5.1NTSC Analog and Vertical Blanking Interval (VBI)
5.1.1Host VBI Pass-Through Test
This test verifies that the Host can receive analog channels with VBI data. VBI data such as closed-caption data/information is carried in the vertical interval (closed-caption is on line 21, scrambling data usually on line 10 thru 14).
Equipment: Device under test (DUT), CableCARD, Headend with analog channels and closed-caption EIA/CEA-608-C, Line 21 Data Services, TV monitor, Tektronix VM700 or equivalent, and remote control of the DUT.
Procedure:
Step#
Procedure
Pass/Fail
PICS
Power up the DUT and connect DTV or test monitor to NTSC output that carries closed-captioning. Turn on the closed-captioning feature on the DTV.
N/A
Insert a CableCARD
N/A
Setup a digital channel that is confirmed to have closed-caption data.
N/A
Tune the DUT to the digital channel and verify closed-caption data is displayed over the active video.
C-M
HSTDCC.1
Setup an NTSC channel that is confirmed to have closed-caption data.
N/A
Tune the DUT to the NTSC channel and verify closed-caption data is displayed over the active video.
C-M
HVBIPT.1
Connect the output of the DUT to the CVBS input of the VM700.
Ensure any other inputs on the VM700 are properly terminated with 75 ohm termination.
N/A
On the VM700, view waveform and select line 21, averaging off
N/A
Verify analog output timing on “Line 21 is within Waveform Timing”.
All waveform characteristics must fall within the timing tolerances as defined in the diagram, table, and accompanying notes in EIA 608 C.
This test verifies that the Host can render and display Analog closed captions.
Equipment: Device under test (DUT), an input NTSC channel with the closed captioning feature, and remote control of the DUT.
Procedure:
Step
Procedure
Pass/Fail
PICS
Setup the NTSC channel confirmed to have closed-caption data.
N/A
Using the DUT remote, enable the closed captioning feature.
N/A
Tune to the NTSC channel with closed captioning data.
N/A
Verify Closed Captioning is displayed on the display (for a set-top) or on the DUT itself (for terminal).
Note: For a set-top it is expected to observe rendered closed-captions on any digital video output (such as DVI/HDMI) or component video output when set to 480p, 720p or 1080i output. It is optional for a set-top to render closed-captions on any NTSC output (or 480i component video output) since VBI reinsertion is already required.
For a terminal it is expected that rendering always occurs.
