CEA-544-C-2010 Low Frequency Immunity of Tuners in a Cable System《电缆系统中调谐器的低频抗扰性》.pdf
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1、 CEA Standard Low Frequency Immunity of Tuners in a Cable System CEA-544-C R-2014 September 2014 NOTICE Consumer Electronics Association (CEA) Standards, Bulletins and other technical publications are designed to serve the public interest through eliminating misunderstandings between manufacturers a
2、nd 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 preclude
3、any member or nonmember of CEA from manufacturing or selling products not conforming to such Standards, Bulletins or other technical publications, nor shall the existence of such Standards, Bulletins and other technical publications preclude their voluntary use by those other than CEA members, wheth
4、er the standard is to be used either domestically or internationally. Standards, Bulletins and other technical publications are adopted by CEA in accordance with the American National Standards Institute (ANSI) patent policy. By such action, CEA does not assume any liability to any patent owner, nor
5、 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 document to
6、 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 copyright law pr
7、ohibits 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 the cognizan
8、ce of the CEA R4 Video Systems Committee.) Published by CONSUMER ELECTRONICS ASSOCIATION 2014 Technology & Standards Department www.CE.org All rights reserved CEA-544-C R-2014 i FOREWORD This standard was developed under the auspices of the Consumer Electronics Association (CEA) R4 Video Systems Com
9、mittee. Signals on cable systems below channel 2 may cause interference on broadcast receivers, especially on the low VHF channels. The return data channel signals for television cable and internet services using cable connection in the range of 5 to 42 MHz are generated by return devices such as in
10、-home internet modems, set top boxes and two-way cable ready television receivers, any of which may be in close proximity to television receivers tuned to low VHF channels. CEA-544-C references the levels to which the tuner should be immune in the 5 54 MHz range, and it describes a test method to de
11、termine the tuners immunity at those levels. CEA-544-C supersedes CEA-544-B. CEA-544-C R-2014 ii This page intentionally left blank. CEA-544-C R-2014 iii CONTENTS 1 Scope. 1 2 References 1 2.1 Regulatory References. 1 2.1.1 Regulatory Reference List . 1 2.1.2 Regulatory Reference Acquisition 1 3 Req
12、uirements . 1 4 Measurement Procedure for Immunity of TV Tuners to Harmonically Generated Interference 1 4.1 Objective 1 4.2 Measurement of Interference Immunity . 1 4.3 Procedure 2 4.3.1 Equipment List 2 4.3.2 Equipment Diagram 2 4.4 Measurement Procedure 2 4.5 Setup of Spectrum Analyzer 4 4.6 Repe
13、at at Other Operating Conditions . 4 Tables Table 1 Example of Typical Spectrum Analyzer Control Settings . 4 Figures Figure 1 Measurement Equipment Diagram . 2 CEA-544-C R-2014 iv This page intentionally left blank. CEA-544-C R-2014 1 Low Frequency Immunity of Tuners in a Cable System 1 Scope CEA-5
14、44-C defines the measurement procedures for the low frequency (5-54 MHz) immunity of tuners in a cable system, based on requirements in FCC regulations that define the assumed levels of the desired signal, low frequency interference and the required receiver immunity. These procedures define the spe
15、cific tests needed to determine compliance with the requirements. 2 References The following regulatory references contain provisions that, through reference in this text, constitute normative provisions of this standard. 2.1 Regulatory References 2.1.1 Regulatory Reference List FCC Regulations, 47
16、C.F.R. 76.605, Multichannel Video and Cable Television Service, Technical Standards FCC Regulations, 47 C.F.R. 15.123(c)(1), Labeling of Digital Cable Ready Products FCC Regulations, 47 C.F.R. 15.38, Incorporations by Reference 2.1.2 Regulatory Reference Acquisition FCC Regulations: FCC Regulations,
17、 http:/www.access.gpo.gov/nara/cfr/cfr-table-search.html 3 Requirements A television receiver or video cassette recorder (VCR) in the play-thru mode (i.e., output to the TV receiver on Ch 3/4) tuned to any channel, shall have an interference output at least 53 dB below the desired signal at the IF o
18、utput of the tuner within the 6 MHz IF bandwidth, which is typically 41 MHz to 47 MHz, when measured according to the procedure in CEA-544-B with signal levels as follows: a) Interfering carrier: 7 dBm (42 dBmV) 5 MHz 30 MHz 25 dBm (24 dBmV) 30 MHz 41 MHz 49 dBm (0 dBmV) 41 MHz 48 MHz 59 dBm (-10 dB
19、mV) 48 MHz 54 MHz NOTEThese levels were standardized here and subsequently used by Uni-Dir-PICS-I01-030903 which became codified by reference in FCC regulations. See 47 C.F.R. 15.123(c)(1) and 47 C.F.R 15.38. b) Desired TV visual carrier: -49 dBm (0dBmV) NOTEThis level is the minimum allowed by FCC
20、47 C.F.R. Part 76.605. 4 Measurement Procedure for Immunity of TV Tuners to Harmonically Generated Interference 4.1 Objective The objective of this measurement procedure is to determine the level of interfering signals that generate harmonics in the tuner or leak through the tuner, causing visible i
21、nterference in a nominal desired signal at the intermediate frequency (IF) output of a tuner under test. The interfering input signal is referenced to a 75 ohm load, and the tuner is then substituted for this load. 4.2 Measurement of Interference Immunity CEA-544-C R-2014 2 The sensitivity of the NT
22、SC spectrum to visible interferers is not flat. The highest sensitivity is near 0.5 MHz and again at 3.5 MHz relative to the video carrier. Sensitivity between these points is reduced by up to 15 dB. Thus, designing tests which hit these sensitive points is the most relevant. Cable systems have data
23、 signals from set-top boxes below 42 MHz. These signals can be as high as 60 dBmV to assure reliable data transfer to the head end. The mechanisms in receivers that create interference from signals below channel 2 include harmonic generation in a receivers tuner. For example, the second harmonic of
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