1、 CEA Bulletin Recommended Practice for DTV Receiver “Monitor“ Mode Capability CEA-CEB5-B R-2012 May 2007 NOTICE Consumer Electronics Association (CEA ) Standards, Bulletins and other technical publications are designed to serve the public interest through eliminating misunderstandings between manufa
2、cturers and purchasers, facilitating interchangeability and improvement of products, and assisting the purchaser in selecting and obtaining with minimum delay the proper product for his particular need. Existence of such Standards, Bulletins and other technical publications shall not in any respect
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5、wner, nor does it assume any obligation whatever to parties adopting the Standard, Bulletin or other technical publication. This document does not purport to address all safety problems associated with its use or all applicable regulatory requirements. It is the responsibility of the user of this do
6、cument to establish appropriate safety and health practices and to determine the applicability of regulatory limitations before its use. This document is copyrighted by the Consumer Electronics Association (CEA ) and may not be reproduced, in whole or part, without written permission. Federal copyri
7、ght law prohibits unauthorized reproduction of this document by any means. Organizations may obtain permission to reproduce a limited number of copies by entering into a license agreement. Requests to reproduce text, data, charts, figures or other material should be made to CEA. (Formulated under th
8、e cognizance of the CEA R4.8 DTV Interface Subcommittee.) Published by CONSUMER ELECTRONICS ASSOCIATION 2012 Technology Phone 202-872-9160; Fax 202-828-3131; Internet http:/www.atsc.org/. CEA Standards and Bulletins: Global Engineering Documents, World Headquarters, 15 Inverness Way East, Englewood,
9、 CO USA 80112-5776; Phone 800-854-7179; Fax 303-397-2740; Internet http:/; Email 1For CEA-CEB5-B purposes, a DTV receiver is defined as an ATSC compliant receiving device. 1 4 Assumptions The following assumptions are made concerning the “monitor mode”: a) A unique 2ATSC transport stream payload is
10、 serviced by the DTV receiver at a time. In principle, any RF channel can be monitored, and therefore this process is referred to as “setting the DTV receiver to monitor mode N” where N is the monitored RF channel number. 3b) ATSC A/65 requires a unique transport stream payload to carry a valid Prog
11、ram Association Table (PAT), Program Map Table (PMT), and PSIP information c) The DTV receiver relies on PSIP data to identify the virtual channels present in the transport stream. The channel map in PSIP may be a Terrestrial Virtual Channel Table (TVCT) or a Cable Virtual Channel Table (CVCT) and r
12、eceivers should be prepared to understand both. 4d) In monitor mode, there may be one or more virtual channels in the monitored transport stream and the DTV receiver may use software and on-screen menus to provide navigation and/or option selection for display or for other use. 5 Recommendations Bas
13、ed on these assumptions, the following recommendations are established to engineer DTV receivers capable of utilizing RF unidirectional interfacing. a) The channel mapping described by PSIP defines the use of virtual channels identified by their major and minor numbers. These numbers are, in general
14、, independent of the actual RF channel that carries the data payload. For this reason, digital televisions are not expected to offer direct tuning to an RF channel to viewers. In contrast, for monitor mode, direct tuning to an RF channel is necessary. Therefore, standard navigation and access device
15、s (such as remote control units, on-screen menus, or buttons on the DTV receiver) for DTV receivers should be engineered with special display controls that allow a viewer to select from one or more monitor modes. Monitor modes allow direct selection of an RF channel and a minor channel. Under normal
16、 operation, when a viewer selects monitor mode N, the DTV receiver tunes to RF channel N. DTV receivers and associated remote controls may select from more than one value of N. In cases where the DTV receiver and the source unit support more than one value of N, it is recommended that user guidance
17、be provided concerning selecting N. b) In monitor mode, the channel mapping, via the Virtual Channel Table (VCT), and its parameters may change completely at any given time. For example, these changes occur when a recorded segment in a digital VCR follows another segment with different channels and
18、programs. Accordingly, the Transport Stream Identifier (TSID) of the monitored transport stream also can change with different recording segments. In normal DTV operation the TSID for a given transport stream does not change; therefore, DTV receivers should be engineered to operate under variable co
19、nditions for the monitoring mode. c) In the VCT, some fields are no longer relevant for the operation of a DTV receiver in monitor mode. The fields that should be ignored include, but are not limited to the following: the carrier frequency, the modulation mode, the path-select field, and the out-of-
20、band field. d) In monitor mode, the major and minor numbers, as well as the short and extended channel names, may be used to provide navigation for services carried within the monitored transport stream. In the 2Unique means that there is no need to compose aggregated channel maps for devices connec
21、ted to the DTV unit since each unit is serviced one at time. 3A statement like “tune to channel 3 for VCR operation” is no longer valid in DTV. Instead, the concept of monitor mode N permits similar functionality. Future digital VCR manuals may carry a statement like “set your DTV to monitor mode 3
22、for VCR operation”. 4The most important difference is the location of audio and video packet identifiers (PIDs). For a TVCT, these are carried as part of the TVCT within the service_location_descriptor, while for a CVCT these are entries listed in the PMT. 2case of digital VCRs, major and minor chan
23、nel numbers also give reference to the original channels from which programs were recorded. e) All time-of-day clock references explicitly or implicitly 5defined in PSIP tables obtained from the currently monitored transport streams should be considered relative to decoded System Time Tables (STT) i
24、n that stream, rather than the local clock of the DTV receiver. Moreover, when the transport stream consists of a playback of recorded material, the currently monitored transport stream contains segments captured at different times; therefore, its time has discontinuities. The time in the playback s
25、tream is not expected to have an association with the local time-of-day clock. The time from a monitor mode N stream should never be used to alter a local time-of-day clock. f) The set of tables identified as EIT-0 give necessary program guide information about services found in the monitored transp
26、ort stream. Future Event Information Tables (EIT) (EIT-1 to EIT-127) are applicable only during a contiguous recorded segment. a) When navigating the transport stream in monitor mode, PSIP may identify programs that are not in the current transport stream. Accessing such channels is beyond the scope
27、 of CEA-CEB5-B. The TSID can be used to make this distinction. Virtual channels with channel_TSID values different than that indicated in the transport_stream_ID field of the VCT may be ignored. 5An explicit time reference in PSIP is, for example, the start time field for events in the EIT. An impli
28、cit time reference is the definition of the time segment for which an Event Information Table (EIT) is applicable. 3 CEA Document Improvement Proposal If in the review or use of this document a potential change is made evident for safety, health or technical reasons, please email your reason/rationale for the recommended change to standardsce.org. Consumer Electronics Association Technology & Standards Department 1919 S Eads Street, Arlington, VA 22202 FAX: (703) 907-7693 standardsce.org
