDTV_NP1 advocates_NN2 say_VV0 ,_, because_CS conventional_JJ TV_NN1 can_VM not_XX hold_VVI a_AT1 candle_NN1 to_II the_AT amazing_JJ clarity_NN1 of_IO high_JJ definition_NN1 or_CC the_AT services_NN2 it_PPH1 will_VM provide_VVI ._. 
When_CS February_NPM1 2009_MC rolls_NN2 around_RP ,_, one_MC1 thing_NN1 is_VBZ certain_JJ :_: television_NN1 will_VM never_RR be_VBI the_AT same_DA again_RT ._. 
Digital_JJ TV_NN1 Overview_NN1 After_II many_DA2 years_NNT2 of_IO anticipation_NN1 ,_, the_AT end_NN1 of_IO conventional_JJ analog_NN1 broadcasting_NN1 now_RT appears_VVZ to_TO be_VBI set_VVN for_IF February_NPM1 17_MC ,_, 2009_MC ;_; after_CS that_DD1 date_NN1 ,_, all_DB broadcasts_NN2 will_VM be_VBI digital_JJ ._. 
Digital_JJ broadcasts_NN2 offer_VV0 consumers_NN2 advantages_NN2 such_II21 as_II22 crystal-clear_JJ pictures_NN2 and_CC new_JJ information_NN1 services_NN2 ._. 
Frequencies_NN2 no_RR21 longer_RR22 used_VVN for_IF analog_NN1 broadcasting_NN1 will_VM be_VBI available_JJ for_IF communication_NN1 by_II emergency_NN1 response_NN1 teams_NN2 or_CC auctioned_VVN for_IF other_JJ uses_NN2 ,_, such_II21 as_II22 advanced_JJ cellular_JJ systems_NN2 ._. 
Analog_NP1 's_GE legacy_NN1 ,_, however_RR ,_, will_VM continue_VVI to_II dog_NN1 the_AT new_JJ digital_JJ era_NN1 for_IF several_DA2 years_NNT2 past_RT the_AT cutoff_NN1 ._. 
